[tunil]

hey all, im trying to get my friends 03 lt50 running. cleaned carb to no avail. checked compression and i can only get 90 psi out of this little thing. it seems low to me but do any of you know what the compression pressure should be?

[cbr1kfireblade]

i would think 120-130

[tunil]

thats about what i was thinking. ive been trying to find a spec online with no results but im pretty sure this is too low.

[cbr1kfireblade]

Post subject: Re: Suzuki LT 50 Help
http://forums.atvsource.com/styles/s...ost_target.gifPosted: Thu Mar 26, 2009 3:14 pm
http://forums.atvsource.com/styles/s...er_offline.gif Still on the Trailer Member
Joined: Fri Dec 05, 2008 10:56 am
Posts: 49 Hopefully you have a friend that has a compression tester.
There are 2 basic types. A hand held gauge that you press into the spark plug hole and turn the motor over.
The better of the 2 is one that threads right into your spark plug hole. I got mine at sears.
Crank motor over with wide open throttle till gauge peaks.
Normal reading would be approx 120.
Under 90/100 is bad.
Then you would need to disassemble the top end and have your cylinder bored to a new piston.

There is a possibility that you have a blown head/base gasket but the fact that it's running makes me believe that they are not the problem.

[cbr1kfireblade]

hope that helps

[tunil]

yeah, i do have a compression tester. i tested and can only get 90 psi out of the cylinder. i took the top end off to inspect and found the most beautiful piston i have ever seen. the cylinder walls still look really good. i can see all of the crosshatching marks. no verticle scarring or anything. i put it back together and retested compression again. still 90psi. i dropped a little oil into the cylinder to see if it would make the compression go up but nothing changed. im probably going to replace just the rings but im still going to search for a different cause to this low compression.

[bladeracer]

Originally Posted by tunil

hey all, im trying to get my friends 03 lt50 running. cleaned carb to no avail. checked compression and i can only get 90 psi out of this little thing. it seems low to me but do any of you know what the compression pressure should be?

Isn't it a two stroke?
If it is, the compression is probably only about 7:1 so it should be low.
The ports are still open for a lot of the up stroke so it only starts making compression halfway up the bore.

[bladeracer]

Actually, I found some specs - Suzuki's new LTA50 Quadmaster - A new standard for "50cc kid's quads". - ATV at Off-Road.com

90psi from a 50cc two-stroke I'd be pretty pleased with that myself.
If you find out the actual test spec though let us know.

[tunil]

wow really, even for a 2-stroke i thought this was low. maybe not. i will keep trying different things then. thanks for your help

[tunil]

well i think i just found the problem. im tired of pulling this thing so i tried some starting fluid directly into the cylinder. it almost kicked off but not quite. i noticed when it tried to start that smoke was coming out of the pull cord case cover. now im pretty sure ive got a bad crank seal on the left side of the motor. do you know of any way to test this without a 2-stroke leakdown tester? i just dont have one yet. but im pretty sure this is my problem now.

[bladeracer]

Originally Posted by tunil

wow really, even for a 2-stroke i thought this was low. maybe not. i will keep trying different things then. thanks for your help

When I saw 5.6:1 in the specs I was impressed you even got 90psi :-)

[cbr1kfireblade]

Originally Posted by tunil

well i think i just found the problem. im tired of pulling this thing so i tried some starting fluid directly into the cylinder. it almost kicked off but not quite. i noticed when it tried to start that smoke was coming out of the pull cord case cover. now im pretty sure ive got a bad crank seal on the left side of the motor. do you know of any way to test this without a 2-stroke leakdown tester? i just dont have one yet. but im pretty sure this is my problem now.

sorry no, i dont think there is any other way other than just replace it or buy the tester

[cbr1kfireblade]

o and of course if it is leaking dont run it for a long time as the leak allows extra air to be drawn it making it run lean

[tunil]

took it apart and found the left side crank seal completely out of the hole its supposed to be in. its all chewed up as well. just ordered a new one for $3 plus shipping. this should solve the problem. i just hope the right seal is also good. ill find out when i put this side back together. thanks for all your help everybody. ill post again when its in.

[cbr1kfireblade]

Originally Posted by tunil

took it apart and found the left side crank seal completely out of the hole its supposed to be in. its all chewed up as well. just ordered a new one for $3 plus shipping. this should solve the problem. i just hope the right seal is also good. ill find out when i put this side back together. thanks for all your help everybody. ill post again when its in.

thats what were here for.. good luck that should fix er up

[tunil]

i just replaced that seal and i got it running. however i also deristricted this unit while i was waiting on parts. now it screams on low end but top end is dead. any ideas? i removed the intake/exhaust restrictors and removed the first pilot jet. now it bogs on the top end. ill start another thread on this problem. thanks.

[bladeracer]

Originally Posted by tunil

i just replaced that seal and i got it running. however i also deristricted this unit while i was waiting on parts. now it screams on low end but top end is dead. any ideas? i removed the intake/exhaust restrictors and removed the first pilot jet. now it bogs on the top end. ill start another thread on this problem. thanks.

Does a 50cc quad really need restrictors?
Are sure they aren't part of the design to boost the topend?
Photos maybe?

[tunil]

there are threads all over the net about de-restricting this unit, everyone else states that it screams all around after removing the restrictions. i think the carb settings may be off a little. i might have to change the main jet to a bigger one. im not really sure though.

[bladeracer]

Originally Posted by tunil

there are threads all over the net about de-restricting this unit, everyone else states that it screams all around after removing the restrictions. i think the carb settings may be off a little. i might have to change the main jet to a bigger one. im not really sure though.

Does it need a different expansion chamber perhaps when derestricted?

[tunil]

according to the de-restriction threads, all you have to do is remove the restrictions and your good to go. does not seem to be the case for me.

[bladeracer]

Originally Posted by tunil

according to the de-restriction threads, all you have to do is remove the restrictions and your good to go. does not seem to be the case for me.

That sounds pretty unlikely on a two-stroke.
Have you got a link to one of these threads?

[bladeracer]

First I got looks good - How to de-restrict Suzuki LT50 quad

I'd definately be raising the compression if it were mine :-)

"The carb uses stacked pilot jets, once de-restricted you need to remove the first pilot jet. Also, the main should be a 55 stock, without the restrictors you should start at a 65 and work from there. These motors are extremely low compression, milling 0.020" off the head provides a noticable gain without any drawbacks. In fact, you could go as much as 0.040" without problems or being required to run better-than-pump gas. There is a lot more a person could do, but this is a good start."

[tunil]

heres a link to one of the many many many threads regarding restriction removal.

[03 LT50 restrictor removal???] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

this one does say something about rejetting. i think im going to try a bigger main jet.