Well here is the deal. About 10 months ago I got my hands on an '87 basketcase Tecate. I thought I got a smokin' deal on, but I was wrong. I finally though, got it working. Here is my problem. I does not idle right. It barely idles at all. About four months ago I put the carburetor together with all of the "factory" jets, or so I thought. I had purchase a stock jetting package from an aftermarket place. It is a Mikuni carb. It, though, does not have a idle/air screw, like many other carb's have. It only has an idle screw and it is all the way in. I called and talked to Kawasaki to find out what the pilot jet number was for stock. It was 35. I then ordered 25 30 40 45 pilot jets. Just to be on the safe side, but thinking that I had to go up on the jet size. When I opened the carb last night I found out that it was a 45 pilot jet. I only had one way to go. I put the 40 pilot jet in and tried it. It did not really help at all. The next size down was the 30. I was kind of hesitant to jump two sizes, but stock was supposed to be 35. I tried the 30, but to no avail it did not help at all, maybe just a smidgin'. The idle screw is still all the way in, and it barely idles at all. Therefore, quite a slow drawn out response on the gas. A friend said maybe the spark plug is bad, but I have a hard time believing him. I find it hard to see that the idle won't change at all after a drop in 3 pilot jet sizes. Please help, any information is helpful!!
P.S. Sorry about the long post!!

 

I believe what you refer to as an idle/air screw is in fact the pilot screw, which on my Mikuni is two turns out from seated. By having the pilot screw seated you're effectively shutting down the operation of the pilot jet itself The pilot screw is located on the engine side of the carb, and air screws, on carbs so equipped, will be on the air box side.It would probably be best to adjust the pilot screw back to the nominal 2-turns-out position & return the pilot jet to stock & go from there in your testing. I'd recommend going back to stock on everything first in order to have a base point for any further adjustments.

 

So, what you are saying is that I should not tighten the pilot jet all of the way, that it should be two turns out and that it should be a 40 pilot jet if the 35 pilot jet does not seem to work. I never thougt that you could leave the pilot jet "loose". You learn new things each day. Thanks for the info. I will try it out!

 

No, I wasn't referring to the pilot JET, but rather the pilot SCREW, which is adjacent to the jet itself, & simply allows very small tweaking of the pilot jet's operation. The jet should be seated slightly with very little torque to prevent distortion of the seat itself. I hope I've made all of this clear; it's a matter of terminology viz- a- viz pilot jets vs pilot screws.

 

Nice clarification. I probably would have left the pilot jet 2 turns out, and it would have fallen out. I am going to have to find that PILOT SCREW. I can not picture it right now, but I am going to look tonight. You said that the pilot screw is adjacent to the pilot jet (inside the carb?). If that is correct it seems kind of dumb to have the pilot screw inside the carburetor. I do not think there is a screw outside the carb except for the idle screw (the one with the spring).

 

On my Mikuni, which is on a 97 Warrior, the pilot screw is located outside the bowl in the front of the carb, just below the drain plug. It's a small slotted screw & it is spring loaded. The idle adjustment is a large (10mm?) circular **** which merely controls idling rpms. Mikiuni does make several different models, so if this description doesn't match the one on your Tecate, yours may be another type.

 

Well, I checked last night. There is not a pilot screw or any screw for that matter besides the idle screw that is outside or inside my carburetor that I could possible adjust. What can I possible do now!

 

Well, apparently your Mikuni is totally different from mine. I'm still confused, however by the idle screw you mention. Is it the idle speed screw which would be a finger-adjustable one or is it a slotted screw? If it is the former, and is screwed all the way in,as you say it is, your engine should be racing big time. My Mikuni is a BTM 36SH.Turning the idle screw in increases rpms, turning it out decreases rpms. I guess you need to identify what the screw is in order to know what to do with it.Last resort would be to take the carb to a Kawi service manager & hope he's familiar with older Mikunis.By your description of it I have to say I'm completely baffled also. BTW I checked the Mikuni web site but the only info on it was related to Harleys, no help there.

 

The screw is the idle speed screw. It is all the way in, but barely idles. If I unscrew it out, the engine starts to idle less. What happens is when I rev the engine it does not have a "2 stroke" response to it. It takes a second or two before the powerband starts to be there. Once I get the engine in the powerband and keep on the gas the bike flies, but it always takes a second to get into it. I know jetting is not related to gears in the transmission, but in first gear and part of second it bogs like a two stroke. (Maybe it is like the engine is flooding). After it burns up what is in the carburetor, it starts to perform like a 2 stroke. If I just sit on the bike a rev the engine it takes a while before it starts to "hit". Once it is in the power band it stays in it as long as I kind of stay on the gas. If I let off the gas for a few seconds and let it idle once again, it takes a few seconds again before the powerband starts again. I hope I am kind of explaining the problem. I wish this thing had a pilot screw. Maybe I will just take it to a bike shop and have them look at it for me!

 

here is my two cents, you need to remove your carb and buy a can of carb cleaner. completely dissasemble the carb(remove jet needle,needle jet,pilot jet and main jet along with the pilot air screw. your problem is more than likely in the passages of the air screw assembly. but clean everything again no matter how many times you have before. After removing the air screw check it for damage and use the small tube that came with the carb cleaner and spray the passages of the air screw very good then use compressed air to blow all the passages again. The pilot air screw meters air mixing with fuel from the pilot jet. A normal setting for the air screw will be 1 turn out. the air screw and pilot jet affect only the first 1/4 of throttle. Don't give up and take it to a shop these carbs are as simple as it comes anyone with alittle patience can fix them.