my 1987 22R with a 32/36 DGEV Weber carburetor is bogging down and i cannot reach over 35mph. when i use more than 1/4 throttle thats when it bogs down and i get an occasional backfire out of the carburetor.

this all started after i replaced the old head, because of a crack, with a new built head. i have gone back to adjusted the valves, double checked the timing, checked vacuum hoses, changed the plugs, and rechecked everything in regards to ignition. i am hesitant to mess with the carb due to my lack of experience with them and because it worked just fine before the head swap but it is the last thing i can think of that could be causing this problem unless i have overlooked something…

I am at a total loss right now and any ideas would be greatly appreciated!

 

Well first before you go into anything else I would double check the cam timing. Its easy to get the sprocket off one tooth. Eliminate that possibility first.

 

yes second to cam timing. that backfire is your biggest hint. they shouldn't be possible when the timing is right.

 

Based on a second visual inspection of the timing mark on the sprocket and the mark I made on the chain link they are exactly where they need to be. Wouldn't it show symptoms at idle and when lightly applying throttle too?
After disassembling the carb it seems that the float level was off and the secondary throttle plate is binding a bit. After resolving those issues I will move the cam sprocket forward and back a tooth.
Thank you for the suggestion! Will report back soon.

 

From what I understand this engine will idle/run when its off one tooth. What kind of mark did you make on the chain? Did you have the crank at top dead center when you installed the cam chain and sprocket?
When putting on the new chain the tensioner can mess you up and get the tooth off by one. Thats why you put the silver link at tdc on the cam sprocket and then check position of the #1 piston. For some reason I have two timing marks on my pully [don't know why] one of them is tdc mark? Always verify.