If you are someone who 'thinks' that since your sled has not burned down (which mine has not) that there is no problem with jetting, this thread might not be worth your time reading. For those who want to keep it from happening, or happening again, read on.

FINALLY got a bit of snow to try out my EGT guage and see just where I am at.

Stock engine with a Dynoport can. 390 mains, stock needle, middle clip, stock shim, 20 pilots, screws 1 3/4 out. Temp about 24 degrees on a sunny day.

These temps are rounded, but you can get an idea what is happening.

5000 - 1125/1000
5500 - 1200/1150
6000 - 1250/1205
6500 - 1320/1310
7000 - backed out of it & headed for the garage.

The top temp registered was 1370 taking it EASY!

390 mains, changed to the 06 needle, top clip position, stock shim PLUS .010, 20 pilots, 1 3/4 out on the screws.

5500 - 1025/1050
6000 - 1180/1175
6500 - 1250/1230
7000 - 1280/1300
7500 - 1360/1364
8000 - 1180/1200

Top temp registered was 1364. Still too high. Need some more time, but am headed in the right direction. Could I get the same results with the 08 needles and adding a shim? Maybe. Stock jetting SCARED me!

Top speed light snow on gravel road was 103 GPS. Not too shabby for a lil ol 500ss!

Where are your probes located? From my experiences, anything above 1300 is really flirting with problems

Probes are 4" from skirts. Yup, I don't want over 1275! I'm headed in the right direction though!

I think your going to high with your needle, go up alittle in your main, your lower rpms are getting to rich with the needle that high. If you switch to a richer needle, run it in the same position first to see what you get before moving it up. Good work though, sounds like your going to dial her in. Melted down a 99 600 at 1250 twice, it was ported though. You should run your sled at those higher temps, and pull your plug to check the color, dont realy on anyone elses numbers. Would hate to see you burn down.

The 06 needle is a richer needle. Raise the needle lowers the temp. Position 1 on the 06 is the same length as position 3 is on the o8 needle. Looks like 1 clip is .020. At WOT, I could try a 400 (bit richer) on the main. 1200 I could live with, but a richer main will drop the 8000 temps to probably 1100. I am on the rich side exceept 7000 - 7500, which the fuel should still be metered by the needle. Going to a .020 shim is going to richen the entire midrange, which I don't want to do. I might go back to stock needles with a shim and see what I get.

Went back to stock needle, but raised it 1 clip position. No shim (other than stock plastic one). Same 390 mains, 20 pilots.

5000 - 1050/1090
5500 - 1175/1206
6000 - 1207/1224
6500 - 1253/1260
7000 - 1299/1305
7500 - 13??
8000 - 1290/1292

Went back to 07 needle and raised it 1 clip. All else the same.

5000 - 1030/1080
5500 - 1135/1150
6000 - 1180/1200
6500 - 1235/1236
7000 - 1335/1337
7500 - 1254/1261
8000 - 1170/1191

So they say the main does not effect midrange? And the needle does not effect WOT????

Next step is go to 400 mains and see what happens at 6500 and up.

Also have been running BR9ES plugs. They are real clean....too clean!

Salt truck just went by. bummer....

thanks for all your work on this; keep us updated;

Learned a few things today.

1. Do NOT drop a shim in the carb.
2. Do NOT drop a screwdriver down into the bellypan.
3. The 07 needles are richer than the 08.


400 mains, 20 pilots, screws 1 3/4 out, 07 needles, middle clip, no shim on PTO side, .010 shim on mag side. BR9ES plugs.

5000 - 1110/1123
5500 - 1180/1189
6000 - 1177/1182
6500 - 1272/1260
7000 - 1319/1317
7500 - 1231/1238
8000 - 1220/1220

I'm scratching my head. Went richer on the mains, and the temps went up instead of down at wot???

Mains do effect the upper end of the midrange.

These 08 500ss are wicked lean at the 6500 -7000 range. I'm surprized they all have not burned down!

Tried the fuel screws at 1 1/2, and have a few seconds of hang. Need to open just a touch more and it is gone.

Hopefully more snow tonight and test tomorrow.

