Sup All I was wondering if anyone has got a link or there own advice for the best way of tuning a WT-603 Walbro Carb for Max performance prefferbly acceleration? Pics would be great
there is no perfect tune for a range or carbies. You have to tune it by trial and error. People can give you a starting point, but every engine and bike is different, aswell as the rider. There are too many variables to compensate for, so you have to tune your carby to your variable. Just get a screw driver and take the bike out, get it warm then play around with the mixture till you find something that works. good luck with it
As a base setting turn the mixture needles all the way in and then turn the high speed (closest to the air filter) screw 1 3/4 turns out. Set the low speed screw 1 1/2 turns out (the screw closest to the manifold). This will be a close starting point. Start the bike and set the low speed mixture in conjunction with the idle speed screw to give the lowest reliable idle that still has a crisp responce when you rev it. With the bike on the stand rev the engine to full throttle and adjust the high speed mixture to give peak revs then richen (wind out) 1/8 turn. Do this abit at a time so the engine isn't just sitting there screaming. This should get you pretty close with fine adjustment (normally no more than 1/16 to 1/8 turn) done while riding to get it spot on. Check the colour of the plug (should be light tan, white is lean dark brown is rich) to make sure its not lean and enjoy!
Hope this helps
Matt.
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tuning the bike of the stand doesnt work when tuning a cag engine. it gets done the same way, but under load whilst riding. have it sat at the standard settings and adjust the high screw about 1/8th of a turn either way and test to feel performance gain or loss. keep doing this until max performance is reached.
1968falconxt, you are half right when you say you can't tune it on the stand but if you richen the top end abit when done to compensate for the fact that you need a richer mixture under load than without load you will get a safe base setting to allow you to ride the bike to fine tune it.
I agree that if you just lean it to have it screaming on the stand you will have a good chance of damaging the engine when riding it, if it pulls at all being too lean. You MUST richen the unloaded mixture setting before riding, and 1/8 turn on a Walbro has prooved to be about right.
Plug chops and fine tuning are still nessesary to get the tune spot on.
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Think outside the box, theres more room to move.
the walbro carb is a very easy carby to tune, allways play with one needle at a time so you don,t get confused, 1/4 turn in or out per test, if you can,t get it right there must be another problem like air leaks between gaskets, purge hole blocked off between carb and manifold or the diaphram has gone. or maybe dirt in carb jets.
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