Mikuni VM29 Carb Air Problem

[Bongoball]

Hi Chaps,
Advice needed please.
I've got a set of Mikuni VM29's on my Z650.
Today I've used a Gunson Colourtune to make sure my air screws are set correctly.
No's 1, 3 and 4 went fine, out between three quarters and one and a half to achieve a nice bunson blue.
No2 however wasn't playing.
Screw fully in, it was blue, screw out still blue!
I presume I've got an air leak somewhere?
Apart from the inlet rubber, is there anywhere else it could be?
I sprayed WD40 onto the rubber while engine running to see if revs lifted but they didn't.
Look forward to any pointers.
Cheers,
Bongo.

[gray]

I assume the valves are set ok?
3 possible leaks
head to inlet rubber
inlet rubber to carb mouth
balancing brass pipe/rubber plug ( try swopping the plugs around to quickly check)
Revs won't rise unless you use something volatile on the area, and the WD40 you tip out of a 5 litre container into a scooshy bottle yourself will have no propellant in it. Try carb cleaner/brake cleaner/ east start instead/
failing that it's a carbs off job to look at the passages

[Bongoball]

Nice 1 gray, I'll try brake cleaner tomorrow (if the rain ever stops!)

[Jeff Saunders]

Were they totally pulled apart?

One of the critical parts is the thin gasket under the jet block. Without that the pilot circuit won't pickup fuel effectively.

Make sure the air jet is clear. That's the little jet screwed in from the air filter side. It's sits deep down in the hole aligned with the air screw.

[Bongoball]

Hi Jeff,
Thanks for the info.
They were stripped and completely rebuilt by NRP Carbs in Manchester.
I hope they didn't forget to put on the gasket!
I'll check the air jet first before having to pull them off....... Again!

By the way, Motion Pro clutch cable arrived last week.
Massive difference to the one that came off, really smooth!
Also made an alloy shim for the kickstart blanking plug.
Gave it a bit of a polish too...



Thanks for a great service.

Cheers,
Bongo.