Pretty much where Ski-B said his was at.
http://www.dootalk.com/forums/index.php?sh...p;#entry2089575

The question remains: HOW do we get rid of a lean condition in the 6500-7000 rpm range without screwing up everywhere else????

I was afraid too when I saw these temp in the mid , after speaking with a lot of guy's it seem like they are all like that , 1300 to 1400 deg before the valves open , I think now that when the valves are in the low position they make a turbulence and some gas burn on the egt more than when they are open it flew more directly . Mine hit often 1300 deg at mid and it goes good, but i don't want to see that deg. at 8000 rpm . Maybe someone could explain better these are my tought

Now there is a thought! Just to see what happens, I'm going to play with the valves and see if the temp changes.

Have you tried puting br10ecs plugs in and trying it again, That is the plug they come stock with and it is a colder plug aswell. You never know it might help!!

Back when I first bought it, I went 1 clip richer on the needle and fouled plugs. I might give it another try, but right now I am dumping fuel into this engine. Guess my 21 mpg average is now history. I'll give it a whirl just to see.

I might even put the stock suitcase ....er....can back on and see if there is a difference.

Don't think this is happening yet with your full thottle EGT going up with a bigger jet but keep it in mind:

In 1989 I made my first trip to the mountains with my 84 Phazer and my first EGT gauge. I'm watching my gauge and trying to get the temp down, so I jet up and goes a little higher and jet a litlle bigger and it goes higher. The fuel was burning in the pipe.


By the book this is how the circuits should work in TM flatslides:

Wish I could post the picture of the TM fuel flow chart in relation to tuning components from my 4th edition of the "Sudco Mikuni Tuning Manual" this is what it says

Main Jet - 0 effect just below 3/4 throttle with full effect by full throttle

Jet Needle - 0 effect just below 1/4 - full effect by 5/8 - tapered down to 0 effect by 7/8 throttle opening

Needle Jet - 0 at 1/8 - full by 1/4 - 0 by 5/8 throttle opening

Throttle valve - 0 at 0 throttle opening - full effect by 1/8 - 0 by 3/8

Pilot system - Full effect at 0 throttle opening tapering to 0 by 1/4 throttle opening

Here is carb tuning from scratch in the book "Two-Stroke Performance Tuning" by A. Graham Bell, page 136

"When an engine has been extensively modified , I prefer to begin tuning with the main jet removed. If the engine will just run at part throttle, but floods as the throttle is opened, then the needle jet is large enough. However, if you find that the engine keeps going at three quarter to full throttle you can be be sure a larger needle jet is needed. Note this test should be done with the needle lowered to the No. 1 (lean) clip position.

This a real long process but later goes on to say : Once the correct needle and needle position has been determined , the bike should be tested at 3/4 to full throttle to find the right main jet size." It goes for another page two on fine tuning.

I have used these tuning procedures and jetting circuit digram on mikuni carbs for over 20 years. I used to put white tape on my handle
bar in back of throttle, with marks for 1/4, 1/2, 3/4 and full throttle, that with the EGT told me exactly the circuit to change using the circuit diagram.

On my mod TNT mtn sled I have the gauge below that indicates digitally in % throttle opening as I put the throttle position sensor from
the 800R carbs on my carbs.

The most rad carb tuning I ever did using this style of carb tuning was on a Phazer Mtn sled in the mid 90's. I put a 617 rotax in that I had ported and built a pipe from scratch for with 38 TMX carbs. Finished putting in at about 3 in the morning, slept a few hours got up and did about 10 dyno pulls from 9 to 11 AM to seat the rings and jetted the carbs. We left for the Big Horns around 12:30. It ran awesome in the mtns and was even with a very fast short track 670.

Hope this might give you some further clues to figure it out. I bought a pair of 07 9DGM15-58 needles last year and mapped them against my 08 TNT needles and as accurate as I could measure they were identical except for 3 clip positions on 07 compared to 5 on 08.

Good Luck

Throttle position is key to figuring out what circuit needs tuning, prior to having that gauge I wrapped the handle bar under the throttle with white tape and made marks on it for 1/4, 1/2, 3/4 and full throttle opening, also cut a index line on the throttle and filled with white paint so that at a glance I could look down and have a clue about what throttle opening I had and reference this to the EGT's I was seeing. I used this method for about 15 years and it works well.


