Craigslist Ad says, it's suppose to be a 1971 - 72 Ski-Doo Rotax 335 Cylinder, or is it a 340 TNT Cylinder? It looks to have better Porting than some 335 Cylinders I have seen.
AgreeI think it's a 335. The T'NT didn't have a decompressor port.
Well leave and start your own thread then, we sure don't need your Negativity here after only 5 post! Some of us here are maybe interested in what can be done to our old Standard 18hp/20hp@5500rpms 335's to make them make more HP, and still be reliable for trail riding.This is getting really Old
Intake ports are pretty close - TNT just a little lower. My stock set measuresIt would be interesting to over lay the 335 and 340 TNT Intake Ports
What is the difference in the Standard 335 Intake Port vs the 340 TNT Intake Port? Anyone got the Spec's of both handy? I believe it was said the Port to be 3mm Higher. How much Wider? These Spec's are only to show 3mm Higher and 3mm Wider would look like. Not actual Port dimensions.-
Thanks for the Info!Intake ports are pretty close - TNT just a little lower. My stock set measures
Top of intake......TNT - 76mm......335 - 76mm from top of cylinder
Bottom of intake...TNT - 105mm.... 335 - 102.5mm from top of cylinder
Total height....TNT - 29 mm .... 335 - 26.5mm
Port Width......TNT - 47mm .... 335 - 47mm
Total window area ..... TNT - 29x47 = 1363 sq mm or 41+ mm circle
Total window area ..... 335 - 26.5x47 = 1246 sq mm or 39+ mm circle
So on the 335 you could bore all the way to a 38 with the right adaptor for even more oomph without over running the internal port window.
The lip would get kinda small top and bottom for sealing. But you could also rectangle the port like the intake on the 247 (or even oval it) for more width 38x36.
That would help with getting all the air you can use.
Goose bought out Spaulding- looks like he is still selling Spaulding's mufflers
http://reproductionvintageparts.com/dir/index.php?id_category=58&controller=category
It's called Progression of a threads Subject, no matter which Cylinder it was above, 335/340 TNT, I wanted to start a thread about Porting/Improving these 335 or 340 TNT Cylinders. Since I now have Both 335/340 TNT Engines, and a few other 247, 277, 299, Singles that all of this Info/Improvements can be applied to them also. With some of my threads now having 10,000+ Views, I would say some people Doo have an Interest in what I'm talking about also, and trying to do. Since very few People really Race these Old or New Sleds today, most are more into Trail Riding and racing their buddies than all out Racing. My interest is wide for these Old Engines, Sleds, Ultralights, Go Karts, etc.Your rite! My Negativity here after only 5 post! Wow what was i thinking?
How do you go from asking (1971 - 72 Ski-Doo Rotax 335 or 340 TNT Cylinder)
To this??????
335cc if 100% efficient at 5500rpms = 65cfm = 32mm Carb Needed.
335cc if 100% efficient at 6500rpms = 77cfm = 34mm Carb Needed. Max Size Standard Cylinder can take.
335cc if 100% efficient at 7000rpms = 83cfm = 36mm Carb Needed. Standard 335 Cylinder would need Bored for bigger 36mm Carb.
Standard 335 rated @ 5500rpms!
8.0cr = 18hp@5500rpms
9.0cr = 20hp@5500rpms
Using the 1.0cr Bump = 2hp or .5cr = 1hp rule of thumb!
9.5cr = 21hp
10.0cr = 22hp
10.5cr = 23hp
11.0cr = 24hp
11.5cr = 25hp <----- Probably Max CR for Pump 91 Octane.
--------------------
12.0cr = 26hp
12.5cr = 27hp
13.0cr = 28hp
13.5cr = 29hp
14.0cr = 30hp
Ski-Doo 1970: 335 32mm vs TNT 340 38mm.
