Mikuni Tuning

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Aug 28, 2007 | 12:25 PM

squishymonkey

Thread Starter

Stage II

Joined: Aug 2007

Posts: 2

Likes: 0

Mikuni Tuning

Hi all. I recently aquired a 1975 XLCH that has a Mikuni carb and a K&N filter installed on it. The bike is running rich. I cleaned and oiled the filter, and now want to adjust the carb to get the proper mixture. I am going to assume that whoever orginally installed the carb and filter jetted it properly. Looking at the carb, I cannot find a model #, but searching the documents on the Mikuni website, it looks like a VM model. I cannot find anything in the documentation on this model about adjusting the air screw, however I did find something in the documentation for the HSR. The HSR document says to turn the air screw all the way in, then back it out 2 full turns and start the bike and let it warm up to operating temp. Then turn the screw in until it idles rough and mark the position. Turn the screw back out until it starts to idle rough again. The best position for the screw would be halfway between those 2 positions. Once that is set, adjust the idle.

Does anyone know if this would be the same procedure for the VM model? Sorry if it seems like a lame question, but I am new to this sort of thing.

Thanks in advance.

Aug 30, 2007 | 01:51 AM

sepixlh

Road Master

Joined: Aug 2006

Posts: 751

Likes: 6

From: 500 miles south from Artic Circle

RE: Mikuni Tuning

That adjusting procedure is basicly same with all carbs... So you have Mikuni VM 36mm ? or someting else ?
I have dealed one VM36 in ironhead, open mufflers, Crane Hi-4, original P cams.
- Slide (trottle valve) 50/5
- needle K4 clip in center cut
- mainjet 175
- idle/intermedia jet 65 ( maybe 60 is better)
- needle jet AB265
- needlevalve 300
Bike runs fine and responces to trottle nicelly.
EDIT: Check float level before any adjustments !