If anybody wants to try this I went so far as to use tape to hold the throttle in a set position until I could measure the slide opening in the carb exactly with a snap gauge at 1/2, 1/4, 3/4 etc. Of course you want to have your carbs tuned for idle cable length adjusted perfect so you don't have to change it later on as it will screw up your reference marks on the handle bar, but a new piece of white tape is cheap, just a little work.

Good Luck

Another fudge factor in this engine may be that it is supposed to have a bunch more ignition advance than previous 500SS engines. The other MAJOR change is about a 4" long intake tract between the carbs an reed cage WITH a dogleg in it.

LRD - I read your post where you compared the 2 needles. I was going to do the same, BUT as soon as I put the 2 together I could see a BIG difference. Opened the calipers a bit and dropped the needles in, and the 07 was dropped down a lot lower (skinnier needle).

After putting all these numbers in a chart and comparing, I see some inconsistancy. Need multiple runs.

I made no changes on a run tonight, other than backing off on the valves. At 6000, my temps shot to 1280, and at 7000 was running 1290. Still too hot, but my plugs are looking richer now. Next step is add another .010 to the needles and see if I can get below 1250. Going up on the mains dropped the top rpm down a bit, but once I get rolling it will climb back up. Prior to the change, it went to 8000 and stayed there.

I need more snow on the road too!

I know there are some guys on here that know a whole lot more than I do about tuning. It would be nice for some insight as to what is going on here. I have been racking my brain on this!

So, when the exhaust valves open, the temps will rise. Let's assume the timing is a bit too advanced at the upper rpm range. IS it possible that this is why the temps are higher? maybe go to an 09 DPM unit? Higher octane fuel burns slower. Would running 92 in essence be like retarding the timing a bit??? How about the pipe? IF stinger outlet has an effect on the temps, what about going to an aftermarket pipe?

Heat range of the plugs do not determine the exhaust temp. The plugs are designed to disipate the heat FROM the plug to the cyl. head slower/faster. Too cold of a plug and the fuel/oil fouls it out. Too hot and it burns things up.

Another thought...By dumping more fuel to the motor, the oil should be richened up a bit too. Will need to figure out what ratio it's at.

ANYONE else got some ideas?????????????????? I'm tryin'!!!!

Some things I've learned over the past 30 years that theoretically should be true:

Higher Compression puts more heat into piston and head and less into exhaust for pipe tuning pressure waves (if you could catch it on a EGT detonation should lower exhaust temp at the time it happens as it blast away boundary layer of molecules protecting aluminum that melts at 1100 degrees or so from 3000 degrees or so combustion)

Advanced ignition timing should put more heat into piston and head, less in exhaust for pipe tuning pressure waves (Retarded just the opposite) High altitude can use more advance, low altitude opposite

The last happens because flame speed is lower at high altitude because of lower density combustion chamber charge (about 30% less from sea level to 10000 ft.

Tighter pipe stinger ID builds more heat in pipe and can build so much on a long pull on a lake or such to take down a piston

Higher octane should burn slower but all gas is different, found that out with race engines I built, at the dyno

When the exhaust valves open, power goes up, so should heat you'd think

Sadly we can't read piston domes on the XP without spending $250 to $350 on a bore scope. The piston domes would tell the tale. Have also heard the single ring pistons need to read lean as compared to a two ring piston at same jetting performance level. Single ring runs bunch hotter and same jetting won't wash as much in front of transfers. I am just finishing putting Wiseco 670HO two ring 78mm pistons in mine to make it a 629

On reading the plugs, go here and print in color and have laminated in plastic for tool box http://tsrsoftware.com/sparkplug.htm
Along with that go to Walgreens drug store and buy a small magnifier with a light in it for about $12, can never remember the name of them, same as what the doctor looks in your ears with. The tool allows you to see down into the spark plug to read it. When your EGT went up with bigger main should be able to read the plug to see if it got richer or leaner. Don't change gas or oil brands when trying to make comparative plug readings. Here is another webite on plugs, read all the links, not exactly what were looking for as its for 4 stroke drag cars but still some good info maybe on ignition advance and heat range of plugs http://www.dragstuff.com/techarticles/how-to-read-plugs.html The first link I gave by Tom Turner is the best on 2-stroke plug reading I have ever found. Have designed and built engines with his software for 20 years, awesome stuff.