Olympique 12/3 HR-37A 1.1875" = 30.1625mm
Olympique 335-335E HR-17C 1.28125" = 32.54375mm
Olympique 399 HR-16B 1.28125" = 32.54375mm
Nordic 399-399E HR-40A 1.28125" = 32.54375mm
Nordic 640 HD-20A 1.5" = 38.1mm
T'NT 640/775 HD-20A 1.5" = 38.1mm
Blizzard 636/776 HD-20A 1.5" = 38.1mm
T'NT 399 HD-21A 1.5" = 38.1mm
T'NT 292/340 HD-22A 1.5" = 38.1mm
Blizzard 292/340 HD-22A 1.5" = 38.1mm
Blizzard 436 HR-77A 1.28125" = 32.54375mm
Nordic Rotax 640/2 HD-20B 1.5" = 38.1mm
TNT Rotax 640/2 HD-20B 1.5" = 38.1mm
TNT Rotax 775/3 HD-20B 1.5" = 38.1mm
TNT Rotax 440/2 HD-2lB 1.5" = 38.1mm
Ski-Doo 1971: 335 32mm vs TNT 340 38mm.
Olympique 300 HR-74A 1.28125" = 32.54375mm
Olympique 335-335E HR-75A 1.28125" = 32.54375mm
Olympique 399-399E HR-76A 1.28125" = 32.54375mm
Nordic 399-399E HR-40A 1.28125" = 32.54375mm
Valmont 399R-399ER HR-40A 1.28125" = 32.54375mm
Nordic 640 HD-20B 1.5" = 38.1mm
T'NT 640-775 HD-20B 1.5" = 38.1mm
Alpine 640ER HD-20B 1.5" = 38.1mm
T'NT 440 HD-73A 1.5" = 38.1mm
TNT 292/340 HD-22B 1.5" = 38.1mm
Elan 250-200E HR-73A 1.1875" = 30.1625mm
Alpine 399R-399 ER HR-16B 1.28125" = 32.54375mm
Nordic,Valmont, Rotax 434/2 HR-1l2A 1.28125" = 32.54375mm
Alpine Rotax 434/2 HR-1l2A 1.28125" = 32.54375mm
Valmont Rotax 640/2 HD-66A 1.5" = 38.1mm
Blizzard (racing) Rotax 440/2 HD-72A 1.5" = 38.1mm
Blizzard (racing) Rotax 797 & 645/3 HD-72A 1.5" = 38.1mm
TNT Rotax 435/2 HD-73A 1.5" = 38.1mm
Nordic, Valmont, Alpine Rotax 640/2 HD-8lA 1.5" = 38.1mm
:blink_old:
I have yet to see anywhere on any of your prior post where you have done any mods with evidence that your speculations work! After all Your making a pretty bold statement when your saying: Some of us here are maybe interested in what can be done to our old Standard 18hp/20hp@5500rpms 335's to make them make more HP, and still be reliable for trail riding.
So! Please tell us what works and what doesn't. I want more power and i want it still reliable and a guarantee what you tell me will give me both!
Never had the luxury of a mill - not sure how hard it would be to actually use on portsOk, so 340 TNT Intake 29mm x 47mm vs 335 Intake 26.5mm x 47mm.
So the 335 Intake Port could be opened to match the 340 TNT Intake Port. I don't have much experience in 2 Stroke Porting, I used to Port my Chevy Big & Small blocks and put in Bigger Valves, but for a Hot Trail Sled I don't think we need to get to Crazy. Just Opening to the Stock 340 TNT Intake Spec's I can see would Help. The Exhaust probably needs some work also. If People can see where the Intake needs opened they can duplicate it. I machined parts on a Drill Press before I got my Mill taking light cuts. 29mm - 26.5mm = 2.5mm or 0.0984249" isn't much.
