djm

The carb slides wear, letting more air escape around them and thus the high idle.  You can either get new slides, have your exsisting slides coated (as I recall Doo-Tint had his chromed to take up the clearance - I would probably use moly coating) or increase the size of your pilots to add fuel to make up for the air leaking around the slides.

I should add that it is really hard to clean pilot jets or even main jets without a jewelers ultra sound tank.  Often cheaper to just replace them.

Stock jetting (280 mains/37.5 pilots) should be penty rich with that sled/engine.  Had one of them back in the day and guess it is still sitting over in the storage garage.

We ran V-Force reeds in ours.. and  we typically ran 270 mains most of the time.    I would look at cleaning the carbs well and look for a possible air leak.

But sure easy on those sleds to change the main to a richer one and see what happens, or richen the pilot.  Do some plug chops with current jetting.

Too be honest, it is difficult to really clean main and or pilot jets and they get a film in them.. Jets are cheap, just screw some new ones of the same size in.

1. Who ported the cylinders?  
2. What carbs are you running?
3. What jetting and needles are you running and how are they shimmed and/or clipped?
4. Stock single 600HO pipe?
5. How much compression does the engine have in each cylinder cold and warm?


24 grams of pin weight pulling rapidly straight to 8100 with a 350lb finish force is a fair amount of horsepower.  If the clutch bushings are new and good as you state.. it might behoove you to go back and degree the engine and check actual timing initial setting and total advance to confirm that is where it is suppose to be.

Just rebuilt the engine last year and it only has 500 mi on it. Which spring between the pink/purple and the green/blue will have a higher engagement rpm? Or are they around the same? Do i need any special tools to take apart my clutches? Again thanks for the info guys!

"Your current spring is a 160/320 lb spring... purple purple part number 414817900 If you want more engagement speed you go to a 200/320 Green/Purple Part number 414762800 and it should cost about $28 at your local dealer. Or if you wanted even more engagement speed, you could go to the 230/320 lb spring, a pink/purple part number 414754200."

Each 10 lbs increase in clutch engagement force is about 100 rpm increase in engagement speed.  160 to 200 is about a 400 rpm increase, from 160 to 230 lbs is about a 700 rpm engagement increase.  Those are very approximate numbers.. but the trend is there.  The higher the engagement speed, the harder it is to hook the track up, the jerkier the sled will be.  Too me engagement speeds above 4200/4300 rpm are really a pain in the behind.  But all the younger generation seems want higher engagement.  I use engagement rpm that suits my purpose.. and if I am using high engagement to race my buddies,,,that spring doesn't stay in the sled.  And with some track conditions, it is amazing but the improved hook up you get with a lower engagement spring can be suprising.  I know a lot of 4 cycle guys use lower engagement springs due to the increased torque they have at lower rpms.  

Were I use and using the sled for general riding, I would only go to the Green Purple as TT suggested.  And yes, you should have a clutch puller and a spring compressor which can be nothing more then a thick threaded rod about 10 inches long with a couple of big washers on either end along with the nuts to compress the springs.   Some peeps use 1/2 inch threaded road, I think 5/8 inch works better.  Or even better buy the clutch tools from Chris at C&T Power Sports on here...

Chri's CT Power Sports - Clutch tools

There are some things to consider if you run a modified engine.

If it is not detonating, there is no need to mess with it.  If you are experiencing detonation, then mess with it.

When you run higher octane in a stock engine and change nothing else, you will have less power.  Probably nothing noticable, so the point is mute.  If you are drag racing and running higher octane than your engine is designed, you might lose a couple hundredths in a race.

Some are talking about modifying an engine to utilize the higher octane fuel.  Changing compression, changing timing, changing jetting changes everything.  Changing nothing and using higher octane is pointless unless you experience detonation.  Then use the minimum octane level to avoid detonation.

I don't run my stuff on the ragged edge for jetting, compression or timing, and stock motors are certainly a long way from the ragged edge.  I build my engines to run on 87 octane, and I run 91-93 in them to be safe like said.  I have no detonation issues.

I am spinning my trail engine 1000rpms higher than stock (8500-8800 range), changed port heights and piston size and have more issues with getting enough oil at those RPMs than anything else. That is another story.

I don't see regular, gas-station premium fuel being an issue with a stock engine and stock jetting.  Just my thoughts...but hey...if you want to spend the money and hassle of bringing race fuel along on the trail go for it.

I ride with a ton of guys with new sleds and they run gas station gas all day long, so do I and no fuel related issues.  Had water in the gas from a station in Houghton a few years back, but octane would not have made difference there.

We ride 200-250 miles most days, some days more.  That is about 20-30 gallons of fuel per day. If lake running at WOT, then maybe more. Most run about 2.5 gallons of race fuel to 8 gallons of 91 octane.  Using that formula, that means carrying 5-7 gallons of race gas with you (more is you ride more than 250 for the day) all the time. If you are talking 50/50, then you need to carry 10-15 gallons with you.  That means a tank full is going to run you about $70-80 per fill up.  That's more than my Tacoma...LOL

You would be better off buying octane booster, than trying to carry race fuel with you all the time.

At max, you would only need to raise the octane rating 1-2 points to be safe on a stock engine.  Something like Nulon Pro Strength Octane Booster – 500 ml treats 60 litres RRP: $20.95  It raises octane levels by almost 3 points.  It is a LOT cheaper than race fuel at what $10-12 gallons, now....not sure what it is in your area.

I carry a jug along just to make sure if out in the middle of nowhere then above ground barrels I throw some in.

Just some ideas.  As long as you aren't doing because you think it will make your sled faster either route will be good.
  
Not trying to ruffle an feathers, or upset anyone.

Maize, you just have to hit a few more Michigan UP out of the way stations and you will eventually find the one with low octane.  Not such a big deal anymore with the newer engines...with knock sensors and spark retard....

I say do what ever works for you.  Race gas is cheap in our area (was about $6.92 a gallon the last time I used it), cheaper then Octane aids... and most gas already has enough toulene in it which I suspect is the major ingrediant in the additives.