Topic: Mikuni 29mm smoothbore on 836 engine problem?

[Bob2309]

Hi all,

First off. Here is my engine mods.

Engine CB750 1975 F0
29mm Mikuni Smoothbore carbs
Stock cam
836 Big Bore kit, (piston, rings,etc)
Heavy Duty Cam Chain
Adjustable Cam Sprocket
New Primary Chain
Ignition Power Arc from Cycle X

Everything looks ok as far as starting, timing and idleing. The problem is when I come to change gears the engine is slow in deccelerating.
What could be the causes of this?

Also noticed when I disassembled the engine that the cam end marks where slightly off mark with the crankshaft at the t1 mark. This was with the stock Cam sprocket.
When I reassembled the engine I lined up the marks.
Could this have anything to do with my problem.
Also tried to advance and retard the timimg with not much difference.

Thanks in advance for all the help.
Bob W.
Ontario, Canada

[turboguzzi]

non synched carbs, idle circuit lean, manifold air leaks,

[PeWe]

- Throttle wire is moving slowly and slow throttle return? Reroute and lubricate the throttle cables for smooth return.
My VM29's have hard springs that press the throttle back direct.
-Leak?
I had leaking Mikuni inlet rubbers (cracked, especially cyl 2-3 with sharp bends), but I do not recall slow deceleration (hanging throttle).

- Air Screw setting  1 1/2 turns out ?
Carb jetting at the end of this link, VM29 CB750  http://www.z1enterprises.com/Z1CarbGuide.aspx

Another cam should help :-)
Action Fours SS-1 is no longer available, Ok with stock engine as the existing still produced WebCam 41.

[Bob2309]

Thanks for all the info.

To answer some of your questions and or suggestions.

Carbs are in sync.
Throttle cable free. Throttle snaps back.
As for leaks at the manifolds, I will check and let yous know of the outcome.

Another cam, well it is just a wish at this time.

Thanks again
Bob W
Ontario, Canada

[turboguzzi]

stock cam should give better idling, if anything...... if synched and now leaks, could be a matter of idle circuit adjusting. does it love choke to start of starts without?