Carb Bowl Interferance VM34's

[johnu]

Just tried fitting my new VM34's to my T500 and the left side carb bowl is hitting the ignition case. Anyone else run into this problem? It is the bump in the bowl casting where the dowel for the float is pressed in. I see 3 ways to rectify the problem but I dont like any of them.

1. I could try filing down the bowl casting but I don't know how much I could take off until it goes through into the hole.
2. I could modify the ignition case (mill a chunk out).
3. I could use the original long manifolds which should give me clearance. However all the engine work was done with the intent to use short manifolds.

I would choose option #1 if I was sure that I could remove enough material without causing an issue.

 

[smajure]

I was unable to get a pic of mine yesterday but ill try this evening

 

[two-smoker]

If it was me, I'd mill a little clearance out of the case. But that's me.

 

[SONICJK]

If it was me, I'd mill a little clearance out of the case. But that's me.

Same

 

[DreadRock]

Its hitting the cover for the sprocket correct ? and only on the one side ? I would agree mill lil off the case cover ...

 

[SONICJK]

Maybe even just drill you some speed holes in the sprocket cover and work one of them into that spot somehow?

 

[johnu]

Well after a closer look the protrusion on the bowl is hitting the crankcase not the cover so that option is off the list. I am hoping I can file or mill a small amount off of the bowl. Just need to know how much I can take of without getting into trouble.

 

[DreadRock]

Could you take a lil off both to get the whole ?

 

[Finnigan]

Could you try angling both of the carbs? Wouldnt look brilliant but would save a load of time

 

[Tim]

Attack the bowl. Worst case you need to close it up with some alum weld or buy a new bowl and try a different approach.

 

[Tim]

Or angled intakes but that would likely impact performance and would likely need to be custom made.

 

[johnu]

Or angled intakes but that would likely impact performance and would likely need to be custom made.

I think I am going to make tapered aluminium shims to go between the intake and the cylinder, it will only need about 5 degrees of taper so it shouldn't impact performance too much.

 

[Big R]

If I'm not mistaken, Mikuni also has a tolerance for degrees off level as well. Worth looking into so you can see how much you can tip the carbs.

 

[Tim]

The Mikuni's on my BMW are well off-level, and behave normally. Considering the angles motorcycles work at, with acceleration and braking forces on top of that, a few degrees of angle shouldn't cause any issues from a functionality standpoint and the difference in air flow should be minor.

 

[HerrDeacon]

Mikuni VM's can be mounted as much as 20 degrees off.

 

[johnu]

Mikuni VM's can be mounted as much as 20 degrees off.

Thx for the info, good to know!

 

[joea]

hi,
my first thought was to use tapered shim stock to angle the manifold slightly ,not sure how readily available it is outside of aviation field but possibly easy to find if you do not want to mill your own. you could also use micarta sheet .
joe
www.joesvcycle.net
www.joesvcycle.wordpress.com

 

[Tim]

You might give these guys a shout and see what they have to help you with.

http://www.jbmindustries.com/index.html

Also if you have the tools, you can make aluminum carb intakes and use a hose to connect the carb to the intake. Welding a tube that is cut on an angle onto an aluminum plate to bolt to the engine would let you do whatever angle and intake length you want.

 

[johnu]

Thanks Tim, that's a great link. I may end up making new manifolds because it is very difficult to make the tapered shims. The hard part is holding them in the lathe to machine the angle on them because they are only a few mm's thick.