You guys helped out a lot last summer with what turned out to be a leaky float value. I replaced it (finally) and and added 1/4 turn shut-off to use instead of the shady petcock. While monkeying with the carb, i thought I'd see what jets were in there. Took a picture and didn't think much of it. On reading some of the applicable threads, I'm wondering if this explains some of the plug fouling I've found I'm getting (in between completely filling the crank case with fuel).

Could I seriously have a 230 as my main jet? Or does the identifier on it mean something else? Bike's got a cone air filter, straight pipe exhaust, and absolutely terrible milage (would that explain it?). Though it seems to operate quite nice!

Ah, didn't know that! Thanks! I'm in Ontario Canada, though this bike's a 95 and I think has been around the block as far a previous owners.

I'll read some more on it and, barring all else, get a proper hole gauge to check what it is.

Yah, I suppose 'coal mine' puts not too fine a point on it.

I've had trouble with poor starting on occasion of the last 2 summers owning the bike and chalked it up to an ignition problem (only seemed to be troublesome starting when below ~18C (65 american)). Had to trailer the bike home from work last fall cause I couldn't get it started, even with jumpers to my truck.

Finally got around to checking for spark last week (has been in the garage all winter) and found a lively arc. Happy it wasn't that, but miffed at what else it might be, I pulled the plug (which might have had 50 miles on it) and thought. "Oohhhhhhh".

For some reason I had got to thinking plug fouling was the kind of thing you'd get in a lawn mower sized engine. Not considering they're fundamentally the same. This lead to learning a rich mixture could do this, (as probably did my leaky float valve), and starting to learn about jets.

From the bottom, if I understand your meaning.  Consistent with this diagram from serowbot's thread, where it says 'main'. Maybe I'm not even talking about the right thing?

That little "square in a square" logo on the jet is Mikuni's logo. That looks like a stock jet but I really doubt Mikuni put it there. Must've been a previous owner not knowing what they were doing.

batman wrote on 04/09/17 at 22:26:16:



Which means the 230 jet is for a carb 50% larger or 1/3 bigger than ours.


should be in a carb of say 45-48 mm, the carb on our bikes is 40

I so Teautillee don't get your math.

area of a circle-A=3.14xr squared, 40mm(20x20 x3.14=1256)48mm(24x24x3.14=1888)    (1256/1888= approx. 1/3larger)  that was my late night math above sorry ,tired. but the 230 jet does put out about 50% more fuel into the mix.

SO what's in the top a 145?