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Please help XT350 timing

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I recently bought a 1985 XT350 way cheap with a badly scored cylinder and piston. I have the new cylinder, piston and head on with new gaskets but I can't see how to time this thing. No, I don't have a manual and since this is a low budget rebuild, I'm hoping someone on here can save me the cost of buying one.

(Yes, I now I should have marked everything before I took it apart, but... :thumbsup: )

Anyway, there are no visible marks on the cam gears or even the flywheel or engine case. I can see something on the outside of the (rust covered) flywheel that looks like it might be a big "T" that needs aligned with something, but for the life of me I can't find a timing notch on the case around the flywheel.

But that still doesn't help me with the cams. I've stared at those gears for five minutes and can't see anything that even resembles a dot or notch.

Any ideas?

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I think the marks are on the back side of the gear to match up with the surface, When in doubt bring the piston to the top and install the cam with the lobes down. The marks might make sense when you do this.

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OK, I'm just guessing here...

bring the piston to TDC...OK, I can find that with a screwdriver in the spark plug hole.

then, when you say "lobes down" you mean to lay the intake cam with the lobes pointing so the intakes open first...

and, lay the exhaust cam with the lobes pointing 180-degrees in the opposite direction.

Right? Is it that simple or am I going to royally screw this up?

Also, there are vertical holes in the camshafts (maybe 1/2 or 3/8 inch in diameter) that line up with holes drilled in the head on the surface where the camshaft turns. I was wondering if I might have to line those up. Does that sound like it makes sense? (I don't remember off hand how the lobes are pointing when those are lined up.)

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OK, I'm just guessing here...

It would eliminate a lot of the guesswork if you bought THIS , for 20-something dollars

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It would eliminate a lot of the guesswork if you bought THIS , for 20-something dollars

HAHA! Nope! Still skating! I figured it out last night. The marks are on the other end of the cams...I was looking on the gears, but they are little dots on the edge of the disc that rides on the outside of the camshaft cap cover, which has vertical lines that line up with the dots. And, for what it's worth, lining up the vertical holes in the camshaft with the holes in the head is the right alignment.

Rock on, bro! :thumbsup:

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Hey, guess what, it did! Took about 20 kicks, but she chugged to life. Idles real smooth. But, the old girl smokes big time! I mean, she SMOKES! The cylinder is almost new with a great bore and the piston and rings are new, so I suppose that leaves the valve guides?

Looks like the head is coming back off, eh? Ha!! Well, at least I know how to put it back together now.

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then, when you say "lobes down" you mean to lay the intake cam with the lobes pointing so the intakes open first...

and, lay the exhaust cam with the lobes pointing 180-degrees in the opposite direction.

Right? Is it that simple or am I going to royally screw this up?

If you got a good Eye and a feel for TDC its that easy, just split the difference between the lobes over the center line of the piston bore. The timing marks almost never line up perfectly anyways because of the chain elongation. And rember that the slack will be taken up on the tensioner side.

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Yeah, I noticed that when I put on the tensioner that it rotates both camshafts toward it slightly, so that it looks like neither are lined up.

Anyway, about that smoking problem... I have the head/cylinder back off. And even though I was told this was a standard bore cylinder I figure what the heck, I should check, huh?

Anyone know what the ring gap should be on the XT350?

Also, are there any tricks to getting to the valve guides/seals without buying any special tools? Isn't there some way to do this with a big C-clamp?

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OOPs Didn't realize this was a twin cam we were talking about, forget was I was saying. it dosen't apply to twin cam.

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For TT350 the stock timing is with the dots dead verticle, I would assume the xt is the same as its basically the same bike. For more power/broader range you can adjust the exhaust cam one tooth so that the dot is pointing towards the headers, make sure the edge of the dot is just touching the line on the cam cap. You can do the same to the intakes (point towards carb) but it makes it more like a wr250 timing curve loosing a lot of torque.

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Cool, man. Thanks for the tip! Actually, though, it's strange (or maybe not strange...maybe normal I guess) but when I took the bike back apart after it smoked to replace the valve guide seals (which are on order), I noticed that there was a good amount of play in the camshafts. In other words, with the piston at TDC and the tensioner, I could rotate the camshafts a bit backward. The piston wasn't turning. It was like the cam chain gear on the crankshaft has play in it.

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Anyone know what the ring gap should be on the XT350?

Don't know what the official spec is, but I would guess .020 or so. It will work fine with more. Maybe as much as .060. You will lose some compression and power. When it gets over .080, you will start to get some oil out the crankcase breather.

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OK, I'm just guessing here...

bring the piston to TDC...OK, I can find that with a screwdriver in the spark plug hole.

then, when you say "lobes down" you mean to lay the intake cam with the lobes pointing so the intakes open first...

and, lay the exhaust cam with the lobes pointing 180-degrees in the opposite direction.

Right? Is it that simple or am I going to royally screw this up?

Also, there are vertical holes in the camshafts (maybe 1/2 or 3/8 inch in diameter) that line up with holes drilled in the head on the surface where the camshaft turns. I was wondering if I might have to line those up. Does that sound like it makes sense? (I don't remember off hand how the lobes are pointing when those are lined up.)

Save yourself some real disappointment and $$$$$ Go to the dealer and buy that shop manual.....you won't be sorry...

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hey guys im doing the exact same rebuild (just top end) and i was wondering how do i tell when the piston is at TDC? i know how to set the cam but not the crankshaft. and as for the person who said stick a screwdriver in the spark plug hole i feel like that wouldnt work because i wouldnt know if the pistons at compression to ignition or exhaust to intake stroke. do i need to take the cover off? is there a mark on the flywheel?

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