Hi there,
I have an LTA50 for my young son which I bought just before Xmas.It seemed a little sluggish so I removed the washer out the intake and the spark arrestor on the exhaust was totally coked up so I cut it off. I removed the stacked jet as recommended. Ive also ground the back of the slide so it get full clearance when the throttle is open. It seemed to be running ok. A lot more power.
Then when I was working away my father in law went to take the kids out in it. I was told he couldn't pull the chord at 1st. Don't know what he done but anyway according to the missus he got it going. However when I got home the fuel **** was in the prime position. It was obvious they had been running around in it like this. The quad was running like a bag of sh*".
Im sure I heard a pop when the little fella was on it but not sure if it was just because he hit a bump. It cut out shortly after. I got it going again but it barely had the power to pull away. I stripped the carb again to adjust the needle etc as the plug was black and wet. Thought it was flooding and it was too rich. Now it wont start at all. Do you think the piston has gone and would this have been caused by running it on the prime? Also I got the chance of a 2nd hand top end from an older model say 85 will that be compatible with a 03 model? Just going to get that rebored and milled etc if it is.



Cheers
Gary

 

do a compression check.....with a gauge and not your thumb. should be >95 psig.

 

The parts fiche says the cylinders are all the same.

 

Done a compression check and its at 105. So Piston rings havent went which is good. Got the thing going however once it heats up it just cuts out and then it wont start again till its cooled down. Any ideas? Cheers

 

It's a electrical problem.
Usually the coil or CDI.

 

Took the head and cylinder off and found the guilty part. The piston was scored pretty bad and the top ring was wedged into the piston. Probably why it was cutting out once it heated up. Strange it wasn't losing compression though.
Anyone ever done a rebore and put an oversize piston in? If so what was the results and what size would overbore would you recommend as Ive seen some kits upto +8.00mm


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A simple top end job.
Next size is .5mm over.
You'll need to get the piston (Suzuki or Pro-X) then get the cylinder bored/honed to that size.

Suzuki part #12100-35611-050
PISTON SET (OS:0.5) | OPT

 

Yeah thanks, ordered a new piston +1.0mm. May as well get what I can out for the next few years till he out grows it. Going to get the head skimmed too while its off. Ive heard about a clutch mod but is this only for the 4 stroke LTZ50. Cheers Gary

 

FYI: going 1.0 instead of .5 will not give it any more power.
You're only wasting a bore.

 

I just did the same as the original poster. I skipped the .5mm upgrade and went straight to the +1mm wiseco top end piston kit. I had some heavy gouging on the cylinder walls and I'm not certain that .5mm was going to get them completely out...it was going to be close. I think the 1mm size will last long enough for my tike to outgrow the lta50. Can always get another jug, or a new sleeve, if I am wrong.