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So it's OK until you ease off at highish speed/load and after that it stutters and won't run. It doesn't break up before you ease off form speed though, just after you start to decelerate?

Could be that coil lead of Geeto's or the carbs sucking something in under situation with high gas velocity/high vacuum conditions.

My guess would be water or small debris in the float chambers being sucked in with high vacuum and dropping back out after it sits for a while. Sounds odd, but that's how I understood your explanation of the circumstances.
 

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Discussion Starter #23
i took the carbs completely apart and they were clean as a whistle. i decided to clean them out again anyway and replaced the o-rings and bowl gaskets. hell i had them on hand so i figured why not. i made sure that i cleaned out all of the passage ways between the carbs and anywhere else that debris could be settling. put them back together and they will go back on tomorrow. i will also take a peek at those leads. i have to work in four hours and have not slept yet so i guess now is the time.
 

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Discussion Starter #24
going to drain the tank and re-install the carbs then sync in a little bit. the mains and slows were clean and open. it did however turn the cleaning solution a bit cloudy but i doubt that it would have made that big of difference. we shall see. not much else i can do besides check the valves and adjust to spec for the setup. i did this when i ran the motor for the first time only 300 or so miles ago. i am pretty sure it isnt the problem. also i did a compression test lastnight and the results were as follows. cyl#1 (163) cyl#2 (160) cyl#3 (165) cyl#4 (163).....pretty consistant. this is the second time i performed a compression test with this kind of result.
 

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Do you have the correct resistor installed to run those 3 ohm coils?
Stock was 5ohms right? The same as a cb750?


Basically you have added a ton of variables to the bike so it's hard to jump around to solve things.
Really need to sit still and run though the systems..
Also just because it's a new part makes no difference to it working or not. and you can't just assume it's installed the right way.
 

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Discussion Starter #26
im ipc whma a-620a certified in wire harness manufacturing and electrical assemblies so yes i did my research, found all the correct wire schematics for this setup. everything was done right with the guidance of a seasoned cafe builder out of studio city, ca. and this setup with stock coils did the same thing so i can eliminate that possibility.
quote:Originally posted by jaguar

Do you have the correct resistor installed to run those 3 ohm coils?
Stock was 5ohms right? The same as a cb750?


Basically you have added a ton of variables to the bike so it's hard to jump around to solve things.
Really need to sit still and run though the systems..
Also just because it's a new part makes no difference to it working or not. and you can't just assume it's installed the right way.
 

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Remember, we are having to guess at your mods and skill level since you provided neither.


Seasoned cafe racer builder <------- there is your problem right there.

Have you checked for things shifting while you ride? I had a coil once that tried to weld my fuel tank to my frame because of a loose bracket. Only happened when braking, and it weirded me out why I would drop a cylinder on deceleration. Maybe something is loose somewhere and shorting out.

We are trying to help, honest.
 

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Discussion Starter #28
when i say seasoned i mean 15 plus years and has modded cb750s for the last 10 to 12. numerous 836 big bore kits and such. not to mention the fact that he is from essex. so across the pond. i ended up dropping in a new rectifier and it was the key. the only thing electrically that i didnt replace. runs fine from idle to 12k. also upped the octane a bit with a new mix ratio of 30:70 turbo blue, 93 octane no ethanol.
 

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Discussion Starter #29
and sorry about the lack of detail. pretty new with the forum thing. ill be a bit more in depth if i need help again.
 

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always find it funny when guys from england that talk about the honda cafe thing....ace closed before the 750 came out right?....sorry thats just a pet beeve with me.

so back to your bike.....didnt really answer many of the questions posed buy people trying to help.
an answer of "it cant be that because its new" or "its not that because a master did it" is not helping anything.

and really for the life of me i cant figure out what your "issue" is because you keep popping back and forth with the old and new motor.....or maybe im just drinking to much....



What resistors did you install for the coils and how did you install them? this IS a difference...

also dont just look for one component thats wrong broken or just messed up....since there are so many variables that you added its hard

Please write up what ALL the mods and settings are and then talk about the symptoms are again
 

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I had same issue. I rebuilt those damn carbs so much I can do it in my sleep. I replaced my rectifier yesterday...and BAM! That was it.
If anyone wants a good price on them go to www.oregonmotorcycleparts.com/rectifiers.html He sells brand new rectifiers for 22.00! Plus he has many other electrical parts. Also thanks to www.dansmc.com/electricaltesting.htm for such great detail on how to test the rectifier, stator, regulator, etc...
 

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Discussion Starter #33
jag, actually ace cafe re-opened. was there two years ago on a 68 t-120r. and i ran a bunch of tests on the old rectifier and there was zero continuity. the coils are 3 ohm and with the way i have the wiring i have them at 5 ohms now which is the stock spec.
 
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