carb synch question

[Zampano]

hello. Firstly, I need to thank all of you for the info I have found on this forum. I recently bought a '92 K75S (first bike I've owned) and this site has saved me from much aggravation. Kudos.

I've read the instructions for synchronizing the carburetors and it appears straightforward. Before I get into it and maybe dish out $110+ beans for a Carbtune Synchronizer, I wanted to ask if there are any subtle tricks to it. I was told the plugs were recently changed but I may put in a new set to be sure. I don't have ability to check the valves so I will have to assume they are within spec.

For the most part the bike runs well. The throttle response does not feel right to me. However, this is my first bike and they are all different. To me, I have to assume the throttle response could be more smooth. It is most pronounced when the carbs first open. You're expecting a certain delivery of power but it is inconsistent and herky-jerky. This makes learning to ride a pain in the arse, especially starting, parking lots, slow speed turns, etc.

From what I've read this sounds consistent with out of synch carbs.

thanks.

p/s

if any one is near san diego and has a carbtune I will gladly float you a 12 of lagunitas for a synch session.

cheers.

[Lawrence]

Zampano, if your K-bike has carbs, it's a rare bird indeed.  I'd recommend you do considerably more research on your bike and its tuning before you go ahead and "sync the carbs."  You may well be preparing to shoot yourself in the foot!  :eek2:
Keep readin', my friend.  Keep readin'.  There's a lot of help here and on other sites to keep you out of trouble.

[Rick G]

The K bikes have a Bosch Fuel Injection System but what you want to do is much the same thing to ballancing carbs on other bikes.
Before you even try to ballance the Throttle Bodies it's best to make sure the valve adjustment is correct or you will be largely wasting your time.
The valves are not difficult to adjust with the correct tools and they are available for a reasonable price.
I would suggest getting a Clymer manual or a .pdf copy you can read on screen and print the relevant pages.
There are many little tricks used to enhanse the rideability and performance of the Ks and most are to be found here and on other sites.
I suggest browsing through the lieberry here after introducing yourself to the bunch of old codgers on the front porch, you will find a well organized lieberry that Frankenduck has put together.

[Zampano]

thanks for the replies. Yes, I realize it is a throttle body synch.

I have read most of the intel (thanks again) and it appears to be straightforward. Will likely invest in a carbtune. The synch is potentially affected by much of the routine maintenance. It would be nice to chart each of their influences.

Also, I'm tempted to build a three column instrument. There are several attempts on youtube which in principle could be accurate; especially considering what is actually being measured. If it turns out well and is consistent with a known (e.g., carbtune) in a side-by-side test I will post a vid.

enjoy the ride.

[Lawrence]

At first glance it may seem like the same procedure as balancing a multi-carburettor engine. The throttle bodies have butterfly valves; so do many carburettors.  However, the K-bikes' are set at the factory and the only thing that's recommended by way of later tuning is setting the air bleeds.  If you jump in and synchronize the butterfly valves (those screws with the "torque paint") you may open up a can of worms.  The other side of the coin is, of course, that the DPO may have already done just that!  :yow 
I've found that the air bleed screws have very little to do with a good running K-bike engine. 
Good luck and welcome to the K-bike club!

[K75RT Keith]

What do you know of the repair history on your new ride?  Does it stumble only when cold or at all temperatures?   Stumbling or the herky jerky feeling you get in a paring lot could be from using the wrong gear or fouled injectors.   Have you tried injector cleaner yet?   As noted in a previous post the throttle bodies are factory set and short of a previous owner messing with them, they should be spot on.