couple questions about things.

[300rman]

ok.
1. about what is a good temperature for a air R to run at?
i took the head temperature/rest of the cylinder temp, and i was getting around 250 to 320 degrees. does that sound good, or out of hand?
and yes, the plug looks ok.

2. after riding for about a half hour, it seems like i get a top end rattle/clank. i dont know what it could be, but it only dsoes it around mid-throttle. it goes away at high RPM, and at low RPM. i dont think it could be detonation, as it doesnt do it until its good and hot.
i will try some race fuel soon to see if that remedies it. any ideas?

i am just really worried that now that i got this thing together, and running good, that i will overheat it and fry the top end. the seemingly high temperature, combined with that off mid-range noise concerns me.

i will be taking the bike to PR Racing to get jetted properly, as no matter what i do, im always concerned about it.

[i58829]

250 to 350 is a huge range, were these different areas of the top end that you checked with a heat gun? Or are you getting a 70 degree variance between several rides? It doesn't sound too hot to me for the 250-280 range but i'm not sure what the ideal temp is, obviously cooler is going to be better.

How close to the exhaust was the 350 measurement taken? It may just be the difference between the intake/exhaust side of the motor, TC...

[trxxr]

You need to check temps at the base of the plug. I would also run it rich for break-in you can do this without re jetting but with the pilot setting. I'm getting my 83 250r up and going. This is my second 250r the first was an 86 and I missed the power and fun. I have always loved the air 2 strokes they rock but need a better carb tune than the WP'ers. Good luck!

[300rman]

the measurements were taken all over the head.
it is definitely running too hot. the plug is very light colored. going to take it to PR Racing to get jetted.
if i still have problems with it, i will wind up selling.

[FLOTEK]

what is your current jetting and carb and did yo uspray around the intake and check the base.manifold for any air leaks ? what octane rating are you using

[Mosh]

Sounds like detonantion to me.Better bump to 110 octane.

[Erics350x]

Sounds like detonantion to me.Better bump to 110 octane.

I second that^ And maybe move to a step colder spark plug

[300rman]

im running 93 octane.

ill do a compression test to see where it stands. anything above around 180lbs will probable need higher octane, correct? i cant afford race fuel, i burn too much. So ill have to enlarge the dome to drop the compression if thats the case.

i have not checked for leaks on this rebuild, but i have every other time i have put her together. and it did it before, with no leaks. to eliminate the possibility, i will check for leaks.

as for the spark plug, i am running a br8es, which is stock.
i could get br9es, but ill do that after eliminating other possibilities. ive gor 10 br8's layin around brand new!

[Kintore]

You know what they say, takes fuel to make power. Either deal with it or lower the compression

[300rman]

You know what they say, takes fuel to make power. Either deal with it or lower the compression

havent messed with the compression at all. last time i checked it, it was at 155, but i think the gage may have been broke.

the main jet is a 175 on a keihin.
others are ??? but it has no problem whatsoever if i kep it in the midrange rpm most of the time.


i am not sure its detonating due to compression, as i have had it running with a mikuni, before i bought the keihin. i couldnt get the mikuni to give me a nice colored plug, it was a little dark. it didnt start worth crap, and the choke wouldnt stay engaged, it immediately returned to choke off position.
but, i ran this carb hard for an entire day without much down time. it didnt run quite right, but even after it got warmed up (cant remember the temps, but they were around 200 max) it didnt make the hammering sound.

i just dont get why it only does it after its warmed up, and only mid-throttle.

I would think a rapid misfire would always be there, and not just only when the motor is warm, correct?