Thanks! I have read all the posts and refer back to them. I guess what alarms me is these readings over 1250. Everyone is getting them, and why these engines are not burning down amazes me. Are we to accept the fact that 1300+ on the guage is normal for this engine?

I just made another change as I believe Ski-B recommended. 400 mains, 20 pilots, 07 needle clipped in the middle plus .020 shims. Now, each clip is .020, so I went to the 3rd clip (full rich) on the needles with no shims. Fired the sled up, and it was way rich on idle, and everytime I backed off and stopped, the sled would load up. and want to die. Under 6000 it blubbered bad! BUT, look where the midrange went.....

6000 - 1225/1231
6500 - 1287/1279
7000 - 1206/1207
7500 - 1150/1180

Don't know about 8000, but should be 1200 range. Next thought was what IF I dropped the main back to 390 in attempt to raise the temp on top end, and cut the pilot back to 17.5 in an attempt to clean up the low end? Feedback on this thought????


Went back to 400 main, 20 pilot, 07 needle middle clip with a .010 shim in mag side. Runs good, no blubbering, but back to 1300 at 6500-7000.

I forgot one other tuning problem with ALL doo reed engines, the goofy head design (tophat with near double width squish band). The head design is not a good thing and might also be part of the high temps. I believe it may prevent complete combustion at higher rpm. Flame front starts at spark plug travels horizontal towards cylinder wall but runs into vertical wall, at lower rpm piston dwells up at tdc for much longer time frame, perhaps long enough for complete combustion inside the bowl around the spark plug.

Old 670 hemi head and how all aftermarket heads are made have flat hemi bowl with narrow squish band. Flame starts at plug and just makes a small jog from bowl out to the cylinder wall, no vertical wall. It may be that the new head will run with higher egt's than old. Just guessing hear, do know my friends 800's have been scary high egt's for years.

My engine has a aftermarket head on it of the 670 style.

I guess on the jetting your going to have to try going with the jetting that it will run correctly with. You have to jet ultimately to the way it runs and spark plug readings/piston dome and then reference your egt's to what is working. Sometimes you have to ask yourself if I didn't have this dumb gauge and all I had to go on was plug readings and piston domes and how it ran (sound etc), what would I do? I have driven myself a little nuts in the past with gauges too.

When I first ran into the new Doo heads building a snowcross 700 engine I discussed it with Tom Turner (2-Stroke Racing Software) and he said only Kawasaki had ever tried it on their dirt bikes and nobody ever copied it because it didn't work.

Oh another problem is that 40 mm carbs are way more than a 105 to 120 hp engine needs. Amazing how well they work.

Good Luck

I have already thought about the guage driving me nuts. But on the other hand, if I was to burn it down, I would drive myself nuts wondering why it happened.

I'm planning a trip north this week, and will see what happens.

No trip this week. Storm coming tonight, so am going to keep messing with this thing.

400 mains, 07 needle clipped full rich, 20 pilots, 1 3/4 on the screw. Blubbered REALLY bad on low end, ran cool on top.

After looking at the numbers, I made another change tonight. I was curious as to IF it would load up at low rpm again. I'll get the numbers tomorrow after a run.

Back to 390 mains, 07 needle clipped full rich, 17.5 pilots, 1 1/2 on the screws. Fired it up, let it idle a bit, ran it on the stand up to 5000, then idle again. Hmmmm. Might have something here!

Stay tuned!

top position would be leaner. would it not? leading to higher temp in midrange. also what was the air density ? on different days air temp, barometric pressure and humidity must be taken in to account they all lead to different O2 levels in air.

