86 250r fouling plugs at 32:1 with golden spectro

[Autophysn]

Ok, Now I know this topic has been talked to death, but the one thing everybody tends to agree on is that they run somewhere close to 32:1 fuel mixture with a synthetic type of oil. This bike is new to me as are two-strokes entirely, and beleive me, I do ride hard, so it is not like I am loading the thing up just putting around. However I am getting large amounts of oil coming out of the base connection from the pipe to the head, and the plugs are soaked, went through 3 plugs this weekend. Now, I played with the jetting this weekend, I only had a 165 and a 200. The 200 was way too much, bogged the bike down badly. The 165 did the same thing, just not so bad. I ended up back to the stock 145, and still fouled out.

So, my question to all you gurus, Should I be changing my fuel mixture leaner? I would think so, but want your guy's opinions.

One more thing, since I am not too familiar with the 2 stroke engine as much as the four stroke, is it possible I could be getting crank case/ trans oil from coming up by passing the piston rings? It feels kind of funny asking this, but I have to put my worries to death. The bike has enormous power and even with my fat ass at 320lbs. Was able to hit a high of 58.02 MPH according to my GPS. So I kind of don't think I have a compression issue. But I can be wrong. Thanks in advance!

[oscarmayer]

are you seeing excessive smoke out the exhaust(worn oil rings)? are you dumping too much fuel and running too rich or too lean (tuning issue)? those things can cause the issue.

[DeePa]

are you seeing excessive smoke out the exhaust(worn oil rings)? are you dumping too much fuel and running too rich or too lean (tuning issue)? those things can cause the issue.

please stick to the 4 strokes...there are no oil rings in 2 strokes. All those rings do is create compression.



tranny fluid cant come up the in the crank case unless the clutch side oil seal is leaking, and it wouldn tbe leaking enough to foul your plugs.

keep looking at jetting, maybe weak spark.

[oscarmayer]

your saying 2 strokes don't have rings? it may not be called an "oil ring? but it's a ring :P

[DeePa]

well oil rings are spec for 4 strokes...these are compression rings, theres 2 of them on larger cc's...just 1 on smaller cc's...

not 3 or 4 rings like 4 strokes

[SYKO]

less oil will make your fuel richer while more oil will make it leaner, what heat range plug are you running? I good measure is most everything runs great on a NGK B8ES, Ive runn hotter plugs on my racing motor B7ES and helped a bit. My 83 300r was natourios for fouling plugs.... becouse it was running with 1/4 part of the piston missing! lol! I could get maybe 30 mins out of it, and it would run sweet! then DEAD plug... change ride, repeat.


ive never really had a plug fouling problem other then the 300 my fiance's blaster ran a 32 keihn jetted rich and still ran on the same plug forever...even got it to run with 2 reeds missing!

[Daddio]

A dirty air filter can cause fouling on a 2stroke. A 145 doesn't sound too out of line. I just asked 1upfront and he said he is running a 135 main in his 300r with a 39 pwk. He is running a 125 main in his 250r with a 36 pwk. They are both running cam2 110 leaded 20-1 with amsoil dominator. No fouling problems here. By the way these are both aircoolers.

[Autophysn]

guess I should have given a bit more info, sorry

New K&N filter, is why I jumped so high with the guesstamate for the jets, thought 165 would work, but was too much

And I do run the stock NGK BR9ES recommended by Honda

As for the rings, I thought so, I know the 4 strokes have a wiper piston ring, and can cause an issue like this, but a 2 stroke is a whole other monster. This is why we have to mix the fuel right? the fuel lubricates the piston walls.

any how, I am getting confused about a different comment

32:1 would be richer than lets say 50:1
but leaner than lets say 20:1
correct?

[gravelyman]

most modern oils have excellent lubricating properties. running at 50:1 in my experience has done well for me. my stock 85 and 86 250r's have the original top ends on them. i use amsoil domniator at 50:1 and it is a synthetic oil. on my 350pv engine im running at 40:1 with 110 octane but only time will tell on this engine.

[Autophysn]

most modern oils have excellent lubricating properties. running at 50:1 in my experience has done well for me. my stock 85 and 86 250r's have the original top ends on them. i use amsoil domniator at 50:1 and it is a synthetic oil. on my 350pv engine im running at 40:1 with 110 octane but only time will tell on this engine.

See, now this is what I am wondering, because golden spectro says to run 50:1 in normal condition and 40:1 in severe conditions

So it would be okay to go as high as 50:1 right?

[oOGoFastOo]

I think you would be ok at 50:1 if thats what it says, iI run 40:1 in all my 2 strokes and havent had a problem. There could be tranny oil getting in to your crank from a bad crank seal and fouling your plug, my Tecate was doing this from a bad power valve seal.. I was able to tell becayse of the smell of the smoke it was producing didnt smell like the mixing oil I run. your carb might also be flooding over from a miss adjusted float and fouling the plugs.

[Autophysn]

thanks! that is a very good possiblity since was tearing into the carb frequently trying to jet it. And as for the crank seal, I could certainly see that since the bike had been sitting for ten yrs and all I have done is change the trans fluid and air filter. I understand how seals can harden over time and cause failure.

Thank You Bro! I appreciate the point in a direction

[Daddio]

A sure way to tell if you are burning up the tranny oil is if the oil level keeps dropping in the tranny, that is as long as you don't have any leaks. Oil coming out around the head pipe isn't too uncommon on a 2stroke and is likely an improper seal there.

[Mosh]

K&N filters come oiled too heavy from the factory.
I always clean them first,then re apply the proper amount of oil.
If your crank seal was bad,That thing would be smoking heavily out of the pipe.

Change your mixture to 40-1 and try that. If it still loads up on the bottom and cleans out on top, you may have to drop down on your pilot jet.

[DixiePlowboy]

If your crank seal was bad,That thing would be smoking heavily out of the pipe.

I know that's the truth.

Had a '92 KX250 at the beginning of this year with a really bad right crank seal. It would not only foul plugs and run like a lame turtle on a glue trap, but would also blow tranny oil about 8 feet out of the tail pipe coating me and everything behind me.

Another possibility:

If you are experiencing a loading/fouling condition that jetting doesn't end up clearing, and are using a stock(or)old carb, the needle jet could be worn to the point that jetting can't cure it.

I had an '85 R back in '03 that absolutely could not be jetted correctly. Turns out that the needle had a burr on it and needle jet had ovaled out. Slapped on a new 38mm A/S....changed the mainjet once....problem solved.

Edited to add additional info on the condition I described above to clarify and help diagnose this specific problem: That machine ran fine at full throttle even with the problem. It was somewhere between 1/4-to-3/4 (+-) throttle that it would load up.

May not be necessary in this case, though.