Carb adjustment & sync

[gimmefuel]

Hey guys. Good morning to ya. Just wondering, is there any secret to adjusting the air/fuel mixture screws while the bike is running?? I read somewhere the best way to visually sync them was to run the screw in on each carb till it misfires and then back out. As you all know, the mixture screws are virtually impossible to get to while the carbs are still installed on the bike. If the best way to sync them is off of the bike, what is the best way to do so?? I have never had to do it before. Thanks a lot and you guys have a great week.

[Newbie2it]

They sell extended screws that you can reach in to turn by hand if you plan on having to adjust them often for fine tuning, or you could get a screwdriver like this.

The screwdriver is a pain to use with the fairings on however.

[gimmefuel]

I have tried that screwdriver before. It's a pain to use with the fairings off!!! lol I never knew about the extended screws though. Thanks!

[Newbie2it]

I have tried that screwdriver before. It's a pain to use with the fairings off!!! lol I never knew about the extended screws though. Thanks!

Yep, the screw drivers a pain in the arse, but if you look closer at the pic i posted above, you'll notice that mine doesnt have just the single bend at the very tip (90 degree) I added a second tweak to mine, only a few degrees more about 2" down from the original. Helped immensely, Tho theres the occasion that it skips and I want to take the tubing bender and just give it 5 degrees more of a tweak. But I cant. I'm not always working on a Kat.

[hardlydangerous]

When you sync the carbs your not syncronizing the fuel/air mixture..
While thay must all be the same this can easily be done with the carbs off the bike for the mixture screws. Index the screws when lightly seated then back them all out the same amount.
When you sync the carbs you are syncronizing the intake vacuum by adjusting the throttle valves.

[gimmefuel]

I have them set at 3.5 turns out right now. And, they have been set at that for quite a while. I am getting a bad stutter at above 5500 rpm now for some reason and can't figure it out. Does it sound like a rich condition to you guys??? I just don't know why it has been at these settings all this time & now it's doing this.

[Black_peter]

That screw driver needs a few mods IMO.
First grind off the ridge on the housing. That is meant to lock onto the ridge on the carb. But on the Katana it doesn't line up right.

Next I drilled a hole in the screwdriver part and pinned it with a piece of thick copper wire. That keeps the tip from retracting into the housing.
Otherwise I found you are trying to keep the tip exposed, line up the tip to the screw and keep track of the turns all at the same time.

[hardlydangerous]

3.5 sounds like a lot.

But... If it ran good at these setting before and just started doing this.. then the carbs settings are not your issue.

it may still be fuel related but it's not the settings. It could also be electrical.
replace the plugs and plug wires...check all electrical connections.

[gimmefuel]

Hey, thanks Hardly. So the plugs & plug wires would also contribute to that mid & upper range stuttering?? Since we are on the subject, do you know of any high perf plug wires for the Kats?? I know they make 8mm wire sets for cars that generate a larger spark.

[Newbie2it]

That screw driver needs a few mods IMO.
First grind off the ridge on the housing. That is meant to lock onto the ridge on the carb. But on the Katana it doesn't line up right.

Yep, your right on the ridge, I toasted mine off working on a Kawi that tempted the tubing bender more than any Kat I worked on.

Next I drilled a hole in the screwdriver part and pinned it with a piece of thick copper wire. That keeps the tip from retracting into the housing.
Otherwise I found you are trying to keep the tip exposed, line up the tip to the screw and keep track of the turns all at the same time.

Ok... I dont see how affixing a turn-able screwdriver into a statoinable one would solve turning the screwdriver thats ment to turn? I could see a thought as being "well, if it cant retract anymore, then pin it. However, How on gods green earth would you turn it?

Maybe I am confused.

[gimmefuel]

Hey you guys, weird question. I can't figure this out. Does anybody know why you could be having a mid/upper range stutter while going down the road BUT if the bike is sitting in the garage & you rev it to the same level it's smooth???? I know you could say that it's because the engine is under a load while riding but is that it??? Anybody ever wondered about this??

[Newbie2it]

Hey you guys, weird question. I can't figure this out. Does anybody know why you could be having a mid/upper range stutter while going down the road BUT if the bike is sitting in the garage & you rev it to the same level it's smooth???? I know you could say that it's because the engine is under a load while riding but is that it??? Anybody ever wondered about this??

Take a starter motor from a car thats not starting correctly, Put it on a bench. Hook it to 12v. Try "starting" it this way till your tired of trying it, then put a load on it, like turning over a motor. See if you can replicate the easy turn of that motor without the load.

Same applies here. While its loaded, theres an issue, while its unloaded, theres none. Unless you have a Dyno handy that you can try replicating a load while staying in one spot. Trying to run a motor in (N) no load gives you the same results as the starter on the bench.

For the same reason you bring your car to the mechanic for a noise, but he cant reproduce it, He will drive it differently than you, and when you get it back, you wont hear the noise either, cause something shifted from when he drove it last... Theres probably a Fig Newton law or some other parable about that. But I'm too tired to think right now LOL

[DimitriT]

Hey you guys, weird question. I can't figure this out. Does anybody know why you could be having a mid/upper range stutter while going down the road BUT if the bike is sitting in the garage & you rev it to the same level it's smooth???? I know you could say that it's because the engine is under a load while riding but is that it??? Anybody ever wondered about this??

Sounds like a carb issue. Carbs are sensitive to throttle position more so that RPM. The throttle position to get 5k RPM while the bike is on the center stand is much different from the throttle position at 5k RPM while you are on the road.

If you are in the middle range of throttle position there are several overlapping paths fuel can reach your motor:

* idle mixture fine tune adjustment
* idle jet
* needle jet

As you close the throttle, the needle jet seals up and doesn't contribute which leaves the idle jet and fine tune.

As you open the throttle and approach WOT, the needle jet maxes out and the main jet becomes the most important contributor.

It sounds to me like your problem is in the midrange which indicates an issue with the needle jet.

I would put the carbs on a bench and disassemble the slider mechanism and carefully inspect/clean it. I would also remove the needle jet tube and inspect it for wear.

Another factor is the operation of the floats. The needle jet sits in a pool of fuel in the bowl. The depth of this pool is controlled by the float and float valve operation.

[DumbLuck]

If memory serves (check me on this one Arsenic) the idle and pilot circut is pretty much out of the system once you get past about a quarter throttle. that's where the needle is being pulled up out of the needle jet and the venturi getting sucked open, and the mains are taking over.

[steves]

First question... is there still a problem because this thread is a month old.

If you are having a stutter around 3k-5krpm you might need to get a valve adjustment done.