Triumphrat

dazco · 10-03-2005, 10:55 PM

i noticed that if i get it perfectly balanced at idle, i can then rev it a bit, probably to around 2500 RPM (estimate) and hold it there and the balance will then be off. I wonder if this would mean at idle they're balanced but when riding they aren't. Obviously it's not quite the same because there is no load and the throttle is barely turned, but it does make me wonder. Anyone noticed this?

Dunnester · 10-04-2005, 01:03 AM

With my BMW I balance at idle and again at 4000RPM. Some guys prefer idle and 2500 rpm. Need to balance at both idle and at a running speed. Maybe some Triumph guys would know the rpm for the running speed

Dunnester

Shorty · 10-04-2005, 07:29 AM

daz...I believe that I read somewhere that carb balancing should be done at about 1500 RPM on our bikes.
I usually tweek my idle adjust up to that value, balance the carbs, verify that it's still running at 1500 RPM after adjustments have been made (if not I re-adjust the idle) and go back and forth until I'm satisfied. I also take a heavy duty industrial type fan and place it in front of the engine to prevent excessive engine temp while adjusting the carbs in case the process takes longer than anticipated. Once done, I take the idle back to about 1000 to 1100 RPM (my bike seems to like 1100 best).

Shorty

PS: Realizing that one can have an unbalanced condition at higher RPM values for various reasons (efficiency of carbs, air intake variations etc.) is the reason why I asked a while back about running the vacuum line between both carbs as opposed to plugging the caps to maintain an equal balance. The answers I got back were 50/50 with more input for thought on the matter and some stating that it could actually damage the bike. I would still like to hear some more feedback from individuals who are more mechanically inclined than I am. I don't want to damage my ride.

[ This message was edited by: Shorty on 2005-10-04 09:33 ]

trashcanman · 10-04-2005, 10:43 PM

Yes the balance will shift back and forth between the carbs as you change throttle input. As shorty posted balanceing around 1500 seems to be close enough.

Liontari · 10-04-2005, 10:53 PM

But cranking the idle screw to get 1500 rpm is not the same as pulling the throttle.

I would imagine the carbs should be checked for balance at several points in the engine's total range. In Zimmerman's book, he suggests they should remain balanced all the way to full throttle, but not to bother going past half as this should be sufficient.

Puffer · 10-05-2005, 06:02 PM

Shorty, I suspect that joining the intake manifolds via a rubber hose (as opposed to leaving the stock rubber plugs in place) would not have an adverse affect on the engine. I base this thought on the fact that my BSA Lightning came this way from the factory........................Mike