Throttle Balance Queston

[thinkjerm]

I know i have read about members performing throttle body balances on this forum in the 2005+ sprints. But in the Service Manual it states "The throttles cannot be balanced using equipment to measure vacuum in each throttle."

Is this all a hoax to get you to the dealer? or do the throttles not sync correctly using vacuum gauges.

Thanks.

[oldndumb]

This could be interesting.

After the answers are in, what is your criteria to decide who you are going to believe?

[CLB]

1050 specific.

I balanced my throttle bodies with a homemade dihydrogen monoxide differential manometer. The device is more commonly known as 3 translucent tubes, joined at the bottom, mounted to a board, filled 1/3 with colored water and tops plumbed to the throttle bodies. A search will yield pictures and more description.

Discoveries:
a) All 3 manometer tubes should be plumbed to their respective throttle bodies with equal lengths of vacuum hose.
b) The MAP sensor should be plumbed to the normally capped off auxiliary port on the center throttle body through a very short hose. A large air volume here will throw off balance.
c) The bike won't idle smooth during the procedure as the MAP readings are used to calculate fuel requirements below 6% throttle. 1 & 3 will be running rich. Besides that, it's cheap. Inexpensive too.

The manometer method may in fact be more accurate than MAP method becouse crossflow through the MAP tubing is eliminated. The crossflow will actually partially compensate for TB misbalance.


Balancing with a manometer:
Using the above procedure I could see that one cylinder (1 I think) was about 18" H2O high in vacuum. I brought the low vacuum cylinders up to match and the idle improved (once I plumbed the MAP back to normal).
The shop manual suggests the low vacuum cylinders be brought up to match the highest. This keeps the idle adjust system in it's operating range and avoids out of control high idle on a warm bike.

Verification:
Last night I scanned the MAP sensor with TuneBoy. All 3 cylinders read 0.457 with about 0.005 jitter. This is more in line with the Triumph method and certainly indicates acceptable balance. I would say the manometer method works fine. I don't have intermittent high idle any more either.

Random pontifications:
So long as portability isn't an issue I prefer the homemade H2O manometer to the commercial offereings. Now that mercury is no longer used many commercial offerings work via springs and seals. H2O is more accurate. The readings are larger because of the low weight. Spring tolerances, preloads and seal friction don't come into play with H2O either.

[thinkjerm]

So basically it is a hoax.

CLB you have proven that it can be done with a manometer and those settings were later verified with software and proved to be accurate.


Thanks for the info, i will be performing this service myself. For those of you that have had the dealer balance the Throttle bodies how much do they charge.

Thanks.

[Calliway]

CLB,
You are smarter than me.

How do you know that your throttle bodies are unbalanced? is there some tell tale sign? Is it just a little ruff running?

[CLB]

Several ways to answer this...

1) The fact that you have to ask this indicates that your bike is most likely fine.

2) Build a manometer.

3) Buy a Tuneboy.

4) Ask a dealer.

5) Rough idle.

6) Hard starts.

7) Poor off idle throttle response.

8) Plugs don't read the same.

Pick a number, or several.

Originally Posted by Calliway

CLB,
You are smarter than me.

How do you know that your throttle bodies are unbalanced? is there some tell tale sign? Is it just a little ruff running?

[Calliway]

Plugs are fine, starts fine, idle is fine

[oldndumb]

Originally Posted by Calliway

CLB,
You are smarter than me.

How do you know that your throttle bodies are unbalanced? is there some tell tale sign? Is it just a little ruff running?

You may have TB imbalance if you notice a tendency for the bike to want to lean to one side or the other whilst stationary.

[oldndumb]

CLB did you appen to get an MSDS sheet with your dihydrogen monoxide, and could you share the cautions?

[Calliway]

Originally Posted by oldndumb

You may have TB imbalance if you notice a tendency for the bike to want to lean to one side or the other whilst stationary.

See now that would of been my first guess as the left throttle body seems to be heavier then the right as it always leans over to the left when parked. I would assume the gyroscopic principle takes over when the bike is rolling but parked... yeah always leans to the left.