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PLEASE help me with this xt350

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Ok, I bought an xt350 for really cheap. I fixed it up a little cosmetics and mechanicaly. I put a new piston in it, had some score marks on the intake side of the piston. Ran it and it partial siezed in a couple of mins riding. i pushed it home and took it apart. What i found was a seizure marks just in the intake side of the piston. So i bored it out thinking maybe the bore was crooked and put another new piston in it. Same thing. I took it apart to look again, same intake side smearing meatal look. I rejeted with a 130 out of an xt600 and shimed both needles thinking it was just a little lean. Same thing. The air boots are good, all the gaskets are good. It actually sounds really good when it running, doesnt pop, idles well, just seems to run great. I cant find anything wrong. It does get hot before it seizes, but frees up right away. So, what the * is going on? I was wondering if the piston is oiled just by sling? Or is there more to it. Does the oil pump oil the piston in anyway? My book is pretty hard to get the info you need out of it. Please, if you have a good idea please Help. Anyone ever have a problem like this? Thanks in advance for replies!

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What does your plug look like?

Was it an oem piston or Wiesco? Did they have the piston and rings on hand when they bored it? Forged and cast pistons have different bore specs so a Wiesco piston in an OEM bore will be tight.

I'm pretty sure the oil pump only oils the head, but it might be a good idea to take a look at it anyway. Put in a new pump gear while you are in there. They are some sort of plastic and do wear out eventually. Never heard of one failing, but mine looked pretty bad(15000mi) so I replaced it.

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Thanks for the reply. I used your method for electrial tabs and the 130 main jet. The plug looks better now more brown than the greyish. It was a wisco piston they had it when they bored it. The stock piston i originally took out had the same score marks on the intake side of the piston, i dont know it if would have siezed, i didnt run it long enough before i tore it apart. It runs really well! When i ride it about a 1 min in make some clattery noise and then you pull the clutch in and it stops turning over instantly. But then it turns over just fine. let it cool a minute and it fires up again. I was going to check the pump, but i wanted to learn more about it. Like are there little passages that may be clogged? How do you know if the cylinder is getting oil?

What does your plug look like?

Was it an oem piston or Wiesco? Did they have the piston and rings on hand when they bored it? Forged and cast pistons have different bore specs so a Wiesco piston in an OEM bore will be tight.

I'm pretty sure the oil pump only oils the head, but it might be a good idea to take a look at it anyway. Put in a new pump gear while you are in there. They are some sort of plastic and do wear out eventually. Never heard of one failing, but mine looked pretty bad(15000mi) so I replaced it.

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Does it look like there is a little hole conected to where the strainer is? Maybe this is clogged and oil isnt getting to the crank and not getting splashed up on the cylinder? Anyone have one of these engines that far a part. I got this picture from an ebay auction, this is not my case side.

http://i1005.photobucket.com/albums/af180/nickpetrich/case.jpg

[http://i1005.photobucket.com/albums/af180/nickpetrich/case.jpg]

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Crankshaft, balancer and transmission sling off lube the cylinder wall.

- Was the filter bled of air?

- Is strainer on bottom clean?

- Spec says if oil comes out of banjo bolt at oil line on head, then lube system is ok. (That's somewhat vague. pressure is about 14 PSI, so don't expect much.)

-Wiseco pistons require a looser piston-to-wall clearance than stock.

- Don't use 20w50, it is thick enough it can't flow fast enough.

- Crank and cams pressurized, as is trans. Everything else is sling.

- Has carb mixture been richened up to compensate for higher compression piston? Too lean= too much heat and thermal overload for poor piston.

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Thanks for the reply! I see how it slings, but there is a plate that oil needs to get up onto. Do you know if the pump gets oil up there. See where the arrow is, does oil come out of that hole? This bike had an air box full of mouse nest stuff and is possible that it cogged some holes???. it seems when i take the valve cover off it has oil in it and there is no signs of wear. I cant find any info on how this wet sump works, other bikes say it puts oil where it needs to be including the bore.Again thanks for replying!

case-1.jpg

Crankshaft, balancer and transmission sling off lube the cylinder wall.

- Was the filter bled of air?

- Is strainer on bottom clean?

- Spec says if oil comes out of banjo bolt at oil line on head, then lube system is ok. (That's somewhat vague. pressure is about 14 PSI, so don't expect much.)

-Wiseco pistons require a looser piston-to-wall clearance than stock.

- Don't use 20w50, it is thick enough it can't flow fast enough.

- Crank and cams pressurized, as is trans. Everything else is sling.

- Has carb mixture been richened up to compensate for higher compression piston? Too lean= too much heat and thermal overload for poor piston.

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Not sure what that hole is for. That tray will get the runoff oil from the head. I doubt that is an oil hole. It's too big. You wouldn't have any oil pressure left to oil the head if it is.

You are going to need another bore and piston/rings.

Did a dealer do the work, or some other shop? Many dealers sub out their machine work so I prefer to go to someone that actually does the machine work. That way you can verify the specs.

It really sounds like they bored it to OEM specs instead of Wiesco specs. Find someone to measure the cylinder and dig up the Wiesco specs. If the cylinder was bored improperly, you might be able to get whoever did it to warranty their work(depending on state laws, they may have to).

+1 on everything Yamaguy said

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Those aren't flow holes.That plate unter the crankshaft is the windage tray: keeps the spinning crank from whipping the oil to a froth, which doesn't lube and doesn't pump. Plus, it causes drag on the crankshaft like you running through water instead of air. I forget what that drainback towards the rear does. It looks like it dumps oil on the primary drive gear teeth.

If the cam has lots of oil, maybe the cam bearings are sloppy enough to allow most, if not all of the oil, to get out up in the head. Cap-to-cam spec is .0008-.002 inch, with .006 inch max. Use plastigauge to check. If those four rubber plugs that go into the cam cap holes are hard/cracked/missing, all of the oil will easily get out, none left under pressure to get to crankshaft, transmission, or cylinder walls. No one pays any attention to them, but they are very critical. I'd replace them either way.

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Well i got it fixed! It was the oil pump gear spinning on the pump shaft. I replaced the gears and pump shaft, now its fine. Hopefully if someone else ever has this problem, this post may help them! Im not exacly sure how, but the oil pump gives oil to the tray under the connecting rod. Thanks TT'ers for your help on getting this bike running right. I put 47 miles on it yesterday and it ran like a dream! Luckly i didnt destroy anything after the overhaul!

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Put in a new pump gear while you are in there.

:ride:

Close enough. What do I win?

Glad there wasn't any extra damage.

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