Throttle Body Balance

[alabrew]

Just to rub it in, it was a nice 65 degrees on Sunday here in The Great State of Alabama, so I took Big Red out to warm the engine to do a throttle body balance.

I made a two bottle balance setup and have attempted several times to balance them, but #1 has about 10 times greater vacuum than the other three. I can completely close the #1 bypass screw and it STILL has more vacuum that the other three.

I have sprayed carb. cleaner in the vacuum ports and the bypass screws. I've even lubed the bypass screw o-rings.

I finally just set it by ear. #1 is 1/2 turn, all others are at 1 1/2. I had to turn down the idle as it was running much better.
The flat spot at 4-5k on throttle is now gone and it feels more like the RS.

Any ideas as to what is going on?

[Laitch]

#1 is 1/2 turn, all others are at 1 1/2.
The flat spot at 4-5k on throttle is now gone and it feels more like the RS. Any ideas as to what is going on?

If starter fluid, propane or carb cleaner is sprayed on the intake manifold and intake bushing of TB #1 at idle, do the revs change?

[alabrew]

Sorry, forgot to tell that all the rubber bits  (#1 & #4) for all cylinders were replaced with new over the last winter when I also did the valve adjustment.

[Martin]

I'm with Laitch it still looks like an air leak. It would be still worthwhile taking it out of the equation before moving on.
Regards Martin.

[The Mighty Gryphon]

Read what you have posted again very slowly keeping this in mind:

Screwing the idle air screw IN makes MORE VACUUM.

If you are seeing the fluid going toward one of the balancer bottles you need to BACK OUT the idle air screw on that throttle body.  According to what you have posted, you have an air leak on #1. 

If indeed you have replaced all the rubber bushings and carb cleaner doesn't increase the idle when you spray it around #1, then you need to look at the throttle butterfly adjusting screw.  Does it still have the blue paint?  Is there anything interfering with the linkage for that butterfly?

When you checked the valves, was the #1 exhaust very tight?  If it was, there is a slight chance the valve is burnt and not allowing a good vacuum to be generated on the intake stroke.  Have you run a compression test on the engine?  That might give a clue if the compression is low on #1.

[alabrew]

OK. Nice 70 degree day yesterday, took her out for a warm up and set about the balance again.

Finally ended up with #1 out about 4 turns, #2 & #3 about 1 1/2, and #4 about a 1/3.

Blue paint on the adjustment screws.

Can't find a leak. I plugged the midrange vacuum line to eliminate it (new hose there too as well as the FPR)

#1 exhaust valve wasn't out of spec.

Took her out again and she ran well, more like the RS. Still pulling over 85, not struggling at 70 as before.

I'll continue the hunt for a leak. Not so sure how many more days I'm going to git to ride her.
I'm 600 miles short of 25k and plan a full service over winter.

[The Mighty Gryphon]

There is something bizarre going on here.  In your first post you say you can almost bottom out #1 and still not get balanced with the others.  Now you say that it is out 2 1/2 turns more than #2 & #3.  I guess that as long as it is running well you can just live with what you have, but I suspect there is something going on with #1.  It might be worthwhile to remove the screw, spray a bunch of carb cleaner in the opening and try balancing again.

[alabrew]

Giving this some more thought. I tried to tighten the clamps more buts they are already touching. I used the Suzuki clamps.

If it ever gets too cold to ride this "winter" (gonna be 70 next 5 days!), looks like part of service is going to be removing the airbox and replacing the clamps. Good excuse to buy the Oetiker pliers. Wow, just searched and a plier and 100 clamps is less than $30.

I read a post on K100 that suggested replacing the o-rings on the brass screws. I looks at Max and I didn't see them listed, anyone know the size?

[John Lang]

Max has them.    13 11 1 257 819    GASKET RING -- $3.00