Hello ATV Connection, I appreciate all the knowledge shared.
My sons quadsport80 would not start. I replaced the spark plug and ignition coil as both were bad. Dumped some gas in the spark plug cylinder, and still wouldn't start. Tested the compression and get 30, so clearly a problem there.
I pulled off the air cleaner box and am now looking to replace my air filter in my quadsport 80, which i noticed had completely rotted away. Is having no filter a potential cause for very low compression? I would think the opposite but..........
I purchased Uni Filter NU-2471ST as multiple sites claim this fits my quadsport 80, however it seems too big(length) to fit in the air cleaner assembly, unless I allow it to be compressed length wise. Either I am not identifying my atv accurately(The VIN is difficult to read), or all those sites compatibility listings are wrong. As I type this, I am thinking I will buy the OEM filter, but curious of your thoughts on the above.

Assuming the low compression test is NOT related to missing the airfilter, I am going to check valve clearance, look for anything damaged in the cylinder, and ultimately buy a new top end cylinder. Are the OEM top end rebuild kits sold on EBAY and the same in quality as the OEM sold at https://www.suzukipartshouse.com/oemparts/a/suz/50d08271f870022710159892/cylinder
There is a considerable difference in price.

I attached pics of the VIN and side view of the atv. My best guess is this is a 2001 suzuki quadsport 80. I see lt80 referenced alot but appears to be submodel from an earlier time?? Maybe mine is an lt80??

Thanks for any assistance.


can you decode this vin? I get LM4AC773X77706839 https://suzukiforum.com/forum/vindecoder.php

 

LT80 is the model. Quadsport was what Suzuki badged it but the name never really stuck. Just as Quadmaster never stuck for the LT50 model. The cylinder kits from China are not well regarded. Jack may be along here to explain his objections to them, but there have been a few on here that have had problems, plus one or two who have found them OK. I go for a re-bore and oversize Suzuki piston. Not sure about the filter, foam filters are usually a bit longer than the case, and squash down to make a good seal, but I've never fitted a new one to an LT80 so can't say for sure. It is a reed valve two stroke so no clearances to set. If you haven't been filling the oil tank with 2 stroke oil, that would explain the lack of compression, no oil = seized engine.

 

Your Uni is fine. Push the top down and get the screw in there. I use them.
The china cylinder kits are junk. Period. I pay 70 bucks for a Suzuki piston, Absolutely no quality for 39 bucks.
Like Merryman mentioned, the best way is to get a oversized piston and have the OEM cylinder bored to it.
I can do that for you if interested.

 

An LT80 it is, thanks for clearing that up.

In reading through some forum posts yesterday, I came across this thread, in regards to his thoughts on the china top end rebuilds.
also

I will see if I can locate a top end kit with a suzuki piston on ebay, but might be easier finding on a dedicted parts website.

The benefit is essentially more power right. Its more of a priority to get it running while the kids can still ride. Living in Minnesota, and it won't be long before the atvs are stored and the snowmobiles come out!

Ok, I read several times to check valve clearance for low compression, but doesn't apply to 2 strokes(TIME SAVED, THANK YOU)

Another thing I read was to inspect the reed valve, however, I cannot get the 4 screws off the reed valve block for the life of me. Starting to strip the screw heads, so I stopped for the night.

After removing the top end, I believe I found the culprit of the low compression, right? I assume that's obviously a problem and likely the compression problem?? Another reason I wanted to remove the reed valve, besides checking to make sure its in good condition, is to see where that chunk of piston went. I dont want to throw a new top end in if there are remains of aluminum ready to do damage.

 

I see that now, after reading your post. It looks great. I will have to buy some air filter oil.

I am looking at this one bikebandit . I couldn't find anything on ebay or amazon, that stated the piston brand as suzuki, except for one that claims to be OEM, which would be suzuki on ebay here
I am thinking I only need to replace the piston, rings, and gaskets, but if that ebay link is OEM, I might as well grab everything for good measure. Who knows what destroyed the piston.
EDIT: I see OEM part is ONLY #11210-40B01 which is the cylinder

 

"I go for a re-bore and oversize Suzuki piston."

"The benefit is essentially more power right. Its more of a priority to get it running while the kids can still ride. Living in Minnesota, and it won't be long before the atvs are stored and the snowmobiles come out!"

No, with almost all engines it is cheaper to re-bore the cylinder than buy a new one, and you are going to need a new piston and rings anyway so buying an oversize is no more expensive. So, if going for genuine Suzuki parts, a re-bore and oversize piston is the cheapest way. You will need a new small end bearing, as well. With a seizure like your machine has had I wold want to be sure the oil lube system is working, After the rebuild, drain the fuel tank and carb, then put a small amount of fuel into the fuel tank with two stroke oil mixed at 30 to 1, start up and remove the oil feed from the carb, if oil dribbles out of the pipe from the pump, it is working, re-fit the pipe and add neat fuel to the fuel tank, if it isn't working, either run on pre-mix fuel all the time, or mend the pump.

Personally I would assume the reed valves are OK unless proven otherwise "if it aint broke, don't fix it".

 

Ok, I was thinking I didn't need to buy a new cylinder, as it appeared to be in good condition. I was only going to buy the suzuki piston, rings and gaskets for about 85$ which would fit my existing cylinder and cylinder head. At Least that is what I was thinking. Are you suggesting that its best to always replace the cylinder as well OR rebore it, in this case, to fit a 1mm suzuki piston? Does the ladder option effectively "clean up" any faulty remnants of the existing cylinder that could have damaged the piston in the picture.

Sorry for my ignorance, just trying to understand.

I will add a small end bearings to my shopping cart as well.

AGREED!! I am not sure if this is an indicator of the oil lube system not operating properly, but after removing the circlips I could not get the piston pin to come out. I literally had to use a screw driver and hammer to tap it out. I tried very hard not to damage the rod and think I am good, there is only lateral play in the rod, which was there before. Again, not sure if that is an oil lube issue, but others seem to easily slide the pin out without much work, at least what I have seen on youtube. A GOOD sign(I think) is when I pulled off the oil hose there was some oil dripping out of it.

I will leave the reeds valves alone, however, I did buy a manual impact driver that should hopefully get those screws out if needed.

 

The piston is wore, so is the cylinder. You have to get the next size piston and have the cylinder bored. You would go to .5 over.
You'll need to get a pin also.
You'd be better off having me do it. I have all the parts here.

 

I am not following, and I would like to understand, excuse my ignorance, can you answer the below.

How do we know the cylinder is wore?

Why do we have to get the next size piston?(not fighting this just want to understand)

I will gladly pay you to do it, I just have to understand.

 

The piston will wear, so will the cylinder. This is a standard sleeve. It is not nikasiled (doesn't need bored). It just ran 20 years, it's wore. And, look at the piston. The cylinder will be scared.
You need the next size piston because you cylinder needs bored, thus a bigger piston.
Plus, you mentioned piston rings and gaskets. You'll also need the pin, pin bearing, and cir clips.