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CR carbs

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onethumb:

--- Quote from: Greebo on January 17, 2016, 11:37:00 AM ---
--- Quote from: Greebo on January 17, 2016, 11:31:49 AM ---MarkCR750

I forgot to mention that I also fitted a electronic ignition [ Dave Silver] & iridium spark plugs.

I would also like to add that when trying to set up the carbs it wasn't easy initially, & with the stock jets it ran like a pig, we tried different main jets & needle settings before we finished up with the set up mentioned previously.

PS... when we tried the needle on the middle slot it was still lacking fuel ,even with the 138 jets,so
we gradually moved it down & to get the correct fuelling the needle finished up on the bottom slot

--- End quote ---



Hi Greebo and Mark CR750 do you think the 138 jets would be OK on my PD carbs I've read somewhere on the USA site about using 110 jets when fitting cone filters to pd carbs, anyone tried this size and what was the outcome?
--- End quote ---

Greebo:
Onethumb

Its trial and error mate, it took us a few weeks of trying different jets & needle positions before we cracked it.

I have 4 into 2 open pipes bought from CycleX USA & K&N pods, our main issue at first with the stock jets & stock needle position was the bike wasn't getting enough fuel, when we finished up with the 138 main jet it was still lacking fuel from 2000rpm, it was like riding a kangaroo , so we then concentrated on the needle position, it was only when we dropped it on to the last notch that it solved the fuelling problem, all we had to then was set the air / fuel mixture.

Don't forget that the main jet only really comes into its own on full or near full throttle.

bladeboy:
Thanks for yr input guys, think I'll keep standard carbs but just re jet them, I will be fitting new electronic ignition so this will all help....

westfieldandy:
I have sold several sets of cr29's to several sohc bike owners now, mainly F2 owners with blocked up throttle pump jets and rough running bikes. and the new ones with idle circuit can be made to run really well, as long as they are set up correctly on a dyno.  I currently have an 812cc K engine running on them with a mild cam and standard unmodified K head, the bike is really tractable and pulls really clean all the way through the revrange. but it was set up on an dyno properly.  I would really recomend.

If the bike were to be used for touring long distance and in all weathers then I would probably point you back towards standard carbs because they work better with air filters. and CR's have open bellmouths, so road grime and dirt dont agree with your engine.

onethumb:
Hi greebo, Is there a quicker way to change needle position than to split the banks of carbs?
I've got the f2 with the pd carbs.


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