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Please someone help me

Jorgy

CB750 Member
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Sylvan lake
:banghead:
I have a 71 cb750 K1
The compression is 150 right across
Out of the box Keihin 29mm roundside carbs, Dynatek ignition.new plugs and can not get this bike to run right.
These carbs look like they have 4 supply spots, should a person T off on the two fuel line coming out of the tanks petcock?
Right now I have only two lines going to the carbs where it looks like there’s a gallery between 1-2 and 3-4 like the original stock carbs.
This bike bogs down when the throttle is cracked, there is no consistency on when it bogs down, I’ve played with the timing. Reset the valves, one thing I did notice is that the tach is out of sorts. The bike is charging properly.
Should these Keihin have four fuel lines going to them?
Could this Dynatek ignition be faulty?
Summer is soon coming to a end and I still can not get this bike to run right. Argh 😤
Any advice would be greatly appreciated.
Cheers
 
New modern keihin 29's or old school keihins? set the timing to stock spec and leave it alone. Carbs will be fine with the two supply line, especially the small 29's. If by cracking the throttle you mean opening very fast under no load then yeah its going to bog, there is not accelerator pump
 
New modern keihin 29's or old school keihins? set the timing to stock spec and leave it alone. Carbs will be fine with the two supply line, especially the small 29's. If by cracking the throttle you mean opening very fast under no load then yeah its going to bog, there is not accelerator pump

They are the new Keihin carbs and the timing is set to stock. Have you heard of any issues with these Dynatek electronic ignitions?
My tach worked normally before with standard point but with this electronic ignition it’s all over the place.
 
so its not a mechanical tach but an aftermarket unit?? Dynatek has been fairly good as far as I know.
 
All the bad word on Dynatek is on the DOHC because the unit is bathed in hot oil to fail them quick. The SOHC does not do that.
 
Hi Jorgy,
Have you checked the floats to be sure gas is available?
How about the tank vent? Petcock screen? Air filters?
I put Dynatecs in five different 750's and all still function correctly.
gunr
 
Thanks...

Hi Jorgy,
Have you checked the floats to be sure gas is available?
How about the tank vent? Petcock screen? Air filters?
I put Dynatecs in five different 750's and all still function correctly.
gunr
Thanks for your input, these Keihin 29 mm carbs are still in question. I was hoping someone on this sight would have
Some experience with these racing carbs. Cheers 🍻
 
Those carbs come with like 10 different calibrations and all the internal parts can change. If they were not specifically metered for a SOHC CB750 it's no surprise they give trouble. If the engine is dead stock it was a mistake to put them on in my view as well. They are intended for higher performance engines with mods on them and at least a good header is a must to me.
 
Thanks for your input, these Keihin 29 mm carbs are still in question. I was hoping someone on this sight would have
Some experience with these racing carbs. Cheers ��

What do you need to know? You never responded back in August so didnt know you still needed help
 
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