esr310

[dizasterzrfun69]

well i have an 86 R with an esr 310 kit on it, it has an ftz out of frame drag pipe and a 39.5 mm pwk carb and v-force reeds. it has a 20cc dome and some other dome, to be honest im not sure which is in it now. The guy said he only ran 110 octane in it the whole time he had it. My question is, do i HAVE TO run 110 in it? If i change the dome will that make a difference? I might get rid of the ftz pipe if that makes a difference. this race gas gets expensive at $4-$5 a gallon and it DRINKS the gas like its water. One reason i want to know is because of trikefest. if i bring race gas with me and run out i dont think there is anyplace close to get it is there? Maybe i should just leave it how it is and not mess with it!?!

[c00t3r]

I would look at ignition timing to make sure its not advanced way up (+4 or more) and check compression with a tester. If timing is not advanced too far and compression psi is below about 240, you should be able to run premium in it. To get it to run correct a/f ratios it may be nessecary to re-jet, usually up a step or so on the main, and maybe a needle adjustment. The pipe shouldn't matter as its design is a function of max rpm and exhaust port size, not nessecarily type of fuel or compression ratio. Hope this helps,

[250rCRazed]

I would look at ignition timing to make sure its not advanced way up (+4 or more) and check compression with a tester. If timing is not advanced too far and compression psi is below about 240, you should be able to run premium in it. To get it to run correct a/f ratios it may be nessecary to re-jet, usually up a step or so on the main, and maybe a needle adjustment. The pipe shouldn't matter as its design is a function of max rpm and exhaust port size, not nessecarily type of fuel or compression ratio. Hope this helps,

Where do you guys make these compression numbers?!?! I got my ESR 310 kit, assembled it and it made about 175psi... my cr250 never made much more than 180 at best... ESR says their pump gas kit should be around 175-180 and race gas dome should bump it to 190-195 tops.. I dont understand how some of you guys throw out numbers like 220 being normal... and under 240psi being pump gas... what gauge do you use??? Anyway, to answer your question, I would first check compression like c00t3r said... only I'm going to say if its over 190psi I'd say either stick with race gas, or swap that dome out because it's more than likely the race gas dome. There should be a product number engraved in the dome next to the plug and you can just call ESR to see which dome it is. As far as exhaust, the only thing you need to worry about with exhaust is that the exhaust main pipe doesn't have a shape that will cause an engine to run hotter than normal (like FMF's SST pipe did for many ATV's and dirtbikes) otherwise it shouldn't make a difference. Too much heat, timing and compression will detonation problems and pre-ignition of low octane fuel so those are what you should focus on.

[c00t3r]

i typed it wrong.. shoulda been 140.. thats my opinion, and its a conservative one. my neighbor's yz makes 170 warm and it runs on 93, goin on three years on one piston. sorry for the confusion.. if esr says it'll run on 93 at 175 i'd tend to trust them.

[250rCRazed]

i typed it wrong.. shoulda been 140.. thats my opinion, and its a conservative one. my neighbor's yz makes 170 warm and it runs on 93, goin on three years on one piston. sorry for the confusion..

oh lol... that makes more sense then... yea 140 is low... but even aside from you... i've heard many guys tell me their motors are making 210-220psi.. I've never had a fresh top end come near that. Most I've seen without being on a race dome is like 180psi.

[c00t3r]

compression numbers are affected greatly by port height, i've seen mx motors with relatively low exhaust ports that make over 250 cold with serious headwwork, and of course serious octane.

[250rCRazed]

Makes sense... more air volume is compressed with a lower port. One day I'll own something producing 2xx numbers.