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fishman
08-19-2009, 10:50 AM
i gots a 70 BSA 441 square barrel thats got some trouble starting. Has a rebuilt carb, by a professional, but when it does go has a bit of trouble accelerating, little bit of a glug to it, took off the head and then intake valve spring seems stuck. The exhaust springs fine but the intake just stays locked it wont move when pressure is applied. Now i am assuming when replaced this will allow it to start properly just looking for any kind of experience with this type of problem

TRUMPNUT
08-21-2009, 8:56 PM
I have had a few of those but not sure what your problem is . The valve can bend causing them to stick in the guide thus not opening or closing . But it wouldn't run if that was the case . Did you di a compression check ? If it is lower then 120psi with the thottle open do a leak down test . if the leak down is also low then it is somthing wrong with your intake track ( you can't compress air you don't have ) if the leakdown is high then just see were it is leaking from. If you remove the valve adjustment caps and kick it throu to see if everything is openinmg and closing good. If you took off the head flip it over so the compresion chamber is up and install a spark plug then fill with solvent ( gas ) and see if it goes down . then drain the head and wipe it clean . Fill the intake port up and look inside the combustion chamber around the intake vale to see if leaks . Do the same with the EX. port . Pull out your push rods and make sure they are not bent . if a valve sticks the push rod will bend .
Mkae sure your timing is spot on ! I always use a deg. wheel not the marks on the rotor . Make sure the points cam is tight . Give it a wiggle it should have no play side to side ( the cam to the shaft ) .

That is a big single so if your clutch is adjusted poorly or it is wore out you will not be able to start it . Every time you kick it as soon as it is on compression stroke it will slip , not giving you the 'snap" needed to start a single . Twins are much easier then singles to start with a bad clutch since one cylinder is on comp. while the other is on overlap . So make sure it kicks trough the compsiom stroke .

Tickle the shit out of the carb and if it pops do it again before you give it another kick .