750 does not rev above 4000 RPM

milepost152 · Aug 3, 2010

I am new on the scene working on a 750. Will start easily but stutters around 3500 to 4000 RPM. Have gone thru the carbs, points adjustment, valve adjustment and timing. Can this be an ignition coil problem?

norbsa48503 · Aug 3, 2010

Sure sounds like a needle came loose off its clip. Or a main jet plugged solid. First things I would check.

Hobot · Aug 3, 2010

If your bike still has points, it make also still have chokes installed in carbs. Its counter intuitive which way the cable goes to open chokes but that could also give ok running up till needs to suck in more flow and can't.
Bad spark plugs, air leaks in crossover carb hose.
It could also be a bad connection or internal broken wire that vibration upsets.
Bad coils usually act up with heat but run ok till hot.

hobot
Arkansas Ozarks

rvich · Aug 3, 2010

I am with norbsa on checking those needles. I had one drop out of its clip when replacing the slide and I couldn't rev above about 3k and the bike had no power when in gear. I also have had a jet holder come loose and start to unscrew...it caused a similar problem. It could possibly be a problem with the timing advance. If you pull the points plate, make sure everything there is moving easily and the springs are on.

Russ

Rabscallion · Aug 3, 2010

might be worth checking that choke. mine vibrated on during a ride and gave those exact symptoms

Rob

prmurat · Aug 4, 2010

I'll second the choke...remember: cable pulled= choke off. cable at "rest" = choke on.
A friend of mine had the same prob on his Atlas!
Philippe

Scruff · Aug 4, 2010

I had the same problem after mine warmed up and then I remembered the choke is back to front to the way you would think it would be.
Ian

MexicoMike · Aug 4, 2010

Before I removed the chokes from my Amals, they would slowly slide "on" as I rode the bike regardless of what I tried to do to tighten the lever assembly. I have never needed them and don't miss them at all. So if you find they are causing your problem you might consider eliminating them completely. The idea that they "fail" to the on position is an interesting design concept...

milepost152 · Aug 23, 2010

Thank you all. The needle came lose.

750 does not rev above 4000 RPM

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