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I "rebuilt" my XL500s carb, and now its running WAY to lean.

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hey everyone- 

 

So I bought a keyster carb kit for my 1980 XL500s. The rebuild didn't go as planned. 

 

First off, I disassembled my carb and put everything in carb cleaner. This was probably a bad idea, because the accelerator pump and air cut off diaphragms both shriveled up a bit in the bucket. 

 

I replaced everything. The air screw came with a tiny gasket and a tiny washer. The gasket ripped immediately and now there is no gasket in the air screw. Big deal? I don't know. There is also supposed to be a gasket that sits next to the air cut off valve, but I couldn't find that either. 

 

Anyways- this is what I got:

-Sub par diaphragms (accelerator and air-cut-off)

-no gasket/washer in air screw

-no gasket in air cut off assembly

 

My plug is white, and my bike runs and idles pretty weird. Anyone know how to best approach this? Does the air screw really need a mini gasket? 

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Same here.   I just re-sealed my head cover then rebuilt the carb (with the eBay kit).   One trip down the street had it running so hot I could hear the oil boiling inside the head...  seriously  :banghead:    

 

Plug is pure white.  When I pulled the carb back apart the float bowl o-ring swelled so large it won't even come close to fitting back into the groove..      

 

What changed?  I removed the head and resealed it.  I rebuilt the carb with the Ebay kit (couldn't find anything else).  I've rebuild hundreds of carbs...

 

 

Hope you figure something out.  I'll let you know if I do.    

Edited by Rot Box

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All of the gaskets and orings are there for a reason. Your carb is sucking air and leaning the mixture. Carb cleaners mess up rubber parts, you have to remove them before you clean. Replace all missing or damaged parts and try it again.

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Aerosol cans of starting fluid have helped me find many sucking air leaks; even found a bad crankshaft seal after removing the side cover and spraying little bursts around the flywheel.   The rpms went way up at idle.

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Thanks for the replies. 

 

Replaced both diaphragms (accelerator pump and throttle valve). Bike seems to idle and run just fine now.

It still seems to be a tad bit lean on the idle side....I say this because the bike has a jerky throttle response from 0 throttle to 1/4 throttle when riding around. 

Also, it now always requires the choke to start up. This wasn't this case before, it always used to start first kick with no choke. 

 

When the user manual states that the air screw be turned out 2 5/8 turns, I assume by turns it means full 360 degree turns right?

 

Thanks!

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  2 5/8 turns is close enough to 2 1/2 for any rational man.  Don't over-complicate things.

 

Having to use the choke to start it is a non-issue.  Quit worrying and go ride the wheels off it.

Edited by Jimmy Pascol

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Rebuilt my carb for the first time since the bike was new. All original gaskets were in good shape. The float bowl was covered with a layer of garnish and at the bottom some garnish that chipped off the sides into frags. The main jet was also clogged and the top of the carb where fuel enters in the float bowl (idk the name lol) was also clogged. The bike was sitting in a storage unit for 10 years so I guess thats to expect.

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Gasoline will varnish up a carburetor over time.  Spray carb cleaner into every jet and blow it out until you feel air going through it.  

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