Mikuni Jetting Question

[Mick Milakovic]

Hi All,
I've got a new engine in my harescrambler and have a question about jetting.  First, 34mm carb and the bike starts easily with a 45 pilot jet. I've got a 205 main jet, and the bike runs strong from half-throttle up, but blubbers a little off idle to half throttle.  My thought is that I need a different needle jet.  I moved the needle to the top clip and it still acts that way, so here is the question:  If I drop one size on the jet and return the clip to the center, do I also need to change the needle?  I'm not sure of the needle number (bad old eyes). I'm also considering going a size bigger on the main to see if it can handle the extra fuel there.  What are your thoughts?  Thanks in advance,

Mick

[tomale]

Does it idle on its own once the bike is started? Also did you check to see if your carb has a Air jet installed, some did some don't, I seem to remember that I was having trouble until I took mine out. If it is blubbering then you are getting too much fueled not enough air, the problem could be a combination of too large a pilot and too large needle jet, by the way, don't change out the needle, there is more going on with it that just determining the right fuel mix at mid throttle. Changing needles can get you all messed up. It is better to change out the needle jet. Needle jet and jet needle are not the same thing.

Thom Green,Still crazy after all these years!
74' 1/2 440 maico
70' 400 maico (project)
93' RMx 250 suzuki
Honda TL 125
2004 Suzuki DL1000

[brian kirby]

Each size of needle jet, either richer or leaner, is the same as moving the clip from the middle to the upper or lowermost slot. In other words, if the bike runs perfect with the clip in the top (leanest) slot then a needle jet with the clip in the middle slot is identical jetting. Since your bike is still rich you may need to go two sizes leaner on the needle jet, but only try one size at a time. Do not change the needle, only the needle jet.

Brian

[Mick Milakovic]

Thanks guys, kind of what I thought but not sure.  I'll take the current needle jet out, find the size, buy one smaller, return the needle clip to the center and start over.

Mick

[Bob Bean]

Or go to a higher # slide. Cures many 1/4 throttle rich bikes.
(can modify the slide too,I have done many this way)

Bob Bean

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany