XS11 SH rebuild status - It started

[RichV]

Well I got the 81 running today. It started right up the first time and runs on it's own (after idle adjustment).

Here's a video on YouTube: http://youtu.be/gppYGR-Rpgs

I only had one problem. Fuel came out of the air intake. Not alot but enough to make a little mess. Further inspection showed it was coming out of all four carbs. Any suggestions?

I have a jury rigged gas tank on a box and it may be putting too much pressure on the fuel forcing it to leak past the floats. Just a guess. Hoping anyway.

The carbs were bench synced but I have not adjusted them on the bike. Only the idle.

Well anyway at least it started and that is a very good sign.

[jetmechmarty]

That's got to feel really good!

So, you have fuel coming out the bottom of the airbox? Is that correct? Is the filter installed?

Any time I've had a stuck float, the affected cylinder goes cold and fuel is dribbling from the airbox at a rapid rate. Yours does not appear to have that problem.

[JeffH]

Well I got the 81 running today. It started right up the first time and runs on it's own (after idle adjustment).

I've been following along your 'build' saga in previous posts.
You sure have made GREAT progress since your Dec 26 & Dec 29 posts when the cylinders were off.

You must be happy to have it running so well. Big effort but looks like you prevailed. Congratulations! zoom-zoom.
Thanks for posting the video. You will have to bring this one to the SE Rally this year.

Jeff

[TopCatGr58]

Hey Rich,

COngrats on getting it going. Now to the carb leaking problem. Those do look like the 81 carbs....and so it looks like you have just the 2 fuel lines...WITH inline filters going to the fuel inlets....those later models don't have the 2nd set of upper T's that are only for vents....but folks have mistakingly hoked them up to fuel....and lots of flooding!

SO....next thing is the float valves/seats. Are you using the VITON tipped ones? Next, did you replace the O-rings around the valve seats? They can also cause leaking/flooding if they don't seal. And of course both the right float height...~23mm....but others will suggest using the clear tubing connected to the float bowl held up to the side of the carb/body as the method recommended by YAMAHA. Also the floats can possibly be hanging up on the float bowl gaskets....folks have had to trim the gaskets while in the bowls to ensure float clearance.

Also there's a TANG on the float to restrict just how much it drops when opening....but if it drops too far, it can allow the needle to come too far out of the seat....and get cocked/wedged/stuck. Keep at it.

T.C.

[RichV]

That's got to feel really good!

So, you have fuel coming out the bottom of the airbox? Is that correct? Is the filter installed?

Any time I've had a stuck float, the affected cylinder goes cold and fuel is dribbling from the airbox at a rapid rate. Yours does not appear to have that problem.

Marty, I only noticed the problem after the bike cooled down. I saw the puddle and thought, for a moment, that I had an oil leak. It was a mixture of air filter oil and fuel so I know it came out of the box. I removed the filter and it was full of fuel. I have a regular foam filter (which I will replace with a high air flow one later).

I had walked away without turning of the pepcock on the test fuel tank. When I cam back I turned it off and noticed that the fuel use was excessive. I then saw the puddle.

I felt the air intakes and all but #2 had fuel in them.

The bike ran ok during the start test and I ran it for ten minutes. This all occurred after shutoff.

[jetmechmarty]

Go through TC's checklist. Maybe it's just very very rich. If the needle doesn't seat and shut off the flow, it's going to keep leaking after you shut it off.

[RichV]

Hey Rich,

COngrats on getting it going. Now to the carb leaking problem. Those do look like the 81 carbs....and so it looks like you have just the 2 fuel lines...WITH inline filters going to the fuel inlets....those later models don't have the 2nd set of upper T's that are only for vents....but folks have mistakingly hoked them up to fuel....and lots of flooding!

