Question about setting float height

I've taken my carbs off my XJ900 and put them on a carb stand. But I've noticed that they don't sit level forward and aft on the bike. My question is do the carb have to be level on all axis to set the float level correctly or should I use the angles that they sit on the bike during normal operations.

Robert

 

Didn't your carb stand come with instructions explaining this issue?

 

IIRC the Yamaha method says to make them level left to right and front to back.

 

Yamaha says to jack up or otherwise position the bike so that they are level. Need to be level front-to-back and side-to-side.

 

Thanks for the help guys. This carb stand is home made which can be leveled left to right and front to back.

 

I set my rack on a flat surface and used a piece of scrap wood behind the rack to jack it up to level.

Your homebrew carb rack clamp is quite spiffy. Check out my homebrew synch bottles in my gallery.

 

So simple. I like it.

 

Looks pretty useful. How about some more detail photos for those of us who would like to build our own.

 

On the 900, I believe the float height according to the factory manual is 22mm from the gasket face of the float bowl to the top point of the float itself. The float has to be sitting gently on the closed valve to be measured correctly. At least that's what the manual says. Something to remember and DAMHIKT - be careful bending that tang on the float assembly to change the float height. They're awfully fragile.

 

how does bending the tang affect fuel level? i.e. does bending the tang up towards the carb body raise or lower fuel level? up = less fuel correct? and it is the tang which is attached to the needle valve right, not the tang that prevents the float valve from raising too much?

I would also like to see more info on your carb rack supero, looks neato.

 

Bending the tang up towards the carb body lowers the fuel level in the bowl. Because the tang is pushing the fuel needle closed sooner which means less fuel in the bowl.

I'll make a new post with some photos and parts on the carb stand soon.

 

I have an idea. I noticed that the front of the carbs face downward on the engine side. What if I put the bike on the center stand. This I believe would raise the back thereby tilting the carbs even further forward. Now if I put some weight on the luggage rack to force the back tire down, it would lift the front tire up off the floor. I believe this might level the carbs from front to back. I could then put a block under the front tire to hold it there. And the side to side should be close being on the center stand.

If this would work, I wouldn't need to build a carb stand and the little bottles for the gas.

Any Ideas?

 

However, using the carb stand and the little gas bottles would allow me to adjust the float levels to within specs. I would need to take them off the bike anyway to do this unless I want to try to do it upside down with the carbs still on the bike. Seems like a better way off the bike. I've had the carbs off half a dozen times anyway. What's once more.

 

Photos and parts list on making carb stand.


http://xjbikes.com/Forums/viewtopic/t=14520.html

 

don't they just make gauge to set the floats? seems like that would be easier than this set up.

 

This method is outlined in one of my service manuals for checking levels while on the bike. It's a good idea for CHECKING, since if everything is OK you might not have to pull the rack. However, if adjustment IS necessary, you have to pull the rack and then you don't want to have to put it back on the bike again to check it, so some form of stand is necessary.

They don't unfortunately. However, a gauge would still only get you "close" because it would not be able to take into account any variations in bouyancy between individual floats. Luckily, this is a "set it and forget it" adjustment, once it's correct it won't need adjusting again unless you replace float valve parts. Doesn't make it any less of a pain in the ass.

 

WOW!! Thanks Supero 1 for the Carb Stand plans. Great pics and instructions. I didn't know it was so simple to build. Should work out great. Now if I can figure out the construction of the gas bottles, I'll be all set.

Anyone have a link to construction plans for the gas bottles. I did a keyword search for gas bottles and came up empty.
Thanks