Yeah but you are forgetting about the "Quick Gulp" effect.Ok, so 340 TNT Intake 29mm x 47mm vs 335 Intake 26.5mm x 47mm. Personally, 6500rpms and a 34mm Carb is high enough for me for a 335, but some People might want 7000rpms which needs at least a 36mm Carb. A 38mm(96cfm) should work up to 8000Rpm
I first used the old Electric Dremel Tool at first doing a set of Chevy 327 2.02In 1.60 Ex Heads that took forever, but I soon went to Air Grinders and Chevy Big Blocks, 396/402, 427, then 454's. Air Die Grinders $20 to $100, come in different Shapes, Lengths and Angles with Carbide Bits. For these light Intake Machining cuts you can use a cheap Drill Press, and they make a Cheap small X & Y Milling Vice for them. Today, you have many Cheap Mini Mills and Mini Lathes that can handle these jobs also, some are even CNC. You also have a lot of fancy used Manual/CNC equipment to pick from today that start out at $600+ if you have the room for them, but most use 220 3 phase. I can't get that at my house last time I checked. I do have a 3 Phase Industrial Variable Speed Drill Press that use's a Phase converter to run it on 220 1 Phase. I don't have the room to use a Big CNC Mill like I want. My Grizzly G1007 Mill with Power Feed I bought New almost 20 years ago for $1400 and my Grizzly 12" x 37" Lathe New was like $2800. They haven't went up much in Price. With Hand Tools, it's hard to keep it straight and level, whereas a Mill makes it straight. With CNC you could Program it to follow a Contour. With the right Fixture this would be an easy task. You spend more Time setting up the Machine than actually Maching it. With Free CAD/CAM Software today and Cheap CNC Machines, you open a lot of things that could be done right at home that you can't do by hand. Even these Small Cheap CNC Routers out today can do light Machining.Never had the luxury of a mill - not sure how hard it would be to actually use on ports
I don't know if you have any porting tools left over from your Chevy days, but for the rest of us I recommend this.
https://www.sciplus.com/p/VARIABLE-SPEED-FLEX-SHAFT-GRINDER_43486
There are others like it for around the same price. But I know this one mates up with any std Foredom type hand-piece. Others might too.
Have had mine for a number of years with no issues. Foot control is really great when doing porting. Compared to std Dremel or air grinder life is much easier.
Hand tool that comes with it is good for 90% of what needs to be done. I bought 45 and a 90 degree hand-pieces for getting inside the cylinder for transfers etc
A Shorter Intake Tract would help some. Aaen, said a Good Flat Side Carb was as close to Fuel Injection as you can get. There are cheap New 34mm Flat Sides on eBay. It would have been nice to Dyno one of these 335's with the Stock 32mm and a 34mm Carbs with Stock Intake Port and then make the Mod to the TNT Intake Port Spec's, since they felt the difference in the seat of there pants just going from a 32mm to 34mm Carb. Yes, changing the bottom end, Piston Skirt is on the list of things that I want to discuss on what can be done, 1st Intake Port, 2nd Exhaust Port, 3rd Transfers, 4th Piston, then 5th discuss a Tuned Pipe once all these Mods that can be done to Improve it. I personally 6th, would like to even do an EFI Mod.Yeah but you are forgetting about the "Quick Gulp" effect.
The "Peak Airflow" calculator works well for a 4 stroke.
But, as Jennings said in his book.
"Selecting carburetor throat size is enormously difficult: The four-stroke engine's carburetor may be chosen through relatively uncomplicated consideration of cylinder displacement and operating speed, but in the two-stroke engine's case there is an added difficulty introduced by the quick-gulp intake characteristic and by the overriding importance of pulsations in the intake tract.
Engines with smallish intake ports and relatively long intake periods respond best to small carburetors; those having very wide, low intake ports will have shorter intake periods to provide the same specific time-area value and need a bigger carburetor-throat size if throttling is to be avoided. "
The 335 does have a relatively short and wide port with a short duration. That 34mm carb will only flow around half the cubic feet you are thinking.
34mm good enough for 6500RPM? Maybe, maybe not. Dropping the floor of the port or raising the piston skirt to increase duration would help.
I always used 36 or 38, preferred primer type. BUT Tilly HD conversion with adaptor was easier - less screwing around with fuel pump and float levels to get it right with vibration of big single.
