I have a 90 Quadzilla and have just recently rebuilt the top end. Stock bore with a Wiseco piston and rings. While I had it down I took the carburetor apart and cleaned it also. Now when I start it up it will only run for a few seconds and then dies. If I open the throttle while it is running it begins to rev then dies. I have taken the carb back apart and everything looks right. I am at a loss. It ran before I rebuilt it so I am thinking it is in something I have done but I cant find anything wrong. Any help is appreciated and welcomed. Thanks.

 

Need more info to give good help.

How did it run before rebuild, why was it rebuilt?

Did you do basics?
Compression
Fuel
Spark (if it starts at all spark is probably ok.... unless you have a wire shorting or grounding out intermittently)

If I were to guess with the information you gave so far.... Check fuel flow to carb , screen in the gas petcock it is known to get clogged. If you have good fuel flow to carb, check to see if float bowl fills(needle&seat stuck?). Is the plug wet or dry?

 

Floats too low maybe?

 

Definitely sounds like a fuel delivery problem to me. Most likely its letting just enough gas seep to bust off, and after that supply is depleated it is not pulling anymore fuel to continue running. Check the floats on the carb, make sure they are not sticking or set to low, also, check all the fuel lines and make sure they are not obstructed in any way. And check all the overflow tubes, I had a LT250 that wouldnt run because one of the overflow tubes had gotten on the exhaust pipe and melted itself shut.

Good luck

 

i also agree with the others . sounds like a carb prob for sure . like 2 stroke said check the lines . let us know if you get it .

 

Sorry for lack of information everyone was still frustrated. Ok here goes:

AllCool it ran ok(not great) before I rebuilt it. The reason I rebuilt it was due to low compression. I bought it used and it would turn over way to easy. Also was hard starting. I suspected some possible carb problems or just jetting as to why it was hard starting and would not run smooth wide open. It would blubber. When I got the top end off I found a crack in the sleeve. Had the cylinder re-sleeved to stock bore and put in a new Wiseco piston, rings, wristpin and clips. Bike was also missing exhaust gasket so got a new one there. While I had it apart I took the petcock out of the tank and cleaned both it and the tank up. Completely flushed both. Seeing all of the junk in the tank and petcock I decided to clean up the carb also. Took it completely apart and cleaned everything. So far I have good flow to the carb. I have tried working the floats with the bowl off and they work. I have adjusted the float level up to the point that it begins to overflow and then backed down enough to stop it. Float bowl seems to be filling fine. Started with a clean(not new) plug and it is now wet. I suspect it may be fouled now since it wont run long enough to get warm and clean up. Buying a new one tomorrow.

To answer the other's questions I took all of the overflow lines off the carb to make sure they were clear. I have found one more thing since posting earlier. I took my carb and reed cage off. Looking at my reeds I notice that they are not closing all of the way. The gap is very small but I know that they should not have any gap, correct? I am wondering if the new top end and thus higher compression has brought to light a problem that wasnt so visable with the lower compression of the worn out piston and rings? Anyone have any other ideas? I am ordering a new set of reeds tomorrow also. Suggestions on a good set of reeds? Boysen? -- Thanks

 

it wants fuel

 

when u open the throttle do u open it all the way fast or....i had a probblem like this with something else had to reset low speed needle