RT Throttle Body Synchronization

[David Sharpe]

I am in the midst of completing a throttle body synchronization. I'm following Ken Harbeck's R-Bike Throttle Body Synchronization (Ken's Write-Up) write-up and I've done the following:

1.Adjusted the valves

2.Slackend both throttle cables until both bell cranks

were resting against the the throttle stop screws

3.Cleaned both brass screws

4.Set each brass screws 1.5 turns from being screwed

all the way in

5.Balanced the carbs by adjusting the right idle stop

screw (not the left one and not the cable adjusters)

 

I am able to balance the carbs with a TwinMax but at the

same time as I adjust the throttle stop screw, idle speed

increased from around 1050 RPM to 1500 RPM. It makes

sense that the idle speed increases but how do I decrease

it to around 1100 RPMs where it should be and still sync the carbs?

 

It looks like from the steps outlined in Ken's write-up that adjusting idle speed isn't done until the very end.

[Voyager]

I think the LBS setting sets your idle (1.5 turns initially, then adjusted to desired speed no greater than .5 turn difference in screws) Then take slack out of left TB cable(making sure not to effect idle) then synch for off idle and high RPM.

 

But, I am no tech guy so consider the source...

[David Sharpe]

Thanks for your help but I am still having trouble. So back to basics.

 

How do I ensure that the fast idle cable has been completely slackened? I've loosened the nut and barrel adjuster by the left had grip but I can still use the lever to increase RPM. So I guess I'm not loosening it correctly?

[Voyager]

David, Try these links here here. I read about four different explanations before I tried my first synch & picked the simplist one. Ed's explanation (first link) for looseness in the cables is better than mine. I've never seen one that referred to adjusting the fast idle(choke) position, but again I am no tech (hopefully one will chime in soon!)

Hope this helps, if not I'll keep tryin'

[Voyager]

David,

 

This is my other source. There are at least three different write ups for TB synch there. If I was still out west I'd give you a hand.

[Jim Moore]

Are the set screws on our throttles resting on the stops at idle? If so, your main throttle cable and fast idle cable are loose enough. Do I understand correctly that you are at 1500 rpm at idle with the set screws on the stops?

[Jake]

Ken's method advocates adjusting the right throttle body stop screw (loose cables, both brass screws 1.5 turns out) to find idle synch early in the process. Why? It seems to be intoducing a variable that is not factory indended, and could create a mechanical throttle body imbalance from the start. If one is adjusting the right stop screw up to match idle with the left throttle body early in the process, you could stairstep your way to a 1500 rpm idle easily, and getting back to stock is a tough job from there.

 

It seems to me that adjusting the LBS is a better idle synch process than the stop screws - who knows what gunk has found its way into the air flow (cleaning the throttle bodies, brass screws, butterfly valves, and intake tubes along with a visual inspection should be a mandatory step before adjusting anything.)

 

Why mess with the right-side stop screw (step 8)? You want idle synch, sure, but I'd rather have throttle butterfly valves that start their travel from the same spot - a hairline difference can mean a lot of air, and a lot of aggravation.

[redryder]

I just did my T/Bs with disastrous results. (Read my post: Help! I've farged up my TB synch!) I really did it to myself because I went into it underinformed and screwed around with my left TB adjustments. DO NOT DO THIS on an 1150!!!!! However, Ken H. was very patient and gracious and sent me his detailed procedures and not only did I get the bike back into running order, it now runs better than ever before. Moral of the story; follow Ken's directions from the start VERY carefully and you should be in good shape. As for the fast idle lever slack, be sure you are screwing the jam nut and adjusting barrel toward the outside of the handlebar. By screwing it toward the middle of the bike, you will make the cable tighter. Also, be sure you loosen the throttle cable at the twistgrip and make sure there is slack. You should be able to flip each throttle plate open and closed and hear a very distinct snap when it returns to the mechanical idle stop.

 

I can tell you with all certainty (if that's a word?) that if you move your TPS or mechanical idle stop on the left TB, you are in a world of doody.

 

Make sure all throttle cables are loose, start with Ken's procedure from the very start and follow them very diliberately and you should be more than happy with the results. Let us know, or PM me if you need more information. I'm not an expert at synchs by any stretch of the imagination, but I've gotten a crash course in it in the last two weeks.

[Ken H.]

David, PM me with your contact information if you'd like to discuss this. 1500 RPM idle with both TBs on their stop screws is just not right.

 

I'm not going to defend my procedure here on an open forum. BTDT too many times before. Got too much other typing to do!

[bmwmick]

David,

Ken's procedure would work fine for an R1100 engine but yours is an R1150RT with MA 2.4 Motronics.

You have one final step to perform: Remove the Motronic fuse (F5 I think) for 10 minutes. Re-install the fuse, set ignition to run but do not start the engine. Open and close the throttle all the way about 3 times slowly, Ignition off. Next, start the bike and see if the idle changes.

This procedure lets the newer Motronic 2.4 'learn' the limits of the TPS. You should now be able to finish your sync job.

 

Mick

Tucson

[Ken H.]

While I agree that re-teaching the Motronic the TPS range is important on the 1150s, I'm not sure that in itself would explain the 1500 RPM idle speed. Presuming the left idle stop and TPS position haven't been messed with.

[BucksTherapy]

Ken is the expert and you are in great hands but I just can't help throwing my $.02 worth in as this happened to me.

 

After you loosen your cables be sure to check and make sure that all cables remain seated in their adjusting scews and indents. My idle jumped by 800 rpm when the cable in my throttle at on the handlebar jumped its indent. I took the direction to loosen cables a wee bit too serious I think. Took me a while to figure out what was happening.

 

Good luck and let us know what you learn.

[AZDrifterus]

Something everybody missed is the initial 1 1/2 turns out on the air bleed screws. Some bikes do not need this much. Mine is closer to 1/2 turn each, synched at 1150 rpm.

 

Set both air bleeds at soft bottoming,

synch right throttle stop to left (at low idle),

adjust idle speed with the air bleeds (synched)-

then synch cables at different rpms.

[David Sharpe]

Success, carbs are balanced! Thanks Ken H. for your offer to help.

Even though I didn't need to talk with you I worked with confidence

knowing someone who knew what they were doing was available

if I really got stuck.

 

What helped?

 

Trusting the wisdom of others and following directions. I made the

mistake of jumping in to the TBS without taking time to study each

step. Some steps didn't make sense but I followed them and they worked

out later. Others I had to play with, like knowing when the bell crank

was resting against the throttle stop screw by listening for it to

make a mechanical click. Some steps I added to, like making sure both

bell cranks clicked against their stops at almost the same time.

 

All in all a great experience.

[Ken H.]

Success, carbs are balanced! Thanks Ken H. for your offer to help.

Your welcome, glad it worked out.

knowing when the bell crank was resting against the throttle stop screw by listening for it to make a mechanical click. ...making sure both bell cranks clicked against their stops at almost the same time.

Yes, I think not assuring this is a critical mistake a lot of people make. It is critical that the bell cranks return to their stops and not end up hanging off of the end of their repective cable when at idle. Otherwise you will chase your tail forever between idle sync and above idle sync.

 

Good work!