Another Hard Start/No Idle

[Keefer700]

I just bought an 03 Lt80 and it has to be choked to start no matter what. It will not idle untill it has been run for a long time.
I cleaned the carb twice and boiled it once.
I have an identical 03 Lt80 that starts instantly and idles without ever having to choke it. I set the air mixture screw to match the good running Lt.
The compression on the bad one is 90 and 135 on the good one. Would this cause the problem? Also the previous owner has been running Suzuki 2 stroke oil in the injector but the bottle doesn't say anything about it being injection oil. Would it help to change to a different type of oil?

Thanks in advance for any help you can give.

[etondaddy]

It's time for a top end rebuild.........



Mike Kozura

[LT80]

Welcome to the forums. :)

The compression is the issue IMO. 90 is down 25% from the normal 120 or so that it should be.
There is no air screw. That's the idle adjustment.
Most 2 cycle oil is good but I would get a oil that does say for injectors. The type of oil will not fix this problem.

[Keefer700]

I am planning on doing the top end. Just wanted confirmation that this could be the problem. Looks like Motorsports Supercenter is going to get an order from me.
The idle adjustements on both of my lt80's are at the top of the carbs where the cable goes in. Have to lift a boot on the cable to see the adjustment.
I have the one with low compression idled high to keep it running but both of the air screws are set to 3.25 turns out.

[LT80]

Dude you are mistaken..
There is no air screw.
The screw is the idle adjustment.
The top adjustment is for taking up the slack of the cable, not adjusting the rpm's.

Please use stock Suzuki parts.

[Keefer700]

My mistake. That will make it easier to adjust since I was trying to get the idle right by using a combination of both adjustments.
I saw an earlier post you made and have priced the genuine Suzuki parts from Motorsport Supercenter. They show a .5 and a 1.0 oversize. Which one would you recommend?
I forgot to mention that the starter is crap on the one I am having a problem with. Just when the engine is about to crank the starter drive kicks out. I have to cycle the starter button several times to get it to start and the starter sounds bad when it cranks over.
I have a new starter that came in this morning that I will put on tonight. Could a slower than normal cranking speed cause a low compression reading? I am going to recheck it after the starter install.
This quad was full of old gas when I got it on Friday. It seems to run better and better the more it gets ridden.

[LT80]

The slow spinning could make a difference. I'd check the comp with the new starter just to see, altho the main problem still exsists.
Piston size: you'll need to take the head off to see what size piston is in there. Being a 03, I'd think it'd be stock.
Look on the top of the piston for numbers.
No number = stock size... Get the next size up. .5 then 1.0

Bad gas...yuck..LOL:blah:
Run the snot out of it, maybe it'll be fine. :)

[Keefer700]

Originally posted by LT80
The slow spinning could make a difference. I'd check the comp with the new starter just to see, altho the main problem still exsists.
Piston size: you'll need to take the head off to see what size piston is in there. Being a 03, I'd think it'd be stock.
Look on the top of the piston for numbers.
No number = stock size... Get the next size up. .5 then 1.0

Bad gas...yuck..LOL:blah:
Run the snot out of it, maybe it'll be fine. :)

My nephew has no problem running the snot out of it. It is hard to work on it when he is looking over my shoulder with his helmet on.

Thanks again for the info.

[Keefer700]

Using the idle screw instead of the throttle cable slack adjuster made adjusting the carb a piece of cake. Still have to choke it to start but it starts the first time every time since installing the new starter. Thanks LT80 for setting me straight.

[Keefer700]

OK, got the piston out. It is scored really bad. so is the cylinder. Got it being bored now to see if it will clean up.
One thing I noticed is that the arrow on top of the piston was pointing to the rear. I would have thought it was supposed to point forward. Does anyone know for sure which way it goes?

[etondaddy]

The arrow is supposed to point twards the exhaust port.

I guess I called that one........lucky guess...lol

Is the oil injection working...or if removed is the gas mixed.....???


Mike Kozura

[LT80]

"I would have thought it was supposed to point forward."

And it does when the exhaust is pointing forward. LOL

Some make that mistake. It takes nice lil chunks out of the exhaust port. :D

Ever wonder why others didn't make the exhausts straight out the back/carb in front? (Like high quality Suzuki mini's)....
BAHAHAHA

[AUSSIE80]

mate, i dont have the knowledge these other blokes have but if you are gunna rebuild, make sure either the oil injection is working, or your premix is the right ratio, also check air/fuel mixture not too lean, check air filter and inlet side for leaks. sounds like lube or dust have been your enemy, and if these are not right, you'll blow ya dough

[Keefer700]

When I bought it the air filter had a quarter inch of dirt packed on it. Oil injection seems to be working since I can smell the oil and see smoke. Maybe the previous owner ran it out of oil or got it hot.
There was a lot of oil in the right engine cover. I thought it was coming from the crank seal but when I cleaned it up I found the oil was coming out of the back of the crankcase where the cylinder meets the crankcase. The head bolts were loose and the back of the cylinder gasket was missing. I don't see how this was even running.
The cylinder cleaned up at 1.998 so I ordered the 50.5 mm piston kit from Zuki. Also had the head milled .030.
Didn't you guys say something about opening the exhaust port too?

Thanks for all the help. I would have put the piston in backwards if it wasn't for the vast knowledge available here.

[Keefer700]

Runs like a top now. Compression is @ 150.

If i remove the injection what ratio do you recommend on the premix. I keep a jug of 40/1 mixed up for the weedeater, would that be ok to use?

[LT80]

I like 32:1
40:1 may be ok if your jetted a lil fat.

[Keefer700]

Thanks LT80. As far as I know the jet is stock so I will go with the 32:1.

[LT80]

I consider the stock jetting a lil fat. You can try the 40:1 just keep an eye on the plug color. :)

[Keefer700]

Will do. Plug color is perfect now, hopefully it won't change. Thanks again.