need some quick carb help.

[monster 84r]

hey guys, i need some advice,

my plugs always black, so im pretty sure my jettings rich. whoever had the bike before me put a 86 250r carb on it, but it has the 86 250r stock jets in. im pretty sure their 148main and 52 slow. my bike came stock with a 132 main and a 42 slow, so im probably really rich, i cant tell. my only mods are a filter, no air box, the 34mm flatside carb, and the dg slip on. i think its bogging in the idle-1/3 reigon, but il do a plug chop to confirm. can anyone give me a ballpark range of what jets to buy to replace what i have in it? im around 1000 ft, and its 80-90* most of the time. thanks for any help!

also, ive tried a few plugs, and im using br8es right now, gapped at .025''. what do you guys with air foolers run in yours?

[TeamGeek6]

Bogging at 1/3 is fouled spark plug from too rich, black plug proves it. My experience is that its not so much jetting as float problems (fuel level too high). Look up the thread I started about carb mods the Geek way. I had the same problem, and that problem is gone now.

025 plug gap is awfully small. Id hope it could go at least 35-40. Jis for fun, try 35-40 and see what happens.

[Dammit!]

Idle to 1/3 is your air screw and some of your pilot. The stock pilot in a '86 is 42 or 45. I can't think this early. Either way 52 is way bigger than stock even for a water pumper.

[Huffa]

hey guys, i need some advice,

im pretty sure their 148main and 52 slow. my bike came stock with a 132 main and a 42 slow, so im probably really rich, ?


Usually the jets jump up in incrediments of 3 I think so to me your bike seems waaaaay too rich if my assumption is right. With no air box that should lean it up some though. Try adjusting the air screw 1st but make sure it's at the stock position to begin with. Go a 1/2 turn lean from stock and test it then go a 1/2 turn from stock rich and see if you feel a bit more response.

What ratio oil-gas mixture are you running? Also some oils foul easier then others and some burn really clean. I don't have an R but I'd think around a 40-1 mixture would be ball park. That sound correct? Most don't run what the manual says and that is probably 20-1. That was years ago though and oils have come a long way sine then so the mixture should be uppped quite a bit.

By all means see if you can get a NGK Iridium plug for that! They are 12-16 bucks but are far superior to the cheap ones. Many guys with CRF's have NEVER replaced those plugs including me. In the long run they come ouy being cheaper then the regular ones.

[monster 84r]

im running 32 to 1 with some crappy no name mix. im gonna go pick up a few new main jets, what size would you guys think be about right? im thinking 3-5 higher than the stock 132. i have the stock jets for the 84 250r, should i put the stock slow jet in? thanks!

[x.system]

Idle to 1/3 is your air screw and some of your pilot. The stock pilot in a '86 is 42 or 45. I can't think this early. Either way 52 is way bigger than stock even for a water pumper.

Actually a 52 is stock in the 85 round slide carb where the 86 is 42 stock. ;)

[monster 84r]

i know its a flatside though, i might be wrong on the slow. all i remember is that it was way more than the stock that came in my rebuild kit.

[monster 84r]

would a 138 sound about right for an air cooled with some small mods?

[TimSr]

There are half a million threads on carb jetting, but you always start on top with a full thorttle plug reading, and adjust it via main jet. AFTER which you then do a half thottle plug reading, and adjust the needle. Then you adjust the air screw for best throttle response off of idle. If you do this in the wrong sequence, it just doesnt work. (Dont get technical on me) but for all practical purposes, the Main jet affects the entire spectrum, the needle affects about 3/4 of it, and the idle screw becomes irrelevant as soon as your throttle slide begins to open. This is why it must be done in sequence.

Before you adjust anything, decide what premix ratio and oil you are going to use, and be consistant. Trying to jet a carb while varying mix every other day is like trying to adjust your idle speed while somebody is playing the the throttle!

[Dammit!]

Actually a 52 is stock in the 85 round slide carb where the 86 is 42 stock. ;)

I didn't know that. Thanks for the correction. Filed for future reference. :beer