bench sync of throttle bodies

[andy york]

I found Murphy hanging out behind the garage. 

My thought process goes like this..... 

set both TB's fully closed, idle screws backed out all the way. Both TB's should be fully closed.

Next ...mount to top and bottom rails to form a complete unit...as in ready to mount on the cylinders.

Once mounted on cylinders, take a couple of dial indicators and put against the throttle plate's (the side that opens to the rear)

Once we have a measurement we will try and install the sync rod as I call it. I want to have the rod installed with no change

in the throttle plates...right ?  Then working with the left TB idle adjustment screw, try and get some idle out of it.

Just trying to get it to run so I can do the basic TB sync. 

I just can't seem to get there.

My carb styx say I am balanced but it idles like an old cold Mack truck...up and down....rump ....rump....rump...rump

well.   tomorrow is a new day and I will be back at it 

Andy

[docc]

Good stuff!

Because the TPS is driven from the right throttle body, and that indexes the throttle opening(s) to the ECU / "map",  setting the TPS baseline (157 mV) needs doing before "balancing"?

[docc]

I gots a fine Triplett DVOM and a TPS break-out harness . . .  and striking distance to your digs . . .

[andy york]

yes....I think I did that ....I will do it again in the morn....maybe Murphy will be gone by then.

But even before you get to setting the TPS, you need to have a "bench sync " as I call it.

Used to bench sync carbs before mounting them up...just to get in the ballpark

[andy york]

SO somebody hands you 2 TB's, a sync rod, and an upper and lower mounting bracket.

How would you "set them up" to work correctly? Thats what I call a "bench sync".

I feel a  moment coming on in the morning

[Scud]

...but how would get the complete assembly back on the bike without major disassembly? Unless, perhaps the bike is already in a disassembled state.

How about just setting the sync rod so both butterflies close at exactly the same time - by feel or by eye?

There is a set screw on each TB. Put them both in enough so they do not stop the movement of the mechanisms. Then attach the rod and adjust it until they are both closed at exactly the same time.

Seems like a good time to clean the injectors too - or send them out for a rebuild to a shop that make them flow at the same rate. Maybe your idle problem is due to injectors and liquid-flow, not air-flow.

[andy york]

yep.  Thats what I was trying to accomplish. Injectors rebuilt and flow tested.new shaft seals to stop the spooge from leaking out.

just trying to get everything working again 

 

[MartyNZ]

4 hours ago, andy york said:

...idle screws backed out all the way...

My air bleed screws are both fully closed. 

[andy york]

I seem to be in the ball park now ....but its bout 400' to home plate and I'm on the warning track.

anyway, I seem to have it balanced and it will start. Both idle screws are out all the way and not doing anything at 

present. So, In my mind that just leaves getting the connecting rod adjusted properly.

I think it will go something like this ...

disconnect right TB and lengthen the end 1 turn ..

reconnect- start- rebalance TB and runs and repeat till I get it right.

I don't know why starting with both TB's closed and the connecting rod attached( with no charge to the TB's)

did not seem to work.

Oh ....and my air bleeds have always been about 3/4 to 1 full turn open. I will have to recheck that as well 

Now   back to the garage

 

[docc]

4 hours ago, andy york said:

 

I don't know why starting with both TB's closed and the connecting rod attached( with no charge to the TB's) did not seem to work.

The throttle plates need to be held open 3.2-3.6º to idle. (Or something near that. But won't likely idle with the plates entirely closed in the bores.)

[andy york]

well thats just dandy...I seem to have misplaced my TB plate degree meter. Now I wonder where that thing went?

I just can't seem to get where I want to be....which is having the left TB idle screw actually control the idle. 

I can get the TB's balanced at about 1200 rpm but the idle screw is still backed out all the way and not doing anything.

I can increases idle speed, just not decrease it.

If it were a 2x4 it would have hit me in the head by now  

[docc]

Did you baseline the TPS at 157mv with the right throttle plate completely closed?

[andy york]

yep

 

[docc]

I can't imagine I have any real expertise or tools that would be significant, but it would be great to get our two hi-milers together this weekend and compare throttle body notes . . .

PM me if we can get a shot at a rendezvous . . .

[andy york]

I'm around