Well Skidoo118, I and most of the rest of us here, and New Members to Sledding, aren't as Smart as You, and since We, only have your Word that You have even done any of this, No Photo's, No How To Threads, Not really much Helpful Info at all from You at all, once you take out all your 95% Negative Attitude Post remarks, already #2 out of 15 post in just this thread! There is always multiple ways to accomplish any Task. You could even hand file these Ports if you can't afford a $20 Die Grinder or have an Air compressor. You do have the option to use Electric tools. You make many Bold statements like "This (A 1.0cr bump equals about 2hp on Average) Not without including other factors!" but with NO FACTS, just your same old BS! But We do have FACTS right from Skidoo that was given on the 335 18hp@5500rpms with 8.0cr with a Muffler to 335 20hp@5500rpms with 9.0cr with a Muffler, that equals 2hp for a 1.0cr Bump!Your quote"
(What have we learned in just a few short weeks, hmmm.
Carb Sizes used on many of these Old Engines.
CFM needed at different rpms used.
335/340 TNT Intake Port Sizes used.
A 1.0cr bump equals about 2hp on Average.
HA Heads are about 3.0cr higher than Standard heads.
Most of these old pipes are just Mufflers, not really Tuned Pipes.
How to CC Heads.
etc
.I think you should have said what i have learned in a few short weeks!
I have known this info for years except, This (A 1.0cr bump equals about 2hp on Average) Not without including other factors!
Once again you say" (I try to show what can be done for as little of money as possible.)
Your really not showing anything more than what you think will work! Show us some real work that you have done that proves all that your claiming.
Take your stock 342cc t'Nt engine and show us what it has stock than show us with some of your coatings what it has! than i would like to see a hand built pipe you made with one of your programs on the 342 and compare that to stock. Port the engine to run a larger carb and compare it to the stock carb..
You have quite an audience here so show us what you can do.
The little 342 single in my profile image has been ported, piped, geared,clutched. tuned, tweaked and is std bore has not had the head shaved has points ign and runs the tilly hd carb and will run with any stock 340 twin in the same vintage and will likely out run them and i weigh 230 lbs. This was built by me in my barn all by my own hands. Never over heats,No Detonation,no special coatings. I changed the piston once in 8 years and the crank brgs once this 342 has had the snot beat out of it at over 8200 rpm.
If you would think for a minute i would try and explain to some one on here or else where how to make their engine work like this guess again. One mistake on their part and all of a sudden your the bad guy for giving them bad advice because their engine did not perform like it was said too.
So when you keep blowing off at the mouth about what works you really need to show step by step a to z what works and why! Not just a bunch of quotes, graphs, and endless CR!
Or maybe you should Keep quiet!
The end bye-bye!
Neither - 2159 is for the 73-74 340 TNT TWINHis response back to Unit Cost. Now is this 2159 Piston he talks about the same as original 340 TNT or is it just a 335?
======================================================================================
You saidI first used the old Electric Dremel Tool at first doing a set of Chevy 327 2.02In 1.60 Ex Heads that took forever, but I soon went to Air Grinders and Chevy Big Blocks, 396/402, 427, then 454's. Air Die Grinders $20 to $100, come in different Shapes, Lengths and Angles with Carbide Bits. For these light Intake Machining cuts you can use a cheap Drill Press, and they make a Cheap small X & Y Milling Vice for them. Today, you have many Cheap Mini Mills and Mini Lathes that can handle these jobs also, some are even CNC. You also have a lot of fancy used Manual/CNC equipment to pick from today that start out at $600+ if you have the room for them, but most use 220 3 phase. I can't get that at my house last time I checked. I do have a 3 Phase Industrial Variable Speed Drill Press that use's a Phase converter to run it on 220 1 Phase. I don't have the room to use a Big CNC Mill like I want. My Grizzly G1007 Mill with Power Feed I bought New almost 20 years ago for $1400 and my Grizzly 12" x 37" Lathe New was like $2800. They haven't went up much in Price. With Hand Tools, it's hard to keep it straight and level, whereas a Mill makes it straight. With CNC you could Program it to follow a Contour. With the right Fixture this would be an easy task. You spend more Time setting up the Machine than actually Maching it. With Free CAD/CAM Software today and Cheap CNC Machines, you open a lot of things that could be done right at home that you can't do by hand. Even these Small Cheap CNC Routers out today can do light Machining.
