Motorcycle Repair Questions? Ask a Mechanic ASAP
Hi Peter my name is Kenny
I'm going to start out right up front that they had a lot of problems with this carb, Mikuni some what admitted they were messed up, the carb on this unit went through about three part number changes.
We can maybe get it a little better but I'm not going to guarantee anything short of replacing it, but lets give it a try first !
OK first you need to make sure that the valves are adjusted to the looser end of the spec and I give you that, I will give you those in inches. Below is what factory calls out, I would run that intake at .004 and the exhaust at .005. All Kawasaki's like running at the looser end of the spec, plus you get a more truer cam timing. So you really need to make sure that those are set at those specs, it will make a BIG difference how this unit runs.
Intake ~ .004 in
Exhaust ~ .005 in
Now in your best guess would you say its running "rich" or "lean" does it require a lot of choke when starting and or how is the spark plug looking, color ?
By chance have you done a compression check on this unit ?
Get back to me and we'll go from here !
Piece of cake Peter !
I'll make it easy, I'll post up that page, hey if you can get it on TDC without removing the recoil then you won't need to get a gasket, just make sure you're on TDC compression.
Plus I just noticed the manual is screwed up, I thought the specs I gave you seemed a little on the tight side, use the ones on this page, so basically you will be setting the intake at .008 in and the exhaust at .009 !!!!! DO NOT USE THE SPECS I GAVE YOU FIRST !!!!!!! Use these I mentioned here.
Check your valves and then let me know and I'll direct you on the carb.
If you have any questions Peter, just reply back.
Let me know if you have any question, I going to be away from about 3-8 pm Pacific time, so if I don't get right back to you, you'll know why
So when you checked them where were they at, were they loose or tight ?
So lets deal with the carb now, you said that your raised the tapered needle, we usually refer to those as the needle, can you explained how you did that since there is only one clip on that.
Also where is the pilot screw set ?
Peter how many clip positions are on that needle ?
OK I'm going to post up the breakdown of the carb on your unit, I made some notes on it, you need to verify the jet sizes and also I want to know if there are plastic washers on both sides of the needle ?
Also when you get back wit h the carb info, do you have an inductive pickup timing light ? (for checking timing ?
Right click on the small picture and save it to your desk top, you can view it easier then viewing it through JA
Well I'm trying to determine if someone has switched the carb or changed things around.
The timing light I want to use as a spark tester, basically look at the light to see if it breaks up.
Will get back to this tomorrow, Thanks Peter
OK I'm going to go over a little carb fundamentals, I'll also post up some pictures that you can reference to.
First let me start off and say that setting up the carb the right way is critical, it is a precise part that is delicate and ultimately in the end will dictate how you machine performs.
I have seen so many times after someone has worked on a carb where they left out parts or damaged a part and put things together wrong....the list goes on.
So you need to start and look at the diagram and make sure that all the parts you see on that sheet are there in your carb, remember it was designed to have all those parts installed.
The pilot screw on this carb is "fuel metering" the base setting for a # XXXXX jet is a turn and a half (1 1/2) now since its fuel metering the more you tun it out the more fuel is added at low speed/idle. (mainly idle) as some as you start to give it throttle its off that circuit.
The starter plunger, you can unscrew the brass nut out of the carb body and then slide the plunger out, if you look on the underneath surface you'll see a black rubber seal, make sure that it sealing when its inserted in the carb body, you should see an imprint on the rubber where it was sealing on the carb body, and make sure that you have free play in your starter (choke) cable.
Now when you unscrewed the top cap off to remove the cable/slide out of the carb body I want you to grab the slide with two fingers and then with your other hand see if you can move that needle up and down, remember you told me that was a washer missing, so I will assume that you should have up and down play in that needle, YOU Shouldn't HAVE ANY PLAY THERE ! if you do then that means the needle is bouncing around and not metering your fuel correctly.
Last you need to check your float height that is really critical and needs to set to that spec.
I'm going to let you look at this if you have any questions rely back, I'll be in and out today.
The problem with those "aftermarket" is the quality control, you never know what you are getting. Basically your carb should look like the picture I posted, if not then I think that someone was in the carb ?
For $18 you can try it, like i said the needle in your carb from the factory is non adjustable so I'm thinking someone changed something ?
Most of those things in that first kit you showed me don't go bad, its usually just orings and gaskets, so if the seals are good then you really don't need all that stuff, plus I would rather have Mikuni parts in my carb then some aftermarket company.