3rd groove down on the 07 needle is full rich. I understand what you mean about the different conditions. I am not tuning a race sled. After seeing around 1350+ with stock jetting, I just can't accept that. I want to ride and have fun, not worry and wonder if/when the thing is going to burn down while I am in the middle of nowhere. Running those temps is asking for it. I also am not one to change jetting all the time. Happy medium suits me just fine. BRP has a problem with the jetting, and obviously has no intention to fix it.

I'm curious as to what percent are actually having a lean problem with the 500 ss motor. My wife and buddy have 06's with 7,500 miles and I have an 08 with 1,500 miles. Other than the hanging idle, none of us have had issues. Not that some aren't having problems, but all the people I have spoke with have had zero issues with this motor.
I understand your concern, but at some point just ride and have fun.

I would be curious too. I would also be curious as to what rpm range most people ride at, and those that have had a burndown, at what rpm range when it happened. How good is good enough? Depends on the person. ALL 500ss are lean. Some, such as myself, have not had any problems. I hope to keep it that way. Once I get settled with the jetting, this sled is the cat's meow!

Temps about 28. Got about 3" or so of new powder, so time for a couple of 10 mile runs down the back roads.

390 mains, 17.5 pilots, 07 needles clipped 3 position (full rich), 1 1/2 on the screws. The valves were backed off 2/3 turn on this run. BR9ES plugs.

5500 - 1200/1250
6000 - 1250/1280
6500 - 1283/1288
7000 - 1227/1230
7500 - 1215/1225
8000 - 1170/1180

NO hanging idle. The mag side seems to be a bit hotter, so I put a .010 shim in and also put the valves back full tight. Out for another spin.

5000 - 980/1017
5500 - 1170/1180
6000 - 1260/1267
6500 - 1281/1274
7000 - 1260/1260
7500 - 1247/1254
8000 - 1152/1157

After recording my readings, I then forgot about the guages, and just rode for a bit. Took it easy, played in the drifts, nailed it a few times up to 100, run about my normal trail speeds for a bit,.... The top temp that registered during this 10 mile run was 1292. My guess was it was in the 6000-6500 rpm range when the valves opened. Pulled the plugs when I hit the garage and they are light tan.

I am running a Dynoport can, and a Cudney clutch kit. With the kit, and my usual speed in the trails, I am in the 6000-7000 rpm range. The temps are still higher than I would like to see, BUT they are a WHOLE lot better than stock. I am sure my mpg will drop, but fuel is cheaper than parts and a ruined trip. For now, this is what I am sticking with. I might try backing off on the valves again. Bitter cold is forcast over the next few days, so I will see what happens then.

On another note, the sled felt dead in the 5500 - 5800 range. I didn't know if it was the clutching or jetting. The dead spot is gone now!

So basically for 28* and minor powder run your testing suggested going back to stock mains, stock pilots, stock fuel screw settings but bump the '07 needles full rich + 0.1 shim?

Did you run the stock '08 needles with this same setup? Just wondering if the '07 needles are really doing that much for you. Also it would be interesting to see how the sled runs with these settings in the 0*-10* temp range.

It has been quite a lot of work so far! Thanks for doing it and letting us know the outcome of all the different scenarios.

DaveW

You are correct. Thats a .010 shim, not .10. And ONLY shimmed on the mag side! AND, run the hotter plug! The 10s will foul in no time.

The stock needles are leaner yet than the 07 at the upper part of the midrange. I should have taken a pic of the 2 side by side, and you can really see the difference. The 07 needles are almost to a sharp point on the ends.... very fragile and easy to bend. From halfway up (thick part of the needle), they are almost the same. At the upper end of midrange, this thin part is the part of the needle that is metering fuel from the needle jet (tube in the middle of the carb leading to the main jet) I might try the 08 needles @ full rich. As of right now, I am pretty happy with this setup, and will know how it runs at 0 to -10 F or below this week. I expect the exhaust temps to rise a bit. Bottom line is, at stock jetting, with the way I ride, I would have no doubt cooked a motor. Only 800 miles on it so far, and now I am ready to ride.

IF you are running stock jetting, try going full rich on the needles instead of just 1 more clip. 1 clip just ain't enough guys! Don't forget the hotter plugs!

