Triumphrat

McQueen · 05-13-2008

OK folks,

Need some advice here.

My 500 is pinking really, really bad. This happens as it gets warm,say, about 25 minutes of riding. It gets progressively worse as it get s hotter. Bad enough that it becomes near impossible to take off from a dead stop without it pinking all over the place. Thing is, it runs great when the motor is cold. I can whack the throttle open in the first part of the ride and she pulls great. But once she's warmed up, the pinking starts.

Some specifics...

- 1971 500cc T100R
- Timing is dead-on (strobed)
- Boyer
- Valve adjustment dead-on
- Compression 130 in each cylinder
- Brand new Amals adjusted as best as I can tell (porbably 1.5-1.75 turns out from full-in; needle in the mid position)
- Unleaded 91 from Shell

Thoughts? Ideas? Sage-like advice?

Red1959 · 05-13-2008

Clean your carb bowls?
Make sure your battery is good, well grounded and full of water. I found out a low battery will overheat the engine, run funky. The motor may quit and restart after a minutes rest, even blow lights on a Brit Bike. That was one experience I went through on a 1964 650 BSA in 1970. If everything is 'right' try retarding the spark a couple of degrees.

mglemans86 · 05-13-2008

Sounds like detonation. Retard your ignition timing. The old stuff usually requires higher octane than is available now. Might be the ethanol

Diego · 05-13-2008

Quote:

Originally Posted by mglemans86

Sounds like detonation. Retard your ignition timing. The old stuff usually requires higher octane than is available now. Might be the ethanol

I agree with the timing recommendation as a possible remedy, but ethanol is not the problem. It actually has higher knock resistance than the basic gasoline formula with which it is blended, and results in the finished product having a higher octane rating than it would have alone.

McQueen · 05-13-2008

Red,
I'll check the battery. It's been holding a charge, but I haven't load tested it or anything. Two cells are down about .5", rest are full. New wiring harness and stator in there, too.

mglemans86 and Diego,
I will retard the timing a bit and see what happens. Unfortunately, we timed it at the local shop, so the strobe is there. If I feel lucky, any suggestions about just how much I can rotate the plate to achieve "a couple degrees?" No degree wheel. I know, I know, I'm ill prepared.

Thanks for the comments!

quagmire · 05-14-2008

McQueen, If you have a workshop manual, there should be a copy of a degree wheel on one of the first few pages. At least there is on mine. You might be able to fashion something with that.

McQueen · 05-14-2008

Quag,

I'll check. I know Classic Bike printed one in a recent issue for people to scan and print.

panda · 05-14-2008

Quote:

Originally Posted by Diego

I agree with the timing recommendation as a possible remedy, but ethanol is not the problem. It actually has higher knock resistance than the basic gasoline formula with which it is blended, and results in the finished product having a higher octane rating than it would have alone.

Yes you need to retard the ignition, keep retarding it a little bit until it does not knock. marke that point and use that. These engines really want 99 octane or better. Ethanol will increase the octane but as it contains a lot of its own oxygen will cause the motor to run slightly weaker.
You might also want to check your plugs, if they are badly worn they can create hot spots which will increase teh chances of detonation. As will hot ash deposits from running weak.

peintremondain · 05-14-2008

dont retard your ignition more than three degrees but you can try this

inking is caused often by poor running;i had the problem on my tr6 AND I WAS ON FACTORY SETTING WITH THE CARB.
i changed the throttle slide for a richer one (from 3.0 to 2.5)......no more pinking at all !!!
try to tickle the carbs at a stop ,it makes a momentaneous enrichment and you ll se what happens
benoit

McQueen · 05-16-2008

OK, update time...

New battery in there, didn't solve the problem, Red. But I needed a new battery anyway, so no biggie.

I richened it up with the pilot screw, and that seemed to help out a lot. Lots pf suggestions that I was leaning out when it would heat up. My pilot screw was at 1.5 turns out. I'm now 3/4 turn out from full-in. I still need to sync the carbs, but I'm making progress.

I will retard the timing a few degrees over the weekend and see what happens.

Can anyone with a 500 and dual 626 Amals tell me how many turns out they are on their pilots? Just for reference...