Throttle body balancing: a couple of questions

[mr_magicfingers]

I've just been doing a service on the bike which has, for the first time, involved me having a go at throttle body balancing with a home made manometer.

I checked the valve clearances and rocker end float which are all now spot on. I did the TPS check and adjusted that to be 0.35.

Made a note of where the brass screws were set, they've not been touched since it was serviced by Steptoe about a year ago:

Left was 1 turn out, Right was 3/4 turn out

Set them both to 1 3/4 turn out. Started the bike and found there was a reasonable imbalance.

Leaving the right hand throttle adjuster locked, I adjusted the left hand throttle adjuster until they were balanced at idle, but the idle speed increased. I turned in the brass screws to lower the idle speed to 1100 and stay balanced.

Ran the bike up to 4000rpm and did some minor tweaking of the throttle adjuster to keep them balanced at both idle and 4k. Bike was now running much better and smoother.

However, the brass screws were now set at Left 1/2 turn out and Right at 1/4 turn out.

Is it reasonable for them to be so far in or should I be looking at changing the throttle adjusters so that the brass screws are further out at idle?

In the Clymer manual is suggests that there should be at least 2mm of free play in the throttle cable sheath at the throttle body before the wheel starts turning. Mine has virtually not play. If there's that much play, would it not give a lot of slack in the throttle before anything happens when you twist the grip? There's a 2-3mm of free play at the grip before any movement of the throttle which is about what I've set all my bikes for in the past.

Grateful for any input.

Thanks.

 

[MikeP]

The BBS have always been about a quarter to a half turn different on my 1150 and that's been the case from new. As long as the idle is balanced and about where I like it (lower than the suggested), I'm happy.

 

[Stewart H]

The BBS settings sound reasonable, have you tried the choke/fast idle lever yet? that seems to be the only thing affected by excessive throttle cable free play.

 

[street_moto]

I may be wrong, but I'm sure you are supposed to leave left hand throttle cable adjustment alone and balance using the right hand side.

http://www.ibmwr.org/r-tech/oilheads/r1100_throt_bod_sync.shtml

 

[ianboydsnr]

I may be wrong, but I'm sure you are supposed to leave left hand throttle cable adjustment alone and balance using the right hand side.

http://www.ibmwr.org/r-tech/oilheads/r1100_throt_bod_sync.shtml

thats what I thought,

 

[littleredrooster]

Yup - set the left TB so that it has about 1-2mm free play in the cable, then do the adjustments on the RHS cable adjuster at 1500 and 4000rpm. Finally set the BBS for the correct tickover. It sounds as if yours might be currently hanging on the cables if there's no free play.

BTW - 350mV sounds a bit low for the TPS; you might want to get it nearer to 370-400 for better throttle response.

 

[Canuck]

Mine likes to be set at 0.371

 

[Steptoe]

I may be wrong, but I'm sure you are supposed to leave left hand throttle cable adjustment alone and balance using the right hand side.

http://www.ibmwr.org/r-tech/oilheads/r1100_throt_bod_sync.shtml

Absolute rubbish.

Mr magicfingers. Don't adjust the idle with the cable adjusters. You must have play in both throttle cables. Don't get hung up on trying to get 2mm, it's not really important how much in the great scheme of things, anything between 1mm and 5 mm.

Balance the idle with the bbs, again it doesn't matter if there's a difference between how many turns out they are, just get them even on the guages.

Then balance the throttles under load by the cable adjusters, working on the side that doesn't tighten the cable i.e. adjust the side that needs to be loosened to balance the set up.

 

[mr_magicfingers]

Absolute rubbish.

Mr magicfingers. Don't adjust the idle with the cable adjusters. You must have play in both throttle cables. Don't get hung up on trying to get 2mm, it's not really important how much in the great scheme of things, anything between 1mm and 5 mm.

Balance the idle with the bbs, again it doesn't matter if there's a difference between how many turns out they are, just get them even on the guages.

Then balance the throttles under load by the cable adjusters, working on the side that doesn't tighten the cable i.e. adjust the side that needs to be loosened to balance the set up.

Thanks Neil that helps a lot, I'll have another go at it tomorrow. Just to check, you adjust for free play in the throttle cables at the adjuster on the right grip, yes?

 

[MattW]

Try an early 1100 with the single piece cable - trying to get a consistent balance through the rev range is enough to drive you mad

 

[mr_magicfingers]

Steptoe once again cuts through the bullsh1t and makes thing easier.

Neil, thanks for the above, after reading through the ADVrider wisdom tome on balancing I wasn't hugely the wiser. With your info it took 10 mins and 5 of that was waiting for the engine to warm up.

Slackened the throttle cable off, backed out the BBS screws, set idle speed and balance on the screws, then 4000rpm on the throttle body adjusters. Job done.

Only thing I've discovered is I have very little adjustment left in the throttle cables, I guess they've stretched over the years as the bike's done over 80k miles now. I imagine that will have to go on the service list later in the summer.

Bike now runs much more smoothly.

J.

 

[street_moto]

Steptoe once again cuts through the bullsh1t and makes thing easier.

Neil, thanks for the above, after reading through the ADVrider wisdom tome on balancing I wasn't hugely the wiser. With your info it took 10 mins and 5 of that was waiting for the engine to warm up.

Slackened the throttle cable off, backed out the BBS screws, set idle speed and balance on the screws, then 4000rpm on the throttle body adjusters. Job done.

Only thing I've discovered is I have very little adjustment left in the throttle cables, I guess they've stretched over the years as the bike's done over 80k miles now. I imagine that will have to go on the service list later in the summer.

Bike now runs much more smoothly.

J.

Glad the job's done, same way as described in the link!

 

[Steptoe]

Glad the job's done, same way as described in the link!

Nope, the link says adjust using only the R/H adjuster. Which is bollox.

 

[Steptoe]

Bike now runs much more smoothly.

J.

Good.

The only way you'll be able to synch perfectly is by constantly doing it, not by reading about it.

 

[street_moto]

Nope, the link says adjust using only the R/H adjuster. Which is bollox.

That's because it's for dummies/beginners I guess?

 

[Steptoe]

That's because it's for dummies/beginners I guess?

In which case even more reason to get the procedure right from the start.

 

[flatdog]

That's because it's for dummies/beginners I guess?

Yep I'll hold my hand up to being a dummy, changed my throttle cables and all hell broke loose with my TB's, the master....Mr Steptoe restored calm and order at his last visit oop north last Month.
Now't better than having it done by da man.

 

[street_moto]

Why is it that, if you have enough slack in the cables at the TBs, it is wrong to just adjust on the RHS TB for high RPM synching? I've used this method and the previous owner too and no problems I'm aware of.

Genuine question by the way as I do believe it's best to listen to someone who knows what they're talking about.

 

[Steptoe]

Why is it that, if you have enough slack in the cables at the TBs, it is wrong to just adjust on the RHS TB for high RPM synching? I've used this method and the previous owner too and no problems I'm aware of.

Genuine question by the way as I do believe it's best to listen to someone who knows what they're talking about.

Just adjust the one that needs less adjusting, left or right.

 

[street_moto]

Just adjust the one that needs less adjusting, left or right.