running issues

[bigdaddysean]

hi, i am new to the forum.i just bought a chopper with a cb750 engine 78 model,it also hs a cycle x 4 into 2 carb and intake set-up.and it has a250 rear tire as well with a jack shaft final drive set-up. so heres my issue the best i can describe it.  when you take off or ride the bike as you throttle into it,it begins to hop excessively,unless you arehard in the throttle and it stops only for a second  and starts right back .it also sounds odd like a drag bike on the starting line hitting its rev limiter.the bike idles awesome and revs just fine in neutral with no abnormalities. losing my religion trying to figure this out dont know where to go next.. it has new chains  and sprockets, as i thought it was in the drivetrain.also can anyone tellme if you can use to different case halfs for the 5motor. please help

[Re-run]

I have never seen those cyclex carbs up close so it is hard to say. You might want to call ken at cyclex though and pass it buy him  once.

I would suggest checking out your spark plugs and see what they look like. The condition sounds like it may be lean. Has there been any mods to the motor itself, 836 kit, porting, new cams?

Timing might be another possible issue. Are you still running points or some sort of electronic?

Another thing to check though I doubt it is the issue. Can you turn the rear tire without it binding and releasing?

The last part I didnt really understand. Were you wondering if it is possible to use 2 different case halves from 2 different motors?

[bigdaddysean]

yes can you use 2 different case halfs from two different motors? as to the first part ,plugs look good ,no binding from rear wheel ,i am not sure of actual motor mods, but it has been swaped to electronic ignition,any thing else to look for would be helpful

[Re-run]

For case halves, I know the 70-76 are virtually identical, the 77/78 should be the same too. The heads are where changes took place. the 77/78 have more oil lines. So cases should be no problem but I have not had cause to do it.

For motor mods, it is hard to say. If the Previous Owner stuck a 1080 kit in, it would be obvious with weld marks in the jugs to seal oil leaks. An 836 is a drop in aside from boring of course but you cant see anything from the outside. you might be able to do a compression test and if you have number close to 170 or higher, it may have a larger bore. Most everything would have to be visually inspected unfortunately, to be able to tell.

One clue could be the ignition. Which electronic is it?

[bigdaddysean]

thanks,i'll get back to you on that ing. info