nzralphy Posted December 30, 2008 Report Share Posted December 30, 2008 Hi All. I have just picked up a second hand Beta Rev4T 250cc. It is standard. I have adjusted the tappets (0.10 & 0.15mm), replaced wheel bearings, cut away the middle seat support (the stupid one that blocks the air flow), removed the light, removed the Beta kill / light switch, modified the hot start to 2mm hole, put on a std trials throttle (white), i still have to get an NGK Iridium plug. How do you adjust the cam chain tension? What is the preferred mixture setting (Lampkin SSDT suggests 4 turns out) for the bike? Does any one have any other little tweaks? Of the Beta parts available (exhaust, cam, ignition) what made the most improvement to the bike? Thanks, Ralphy Quote Link to comment Share on other sites More sharing options...
rlracer Posted December 31, 2008 Report Share Posted December 31, 2008 Ralphy, Welcome to the beta 4-stroke ! I would suggest getting your hands on the Work Shop Manual for the Beta 4-stroke, all the motor info you need is in there. I add a high quality heat reflective material to the bottom of the fuel tank area, front side of the air box were the exhaust passes by, a small piece on the pipe were the fuel line runs into the carb and some heat reflective tubing on the fuel line. Went one spring lighter in the carb. Added a carbon & kevlar pipe guard no more melting marks on the pipe ! I change the oil often and keep the air filter clean. As far as motor mods I added the 300 kit and the aluminum pipe and just tickled to death in the way it runs. 300 kit adds more torque,more power. Aluminum pipe lets it breathe, it adds more across the board from bottom to top and only slightly louder if you can say that, very exceptable !!! The stock throttle is 1/4 turn, you say you installed a white throttle that is 3/8 turn so you slowed it down ? why ? Install a jitsie fuel screw or some one else's so you can get to it. Quote Link to comment Share on other sites More sharing options...
postmanpat Posted January 1, 2009 Report Share Posted January 1, 2009 Forget the posh plug,i've been told today that Lampkins say change the plug after 3 trials,that'll get expensive if you go iridium!!!!! Quote Link to comment Share on other sites More sharing options...
rlracer Posted January 2, 2009 Report Share Posted January 2, 2009 Why do you need to change the plug that often ? Quote Link to comment Share on other sites More sharing options...
nzralphy Posted January 2, 2009 Author Report Share Posted January 2, 2009 rlracer. I'll go to the auto store and get some of the heat shield. Good tip as the 4 banger runs quite hot. The throttle is Domino, quick=white, that i had lying around and thought i would give it a try because i thought the standard throttle was too quick and made the bike a little clumsy. It works out at 5/16th of a turn. Real nice and i love the action now. I'll chase down an extended mixture screw. A well tuned bike, and most of mine are/were, will have plugs that last over a year no problem. So i'll ignore this advise.....every three trials.... my a***. Iridium plugs give a stronger fatter spark that makes a bike start easier and have a more reliable idle - good for trials. Ralph Quote Link to comment Share on other sites More sharing options...
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