Keep in mind that I am running an aftermarket can, and that COULD make a difference. For those following this thread, looking for some help and answers, I will put the stock suitcase back on and see what I get. I am curious, and after going through this, might as well find out.

Ok, I opened the valves back up 2/3 turn, and put the suitcase muffler back on. Out for a spin, and it is getting colder out.

5000 - 1180/1200
5500 - 1165/1177
6000 - 1263/1275
6500 - 1260/1263
7000 - 1245/1249
7500 - 1215/1202
8000 - 1213/1227

Highest temp recorded was 1281. On gravel road, with packed snow, 105 on the GPS.

Just a hint of idle hang for about 5 sec, then drops right down. Open the screws just a tad should fix that.

NOW, I think I will run THIS setup for a bit! I hate dealing with those spring locations though. Seems to run just a bit cooler EGT with the stock muffler. Accelleration didn't feel as strong with the stocker, but top end sure didn't suffer.

With stock 08 needles, I would expect the temps to hit 1300 when the valves open.

Just to clarify, the RAVE caps have an adjustment in the middle. Stock is full in. I backed off from there. Less spring pressure allows the valves to open sooner/easier. Fully in, the pressure has to build higher to overcome the spring pressure and allow the valves to open.

I think I have more explanation to help first all brp are going this lean in the middle not only yours and it's related to the timming at this range of rpm , the timming at this range make the flame just going burning farther in the pipe so it was soo hot for egt at this rpm . i'm sure you can back to stock and don't worry about it , only ajust the main jet so you can achieve 1100-1150 deg

Fast Pat.....Going back to stock is not an option for me.

I am sure BRP engineers have put a lot of time into R&D, and maybe in order to meet emission standards have decided to lean these things out. No matter what BRP says, a 2 stroke will not survive very long running these 1350 temps. I know, it's my opinion, and who am I to say? The number of blown motors reported on this site dwarfs the amount worldwide I am sure.

BRP thought 2 rear wheels were enough. They aren't.
BRP thought no adjustment was necessary on the secondary. It is.
BRP thought no additional support was needed on the tower. It is.
BRP thought the jetting was good. It isn't!

Warrantees are good, but what about when they run out? Who pays? Who has to deal with a dead sled 300 miles from the truck, warranty or not? Who has to deal with the incurred expenses of a trip and no sled to ride? Not BRP!

Where I see a problem, I will adress it, because it will be ME that has to deal with the consequences. I ride for FUN, and being miles from the truck with a broken sled is NOT fun. Being At the truck with a broken sled while your buddies go riding is not having fun. Been there.

I have shown the figures from my tests. There have been others who have reported their test results. What anyone does with this info is up to them. How many more threads will there be about blown 500ss before the light comes on? I'm ridin'.

They also thought moly filled rings would work with nik-a-sil cylinder walls!!!

I think the temps are at least acceptable now. Sooooo, I been wondering about the piston wash. Put a bore scope down for a lookie see.

Mag side looked just like the pics of proper wash! PTO side was washed about 1/4" back in the port areas....more than the mag side anyway. So I figure that means the PTO side is running a bit richer. The egt verifies this.

QUESTION!!! How long does it take for the piston wash to change after an adjustment??? If I go leaner, it has to take time for the carbon to build on the washed areas, yes???

As for plug readings....with the magnifying glass.... Dark brown - A tad on the rich side.

I have not ridden the sled in this sub zero weather yet. Been waiting to check the wash. MAybe in the morning, and am also going to turn the carb heater on ot see if it changes things.

Why are your carb heaters off?

Never had a sled before with them. I thought it was for high humidity and cold temps, like when a carb ices. Dealer said leave them off unless I had a problem, and never turned them on. Some guys are disconnecting.

So after all your work give us your final set up. ,,,,But check your MPG too. I have done alot of testing with this motor last year. The stock setup with scews out to 1 3\4 and running the br10es was the safe set up. Thanks again for your info the test looks great. I have 3500 miles last year and I ride or as we are called....WE RIDE!!!!!!!

I'll post my final settings. Heading north next week for a few days, and will have some solid info as to how it performed on the trail. I try to ride 225-300 mi. a day.

