New Throttle Cables -- need carb sync?

[pswanson]

Hi -- I just got a reply from Wolf BMW service that after replacing my throttle cables, I WILL in fact have to re-balance my carbs. I couldn't imagine this being the case. I will naturally adjust the new ones to remove any slack, so the valves are opened together, as before. Am I getting scammed here? Seems perfectly mechanical. Now, it's also been 30 K and 7 years since they were balanced by the previous owner, and I've had them apart and cleaned and reassembled in the meantime... should I go ahead and get it done in any case? Advice? I wouldn't mind learning to do it myself. Thanks,

Paul

[20774]

I vote for getting the carbs synched. You've changed something in the system, thus it needs it. And given the fact that it's been a while since it was done...they need to be resynched.

It's really not that difficult to do by yourself...there's plenty of self-help on the web plus it's been discussed numerous times here in this forum.

[67461]

Go to snowbum archives link to yardstick balancer . FOLLOW INSTRUCTIONS!!!!! Works better than a $2000 gauge that measures in pascals !!! bmw motorcycle tech Best Wishes do it yourself! The Bear:wave

[lkchris]

Seems perfectly mechanical.

That it is.

How are you going to screw the new cables to the carb tops EXACTLY as before?

Are you pretty sure that the ratio of cable stretch between the left and right cables will remain the same?

Sounds like you're about to experience the best-running bike you've ever had.

[kbasa]

That it is.

How are you going to screw the new cables to the carb tops EXACTLY as before?

Are you pretty sure that the ratio of cable stretch between the left and right cables will remain the same?

Sounds like you're about to experience the best-running bike you've ever had.

:nod

Once you take the old cables off, installing the new cables will absolutely require a carb synch.

[nealart]

In fact, adjusting the cables is a major part of synchronising the carburetors.

[robertklee]

Hi -- I just got a reply from Wolf BMW service that after replacing my throttle cables, I WILL in fact have to re-balance my carbs. I couldn't imagine this being the case. I will naturally adjust the new ones to remove any slack, so the valves are opened together, as before. Am I getting scammed here? Seems perfectly mechanical. Now, it's also been 30 K and 7 years since they were balanced by the previous owner, and I've had them apart and cleaned and reassembled in the meantime... should I go ahead and get it done in any case? Advice? I wouldn't mind learning to do it myself. Thanks,

Paul

Which bike/carb do you have?


:usa

[PGlaves]

Oh boy! It is possible to install cables without adjusting them - but the act of properly adjusting them is 98% of what it takes to synchronize the carburetors. It takes about two minutes once the engine is warmed up. I don't know any way to properly install cables and not synchronize them.

[tghsmith]

you might as well make the yard stick balancer, as the new cables break in ajustments will need to be done.

[James.A]

A few months ago, I did a rebuild on the carbs on one of my R75/5's. (I did the other one last year) After using the Twinmax to set the idle stops, then the idle air screws, then the idle stops again, I found the 3kRPM reading to be in perfect balance. I know that replacing cables is very different than rebuilding carbs. However in either case, the carbs are seperated from the cables and the potential for inducing an imbalance is real. Having said that, I think it is possible to fit throttle cables and and achieve acceptable balance through careful observation and adjustment with the motor not running. The trouble with this approach is that it is impossible to KNOW you have achieved balance without using a calibrated device. Therefore, a proper syncing at full operating temperature would be advised.

[Isamemon]

I agree with all said,
if you want things right on
you will need to rebalance, and you will have to check after a few hun miles as the new cables do stretch
even old ones stretch and they do not do it equally

the yard stick balancer is great and cheap
if you cant find it at snowbums site you can find it on the airhead site with full instructions how to balance

I do often borrow a twin max , but I have the yard stick and they both work very well

with the exception if the carbs are way out of balance, wiht the yard stick you can suck fluid through the tubes and into the carbs, making it a lengthy time job as you wiat for fluids to resettle, but if your near at start, the yard stick works great and is cheap ($5)
if you make the yard stick, using auto trans fluid is good, as the light oil , if sucked into the carbs, will not do damage, plus the red fluid is real easy to see


remeber though no balancer is perfect if your carbs are gummed up, if the butter fly is not closing 100%

[sumran]

You will certainly need to sync them when you put in the new cables. As has been mentioned, that is what syncing is about. You will probably need to do it again after a few weeks. Once the cables have operated for a while they will change slightly. It doesn't take much change to affect balance.

[PGlaves]

I want to add to what I posted above:

Synching is an inherent and essential part of installing the cables. You can attach them but that is not installing them properly.

I don't really understand the first post in this thread at all. Why a dealer would even mention synching in conjunction escapes me, and why the owner would think they can be installed and not synched escapes me too.

[rvbeemer]

I want to add to what I posted above:

Synching is an inherent and essential part of installing the cables. You can attach them but that is not installing them properly.

I don't really understand the first post in this thread at all. Why a dealer would even mention synching in conjunction escapes me, and why the owner would think they can be installed and not synched escapes me too.

I second what Paul said!

Ronnie

[pswanson]

Ok ok ok. The bike (my beautiful '89 R100RT) had been completely tuned and sync'd when I bought it and has run well, esp on the highway for 7 years apart from being a huge headache in the electrical system. I had thought balancing the carbs was something to do with adjusting the vacuum or fuel flow, not how the cables are attached. I figured new cables should simply be adjusted to allow the levers on each to reach their stops without any slack. I did read up on how sync'ing is done a few years back, but haven't ever done it yet. I'll check out the yardstick. Thanks -- I'll let everyone knows how it goes. Mebbe I'll get rid of some of that footpeg massage I seem to be getting more of lately!
Although I hear that can be from crank bearing wear...

Thanks so much!
Paul (the original Paul)

[woodgrain]

I'm surprised you actually got Airhead parts from them. In the past they've left much to be desired for Airhead service or advice. Things haven't improved since Ailsa Craig...

Woodgraon

[woodgrain]

I'm surprised you actually got Airhead parts from them. In the past they left much to be desired for Airhead service or advice. Things haven't improved since Ailsa Craig...

Woodgrain

[pswanson]

Yeah, I used Wolf a couple times years ago, and they were great. Esp. in terms of actually answering my emails. This time around however, they quoted 2-3 times what some of the parts should have been priced, and now they're trying to scare me into taking my RT in for a complete service. Although I must admit, my lack of knowledge about the need for carb balancing must have seemed like a tip-off to rip-off...
Funny how they would actually call themselves "Wolf" BMW...
I ended up ordering the black coil and new ICM from Euro Motoelectric in the States, but they didn't have the cables, and Wolf WAS actually a bit cheaper than the BMW dealer in Oshawa and seemed to have them in stock, so... there you have it.
Paul