My Mill being converted to CNC. You can buy all the parts off eBay today, about $1,500 each to CNC the Mill & Lathe, if you shop around. You may have to Design your Motor Brackets depending on what Model you choose.
Things you could make, your own Billet Heads, Case's, Machine your own Stock Heads for different CR's. Machine your Case's for Bigger Cylinders, Bore your Cylinders, turn your own Cranks, make Head Inserts, etc.
If you are sticking with the 34mm carb there is very little to do port wise.A Shorter Intake Tract would help some. Aaen, said a Good Flat Side Carb was as close to Fuel Injection as you can get. There are cheap New 34mm Flat Sides on eBay. It would have been nice to Dyno one of these 335's with the Stock 32mm and a 34mm Carbs with Stock Intake Port and then make the Mod to the TNT Intake Port Spec's, since they felt the difference in the seat of there pants just going from a 32mm to 34mm Carb. Yes, changing the bottom end, Piston Skirt is on the list of things that I want to discuss on what can be done, 1st Intake Port, 2nd Exhaust Port, 3rd Transfers, 4th Piston, then 5th discuss a Tuned Pipe once all these Mods that can be done to Improve it. I personally 6th, would like to even do an EFI Mod.
34mm Flat Side $30 on eBay.
Ok Thanks. They did lower their Price and minimum Quantity you had to Order for a Custom Piston. I think years ago when I was looking for that 583/617 79.4mm Big Bore Piston you had to order then 25 Pistons minimum and they were like $185 each.Neither - 2159 is for the 73-74 340 TNT TWIN
335/ 340 single was low dome part number 2142P8
Never made a high dome TNT piston - you would have to send them a OEM sample for them to copy
I just got a email notice a box is being delivered, hope it's my 335 Cylinder & Piston I ordered. Got the whole house re carpeted yesterday to keep Honey Doo happy, so I'm wore out from moving stuff. I'll try later today to get it cleaned up and take some Measurements & Photo's. Supposed to be a Piston with it also that looked good in the Photo's.You said
"Every body has different Incomes and Talents on what they can do, Welding, Painting, Machining, Fabricating, etc. I try to show what can be done for as little of money as possible."
For 99.9% of the people in the world riding sleds - investing in a mill set-up is complete overkill. So is investing in a lathe etc.
===> Yes, if your just doing (1-2) projects. A Tool, any Tool, usually Pays for itself almost the first Job you use it for, even expensive Tools like a Mill and Lathe which can be used to make almost anything you can dream up. <====
Aaen and others will port a cylinder for $250 or less.
====> Yep, but at just $250 each to Port them. Let me see now, I have alone one 247(1 Cylinder), three 277(3 Cylinders), one 299(1 Cylinder), four 335(4 Cylinders), one 340 TNT(1 Cylinder), probably 3 spare Cylinders alone, that's 13 Cylinders @ $250 each, equals $3,250 alone for just these Old Singles. Then through in all the Twin Cylinder Engines and probably some spare Cylinders, probably another 16-22 Cylinders. With the right Lathe Jig, that lathe can Bore your own Cylinders @$65 each today just these Cylinders say 30 Cylinders could cost you $65x30 = $1950. Factor in Head Machining Average $100 each, that's another $2000+, Case Machining, and then Custom Billet Parts you could make also, so even those expensive Tools Pay for themselves pretty quick. There's used small/large CNC mills on Craigslist for every Budget that would be ok on these Aluminium Sled Engine parts. A used Mill similar to mine only CNCed was on there last week for $1400 about 4hrs away one way. Just like restoring/fixing up Sleds there is cheap Manual/CNC Tools out there that can be cleaned, rebuilt, repainted, even upgraded fairly cheap if you look around. With New Billet Race Heads averaging $400 each, Cranks $1500+, Case's $2000+, that machine could pay for itself fairly quick. What would a Billet 246/292/340 Blizzard Free Air or 292/340 TNT Billet Head, Case, Crank sell for today? A piece of 6061 off ebay to make a 583/670 head was around $25, a CNC Machinist guy I talked to once said he could make one complete 670 Head on his oldest, slowest 1st generation CNC Mill & Lathe in about an 1:30, thats Head Shell and Domes. With Machining Time today around $80hr. So $120 Labor +$25 Material. Once setup, the more you make the cheaper they get.