There has been a lot of guesswork from a lot of people as to the jetting on the 08 500ss. Most agree that they are lean in the midrange. There is still a lot of confusion and opinions as to where and how much, and people are STILL burning them down. Running temps nearing 1380 is just waiting for the problem to arrive and bite you. I wanted facts on the 08, and hopefully this setup works. I expect my milage to drop from the 21 mpg average that I was getting. I would rather burn more a bit more fuel riding than being parked on the side of the trail looking at a dead sled.

Thought I would take a quick ride in this arctic air and see how it runs. Temps about 0, with wind chill running 20-30 below.

Fired it up and let it idle for a couple minutes to warm up.

5500 - 1135/1166
6000 - 1225/1240
6500 - 1265/1272
7000 - 1288/1292 (end of half mile)
7500 - 1222/1207
8000 - 1276/1270

Carb heaters were on. Temps are noticably higher with this crisp thin air as expected.

That's about where mine are at too on the 662 motor. I know its a safer setup and probably a little richer than it could be but it works.

I'm going to keep an eye on things. Better safe than sorry, 'eh?

yes. Gas is a lot cheaper than aluminum(pistons) and brass(jets) even at $4/gallon..Sometimes it gets a little lost on people, but think about the scenarios that can happen, especially with the cold temps we are seeing this year. Your out at night (-20F or colder), small group and 1 sled goes down. Now you either leave the sled or tow it, well the guy on the sled getting towed is gonna get pretty cold quickly. Also, other stuff always happens and murphy's law kicks in. Bad stuff can happen quickly and BRP aint out there to take care of you with a warranty when its -20 or -30F.

Ok boys, here is where I am at with this 'project'.

Temps are still on the cold single digit side, but with a fresh powder snowfall I had to take a run. I ran the snow covered road for my temp readings.
The mag side is consistantly hotter and very little wash, so I went with an addl .010 shim. SO, this is MY jetting for the 08 500ss...

390 mains, 17.5 pilot, screws at 1 1/2 (plus just a hair more) out, 07 needle clipped in 3rd groove. STOCK NYLON SPACER stays! This is NOT a shim! No additional shim on PTO side, .020 added on the mag side. Stock can, RAVE valves backed off 2/3 turn. BR9ES plugs. Carb heaters were on.

5000 - 1100/1134
5500 - 1144/1161
6000 - 1234/1240
6500 - 1265/1265
7000 - 1238/1245
7500 - 1191/1193
8000 - did not record

I hit the gas station and filled up with 91 just to see how it ran, then went play riding. Some trails, some riding in 20" of powder, and some roads. I wanted to just RIDE! Hit a long straight and held it at 7000 wondering where the temps would settle. 1234/1236. Overall riding I had a highest reading of 1279/1278 in the 6500 range. Hit the garaage and checked piston wash and plugs. These settings I believe are safe! HOWEVER, at 6500 this is STILL on the lean side, so I won't be running the lake for no mile at this rpm. WOT is fine.

I will be checking my milage, but bottom line is "it is what it is". DO I like the idea of running richer than stock, NO, but I do NOT want to burn down, and a bulletproof sled is what I am after. IF gas was all I was worried about, I wouldn't be using a truck that gets 12 mpg to tow a trailer 300 mi to ride around in the woods on a snowmobile that I nail the throttle on every chance I get. I'd still be riding my 68 Super Olympic.


Anyone else try this, post your results.

For those following this thread and interested, I have some more results. Put over 100 mi the trails this afternoon. Temps outside were around 5* F or so.

These were peak temps for long pulls. Casual riding in the trail, on/off the throttle, temps were much lower.

Up to 6000 - 1270/1272
6500 - 1287/1287
7000 - 1260/1263

These are using my latest specs. Sled ran GREAT! Pulled the plugs for a look, and they were a bit on the dark side. Maybe I could lean it out some. SO, I dropped the needles .010 each side, and back out for a run. I didn't get out of the parking lot, and the sled felt lithargic. Hanging idle returned too. Rode about 1/2 mile. It didn't feel right. Temps were running noticably higher, and couldn't believe that a .010 difference I could actually feel. Hmmmmm. Did I screw something up? Back to the truck for a look, found nothing, and I put that .010 back in both sides. Back on the trail for one last 30 mile spin tonight. Sled ran GREAT!!! Highest temp for my ride tonight ( LOTS of 5000 - 6500 rpm ) was 1294.

