ok. i found out that ist most remarkable with 5000rpm. not only constant speeds. between 3000 en 7000rpm is the worst. when it stutters and i open the choke a bit that helps against the stutter i think.

 

if you have a jet kit, then maybe the clip position is off. if it runs better with choke on it may be lean, but that isn't the greatest test.

Be sure your bike is cold. start it up and let it run for a minute just to get the carbs and everything flowing properly. Go out and fully (WFO) roll on the throttle quickly but smoothly. Start at around 3k rpms in 2nd or 3rd gear and go all the way to redline. Do it a few times to get the feel. This test needs to be be done with the bike cold. Now repeat when the bike is hot... you are looking for differences through your RPMs cold vs hot.

Runs OK cold but BAD hot = rich mix
Runs BAD cold but OK hot = lean mix
Runs good cold but Great hot = good mix

 

And if its too rich, you tighten the pilots? How much of a turn should I be starting with when tuning? A quarter turn or so each time?

I don't have the tool to turn them but I dont want to damage the screws by sawing them. Couldnt I just turn them with a small flat head? Or should I just go to Honda and get a tool if I am going to be tuning anyway?

edit: Also, what would happen if I tightened one of the jets more than the others? It was the smaller one that I think was not tightened the same amount after I cleaned my carbs and my bike feels a little light on power in the low rpms.

 

I have made a picture of the old sparkplugs.
They look very nice to me, so the mixture should not be the problem I think.
I am still going to try to clean the carbs.
Can the problem also come due false air?

 

If you aren't a poor shmuck like me, I would just go get the correct tool. Especially because it allows you to adjust the pilots on the bike, where the thing I do requires the carbs off the bike.

Yes, tightening will lean out, backing out will enrich. Depends on how bad the problem is, you can start with 1/4 turns or if you get some serious bogging or hesitation do a half turn. All of the pilots should be equal. If you fear they are not, just screw them all in till they seat (gently) and count how many turns they went in, and back them out again.

 

4th plug looks richer than the rest. i personally like my plugs to look like your 3 left ones, white, but a clean white, no detonation spots and no damage to the plug. It means you are running hot enough to burn all the fuel, keep the plug clean, but not so hot that you are doing damage to the plug. But it is hard to tell.. not sure how many miles are on the plugs, maybe those 3 are a tiny bit too lean. I would look to even up the mix first.

What you should be looking at is the white porcelain insulator in the middle. The tip of that shows pilot mix, the middle of it shows needle mix and the base, way in where you can't even see on the picture, will show main jet mix.

Check the pilot screws like I just mentioned. turn them all in and seat them, count the turns, are the turns equal? If that is not the case you may need to clean your carbs. maybe the 3 on the left are a little dirty, which restricts fuel and leans out.

By false air do you mean air leaks? Yes, it could cause problems... be sure your air box is sealed nicely, all your gaskets from box to carb are in place, your carb boots are all on and seated down nicely and that your exhaust from engine to pipe has no leaks.

If you find no air leaks, I would start looking at the carbs. check to make sure pilots, needles and main jets are all equal and even adjustments.

 

I finally cleaned my carbs!
I didn't do a testdrive yet.

I only found out that 3 air/fuel screws were turned 3 and a half turn out and one 4 and a half turn.
is this normal?
I think this is maybe also why one sparkplug is darker and else then the other 3.
anyway I now turned all the screws 3 and a half turn out.

also I found a number "135" on the pilots. is this the default?

btw I couldn't see any serious mess but cleaned everything anyway.

 

No, not normal, you want them all equal.

I can't remember what is stock on the mains because I have had a jet kit in my bike for as long as i owned it. Don't worry bout it though, you made your first adjustment. The pain in the butt part with carbs is that you want to fix 1 thing at a time, go test it, if you still have a problem, figure out at what RPM you have the problem and whether its better hot bike or cold bike. Then you tear it apart again. Very tedious, I know...

PS, you didn't mention your floats or diaphragms. I hope you cleaned the floats and checked out the jet needles as well while you were in there.

 

i did. i cleaned everything. but couldn't find any visible mess.the good news is... he problem is gone now! i went for a testdrive and everything felt good. so i think it was the wrong mixture in one cilinder... thanks for all the help. i am happy now

 

Hmm, I currently have this problem...