SO....next thing is the float valves/seats. Are you using the VITON tipped ones? Next, did you replace the O-rings around the valve seats? They can also cause leaking/flooding if they don't seal. And of course both the right float height...~23mm....but others will suggest using the clear tubing connected to the float bowl held up to the side of the carb/body as the method recommended by YAMAHA. Also the floats can possibly be hanging up on the float bowl gaskets....folks have had to trim the gaskets while in the bowls to ensure float clearance.

Also there's a TANG on the float to restrict just how much it drops when opening....but if it drops too far, it can allow the needle to come too far out of the seat....and get cocked/wedged/stuck. Keep at it.

T.C.

T.C.

There is only the one set of "T"s. If you remember, I removed the original fuel lines and replace them with new lines with inline filters and a cross over so only one line needs fuel to run the engine. For test purposes, I have the left line connected through a pepcock to the test fuel tank.

I originally rebuilt the carbs a year ago and went the cheap route by cleaning it and replacing the "O" rings. I was fairly sure I did them all. Anyway, they ran okay on the other bike I had (the leaking one) so I felt I was good to go.

Before putting them back on this bike, I removed the bowls and did a simple cleaning with carb cleaner. I also checked the float heights. They were in spec and moving properly.

I suspect that the "O" rings I used did not hold up well over the year. No proof yet but I suspect it. I did a cheap rebuild to save money and should have done a full one.

So should I just get the rebuild kits? Any suggestion on a source? Many on eBay for $20+ per carb.

Any suggestion would be welcomed. I have always had a problem with carburetors and embraced fuel injectors with open arms.

[bikerphil]

I have a jury rigged gas tank on a box and it may be putting too much pressure on the fuel forcing it to leak past the floats. Just a guess. Hoping anyway.

It is possible, I have heard of this happening before, you never know. Try lowering the aux. tank to the same level as the normal tank would be. GL

[jetmechmarty]

I don't think you need kits. Replace only the failed components. I prefer an OEM supplier like Partzilla when I need first quality. There are quite a few options for OEM. 2nd rate rubber bits aren't worth the trouble.

[RichV]

I don't think you need kits. Replace only the failed components. I prefer an OEM supplier like Partzilla when I need first quality. There are quite a few options for OEM. 2nd rate rubber bits aren't worth the trouble.

Actually, I was thinking of this one.

The main advantage of doing a kit is that I'll have a higher likelihood of fixing the problem. Since it's difficult to remove, tear down, and reinstall the carbs I would rather do it only one time.

First, I'll try lowering the test tank to see if that helps.

[jetmechmarty]

Actually, I was thinking of this one.

The main advantage of doing a kit is that I'll have a higher likelihood of fixing the problem. Since it's difficult to remove, tear down, and reinstall the carbs I would rather do it only one time.

If you buy this kit and it comes with genuine Mikuni parts, we will all want to know about it! Chances are, the jets will be useless to you, but it still might be a good buy. I'm encouraged by the fact that the seller knows what the stock jetting was. That's impressive!

[RichV]

I tested the bike with the tank lower. I placed a paper towel below the air box with the filter removed. Ran the bike at idle for 15 minutes and it didn't leak. I then left it for 3 hours with the petcock open with no leaks. I'll test it later with the filter back in.

I still think I need to rebuild the carbs. It shouldn't have leaked before.

[jetmechmarty]

Are you putting this together without the vacuum shutoff? I don't see it, and I assume you know there should be no fuel at the float valves if it is there, so long as no vacuum is applied.

[RichV]

Yes, it's removed. I did it over a year ago and forgot that part. At the time I just thought I would remember to turn it off.

It was removed from one of the bikes and I could not confirm that it was working correctly on the other so I just left it off. It eliminated the need for the prime lines and, of course, the octopus.

I guess this is the root cause. Thanks for the help. I'm glad I don't need to remove the carbs again.

[RichV]

I ordered the Pingel 9050-AV cutoff to replace the function. I don't want this to happen again.

The oil appears to be okay which is good since it's synthetic.