dalmahoy Posted August 23, 2010 Report Share Posted August 23, 2010 My 2007 Beta Rev 3 250 has always felt just not right at the bottom end. Couple of blokes yesterday mentioned it just dosen't sound 100% - thing sounds like it's fighting itself. Plug is slightly sooty but never had a problem with it oiling up. Generally the bike runs ok. Running the mix at 75cc of 2 stroke per 5 litres of fuel. I removed the carb yesterday, its running a 150 main, 30 pilot and the air screw was sitting at 3/4 of a turn out. Any advice on the carb settings before I start tweeking. Cheers Quote Link to comment Share on other sites More sharing options...
betabonkers Posted August 23, 2010 Report Share Posted August 23, 2010 Ive always had my air screw one and half turns out on all my betas, you may have to adjust slightly from time to time. Quote Link to comment Share on other sites More sharing options...
dan williams Posted August 23, 2010 Report Share Posted August 23, 2010 Mikuni VM26-208 drop the pilot to a 27.5. You may drop the main one or two sizes as well. I think my 05 has a 140 or 145 main but I don't remember. The 27.5 pilot is pretty much the first thing anybody did around here with the Mikuni. VForce carbon reeds also make a big difference in the way the bike runs low. Adds tremendous grunt. Quote Link to comment Share on other sites More sharing options...
nzralphy Posted August 24, 2010 Report Share Posted August 24, 2010 Agree with Dan's jet sizes Quote Link to comment Share on other sites More sharing options...
samo Posted August 25, 2010 Report Share Posted August 25, 2010 I have the same bike. Mine has 27,5 pilot and 145 main and it runs lean. I wasn't happy.. Now I put 30 pilot and 140 main and it runs much better ) I ride most of the time around 5oom altitudes. Quote Link to comment Share on other sites More sharing options...
dan williams Posted August 25, 2010 Report Share Posted August 25, 2010 All the Betas are on the high compression side so race gas is kind of a necessity. Jetting rich can help to some extent but you end up with a boggy engine. I suppose you could go with a thicker base gasket to lower the compression if you want to run pump gas. Quote Link to comment Share on other sites More sharing options...
dalmahoy Posted August 27, 2010 Author Report Share Posted August 27, 2010 Fitted a 27.5 Pilot and a 145 Main Jet for a midweek trail. Air screw out 1 3/4 turns. If anything - I reckon its very slightly - might need to tweek the needle. But overall - the differance is just superb. Even on tick over - the bike sounds different. Think its not far away now. Quote Link to comment Share on other sites More sharing options...
dan williams Posted September 2, 2010 Report Share Posted September 2, 2010 Ah now add a VForce carbon reed valve to the beastie and you're done. Quote Link to comment Share on other sites More sharing options...
stork955 Posted September 3, 2010 Report Share Posted September 3, 2010 Clean the exhaust. It will need it by now. See how it goes after. Cheers, Stork. Quote Link to comment Share on other sites More sharing options...
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