310 overheating

[machrburt]

i just bought a 310 bolt on kit from ESR. did the proper break in and only got 10 min run time before the rings /piston melted. 38 air stryker 185 main, 52 pilot,needle in middle, pump gas, 32:1 honda hp2 oil, esr trx6 pipe, cool head, engine ice. i was running at sand lake, oregon. 75 degrees out. i am 285lb. rider anybody know what could have caused this??? ESR says overheating, but what else can i do??? i hear alot of people who are runnig below 185 mains with no issues

[pimpt250r]

you weigh almost 300lbs, your jetted for like a 200lb rider,+ they say you should perform a leakdown test, a 310 puts alot of pressure on your seals and you coulda sucked some air ,
and you said pump gas whats your compression , thats probably your problem
those are the answers your gonna get

Im a painter not a mechanic,
so a mechanic can chime in whenever they want

got any pics of the carnage

[deathman53]

I'm using a 170 main, BUT its not all your main jet. Get a richer needle for one. The main jet is only the primary factor in ~3/4-wfo. The needle and pilot jet play a big part, also the air screw can too!!! Next question, what radiator are you using/how good of condtion is it in, and how is your water pump????? All these are factors. Did you check your carb-motor flange too??? If that has the smallest of cracks it can lead to lean condition like is happening to you. And finally is your crank seals good??

I had a 330 that ran very hot, I had a really rich needle and a 205 main in it, it still ran hot. I blew the top end, due to the crank seals, rebuilt everything and it didn't run quite as hot, but still too hot. I replaced the carb-motor flange, it ran extremely rich. I put a normal sized main in it 170-180, put a much leaner needle and it ran alot better.

pimpt250r: I didn't think about the pump gas.

What size dome do you have in it, it better be a 21cc at the least for pump gas, the smaller the number the more compression. Check your whole system, compression, water pump, radaitor, leak down test, crank seals, intake tubes. One or several of the problems is probably between them.

[RichM1983]

I will chime in with this. You dont jet the bike to weight of the rider. Maybe I misunderstood what the one guy was saying but Ive never heard of such a thing. Seems to me like your rings may have melted from an air leak or a main that is to lean. I dont know what jet a 310 motor should use but someone can tell you that.

[Aceman]

75 degrees at Sand Lake, huh? I thought it was raining like hell on that side of the state?

My 310 runs about 180-190 degrees duning during the hot days over here. You weigh about a hundred more pounds than I do, so that, combined with the heavy strain of duning it certainly is possible your motor ran hot. I'd do a double check and make sure ESR sent you a pump gas dome. It may of been fine to run it on pump gas during break in when it was lightly loaded but when you took it out and really poured the coals to it, it was too much and burned it up. Buy a temperature gauge immediately, I consider it a necessity, rather than a luxury. If all you took off was the head to check the damage, I'd consider temporarily putting it back on just to leakdown test it before you rebuild the whole topend. Good luck.

[pimpt250r]

I ment by weight is he did unloaded heat cycles and then put a load on it and BAM ,its fuct
my buddy has a lt250r and it idles fine, revs fine ,put a load on it and it fell on its face,changed the jets ,and it boogies (for a suzuki) ,

[machwon]

Without seeing a picture of the piston you likely needed higher octane fuel. Melted pistons are common with detonation, one of the causes not being enough octane. Your jetting sounds spot on, what needle are you running?

[jcas]

I have pretty much the same setup as you, and I had the same problem. ESR's pump gas dome requires at least 98 octane (Believe me, after 3 piston meltdowns). Your jetting sounds good, and other than an air leak I would say fuel. I run 110 octane fuel, high compression dome, inline cooler, and PWR radiator. No problems for 1 1/2 years.

[machrburt]

the only issue i would have to run 110 octane is the other 4 quads in my family. my trailer only has 1 fuel tank that is about 20gals. i really dont want to use a bunch of cans. what about octane booster instead??? what #s are on the top of your dome. the one i have does not say what cc it is. thank you