Vm32 help!!!!

860go

New Member
Hey guys, I’m pulling my hair out here; I know I’m desperate when I hit the forums haha.

Xs400, ignition timing is checked and rechecked, compression is good, Spark is great, can’t get fuel into this engine.

I’m running brand new Vm32’s ball park jetted from DCC for 400cc’s, fuel supply is flowing great, battery power is great, fuel is in the bowls, I can not even get the plugs wet with fuel on either side. The engine runs on starter fluid but only spits and coughs occasionally without it.

I’ve never worked with Mikunis before, am I missing something?

Thanks, clayton
 

teazer

Active Member
DTT BOTM WINNER
They are a little large and that will make it hard to jet at small throttle openings and/or low revs. As Nebr-rex suggested, try to screw the air screw in to see if that richens it up enough to start and idle, but you will probably need larger pilot jets.

Most re-jetted carbs are jetted all wrong for a 4 stroke motor and need changes to air jet, needle jet and needles to get them close, but maybe DCC are jetting them for a 4 stroke. I suspect they came with 159 series needle jets and 2.0 air jets which are fine for a 2 stroke and not much use on a 4 stroke. You can make them work, but better off with suitable needle jets and 0.5 air jets.

But for now try a larger pilot jet and see if you can get it to start and idle.
 

860go

New Member
Thank you for your reply and time. You are spot on with your assumptions.

185 main, 35 pilot, 6dh7 jet needle, 2.0 air jet, 159 p-5 needle jet. I went with these because they specifically mentioned the xs400 in their production description.

I will try some different pilot jets first and go from there just to try and get some headway.

I have gone in and out with the air screws to not much avail. I suppose I fell ignorant to the hope that DCC jetting would be pretty close out of the box. The only thing that makes sense from here is to go down that road.

Thanks again, Clayton
 

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Nebr_Rex

Member
860go said:
Thank you for your reply and time. You are spot on with your assumptions.

185 main, 35 pilot, 6dh7 jet needle, 2.0 air jet, 159 p-5 needle jet. I went with these because they specifically mentioned the xs400 in their production description.

I will try some different pilot jets first and go from there just to try and get some headway.

I have gone in and out with the air screws to not much avail. I suppose I fell ignorant to the hope that DCC jetting would be pretty close out of the box. The only thing that makes sense from here is to go down that road.

Thanks again, Clayton
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860go

New Member
Thank you, still a bit to go the get it wrapped up but hopefully this is the year it gets finished haha.

After a crazy busy week at work I pulled the pilots and found 25’s. I just placed an order for 37’s and 50’s. Fingers crossed
 

teazer

Active Member
DTT BOTM WINNER
Don't be. Some of us have tons of jets in boxes after years of this sort of trials and tribulations. We just have a (slightly) better idea of where to start looking.
 
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