$800/$400 (2) Billet Heads
https://cedarrapids.craigslist.org/tls/d/dyna-myte-2400-cnc/6401050772.html
$1850/$400 (5) Billet Heads (Most of these older CNC Mills/Lathes can be updated to use a cheap PC with Mach3/4 Software and a Flat Screen.
https://stlouis.craigslist.org/tls/d/1999-victor-cnc-bed-mill/6362212288.html
$2500/$400 (7) Billet Heads
https://stlouis.craigslist.org/bfs/d/kitamura-mycenter-1-cnc-mill/6387126189.html
$5000/$400 (13) Billet Heads
https://kansascity.craigslist.org/tls/d/cnc-mill/6378146068.html
<======
For the average Joe who is working on a $700 sled who wants to port a cylinder - hand held grinders are the most likely tools of choice and will cost less than $100 for a basic set-up
=====> Yep, I agree for a 1-2 off Porting job, but like Time is Money in a Business, Time doing your own Porting is Time away from Family & Friends & Riding that Sled. A Professional Boat Racer I talked to years ago, said his Race Heads took on average 30+hrs to Port & Polish them. One of his friends bought one of them New fancy CNC Porting Machines and it took less than 2hrs. Now the Home guy isn't going to buy one them big machines for doing Big Engines, but if you look, today they have small 3, 4, 5 axis machine attachments that would work for doing these small Sled Engine parts. Once you make the Jigs to hold the parts to Index them and have them programed right, your setup time gets reduced.
$455 attachment
Rotary axis. 4 axis , 5th axis A axis for cnc router / cnc engraving machine
<=====
Most will try a Dremel style tool first because they are cheap and available. Not an issue for porting one or two cylinders, just takes a little more time. Get a flexible drive too. I still use one like the kit below for a lot of quick jobs including filing ring end gaps. $40 total investment to port a cylinder.
======> Yes, You can keep it simple. But like me, I have multiple hobbies, so I use my tools maybe on a broader scope then most people to justify the cost. Well, maybe not if you talk to the ole lady! I shut her up once, when I made her a Custom attachment for her Vacuum Cleaner.<=====
If you plan on doing more cylinders - Get a heavy duty foot operated hanging motor, flex drive model along the lines of of the Foredom Units. For $ 100 bucks total the one I showed will get you in business plus the leftover $$ will allow you to buy a bunch of other bits etc.
====> I already got Air Tools to do most Porting & Polishing jobs, I do like that mini Blue Die Grinder you show. <======
Air die grinder - Been there done that. Hard to use on sled cylinders because they are BIG and typically are On/Off no real speed control. Don't forget they use a lot of air. Typical small compressors like most folk have nowadays - have enough pressure but take a long time to recycle - Good for air nailers, impact wrenches set. But for use on an air grinder with constant flow, a lot of start/stopping required while grinding a port. Figure the price of a new compressor too if you don't have one big enough.
=====> I have a Industrial Large Air Compressor that handles anything I use, Glass Bead Cabinet, Sand Blaster, Soda Blaster, Air Tools. Yes, I agree they are big, but they have smaller ones out today, also longer Carbide Bits. I have been thinking of maybe trying my Mill with one of my Mini USB Cams, one has a LED Light on the end mounted on it to see down inside and use those long Carbide Bit's. With just a DRO on a Mill you could take accurate Straight cuts and go slow. <=====
And count on buying a pencil grinder also for the fine detail work needed. Just be sure to get one with a throttle control - they spin mega-fast wide open.