Bridgestone Motorcycle Parts Discussion Board

Bridgestone Tech Talk => 350 Talk => Topic started by: AlanJohn on July 01, 2018, 10:54:35 AM

Title: Engine timing
Post by: AlanJohn on July 01, 2018, 10:54:35 AM

Can anyone help me with a problem l'm trying to get a 350 running and have it running nice on the right cylinder but the left side is popping and backfiring would opening the left points a little help?
Thanks for any ideas you may have.

Title: Re: Engine timing
Post by: Bridgestoneboy on July 01, 2018, 11:59:17 AM

Make sure your timing is set with the crankshaft. The crankshaft is designed with divits that mark the firing points. The screw to remove to access these divits are on the left side of the motor. Once removed, you can find something to insert into the hole to feel when the (say a screw driver for example) drops down into the divit. Then make sure the point for that side is just starting to open at that point. This is very risky though because if something soft is used to find the divit it could be snapped of and end up in the bottom of your motor, which is a whole nother issue.

Title: Re: Engine timing
Post by: AlanJohn on July 02, 2018, 03:24:58 AM

I done that procedure many times but still it wouldn't start but lots of playing with it its now running it took 12 hours.

Title: Re: Engine timing
Post by: BRT-GTR on July 02, 2018, 05:33:37 AM

           Are you able to say what the issue was.  Questions re running on one cylinder appear quite often, could help others.

Title: Re: Engine timing
Post by: AlanJohn on July 02, 2018, 07:24:54 AM

We set the timing as the book but it would not start so we opened the points to 17 and just kept on moving the back plate very slightly until it fired on two then painfully fine tuned it a fraction at a time.l think l had one of the chokes on with the cable to tight but that's now done believe me at times l nearly gave up and hung it on the wall as an ornament.
We had that timing right by the book and even removed the right side clutch etc to make sure it was on the correct marks but it still wouldn't go in the end we did it the old way by persistance and paitince and eventually got it right.
Why is it so difficult to do?

Title: Re: Engine timing
Post by: coxy on July 06, 2018, 06:07:18 PM

its usually pretty simple
one of my bikes for some reason has had the hole for the timing bolt welded and tapped to a smaller thread making the timing tool useless  ,I just knocked the head off and set the points to that by eye ,the bike actually runs really well now
with a tdc tool I think its 3 degrees before tdc  .in the book it says how to do a continuity test as well
there is another download for tunning for speed its worth a look

Title: Re: Engine timing
Post by: OldSwartout on July 07, 2018, 08:45:24 AM

Coxy, the timing on the 350 is 25° BTC or 3.4mm piston stroke. If yours is 3°, it probably would make more power with additional advance.

Title: Re: Engine timing
Post by: coxy on July 09, 2018, 03:43:30 AM

yeh sorry about that

Title: Re: Engine timing
Post by: BRT-GTR on July 09, 2018, 08:47:44 AM

   Coxy,
              Early engine, timing pin holes were tapped 8mm.  Some time later, BS changed this to a 6mm tapped hole, so yours may be original and not have been welded up.

Title: Re: Engine timing
Post by: coxy on July 10, 2018, 03:01:26 AM

its on a GTO my earliest GTR is 00568 and that's fine there must have been a reason but I think we will never know