TOPIC:

No eBay APP ID and/or Cert ID defined in Kunena configurationBike is 100% stock. Bike had been off the street for 6 years started only a few times during that period. Carbs leaked gas so I figured it was a good time to rebuild them as I wanted to start riding it once again. Bike is a 1983 KZ550 with TK26 carbs.
Recently I purchased K&L carburetor rebuild kit. Took the carbs apart three times, last time the rack was split and each was put in a ultrasonic cleaner for a few minutes. Carb cleaner was sprayed thru all passages, I ran a thin copper wire thru as much as I could to confirm the passages were not blocked. From the first time the carbs were disassembled they looked quite clean, not signs of gunky dried gas.

After each of the three reassemblies, the bike is hard to start. Once it starts it takes a lot of playing with the choke to get to finally be able to close the choke all the way and have the bike idle. Carburetors have been syncronized. Bike idles fine. 

When trying to ride it almost feels like it wants to stall, if I am able to get it going, any gear after 3k I open the throttle and it bogs down. I don't know if this is an indication of too rich or too lean? Bike is almost not rideable. 

Stock airbox, brand new air filter. The rubber boots are pliable and appear to seal well and I could not find any vaccuum leaks. Fuel seems to be flowing well, I have fresh gas and an inline fuel filter.

Pilot air screw is 2 1/2 turns out from closed. I have tried to run the bike at 1 1/2 turn from closed or 3 1/2 turn from closed with not apparent difference. 

What else should I be checking? I am stumped and hard to believe that I would have to take the carbs apart for the 4th time since they are clean. 

This is the rebuild kit I used: 

 

Welcome, from what info i have the fuel level could be out.

27mm to top of float or 7mm +/- 1mm down from float bowl i think is the spec for the TK26 CV carbs

also the idle mix adjust needles in pattern kits are sometimes not right, this was the case with my 1200 Mk2 bandit so i used the stock Suzuki ones with the pattern seals and washer.
I do not have a link for the Z550 with CV carbs and the GPZ550H unitrak is similar but not the same jet sizes. Please post the jets you have used and ones available in the kit

When it bogs at 3k apply the choke.
If it pulls through it could indicate lack of fuel/lean mix.
If it makes it worse or no change then too rich/overfueling.
Also which brass parts did you change ?
You should avoid changing any brass parts unless they are physically damaged as many aftermarket parts will cause more issues than they solve.
I would re-fit all original brass that is not damaged.


 

I don't know what the problem is, but I do know that ultrasonic cleaners don't clean internal carb passages as well as carb dip does.

I checked the float bowl level and was in spec per the owners manual. Forgot to state that on my opening post. Good point about jet sizes, I kept everything from the original carbs as the parts were not damaged, but replaced since I had new ones. I will be taking these apart once again and replacing the new brass parts with the old ones. I will report back afterwards. 

wrote:

When it bogs at 3k apply the choke.
If it pulls through it could indicate lack of fuel/lean mix.
If it makes it worse or no change then too rich/overfueling.
Also which brass parts did you change ?
You should avoid changing any brass parts unless they are physically damaged as many aftermarket parts will cause more issues than they solve.
I would re-fit all original brass that is not damaged.


 

This is useful. I will tear them down again and replace all the new brass parts with the old ones. I basically replaced everything that came in the kit. 

loudhvx has a motorcycle stuff page w lots of info about the TK26 carburetors. see links in his signature.

loudhvx has a motorcycle stuff page w lots of info about the TK26 carburetors. see links in his signature.

Thanks. I have read thru his page before, great resource for sure. I seem to be following everything he has listed on it. 

wrote:

When it bogs at 3k apply the choke.
If it pulls through it could indicate lack of fuel/lean mix.
If it makes it worse or no change then too rich/overfueling.
Also which brass parts did you change ?
You should avoid changing any brass parts unless they are physically damaged as many aftermarket parts will cause more issues than they solve.
I would re-fit all original brass that is not damaged.

 

I finally had a chance to tear the cabs again (4th time). I put back in the pilot jet (marked #32, same as the replacement jet that came with the kit). The holes on the sides of the jet appeared to be of larger diameter on the old jet compared to the new jet. Either way, the bike seems to ride barely better, basically similar symptoms have continued. The rest of the parts replaced where o rings. 

When I apply the choke it becomes much worse, almost makes the bike stall- so that means its running too rich? 

wrote:

Welcome, from what info i have the fuel level could be out.

27mm to top of float or 7mm +/- 1mm down from float bowl i think is the spec for the TK26 CV carbs

also the idle mix adjust needles in pattern kits are sometimes not right, this was the case with my 1200 Mk2 bandit so i used the stock Suzuki ones with the pattern seals and washer.
I do not have a link for the Z550 with CV carbs and the GPZ550H unitrak is similar but not the same jet sizes. Please post the jets you have used and ones available in the kit

The original jets were #32 as were the ones that came with the kit. Per the suggestion above, I tore down the carbs and reinstalled the original pilot jet. When I tore the carbs down, I rechecked the float height and they appear to be within spec. 

Is there any chance that this isn't carb/fueling related issue? 

Welcome gvin.

Have you looked at the spark plugs? They will "speak" volumes...
Post some pics of their electrodes here ... for a free evaluation!

Nice machine you have there!

H.