As long ans the needle is tight with that spring and you have one of those plastic washers on the bottom of the clip you might try it, so set this carb up the best you can then run the unit and tell me what its doing them. Remember I asked about the timing light, maybe we have an ignition problem, just remember we are crawling right now before start walking.
Sometimes you have to go through the process of elimination before we can get to the problem, that is why I wanted you to check the valves, now we need to make sure the carb is put together right and if this doesn't work we'll check the ignition.
OK Peter, talk you later
Yes you turn the carb upside down where the float is resting lightly on the needle, (don't apply any pressure to it) then you measure from the body (where the float bowl meets the body) to the bottom of the float just like the picture, it should be real close from what it was unless something got dropped, usually they are not off but since you have this apart then I wanted you to check it.
When you had the carb on your machine, did you try draining the float bowl to make sure you had gas in it when you were trying to start it ?
When you say no start, if it has spark and fuel in the float bowl ???
So as we know you must have compression, fuel and timed ignition for one of these things to run, did you ever do a compression test on this engine ?
Hey Peter 22.6mm == 7/8 of an inch, if you have a small ruler just hold up next to the float from the carb body, maybe tape measure, there is a plus or minus of 2mm, but if you check it and its at 7/8 of an inch you're fine.
We use a set of veneer calipers when we set float heights
Now if you can ride it a little and pull the spark plug and lets try to get a plug reading !
When you say backfiring and bogging ? backfiring is usually an electrical problem, so right now does it start and Idle good ?
I guess if you can try to stay on the throttle when its running rough so you can pull the plug and get a look at it, if you have a digital camera you can snap a picture and post it up so I can look at it ?
Ride the unit a little so you can get some color on the spark plug, then stop the unit and pull the plug so we can get an idea how its burning
I can't really see, where you want to look is down in the plug, around the porcelain, from here it looks lean, I was looking and you have a Harbor Freight Tools in Des Moines, they have a $5 in line spark tester and also saw a compression gauge (pretty nice one in a box) for $25, the number on that was # XXXXX
So I'm thinking and hoping your carb is OK, it starts and idles good, as you say, so now what is it running out of fuel or the ignition is going away ?
Harbor Freight has some low cost tools that aren't that bad for home use, if you were to use a lot of there stuff everyday it wouldn't last, I checked its about 30 miles from your zip.
Maybe in some better light get a picture of the inside of the plug, but it looks a little lean, is your needle still raised all the way up ? (clip on the bottom groove)
I'm hearing what you're saying Peter it does sound like its starving for fuel, so your telling me that you think its fuel related,(that is good thinking) that is what you need to do, because your doing the seat of the pants.
I'm a few thousand miles away, so if you think that its running out of fuel then generally this can be caused by a couple of things, float level to low, or its a fuel delivery problem, then is there something wrong with the pet-cock, hose pinched, the vent on the fuel tank is blocked ? You checked the carb and you feel that's good, might look at the tank and the things I mentioned, you see what us technicians go through, we are still going through this process of eliminations, its not that cut and dry as we always wish.
Also I want to throw this at you (because I see your thinking which is Great) What about a broken baffle in the exhaust, when the pressure increases in the exhaust it tries to push the piece up against the exit and is blocking the exhaust ?
Tap on the pipe to see if you hear anything loose ?
I'm thinking if you can run the unit where it starts to miss then bring a plug wrench with you, kill the ignition when it starts missing and pull the plug and see what you got ?
We'll keep going here !
Thanks Peter, let me know
I think you're right, it sure sounds like fuel, now southing you might try is, and I mentioned it earlier about the vent being blocked, maybe try cracking the cap or put a longer hose on the (cap) vent and when it starts to act up, blow in the vent and try forcing in more air, also think about if you could rig up an external fuel tank and gravity feed the carb so you'll be by-passing the fuel tank along with the pet-cock ?
Those are my thoughts
Thanks Peter for keeping up to date
Do you have oil in the engine ? check the level, it sounds like something locked up in the engine, also you obviously have an electrical short. Sounds like you have some checking to do. pull the recoil off and see if you can turn over by hand, maybe something is wrong in the recoil ?
Peter I think we need to close this question out, I think that I answered or we figured out your running problem with the carb issue, and now you are on to something else, or this unit has another problem.
Now you are going to be into an engine rebuild, I think you'll agree that we fixed the running issue but unfortunately your engine gave up now.
Give me your thought ?
Thats fine we'll close this one out, do you have a service manual ? for this unit ?
Its a 250 but everything is the same except for the displacement.