doo guys need help with E.G.T.s

[wellfed777]

so my friends all ride revs and are having trouble figuring out egt temps
first off their probe is 1.5 '' from Y pipe and pipe junction on pipe they are running slp heads mild porting wiesco pistons and slp can they are trying to keep temps under 1400-1430 one guy has his jetted all the way up to 500 mains but that seems crazy to me
can anyone tell me what are good temps or at least to hot for this sled(engine)
they only see temps above 1400 when climbing big hills/long pulls
these are 06 revs running 5500-8000 ft with 50% race fuel/prem.
thanks for any help

 

[hymark860]

My probes are 2" from the flange of the ypipe. I never run much over 1200 degrees. Midthrottle is 1100 to 1200. I run 410 mainjets. Mines a 860ho bb so not much a comparison.

How do your plugs look? If ran with temps in the 1400s for any length of time it would burn down. Aluminum starts to melt at 1250 drgrees.

 

[wellfed777]

hymark so are your probes in the Y pipe?
because these guys got a single probe in the pipe where it meets the Y pipe and on ceramic coated Ypipe and pipe the coating gets hotter on the pipe to about half way into the bend but the Ypipe does'nt change color at all so are temps going to be hotter at the pipe than at Ypipe seems like it would be ?
thanks garth

 

[summit800]

I have 2 probes and mine are 100mm from the skirt of the piston with a cpi pipe and can 460 mains 20 pilots and mine run 1100- 1240

 

[JROD]

Ski-Doo race manual says run them 100mm from the face of the piston.

 

[summit800]

I still am concerned with a 1250 3/8 throttle can any one tell me what affects the fuel screw on the carb will do if I go from 2 turns out to 2.5 out ??? or will I have to lower my clip on the needles??????? Who is the carb goo roo here???

 

[wellfed777]

thanks all
i was hoping to find somebody that had a probe in the same spot because i think the temps are higher at the begining of the pipe than in the Ypipe but i guess i'll keep testing

 

[JROD]

if your mid temps are that hot, I'd recommend raising the needle at least one notch. Rotax engines are bad for mid range burn downs. They tend to build a lot of heat in the mid if you hold it there without brapping the throttle. 1000-1100 should work.

Again, make sure you're comparing your temps with your plugs and piston wash if you can even see it. On the Revs, it's almost impossible to check wash.

wellfed- the exhaust gases coming out of a two-stroke are a lot like a cutting torch. You'll find the gases are hottest at the "point" of the flame so closer to the piston doesn't always mean hotter. The ideal spot for probe placement is at this point. Not easy to find! Ski-Doo race manual says 100mm from face of piston so I'm assuming they are fairly close with their placement to the ideal spot. Hope this helps.

 

[hymark860]

hymark so are your probes in the Y pipe?
because these guys got a single probe in the pipe where it meets the Y pipe and on ceramic coated Ypipe and pipe the coating gets hotter on the pipe to about half way into the bend but the Ypipe does'nt change color at all so are temps going to be hotter at the pipe than at Ypipe seems like it would be ?
thanks garth

Yes I have two probes in a single coated ypipe. 2" from flange equal 100 mm from skirt. The further out the hotter it will read.

 

[wellfed777]

send it around again see if anybody else has got info
thanks

 

[sledsrock]

Probably no help.............single pipe, place probes in Y pipe 4 inches from piston skirt, puts it as close as you can about get it to the rave cap (if you put it on top anyway) temp run about 1150-1200, plugs and wash look good (safe).