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Discussion Starter · #1 ·
Ok, I have always wanted a quad since the day they came out, but I could never afford one until recently. I finally found a very nice one and arranged to pick it up the Monday after thanksgiving. I was like a kid on Christmas morning for a few days, and then disaster struck. I spent the better part of my Christmas break trying to figure out why my 300ex (that I only got ride a total of 5 hours) wouldn't start. The last day that I got to ride it, I was putting it in reverse to back it into the storage building and the engine died. No unusual sound. It just went dead. I only got it to start up once after that. I took the tank off and cleaned it out. I also cleaned up the petcock and got a new fuel line for it and then I put everything back on it. It was no use. I killed the battery trying to get it started. It had started to leak oil before all of this but I kept a check out it and it never let it get below safe operating range. A closer inspection of the top end revealed that the head and the valve cover had been put back in at some point using only rtv silicone. Not a gasket in sight. I should have caught that before I bought it, but it wasn't leaking and it would have never crossed my mind that someone would attempt that. I'm not a mechanic by any stretch of the imagination, so I decided to take it to a guy that my brother in law recommended. I talked to him last night and he said that he pulled the spark plug and that it had oil on it. Then he checked the compression and it's got 50-60 psi. He didn't take anything off or check anything else because he says the engine is blown. He said I'd be looking at around $800 for parts, and that I might be better off to buy a used engine. So here is where the dumb questions begin. Would a bad seal on the head gasket not cause a low compression reading? There are 330 top end kits on Amazon and eBay ranging in price from $80 to $160. Would that get me going again or is it likely that it damaged something other than the piston and or rings and cylinder? Would it even make since to spend $800 on a 2003 quad? I know the last question is subjective but I've already got a pretty good chunk of change in something that I only got five rides out of. I've wanted a quad since I was a kid, but I can't afford to keep throwing money at it I made the first payment on it yesterday morning and got the news that the engine was fried about 3 hours later. I'm sure you can understand how disgusted and frustrated that I am right now. Thanks guys...
 

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If they used RTV instead of a HEAD gasket then for sure its going to blow and have lousy compression.
Since you already have it, pull the top end. Check the free play in the rod. If that's good and the cylinder
looks good, give the cylinder a light hone, new piston and rings, lap the valves, new valve stem seals
and Bobs Your Uncle. Should be good for many more years. If the rod play is excessive, I'd get another
engine.

Mad
 

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sounds like a typical used atv problem.
walk away if money is tight because it could keep adding up, especially if you pay somebody else to do the work.

Now if you are willing to learn and attempt the repairs yourself then its a challenging and interesting road to take and the experience will pay off.

Get a service manual and go through it, figure out what tools you have and what tools you may need this will give you an idea if its worth spending the money and time yourself vs paying somebody else to do it.

If compression is low, the manual walks you through what to do.
Chances are as Mad mentioned, all missing gaskets need to be replaced,
while doing so, inspect rings, piston, rod, head (valves, seals) etc

Then put it back together to spec and go from there.

if you have compression all you missing is fuel and spark. if you got both you are ready to go.
 

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Discussion Starter · #4 ·
I've decided to take it to a mechanic because I don't have half of the tools that I would need. I'm pretty sure the carb needs tweaking too and I don't know anything about a carburetor. I've already ordered a top end kit, do you guys have a rough idea how much it would cost for a mechanic to rebuild the top end?
[
sounds like a typical used atv problem.
walk away if money is tight because it could keep adding up, especially if you pay somebody else to do the work.

Now if you are willing to learn and attempt the repairs yourself then its a challenging and interesting road to take and the experience will pay off.

Get a service manual and go through it, figure out what tools you have and what tools you may need this will give you an idea if its worth spending the money and time yourself vs paying somebody else to do it.

If compression is low, the manual walks you through what to do.
Chances are as Mad mentioned, all missing gaskets need to be replaced,
while doing so, inspect rings, piston, rod, head (valves, seals) etc

Then put it back together to spec and go from there.

if you have compression all you missing is fuel and spark. if you got both you are ready to go.
[/QUOT
 

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Discussion Starter · #5 ·
sounds like a typical used atv problem.
walk away if money is tight because it could keep adding up, especially if you pay somebody else to do the work.

Now if you are willing to learn and attempt the repairs yourself then its a challenging and interesting road to take and the experience will pay off.

Get a service manual and go through it, figure out what tools you have and what tools you may need this will give you an idea if its worth spending the money and time yourself vs paying somebody else to do it.

If compression is low, the manual walks you through what to do.
Chances are as Mad mentioned, all missing gaskets need to be replaced,
while doing so, inspect rings, piston, rod, head (valves, seals) etc

Then put it back together to spec and go from there.

if you have compression all you missing is fuel and spark. if you got both you are ready to go.
I managed to get my hands on a repair manual yesterday and I think I will go ahead and try to tackle the repair myself. I'm never going to learn to do it by paying someone else, and I want to be able to do my own repairs. I have some questions before I get started though. First of all, the 330 kit was fresh when I got it, so is it likely or even possible that the blown head gasket could have caused damage to the piston and or rings? The fact that the guy basically glued the top end back together doesn't instill me with much confidence in his abilities. A new 300 kit is only $179, so should I go ahead and get one so I know know the top end is good to go? The guy that I carried it too said there was oil on the sparkplug. Doesn't that mean I have oil getting past the oil ring? I'm thinking about switching out the carburetor with a new one while I'm at it. How do I tell if it has the right jets in it? Mad said I should check the rod for excessive play. What would be considered normal play?
 

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As Valley Wrenching said. At a minimum I'd replace the rings , gaskets and valve stem seals. There are measurements in the manual for rod play. Measure the piston at the top and at the skirt 2 ways 90 degrees to each other. The skirt can collapse if its worn or overheated. If you're not sure, get a new piston. Measure the ring end gaps before you install the piston and rings. It sounds like a lot but you're going to learn a ton.

Mad
 

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Pro Tip.... Once you have the cylinder off, stuff rags down into the crankcase. That will keep things like
dirt and rod clips from falling down into there. Ask us how we know......

Mad
 
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