Hey guys, i am new to the forums... this a great place! Lots of information.
ok, so I am a service manager/mechanic at an automotive repair shop in St Louis. The owner of the shop has a bunch of fun toys, one of wich is a
1990 Zuki LT80 that he picked up a few weeks ago for one one his kids.
ive worked on all of his toys with good luck, but this one is giving us all kinds of problems!
when he first brought it to the shop, it was having issues to where it would take a loooong time to start, and when it finally did, I had to keep on the throttle
to keep it running. naturally, the first thing i did was pull the carb and cleaned every inch with carb cleaner and compressed air. it helped a bit, but still wasnt running right. It almost seemed as if it wasnt getting enough gas, so I wanted to check the petcock fuel valve to see if it was opening with vacuum from the carb. i put my hand vacuum pump on the hose and applied vacuum, and it turns out that the valve is bad...It was pulling fuel through my hand pump! so i capped off the line, and the outlet on the carb, and turned the valve to "reserve" for further testing.(is it ok to run the quad with the valve on reserve?)
I checked the spark plug, was a little fouled so i installed a new plug. Spark is good and strong. with the choke on, i still have to tickle the throttle to get it to start. once it starts, it runs at a pretty high idle, i'll let it run for a good few minutes. i then drop the choke, and the idle drops down... it will run for a few minutes, but soon after, it will die unless I keep on the throttle.
I ckecked the compression, its pumping around 80 PSI, wich from what i have read in the forums is a little low. by the way, does anyone know what the stock compression should be?
Ive heard that the crankshaft seals can leak, could that be a possibility?
so from what Ive read about these quads, it seems as if the compression
may be the main problem, am i right? maybe crankshaft seals? could my fuel valve on the bottom of the tank (set to "res. or Pri.") be the cause since i cant run vacuum to the valve?(basically relying on gravity to feed the carb)
Im sorry to write a book, but it seems that more information is better than not enough
im ready to pull the head and replace the rings, i just want to make sure im headed in the right direction.
thank you everyone in advance!!

 

All I know is keep the choke lever down and put the gas lever to pri--which is prime. It might not have enough gas going to the carb. Thats what pri does. Raise the choke up once it really warms up and put the gas switch between prime and res. It might be revving high because you have it in pri and its getting to much gas then its flooding..........

Jeff

 

The problem is compression. You need a new bore and piston. Not just rings alone. Comp should be 120#.
Petcock: Ya, they sorta suck. Simple fix is to leave it on prime (it runs fuel all the time) and get a on/off valve at the lawn mower shop or advance auto. Get a inline fuel filter while your there.

 

awesome, see i knew I was in the right place! well thats what I'll do, LT80 wheres that place you were talking about in the other thread about the kit with the piston, rings, and all the parts i'll need?
I put an inline filter on the fuel feed line already, but i'll go ahead and pick up
a shutoff valve also.
thanks again!

 

OEM parts source (they are in Canada).
888-672-5141