UK '86 bogging down at 4000 rpm after ear shave - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 5 (permalink) Old 03-06-2017, 08:42 AM Thread Starter
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UK '86 bogging down at 4000 rpm after ear shave

Ok so I got a UK '86 a few weeks ago that had been badly neglected by the PO. I took the carbs apart and cleaned them and did an ear shave while I was at it. While I had it apart i did the splines and got a new R/R and relocated it, all according to the great info on here.
So I read everything I could about jet sizes and decide that +1 on the pilot and +3 on the mains was probably what was needed.
The thing is that the UK model comes with 38/110 as stock so I put in 40/118.
The bike starts great, idles great and rides great up to about 4000 revs then it just dies as though the fuel is restricted. So I followed Knifemaker's advice and pulled the choke open when it started spluttering and it went straight up beautifully.
So, it's running lean on the main jets right?
My question really is what is different about the UK model that it can use 110 main jets and have I bypassed whatever it is with the ear shave so should I now be going with 140s?

'86 UK Model
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post #2 of 5 (permalink) Old 03-06-2017, 09:35 AM
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You did the earshave? Where did you route the carb vent line that was stuck into the back of the right ear?

This hose needs to be routed someplace where there is no moving air. Like up under the gas tank somewhere. If not, the bike will stumble at higher speeds like it's running out of fuel.

Your jetting sounds lean. 118 main jet? Most here don't reject for just an earshave but some do go to 140's. Stock here are 138's. I'd try that first.

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Last edited by Knifemaker; 03-06-2017 at 09:40 AM.
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post #3 of 5 (permalink) Old 03-06-2017, 09:43 AM Thread Starter
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Yeah, I read all the posts about that and I've had it attached to the nipple under the tank, hanging out the side and (currently) zip-tied to the inside of the frame by the front right tank bolt. I tried it yesterday on the centre stand with the vent pipe just hanging out the side and it still bogged down at 4500rpm. When I pulled the choke on it went cleanly up past 6000.

I've just ordered some 138s.

'86 UK Model
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post #4 of 5 (permalink) Old 03-06-2017, 04:03 PM
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Sounds like the main jets to me. Not enough fuel flowing at higher RPMS.
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post #5 of 5 (permalink) Old 03-11-2017, 03:35 PM Thread Starter
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Thanks guys, popped some 138s in and it revs right up to the red line. Now to clean out the brake system.

'86 UK Model
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