Hello,

I have a question, I have a Cat 375 its a 2002. High miles/hours I have gotten my use out of this machine but its starting to fade. So I have decided it will make a good winter project to rebuild the top end. I can get a over sized piston set for 80 bucks its .5mm over. My question is can I get that in there if I hone the cylinder, or will it kneed to be professionally bored out? im just not sure if the cylinder can handle .5mm more has anyone attempted this. "just hone it and through in the over sized" Let me know if this will work im just curious at the moment.

Thanks in advanced

paxfam

 

Ummm, good question. I say give it a shot with just honing yourself (that sounds sick doesn't it [img]i/expressions/face-icon-small-shocked.gif[/img] ) and if that doesn't work take it in. Go to the ATV Maintenance section Arctic Chat and those guys should be able to tell ya.

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When I re-bored my snowmobile it only cost 35 bucks. If you can get it done for that I would just take it in and be done.

 

You are talking about 50mm, if you were to hone that out you would be there all day and half the night. You need to take it to a place that can bore it for you. You will save in the long run.

 

You should take it to a machine shop. Any atv or motorcycle dealer should be able to help you find someone to do it. You will never be able to hone the cylinder that far and be sure the cylinder stays true (a perfect circle from top to bottom). You should only hone the cylinder if you are putting same size piston and rings in without boring.
Like Chumley said most places will do the work fairly cheap, 25-50 bucks.

This is my opinion.

 

paxfam,

I just finished a rebuild of the top-end on my 2003 AC 400. I am pretty sure its the same or similar motor as the 375. It cost me a little more than 80 bucks to rebuild but I had a lubrication problem onthe top-end.

I had to replace the entire head and cam. So I replaced the jug, piston, rings and wrist pin while I was at it. I think I spent $1000 or so on new parts. I would have bored it out and went that route but I have seen too many of those jobs done poorly and effect the reliability of the engine afterwards. If you took it in some place and had it bored to the right size I think you would be better off.

Also, it is not necessary to take the engine totally out to do the work but it is much easier to work on out of the machine. Besides, if your frame has rust on it. You can use the extra space to touch up the paint on the frame.

Hope this helps

SJ

 

On the other hand is would be cheaper to just put new stock rings on there, can I use the same piston and just put new rings on there? I mean I would hone it but will it be as good as when it cam off the pallet or would there still be a power loss?? I mean I would of course do the top end bearing======Let me know what you think???


PS "Tork" WHY in the world would I be talking about 50mm the whole dam bore is only 82 mm.

 

Paxfam, my fault, I forgot my decimal point. Bad morning, felt like Monday all over again. Rest of post still holds true though. Not a job you want to do with a flex hone. Sorry about the typo. TORK

 

You will need to measure the bore to see how much the cylinder is wore to determine if stock size rings will work. If you have to much ring gap then you will have compression loss or possibly even blow by. My advice is if you are going that far to tear it down then get and oversized piston and rings and have it bored and do it right so you don't have to worry about it. But you need to have the head rebuilt to. I reccomend new valves valve seals maybe even valve guides.