OK I dropped on a new jug, piston, rings, bearing seals etc (all OEM Suzuki from oempartsource on ebay) I'm getting like 145psi plus compression now. I cleaned out the carb again since it was off and noticed a few odd things.

1. Needle was set on the leanest setting and the tip was broke off?
2. The float valve had a nice lip around the pointy end
3. The main jet was a 90 and my book says it should be a 92.5
4. There was no "cap" over the main jet like the book calls for

Bike runs good at idle but kind of crappy midrange and then seems to run decent at full throttle. (this makes it real hard to break it in easy) The bike only runs decent with the air filter tube off of the carb. Makes me think it is running rich ? ?

So I ordered a Moose Carb rebuild kit for my 1994 LT80 and it came with a new needle, main jet at 92.5 new o-rings and gaskets, float valve etc. It had two little o-rings in the kit I was not 100% sure where they went. The slightly larger of the two went on the idle set screw along with the spring and a tiny silver washer. In this order Screw -spring -washer - oring. There was another small o-ring that I put under the main jet I. I reset the needle back to the second from the top knotch and and put everything back together and fired her back up. This time the bike needed a little choke to start up but idled fine after an idle screw adjustment. I put the air cleaner tube back on the throat of the carb and now it feels like it is having trouble runnning again. I'm going to look at the filter and see if it is clogged but can anyone else shed any light on things that I should be checking. I've rebuilt plenty of carbs from boats, to lawnmowers to motorcycles to Ourboards motors. I've got the oil pump disconnected on this machine and run 40:1 mix gas in her. Any ideas why the differences in jet sizes. My book says the carb should be a Mikuni 40B00. It says Mikuni but the stamp says 40B with 10 underneath it. Also my book says to remove the air jets on the front of the carb? How do you get those things out of there? I cleaned this carb in a L&R Ultrasonic heated ultrasonic cleaner with Omegasonic carb cleaner and blew it out with 120psi compressed air. I also probed the air jets with a soft copper wire to loosen any gunk. I'm still going to try a few things but I'm looking for some suggestions here guys, I'm getting a little frustrated and you all have steered me right this far . . .Got to get to bed, hope tomorrow is a better day.

 

The 90 main is cuz they are jetted way fat from the factory. I recommend the 90 to those that ask.
The rubber boot thing is gone cuz it's a stupid part. Most ppl squish it when they put the bowl on thus covering the main jet.
I've never had to mess with the air jets.
I think you put the orings in the right place.
FYI: a stock piston don't need much, if any, break in. Run it!
Mess with the needle and see if the mid range comes back. Maybe they had it lowered for a reason.

 

Well that answers my questions and makes me feel better. Looks like the carb is coming off again to put the 90 main jet back in and I'll start messing with it from there. Might as well check and clean the air filter while I'm in there too. I might just have to drop the needle one notch before I tear it down just to get some smoke in the air. For some reason the smell of burnt 2 stroke oil inspires me to get working.

Thanks LT80 I'll check back in with my progress

 

Well where to begin . . . . I'll save you the long string of words running through my head right now as I type this {deep breath}

OK . . . .

I tried the following things so far in this order with little to no change from the above setup.

Started the quad cold and in condition listed above. Removed air filter tube and had little to no improvement. Moved clip on needle jet up and down through all notches with little to no change. Best speed I could manage is a fast walking pace around the yard.

Interesting things to note.

1. The quad requires choke to start now and it did not require it before

2. When it was running only mildly crappy at first I could put my finger over the drivers right side air jet on the intake side of the carb and it seemed to give a little more power.

3. The air screw on the side seems to have little effect on the idle speed.

4. I pulled and checked the plug and it was milk chocolate brown and not gunked up.

Where I'm heading next

Pull carb, install 90 jet again and do a quick check for junk


Things I think may still be wrong

1. Float Height? How the heck do you change the float height in these if they are wrong? No brass tabs to bend?

2. Tiny O rings in wrong spot?

3. Outer hoses. Other than the fuel supply is it possible that the lack of the the other hoses on this carb could be causing other issues?

4. The only odd thing I got in my kit that my carb did not have before was a small thin silver washer which I put on the air /idle screw

Thanks for your help guys, I'm really reaching my end with this thing It's become too much of a project with not enough fun.

 

Most LT's need the choke to start..Unless the motor is warmed up.
The idle screw is just that, it's not a air adjustment.
I've never had to adjust the float height. The newer floats have a metal tab but I don't think thay intend for it to be bent to adjust float height.
I think the orings are correct.
Hoses shouldn't matter altho the vac hole should be plugged if not using the vac petcock.
Carbs do go bad.

 

Well I'm not using the vac petcock and that hose has been off and on the carb at different times so I don't know how that may have affected things. I think I'll just plug it off and remove the hose to the petcock I'm not using. Still gonna tinker some more with it. It ran decent before the bike lost compression why does the thing just go bad all the sudden?

 

After pondering my situation last night I came to one conclusion.

If the engine falls on its face on anything past part throttle and it will not hardly run without the choke on then the circuit that feeds the main jet has to be clogged. The other thing that sold me on this is that adjusting the idle screw did very little where as before it made a huge difference with every half turn. I removed the carb and probed the main jet with some fine copper wire and could not get it through. I think the O ring got a little sideways in there somehow. I pulled the 92.5 jet out and put the 90 back in. I also switched back to the tiny old flat rubber washer that I found under the main jet. I don't know what it is supposed to do but I figured what the heck! I put everything back together and plugged both extra hose ports on the carb by wrapping electrical tape around them. I set the needle on the leanest setting and fired her up on choke. I had the air filter off at this point for ease of removal and installation of the carb. It took a minute to warm up but after a minute or so I let the choke off and rode around the yard. It had a decent hole in the midrange close to the top end. I kept richening up the mixture until I got on the second to last notch (almost full rich). Every time I made it richer the hole got narrower and less noticable. It ran pretty decent. I put the air filter back on it and and rode it around. The hole in the midrange is almost entirely gone and the quad runs as good or better than it ever has. The power seems to come on much smoother and the huge hole from fast idle to wide open is gone. It's much more maneuvarable in the woods now that you have part throttle power. Took both of the kids on a big ride in the woods. You can't put a price on grins and giggles like that. I appreciate the help guys and talking me through some of my questions. It's good to get some advice from somone who has held the same parts in their hands and knows how things are supposed to go together. You put alot of your time into this forum LT80 and I hope the vision of my kids giggling and laughing on a quad ride with their dad brings a smile to your face. Have a great weekend guys . . . .I think I'm gonna find something else to work on this weekend.