Stopped into 2 dealers today for some questions for the boys in the back. Both said the 500ss are reeeeeal lean, and also agreed temps below 1300 is SAFE. Cross into 1300+ and who knows what you will get in a long run. So I am ok with my temps, and wash. I just wish my plugs were a bit cleaner. I think running BR8ES plugs would take care of it, but I don't have the guts to try.

Now for the bad news. Stock jetting got me an avg 21 mpg. Today, (and I was running it hard) I managed about 13 mpg. BUMMER!

hey gadget, not to be off topic but could you post a couple of pics of your egt's mounted on your sled for us.

Here is a thread on snowwest on filing the needles to fix lean spots

http://www.snowest.com/forum/showthread.ph...d=1#post1187750

Good Luck


Best instructions on thread:

"Mark your throttle where you want to richen it (in the field).

Back at the shop, pull the carbs off (throttle cable still attached). Tape the throttle at the correct spot and mark the needles from the front (outlet), right where they exit the needle jet (not the hood on the back of the needle jet)

Pull the needles, and just file a very small flat (works fine and more acurate) below that mark. Doesnt take much.

Use to do it lots when tuning hot 2-stroke ice racing bikes where you need to use the midrange to control the slide. Did it to my 800 Doos to make them live too.

Geo"

Will do tomorrow when I get back home.

I wondered about how to do that LRD. Good link!

Did another 220 miles today, and even put the Dynoport can back on. Wondered where the temps would go. I ran a lot of senarios (sp?). Putted around like grandma at 5000, 5500, 6000 rpm. Went nuts like Grandpa ( I am one) for a few miles of 7000-8000. A whole BUNCH of miles corner to corner at 5000 - 7000. Each time I gassed up, I checked the highest temp recorded. 1303 was max. Plugs are a dark tan. MPG varied...12.9,10.9,13.5, 12.3, 11.6. One of the best ones was when I was chasin' a couple of AC 1100 Turbos. Them boat anchors haul pretty good!

An observation. Cruise at 6000 for short spurts on the trail like 1/4 mile or so - temps look good....1245*...but keep holding it steady, keep going for maybe another 1/4 mile, and watch them temps climb to 1300. I can run at any rpm all day, but not 6000. Run at over 6000, it's good, but back off to 6000 the temps shoot up FAST. Run below 6000 then increase to 6000, temps take a while to climb. So if I'm just a gittin' it and decide to back off, I just don't back off and hold it at 6000.

I have a 08 500 SS trail with ~1000 miles on it. My last outing it started idle hanging and spark knocking bad at low RPM. I was contemplating adjusting the ignition timing, although I had no luck finding any info on timing adjustment.
This is when I can across your post, THANKS ALOT. I could only imagine the exhaust temps if I retarded the timing.
Im going to try your recommendations this weekend, hopefully everything goes well

again Thanks
Dave

As requested, here is a pic of EGT guage location.

Probes are mounted 4" from the piston.

Got back today from the North. Went for 1 more 70 mile spin this morning. Flat trails all to myself. It felt real warm at 21*. Found out last night it was -22 Tues morning. It made a diff EGT readings and I understand why. Today, at 6000 rpm for as long as I could maintain it in the trail, temps held at 1254. I tried everything to get them to peak at the 1300 like yesterday. Even put 87 fuel back in. Turned off the carb heaters. Tried higher rpm.... tried lower rpm, rode slow....rode fast.... Peak temps were 1285. Right where I want to be.

Then, found a powerline. Put it at 6000 and held it for over 1 mile. It hit 1297. That's what it took to almost hit 1300.

In all this, I found what I believe to be the best jetting for reliability. I wish my mpg was what I had, but in -22* the sled ran great. In 22*, the sled ran great. Over 400 miles in the past 1 1/2 days cruising the woods, WOT down the powerlines & railroad grades. Sled ran flawless!