Its all about the Carbs ....

About two weeks ago a carb for a 2004 crf 50 came up for auction on eBay, having been removed right away to be replaced by some 20mm racing carb as many of these mini-moto guys do. Since I got the PC50 I have been having issues with the existing carb, though I have cleaned it several time, it was still not reacting on the adjustments etc. Well, long story short, I won the auction for little money, it arrived on Tuesday and on Friday, thinking I would have to make a bunch of adaptors and other parts to get it to fit, I realized to my surprise … it’s the same carb! Yup, 30 some years later, and Keihin is still running the same carb! Great news for me, undo the old one, fit the new one … done! Only one slight difference of a hose out of the side, but that was irrelevant.
Once installed, she started in a quarter turn, and for once …idled! That was new. I played around with the settings, kept checking the plugs for mixture etc, but all in all, I have it running now to the point where the idle is so low, I keep thinking its going to stall, which is good, because the lower the chance of the clutch slightly engaging, thus heating the thing up due to a dragging clutch.
So, lets recap this boring story, 1972 PC50 carb can be directly replaced by a 2004 CRF50 carb. You can get jets for these things, oring sets, and since they are MUCH newer, are more tunable. Ie. No more backfiring upon throttle release due to a slightly worn throttle slide etc ….


Here's a pic of the new one on there ...