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Discussion Starter #1
Hi Folks,

I had to replace the original Mikuni butterfly style carburetor on my 87 Enticer 340 - had some plugged internal passages that there was no way to get cleared (tried everything many times). I found a Mikuni VM34 round slide carburetor, off a 377 Bombardier. Took it apart, cleaned it up and everything looks as new. Also added a primer so I could get the machine started more easily.

The main issue remaining is the top end lack of power (from about 3/4 throttle to full). Starts & idles perfect, mid range okay, upper mid-range screams, but bogs out past 3/4 throttle. Sometimes has a bit of a hard time finding the "sweet spot" but when it does it goes like a scalded cat. It also seems to run better when cold.

After playing with the air screw, I have gotten it to accelerate from idle smoothly, without hesitation - seems to like to be around 1 turn out, or less. Too much and it bogs hard from an idle.

I have had the jet needle up and down through all the notches on the stem. It works best with the c-clip on the top notch (needle at lowest position, leanest).

I also lowered the float a bit (less fuel in the bowl). That seemed to help somewhat, but I am not sure.

I am wondering about the size of the main jet. The jet that was in the VM34 was a #320. I took that out and put in the jet from the original Mikuni butterfly carb. I could not find a marking on it but it appeared to be about the same size.

Could the main jet be too large and causing too rich a mixture above 3/4 throttle? Any suggestions on what size jet may be appropriate? I am at sea level (Nova Scotia) and it is usually fairly mild.

Any help is most appreciated.
 

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Is this a single carb you put on there? I thought the 1987 Enticer 340 came with dual butterfly carbs. I think you are right in thinking you need smaller main jetting.
 

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No, the 1987 Enticer has a single butterfly carb on a y-manifold. I replaced it with a single VM34. BC Dan posted an excellent guide to determining which way I should go on the jets. I will perform those tests and report back. Thanks.
 
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