Scooterotica

Rebuilding a Monza 225 with a 'Jimmers' CNC-machined billet Manifold ( if I remember correctly, bought over 4 years ago) with what appears to be a 'M-VM28-200 (K?)' Mikuni rubber mounting flange and a Mikuni TMX30.
A leak down test confirms it's leaking at the ruber carb mounting. I assume this has been caused by overtightening the flange bolts in the past.
Can I use some type of sealant like Yamabond or something to create an airtight connection or do I need to replace the rubber flange?
What is the exact type of rubber I need? Most online places and evilbay state 'M-VM28-200-K' as being 26-28mm typical bore size.
Are there different diameters of rubber flange available?
Also recently I saw a picture somewehere of the same type of rubber flange but with a small ruber sleeve protruding that I assume would fit in the manifold bore. Does this type seal better? And where do I find these?

Ive got a similar kind of flange type manifold on mine and it uses a Kawasaki 550 rubber, sorry i cant be more specific than that but the PHBH 28/30 fits well.

Slightly off topic, but that looks like a CNC machined manifold, whilst Jimmers are cast. I was able to machine about 8-10mm off the face where the rubber is located to allow the carb to sit closer to the frame and get a air hose in.

I did need to do a bit of ali welding where the RHS rubber stud sits, but I was surprised that I was able to remove that much metal.

The rubbers can be purchased from Allens Performance.

Oh, and Yammabond will do the trick (leave it 24 hrs before you repeat the leak down test)

Hi Knowledge....................what's the best manifold to get for a TS1 to allow a breathe easy air filter to be used on a 30mm VHSH so that it sits beneath the side panel without cutting any holes ?

Knowledge wrote:Slightly off topic, but that looks like a CNC machined manifold, whilst Jimmers are cast. I was able to machine about 8-10mm off the face where the rubber is located to allow the carb to sit closer to the frame and get a air hose in.

I did need to do a bit of ali welding where the RHS rubber stud sits, but I was surprised that I was able to remove that much metal.

The rubbers can be purchased from Allens Performance.

Oh, and Yammabond will do the trick (leave it 24 hrs before you repeat the leak down test)

I'll try the Yamabond then...
I'm all up te date on the details but wasn't there was a version that was CNC machined and another that was cast. I believe the CNC version was a 'copy' of the cast one and there was some debate on intellectual property and cheap copies....
Anyway... I bought a CNC version somewhere 'cause it was available at that time...
I won't be able to machine 10mm of the mounting face as it's already flush with the barrel reed valve sealing face, I might be able to machine it at an angle but that would sit the carb at a weird angle and there would hardly be any benefit... I already machined the mounting flange of the manifold to the barrel to recesss the reed cage so the manifold sits 4mm lower to create soem clearance to the frame tube.

If you can't get yammabond for any reason loctite 510 is an excellent if not superior alternative

Strummer10 wrote:Hi Knowledge....................what's the best manifold to get for a TS1 to allow a breathe easy air filter to be used on a 30mm VHSH so that it sits beneath the side panel without cutting any holes ?

I have gone for the Jimmers cast manifold with a rubber from Allens Performance on my Pro-Porting barrel. Despite the extra capacity, the inlet reed valve sits in pretty much the same position as a TS1. Here are some photos:







This has been done to get the carb as close to the frame tube as possible. Of course, carb dimensions vary from manufacturer to manufacturer, and from model to model.

Fitting an elbow and air filter is now up to you.

I won't be able to machine 10mm of the mounting face as it's already flush with the barrel reed valve sealing face

Mine is now cut back to the gasket face, and I will be running with only three securing screws, not four.

I'd say that your CNC manifold is an LTH version. I've had some manifold and rubber combinations where the holes didn't quite line up making me think that the rubber might "lift" in the centre once tightened down ..... and potentially leak.
The rubber with the inner elongated lip will be an MB one.
https://www.lambrettaspares.com/spares/ ... b0833.html

corrado wrote:I'd say that your CNC manifold is an LTH version. I've had some manifold and rubber combinations where the holes didn't quite line up making me think that the rubber might "lift" in the centre once tightened down ..... and potentially leak.
The rubber with the inner elongated lip will be an MB one.
https://www.lambrettaspares.com/spares/ ... b0833.html

It is indeed the MB-version I saw somewhere, thanks for pointing it out to me!

Fruitjuice wrote: The rubber with the inner elongated lip will be an MB one.
https://www.lambrettaspares.com/spares/ ... b0833.html

It is indeed the MB-version I saw somewhere, thanks for pointing it out to me![/quote]

Rubber is spot on but not all manifolds have the bolt holes in the correct position meaning that the "lip" had to be cut off.