EGT Troubles (Help?)

[Rucky]

We recently installed an EGT guage on my sled. The "old" analog style. We are having a problem with my mag side temps jumping up to around 700-800 degrees around 1/4 throttle. After that, they basically even out at 600-700. I just find it odd that it very suddenly jumps too around 800 while the PTO side lingers around 400. Anyone have any suggestions? And also what should a sled be running at as for temperatures. I've read that Aluminum melts at around 1300, so clearly don't wanna be up there. :d

 

[Rucky]

Just to specify, this is in CELSIUS.

 

[thump]

Sounds like a fuel delivery problem. I would pull the carbs and check the position of both needles and give the carbs a good cleaning, float bowl may have contamination. Check carb boots for cracks, mine broke at the boost bottle ports. Once everything is back together check that the carbs are in sync with each other. Had a 99 RMK 600 run it around 1250F , seemed to run best at that temp.

 

[Rucky]

Sounds like a fuel delivery problem. I would pull the carbs and check the position of both needles and give the carbs a good cleaning, float bowl may have contamination. Check carb boots for cracks, mine broke at the boost bottle ports. Once everything is back together check that the carbs are in sync with each other. Had a 99 RMK 600 run it around 1250F , seemed to run best at that temp.

Thanks. Mine runs around that temperature once I pass quarter throttle. The needles are both in the middle position where they are supposed to be, and we just changed jets and everything in there appeared to be fine. I'll check the carb boots though!

 

[Modman]

Your readings cannot be in celcius! 800 C is approximately 1472 F, there is no way your sled would even run at that temp at 1/4, your piston would be liquid. Those readings have to be in F.

As for the fluctuation, could be anything, more info is needed. Are these twin pipes or single? How far are the EGT's mounted from the exhaust face of the piston? What do the plugs look like? at 800 F at 1/4 throttle, the plug should be lean looking. If plugs look ok or black, there is the possibilty that you are running too rich and the extra fuel is burning in the pipe, which is causing the temp to read that high. First thing I would do is switch the probes and see if you have a malfunctioning probe. If its the probe, once you switch it over, the other cylinder should be the one reading the hottest. If not, it confirmes that you have a hot side.

Double check carb settings and air screw adjustment, pilot etc if have not already. Then sync the carbs as stated.

Running temp means nothing, each sled is different. Do not go by what the EGT says, tune to plugs and then correlate that plug reading to a temp on the EGT. You might be bang on with plugs at 1220 on the EGT, so running 1250 will be starting to be too hot on the motor. Conversely, 1200 might still be slightly rich on the plugs, so 1300 might be more where you need to be. Each sled is different. There is a good procedure on F-bombs website: on how to set your baseline. DigatronTech

Always air on the side of caution. Twin pipes like more heat usually.

Hope that helps.

 

[Rucky]

Your readings cannot be in celcius! 800 C is approximately 1472 F, there is no way your sled would even run at that temp at 1/4, your piston would be liquid. Those readings have to be in F.

As for the fluctuation, could be anything, more info is needed. Are these twin pipes or single? How far are the EGT's mounted from the exhaust face of the piston? What do the plugs look like? at 800 F at 1/4 throttle, the plug should be lean looking. If plugs look ok or black, there is the possibilty that you are running too rich and the extra fuel is burning in the pipe, which is causing the temp to read that high. First thing I would do is switch the probes and see if you have a malfunctioning probe. If its the probe, once you switch it over, the other cylinder should be the one reading the hottest. If not, it confirmes that you have a hot side.

Double check carb settings and air screw adjustment, pilot etc if have not already. Then sync the carbs as stated.

Running temp means nothing, each sled is different. Do not go by what the EGT says, tune to plugs and then correlate that plug reading to a temp on the EGT. You might be bang on with plugs at 1220 on the EGT, so running 1250 will be starting to be too hot on the motor. Conversely, 1200 might still be slightly rich on the plugs, so 1300 might be more where you need to be. Each sled is different. There is a good procedure on F-bombs website: on how to set your baseline. DigatronTech

Always air on the side of caution. Twin pipes like more heat usually.

Hope that helps.

The gauge says it's in Celcius on it???. I can snap a pic later if you like. I'm running the stock pipe. Only motor mod is a boost bottle. The probes are brand new and 6 inches from the spark plugs. I did a few full throttle pulls and checked plugs. They look pretty good. Medium brown in color. The mag side (side that is acting up) might be a little lighter in color. Next time I have the sled out I think I'll run it at quarter throttle for a little bit then check the plugs. I believe it could be the gauge, as my father checked the guage with an ohm meter and the right side appeared to have more resistance. Also, when hooked up to the meter, the right side would show about 100 degrees. The left side barely moved.