Backfire

Wouldn't it be prudent (as GB would say) to replace them once I have taken the manifolds off?

 

You bet I would definitely replace them. I actually thought you had done that when you took them off.

 

Hi Bill and Fitz! I was having running problems as well (1000 RPM on choke) and was thinking I had an air leak but wd40 all over the place didn't work and I remember I told Fitz that when I took out the air filter and ran the bike it was fine. Well I did it again and it was not fine. bumped it up 200 RPM at idle but still running like crap. I need help...

If it's not air, does that mean it's a gas issue?

 

If I recall you have a Uni filter. IT should be cleaned and reoiled with foam filter oil. They actually allow more air flow than the stock paper filter. I returned when I added the Uni to my bike.

The fact that it runs without the filter says to me the filter is clogged and restricting air. I would clean and reoil the filter properly to start.

 

The Gaskets are SIMPLE to make. If not the Easiest!
Scissors, ExActo, Razor Blade
Old 19mm Socket
PaperBoy Type "One-Hole Punch"

Sharpen the 19mm Socket's Inside and Outside Diameter to a SHARP Cutting Edge.
Trace an old Gasket onto Gasket Material
Cut-out the Outside Line
Paper Punch the two Stud Holes
Lay the Sharpened Socket along the curve of the Inside Diameter of the Gasket Big-Hole. Hammer and Cut. Folo the Curve.
S-I-M-P-L-E !!

O-rings you can get at the Hardware Store that will be better than the ones you replace.

Add: Indian Head Gasket Shellac. Bonds Air Tight!

 

Sorry Rick, I have to take issue with that. Hardware store o-rings are generally intended for use in household plumbing applications, and are NOT superior to PROPER O-RINGS for the motorcycle application. In most cases they aren't designed to withstand the much higher temperatures generated by a motorcycle engine.

Agreed there are probably a lot of aftermarket parts out there that may or may not be inferior, but the correct o-rings are going to be rated for a much higher temp than what you'll find at the hardware store.

I would get "real" manifold o-rings from chacal or your Yamaha store.

 

Bill,

That's the thing, the filter barely changes anything at all. So I don't think it has anything to do with air anymore.

 

New info!! I took the airbox off the carbs and started it up and revved it and the black things on top that move in and out when you throttle, were only moving on carbs 1 and 2. 3 and 4 moved only a very little when I revved it up high

 

Ok spent a little more time on it. The black things I'm talking about are diaphragms and I also realized that 3&4 butterfly don't open at the same time as 1&2. 1&2 get like a cm open before 3&4 kick in. Is it supposed to be like that??

 

Let's not hijack this thread - please start a new one and I will post some stuff for you to look at

 

k thanks

 

It is virtually impossible to find an o-ring that is made from natural rubber - the stuff that comes from rubber trees - today. What you will find instead is a product that is made out of a synthetic material, called an elastomer, that looks, feels and behaves like one might think natural rubber would.

But today different synthetic materials have been developed to withstand greater temperature and pressure ranges, to resist harsh chemicals, and to stand up under tough conditions such as abrasion and exposure to ozone and sunlight.

 

Wouldn't it be easier to just by from Len. Where would I look for such an o-ring?

 

Yes. It will be easier to buy from Len ...

Unless ... Your Hardware Store has a Section of "Pull-out Drawers" with EVERY O-ring in the known Cosmos.

Then, you ... Scrape-out the Old O-ring from the back-side of the Manifold.
Measure the Diameter with Calipers ... or, ... bring the Manifold with you.

The "Right" O-ring will FIT in the Channel and be RAISED enough to provide a SEAL.

The Store-bought O-rings are SYNTHETIC and when you buy 4 of them with a 5-Dollar Bill ... you get Change!