TOPIC:

1976 KZ900, 1015 block with 28's, 4 into 2. Just to summarize, posted in "ENGINE" section that I had some fairly heavy smoke coming from the right side (#3 or #4). Narrowed it down to #4. Changed the "new" 28's to the old 26's and after about 6-8 miles, the smoke appears to be almost gone!

It now appears I have a carbuerttor problem not an oil problem?

What I'm having a small problem with is that the right muffler inside the tail end, when I had the 28's on, was very black/sooty and quite wet. On my finger, this "looked" like oil but could it have been gas + carbon/soot?

Second.... could a hight float on #4 carb cause these symptoms?

Third..... If I have four carbs with identical jetting, why would only #4 cause heavy smoke?

Owing to the fact that the rebuild is only 100 old, the bike has not been riden over 4,000-4,500 RPM.

Fourth.... Which jet(s) do I need to downsize to alleviate the smoke between 1,000 RPM & 4,000 RPM?

Thanks.

Things are looking up!

If you purchased the carbs used and don't know their history, perhaps they deserve a very close inspection.

-Duck

Duck, Got them on E-bay so stripped them TOTALLY down, cleaned and blew out all the passages then re constructed BUT, must admit, I had a lot of spare jets etc lying around from previous carb jobs so, I decided to "go large" where perhaps I should maybe have shown more restraint AND.... I also moved the needles to the #3 slot.

Think maybe now I should have stuck with the regular value meal jets!

I think the 28's I have are 74/75 vintage (2 screw tops & sync screws on the outside) so any ideas on the correct jetting and needle position for 1024cc 10:1 comp with 4 into 2 macs (with mufflers), pods, dyna and stock cams would certainly be most appreciated. Thanks.

Sounds like a job for SUPER WIRED GEORGE!!!!

Come back WG....All is forgiven.

have you checked your carbs? hehe sorry couldnt help that one,that was my second idea i posted!goodluck,happy wrenching!

BH-

Assuming you're on the right track with the carbs. You've gone through them carefully. They are all clean and assembled just so. Why would one be acting up?

What I mean by close inspection is...
Making sure the parts are right.

If I had gone through a set of carbs and one appeared to be acting up, I'd lay out all the parts and make sure the wonky carb had the same parts, by visual inspection and measuring, not just by nomenclature. What if main and pilot jets were drilled? Say your main says 115 but it's been drilled to 135! What if slide got dropped by PO and needle broke and he subbed whatever was on hand?
What if main jet emulsion tube has a different hole pattern and ID?

-Duck

sounds to me that your over jetted and it is hard to tell since u havnt gone up in rpms enough yet to hear the engone sputter. With a main jet thats too large already, raising the needle really makes it rich. Wich means soggy spongy midrange, popping and cackling at idle, and sooty plugs with raw fuel running down the driveway lol. Some needle jets from 28's have larger holes drilled in them and the main jet required for proper mixture is much smaller when used in combination. If you plan to use the 28's and select a smaller main, take them apart and drop the needles one notch also. Wired G will coach you im thinking, since he knows what belongs where and why. Whats an engone?
I have to add that it depends upon what needle you have as to whether the second or third notch is the best place to set the clips. To find wether one of the choke plungers is not seating when the choke is off,close the choke lever, take a rubber hose and press it tightly against the hole in the mouth of the carb and try to blow air through. NO air in off position means the plungers are closed as they should be.
Post edited by: nads.com, at: 2006/04/14 00:25

Post edited by: nads.com, at: 2006/04/14 00:35

Barney, if you have carb related questions and want me to answer promptly, I have a carb forum on my web site that I check in on regularly. I have been in the process of moving into my new and larger building and have been pretty distracted for the past week. The building is now up and I am looking for an electrician so will probably be distract for another couple weeks while I get the electrical hooked up and the interior insulated and finished.

If you want some help, tell me what type of carbs you are talking about when you ask your question... I personally think you are kind of sensitive and I personally would see if seating the rings didn't cure the problem. Rings DO NOT seat in 100 miles. Live with the smoke for a bit and see if it doesn't subside after a few weeks. Could be the #4 rings are not quite seated where the others are.

I agree with wiredgeorge. The motor does not have enough miles on it (100) to start looking at smoking problems. All of the motors that I have built start to run normal about 400-500 miles. Some will smoke alittle and some will not. It all depends upon the fit of the rings and the finish on the cylinders. Also you need to put some heat cyles into the motor also. If the motor has 100 miles on it how many rides did it take to do that? I always try to put 4-5 heat cycles into the motor the first 100 miles.

oldkaw79... looking at the type of bikes you own and the type bikes I own tells me that you probably seat in rings a lot faster than I do! bwhahahaha

Honestly, I have never felt that riding slow did much good in seating in rings. If you have a BRAND NEW engine, maybe it might be best to baby it during break-in but if you are seating rings, ride it like you stole it!

Amen to that. Ride it like you stole it!!!!!!!!!