2 Stroke pipe install

[red5.0fogger]

Anyone have info on 2 stroke egt or plug reading? There's a bunch of threads about reading piston wash on google search.
I have an egt gauge I can use. working on a 2002 600 edge polaris snowmobile. I'm installing a better exhaust system which will need a touch more fuel.

[decipha]

thats pretty cool, i wish i could be more helpful but I've never tuned a snowmobile before!!!!

I'm interested to check it out though, can you pull the plug and post a pic of it?

[red5.0fogger]

Ok. Think of a jet ski. But about 100 degrees colder!

[decipha]

you gotta turbo on that snowmobile?

[red5.0fogger]

No. All stock 112hp 600cc 2 cylinders. Goes to 122 HP with the new pipe.

[red5.0fogger]

Here's some plug pix. Had the egt showing 1200 at the end of a 15 second wot pull.

[decipha]

looks good, looks slightly above the apex

[red5.0fogger]

That's good to hear. Can you give some background as to how the color mark works to indicate Afr? Note: The base of the ceramic was med to dark brown but pic would not come out good.

[decipha]

the top of the porcelain will show the wot fuel ring, it should be slightly discolored with no melting or specs of pistons present (detonation) depending on if your running pump gas or race gas it will be slighlty brown to greyish in color, whats important is that its not overheated and that it shows some fuel on it

the bottom of the porcelain will show the part throttle fueling, it shouldnt be dark colored indicating its overly rich, you really cant go too lean during part throttle

at idle the top of the threads will show the idle fueling, if shouldnt be rich darkened, again u cant go too lean at idle the engine will just suck down more air

dont confuse that with the actual threads being discolored, ideally you want the top 3 threads to be blued showing that the plug is pulling the heat out the chamber, if more than 3 threads are heated then the plug is too hot and u need a colder plug, if u have less than 3 threads showing heat then you should probably consider a hotter plug, it looked like your plug was at about 2 threads

the backstrap will show the burn which is indicative of ignition timing, usually the burn mark right across the middle of the bend "apex" will yield the best performance, over advanced will put the burn closer to the threads, underadvanced will be closer to the tip, there will be a second burn near the tip of the plug, thats idle spark since idle should always be under advanced for torque reserve

[Bullzi91]

Is that per 2 stroke spark plugs or spark plugs in general? Good knowledge.

[decipha]

thats combustion in general

[Fasterthangas]

You might want to hit one of the sled forums like Snowest. http://www.snowest.com/forum/ Tons of info. I drag raced two strokes for years and I can tell you that an EGT gauge was the difference between a burnt piston or a successful weekend. I believe the units I used were from Westach. You'll read how the EGT or an AFR gauge is hogwash because the probe gets contaminated from the two-stroke mixture. That's BS! Check out small two-stroke aircraft and tell me what they use to monitor exhaust temps. EGT's!

Anywhoo; an EGT will save you when modding a two stroke. Learn how to read it and what exhaust temps are acceptable at 1/8 . 1/4, 1/2, 3/4, and WOT. The new digital ones come with warning lights to alert you of a lean condition. Did you know that most owners burn up a two stroke at cruise and not WOT? Yup. That's where you spend the majority of riding time also.

Also; to read a two stroke plug properly; you need to do a throttle chop. Let's say that you want to test your tune at 1/2 throttle. You would take off and hold her at 1/2 throttle for a short distance. You then hit the kill switch while holding her at 1/2 throttle until she comes to a dead stop. Now read your plug immediately. If you wait an hour or day to read the plug; the color will change and give a false reading.

Also; to get the best bang for your buck after adding any mods to a sled; you must dial in the clutch. Even a stock sled can benefit from a clutch kit. The factory sets them up generically and tries to soften the holeshot for liability reasons. Toss in a proper clutch kit and belt and that sled will really come alive.

Here's some pics of my old racers for your entertainment pleasure: (Click on pics for a larger view)
I sold this '99 to my business partner Dennis so it doesn't list the quad as mine. The first pic shows the changes in graphics he made at his house. The remainder of pics are in my driveway during build. I ran a successful campaign on alcohol without a glitch thanks to Lectron Carbs and Westach EGT.

http://www.angelfire.com/or/Gurgorama/readers/dennis2.html

This bike started life as a 4x4 Polaris! I built the first Polaris 400 stroker engine ever built for this bike. I was told it could never be done.

http://www.angelfire.com/or/Gurgorama/readers/eric3.html

My first and last racer. This is a '98 that I purchased new when working as a Polaris technician. It became so competitive in sand drags that the other racers with more cc's whined that I should be in a separate class. The tuned auto clutch gave me quite the advantage despite what folks will say about manual bikes being superior. Nothing holeshots like a tuned sled clutch.

http://www.angelfire.com/or/Gurgorama/readers/eric1.html