Topic: Keihin CR31 Carb settings

[lordmoonpie]

Anyone used Keihin CR31 carbs on a CB750 engine - the pukka old ones with ticklers? I could do with a base setting for jets, needles etc if anyone knows what I should be using??

Thanks 

[Sam Green Racing]

No.  but I know a guy who dose, will go find his name.

Sam.

[JLeather]

Did you happen to pick those up on eBay recently?

[Jim F]

Dont ask me..............Still waiting to here about what the air screws should be set at, what size pilots and where the clip needs to be (836 motor)
Would ask Sam but he only runs WFO

[Sam Green Racing]

Yes Jimmy, the ones that Simon is referring to are not the same as the ones we use.
His are the early ones that were used in 69/70s on the factory bikes, they were part of the race kit.

Sam.

[lordmoonpie]

No - didn't pick them up on ebay recently, had them for four or more years - not common little fuellers these so I got in well early for my build knowing they'd be needed at some point...

[Bodi]

Ahh. Real man's carbs!
I worked on a 750 with them installed back in the 70's, electrical stuff. I don't know what else the guy had done to the motor, but it was very fast and had a wicked sound from the velocity stacks when at full wick. One definitely needed ether spray to get the damn thing going from cold, though. And a strong leg or well charged battery... the new series CR carbs with chokes are for sissies.

[lordmoonpie]

Guess it'll be strong legs for me then - this is gonna run a self generating system so no batteries for me - woohoo!

[Bodi]

I've seen dirt track bikes with chokeless carbs started using a piece of cardboard with a hole (about 1/2") held over the velocity stack as a choke to get the engine going first thing out of the trailer if they have a starting roller or kickstart. Maybe something could be made to bridge all four - assuming velocity stacks. Without starting spray or some sort of choke, though... well, good luck!