betablounty Posted August 31, 2008 Report Share Posted August 31, 2008 hi guys i dont know if anyone can help me with a couple of questions or not... firstly i have one of the first batches of 08 250's, alot of the other guys around my end who got there bikes a couple of months after myn, there bikes rev up alot quicker than mine, could there be a reason for this or is it just a case of its my bike and i have to live with it that way?? secondly my carb is still peeing out fuel, i have adjusted the carb must be four or five times now (by that i mean the float) and its ok for a week or two but then it goes back to normal....again the guys around my end whoo have had there bikes a couple of months after me, there bikes havent seemed to leak?? do you think that both of these arer because it is one of the first batches or some other reason??is it could be another reason, could someone maybe shead some light on what Quote Link to comment Share on other sites More sharing options...
dan williams Posted September 1, 2008 Report Share Posted September 1, 2008 OK, couple of questions, Do your friends have 270s? There is an additional flywheel weight on the '08 250 that's not on the 270. When you take the carb off do you blow out all the passages with compressed air? I have noticed the Keihin is a lot more prone to getting blockages in the pilot jet circuit because the holes are a lot smaller then the Mikuni. Yeah I know they look about the same but if you put it under a microscope you'll see that a few mm down the hole the diameter gets much smaller. Even a bubble of water can plug it up and make your bike run soft off the bottom so it's worth the exercise of pulling all the jets and screws out and blowing the passages out. Even though your '08 is one of the first the carb on it has been in production for many years so it's unlikely you got a bad one. One thing that I'm not thrilled with on the Keihin is there doesn't appear to be a removeable needle valve seat so if you have even the smallest scratch in the float valve seat your only option is to relap the valve seat. Next time you take the carb off make sure the vent hoses aren't kinked. It's easy to pinch them when stuffing it back into the bike. I can't think of much else that will cause it to rev slower that doesn't involve a timing or compression issue. Maybe blocked exhaust. OK I'll stop rambling. Quote Link to comment Share on other sites More sharing options...
max1956bikes Posted September 1, 2008 Report Share Posted September 1, 2008 i would say if its flooding dont ever touch float height adjustment,thats not the reason its flooding,too many people go down this route and mess the bike up,i have been working on bikes for 30 years and never have i had to touch float height.the chances are a speck of dirt on needle or seat 99% of the time.try putting a inline filter on fuel pipe. Quote Link to comment Share on other sites More sharing options...
dan williams Posted September 1, 2008 Report Share Posted September 1, 2008 Max is right. The Keihin is a tricky little beast to set the float on. I think I could do a Mikuni in my sleep at this point but the Keihin took me three tries. It's also really tricky to get the float bowl back on as you probably discovered. I found that the usual way of doing it holding the carb upside-down is not as easy as holding it rightside-up and putting the bowl on with the floats at the bottom of their travel. Only took me three weeks to figure that one out. I hate that angled overflow tube. You didn't damage that tube by any chance did you? Quote Link to comment Share on other sites More sharing options...
betablounty Posted September 1, 2008 Author Report Share Posted September 1, 2008 You didn't damage that tube by any chance did you? first of all thanks for the advice. no i was very carefull with that tube as it was a bugger to get on and like yourself i dont like the angle of it....poor design i think?? also dan no al of them hav got 250s and its not just a bit quicker its alot quicker...i wounderd if it had owt to do with maybe jets or needle height??i dont know much about working on motorbike i work on push bikes so forgive me if i seem a bit dumb to things. also yes i take the jets out that i can and blow air through them with a compressor, i see where max is comming from but why would lampkins(british importer) issues a set of float changing instructions?? to me this is the only thing that is wrong with the betas everything else is spot on...why they cant sort this problem out at the factory i dont know!!i think that it must have lost them alot of sales in the UK i dont know about across the pond but people here just dont want the hassle...they just want to be able to clean it take the air filter out and clean it then put it back n thats it done. cheers Jono Quote Link to comment Share on other sites More sharing options...
laser1 Posted September 2, 2008 Report Share Posted September 2, 2008 Can you swap the carb off your friends bike to rule out other potential problems? At the same time you could confirm the jetting/float settings. I take it you have ruled out simple things like if your bike has a slow throttle and theres are fast. I thought a friends bike had low power one time and it was just that. Quote Link to comment Share on other sites More sharing options...
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