netley Posted July 9, 2016 Report Share Posted July 9, 2016 Hi, I've just bought a 1977 Sherpa 350 with a mikuni carb. I've cleaned it thoroughly as it was leaking from the overflow pipe. Does anyone know the float height setting? I have it running but not easy to start and it dies like it's out of fuel after just a short run but starts again after. The air screw is only about 3/4 turn out and I've seen elsewhere it should be 2 turns out. Can anyone confirm this? Cheers Neil 1 Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted July 9, 2016 Report Share Posted July 9, 2016 (edited) Hi Netley welcome to the tc forum. Probably best to strip the carb and clean with compressed air, check the condition of the float sometimes they can split if they are the hollow type, clean air filter, check ignition timing, check wiring contacts maybe a condenser as well then fit a new plug and try again. On the Beta section there is info on Mikuni settings, best place for Mikuni spares if required is Motocarb. Good luck Edited July 9, 2016 by trialsrfun 3 Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted July 9, 2016 Report Share Posted July 9, 2016 Hi My 199A runs quite well with the following jetting (26mm VM carb): Needle 5C23, throttle 2, main jet 140, idle jet 30, needle jet O3, needle first groove from top. The problems with dribbling VM carbs are well known (see Beta forum). This is why I´m now testing a Dellorto PHBL. /Carl 2 Quote Link to comment Share on other sites More sharing options...
model80 Posted July 9, 2016 Report Share Posted July 9, 2016 (edited) Welcome to the forum netley. Here is a very well laid out fix you can read through http://www.motomerlin.co.uk/moto/betacarb.pdf I also came across the following article as well, "Is your BETA drooling fuel? By Clark Pittman" on a Club newsletter from the States http://www.ntxtrials.com/web_newsletters/RCR0106.pdf scroll down to the 2nd page. Hopefully this might sort your carb. Edited July 9, 2016 by model80 1 Quote Link to comment Share on other sites More sharing options...
smelling123 Posted July 10, 2016 Report Share Posted July 10, 2016 Neil, my 340 runs with air screw at 1 1/2 turns out with a 35 pilot jet. Runs very well on the vm26. Also had a 250 on one, also very nice runner. Both needed a good flood for cold start (lean bike over) but 1st kick when warm. Just fitted an OKO to a Montesa 348 and very impressed, if you don't percevier with the mikuni, an OKO might be a good option - eBay for about £65. Don't be tempted with the cheap ones which are likely copies. 2 Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted July 10, 2016 Report Share Posted July 10, 2016 Hi My 199A runs quite well with the following jetting (26mm VM carb): Needle 5C23, throttle 2, main jet 140, idle jet 30, needle jet O3, needle first groove from top. The problems with dribbling VM carbs are well known (see Beta forum). This is why I´m now testing a Dellorto PHBL. /Carl have you got dellorto settings at all yet? 1 Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted July 10, 2016 Report Share Posted July 10, 2016 Hi, It runs OK at the moment but it is really not sorted out yet. If you like I post the settings later when I think I got something to share. /Carl 1 Quote Link to comment Share on other sites More sharing options...
netley Posted July 10, 2016 Author Report Share Posted July 10, 2016 Thanks people, Really appreciate the help. I've now had it running but there is still some fuel overflowing but I won't have time to reset the float height until next week. Cheers. Neil 3 Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted July 14, 2016 Report Share Posted July 14, 2016 (edited) This is the jetting for PHBL 26mm that I´m currently using: Pilot 30 Needle jet K266 Needle D56 4th groove Main 105 Throttle valve 60 Low and mid throttle is as good as it was with the Mikuni but I get some more revs from tne engine at top end and it feels sharper overall and there is no dribbling. Both the Mikuni and Dellorto are way better than the original Bing Adaptors for both carb inlet and outlet must be made. Do I have to say that I stay with the Dellorto Edited July 15, 2016 by carl ekblom 5 Quote Link to comment Share on other sites More sharing options...
netley Posted July 17, 2016 Author Report Share Posted July 17, 2016 Hi, Thanks for all the replies. I wondered if anyone could identify this carb? That way I can make sure I have the correct settings and float height. I'll be adding the air filter Tuesday. Cheers Quote Link to comment Share on other sites More sharing options...
netley Posted July 18, 2016 Author Report Share Posted July 18, 2016 I think I have answered my own question having taken some higher quality pics and googled the numbers on the carb. https://yamahaclub.com/forums/topic/28494-dt-175-mx-main-jets/ see advice from Airhead. Not really suitable for an engine nearly twice the capacity ? Neil 1 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 18, 2016 Report Share Posted July 18, 2016 A Yamaha 3U5 carby is a bit small for a 325. Marginally OK on a trials 250. I run that size Yamaha-Mikuni on my 210cc TY175 and it goes great 1 Quote Link to comment Share on other sites More sharing options...
netley Posted July 18, 2016 Author Report Share Posted July 18, 2016 Do you want another Quote Link to comment Share on other sites More sharing options...
netley Posted July 19, 2016 Author Report Share Posted July 19, 2016 (edited) This should do the job. The Mikuni it should have fitted. Edited July 19, 2016 by netley 3 Quote Link to comment Share on other sites More sharing options...
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