82 Yamaha Maxim 400 Carburetor rebuild kit

[GuyS]

Hello. I am brand new to the forum. I am anticipating buying the bike. The carbs need rebuilding. I believe they are Mikuni BS34’s (32mm). I haven’t been able to find a rebuild kit. Can anyone on the forum help me? Other parts too like the front brake system will need rebuilding. The rotor looks scored pretty good.

 

[JohnP]

I found all the parts including carb kits and brakes for my 82 heritage special at MikesXS.

 

[GuyS]

Thanks, I’ll check them out.

 

[XSSmith]

Welcome aboard bud!

 

[GuyS]

Thanks. Just getting started on my 1982 Yamaha Max 400. Mike XS had some parts I was looking for. My front hydraulic system is toast. Gunk etc in the master cylinder and reservoir. My tubeless tires won’t seal. My carbs need to be redone. And my seat needs recovering. It would be nice to find a solution for that! An upholster wants $375 to redo it but that’ll take too much of a bite on the budget.

 

[2MuchXS]

Hi I don't think they are tubeless rims. I've owned an xs400 (seca) from new 1982 and it came with inner tubes
Check out eBay for seat cover quite straightforward to fit. YouTube is your friend if you're not sure

 

[GuyS]

The rims say “Suitable for Tubeless Tires” but the front tire has “Tube Tyres” on it. Just yesterday found a company in Texas that makes covers for all sorts of motorcycle seats, that you install yourself. It’s called B&H Specialties. I’ve just ordered one so can’t comment on the their value yet. The seat cover was reasonably priced. And yes Youtube has a ton of video’s on old bikes. It just makes it so much easier for a backyard mechanic.

 

[2MuchXS]

You can use a tube with tubeless tyres and personally I think I'd feel safer with a tube in. It's not gonna affect the way it handles.

 

[GuyS]

I’ve taken off the carbs now. Thanks to the forum for describing the essentials to removing the carbs (like removing fender bolts so the carbs can be pulled back. When I got the intake manifolds off, I noticed there were no gaskets. My manifold has 2 rubber O rings on each manifold about 40mm x about 1mm on the manifolds. Are those O rings intended to take the place of gaskets? My O rings look a little flattened in some places.

 

[GuyS]

Update: My right side carb manifold was damaged but thankfully I was able to find another. Regarding the O ring/gasket issue so far I have discovered that there is no gasket, ……O ring ONLY. That makes sense because the O ring is only 2mm thick so a gasket would negate the O ring space and ability to seal. The boots mate to the cylinder head surface, with the O ring providing sealing to an almost metal (cylinder head) to metal (metal flange on carb boot) surfaces. My right side carb boot O ring was flattened out and harder than the other. Probably because of the small air leak (from the damaged boot), made that cylinder run leaner, hotter. Both O rings on the carbs were nitrile, aka buna-n. That material has a heat limit below the potential cylinder temps. I was able to finally find O rings made of “Viton”, which has a heat range within the cylinder head temps. I haven’t got the bike running yet but will let others know how well my carbs work after I rebuild them. Thanks for other forum members for their help along the way to restoring this old bike.