Mikuni vm38 round slide carb setup

Production K Models

Re: Mikuni vm38 round slide carb setup

Postby Ferrous_Head » Mon May 07, 2018 7:46 pm

It can be painful at times when they don't seem to want to play the game.

On the upside, once you sort this out the bike will most likely run the best it ever has or can !
"I know only too well the evil that I propose, but my inclinations get the better of me."
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Re: Mikuni vm38 round slide carb setup

Postby Maxcapacity » Mon May 07, 2018 8:13 pm

If you have enough compression to detect TDC with your finger that's enough to start a K model. Did you remember to open your throttle when you ran the compression test? If you've been twisting screws on a round slide you could possibly have the slide closed enough to effectively prevent any air charge. If the air can't get in, it cant compress.
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Re: Mikuni vm38 round slide carb setup

Postby RunninWild » Mon May 07, 2018 8:46 pm

Throttle was held wide open while doing the compression test
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Re: Mikuni vm38 round slide carb setup

Postby Maxcapacity » Mon May 07, 2018 8:54 pm

Then I wouldn't mess around with a leak down test. Pull the head on the worst cylinder and take a look. You're going to end up doing that anyway. It's 8 bolts and you don't even need a gasket.
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Re: Mikuni vm38 round slide carb setup

Postby rigidKHK » Tue Jun 05, 2018 7:57 am

Hi, maybe I am little late with this but just came across old notes of mine. -56 KHK with mikuni VM38:
pilot 40
air screw 2 turn open
slide 2,5
needle jet Q-2
needle 6DP1 clip middle position
main jet 340
air jet 0,5

with these it should be close enough to start and run.

regards, Vesa
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Re: Mikuni vm38 round slide carb setup

Postby 55panman » Tue Jun 05, 2018 9:52 am

Mikuni 38, First it would probably run better with a 36mm Mikuni. 38 good for Sporty or 74 ci. Better fuel signal at low RPM. Next did you just put on the Magneto???? Just because it has spark when turned by hand doesn't mean it's good enough to run it. A buddy had trouble with his Panhead after putting on a magneto from ebay. I kept telling him to send the mag in for service after he called me numerous times for advise. He finally sent it in, got it remagnatized and serviced. Started right up and now starts easy. Depending on where you got the mag you don't know it's condition. If rotor was left out of body it looses it's charge.
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Re: Mikuni vm38 round slide carb setup

Postby RunninWild » Tue Jun 05, 2018 11:54 am

Thanks for the setup info rigid! Glad to find a solid baseline and not just my guessing. Panman, the mag was off of a running XLCH I had so it's a running mag.

I pulled the heads and found scoring on both cylinders and a bunch of dents in the combustion area of the front cylinder head. Not sure what I let get into the engine but I fucked it up haha. I don't have money for repairs right now so it'll just be sitting for now.
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Re: Mikuni vm38 round slide carb setup

Postby 55panman » Tue Jun 05, 2018 5:03 pm

Missing any nuts or bolts from the air cleaner arrangement?
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