250ES bottom end & timing chain

[Airmapper]

I'm trying to piece together the info I'm finding on a few items I want to fix on my 250ES. I have one of the 250SX service manuals I found linked here to go by (I assume the engines are nearly identical.)

Right now it's my belief the timing chain needs replacing. It started a rpm matching clicking knock a while before I parked it, and from all the descriptions it seems to be the most likely issue. I also just pulled the tensioner and when I put it back in there was very little adjustment in it.

At the same time I think my one way clutch bearing is shot. As long as I've had this bike the kick start never worked, and it seemingly slips into neutral if I let the rpm's drop.

So what all do I need? As in replacement parts and tools.

Timing chain and guides.
Gaskets for the clutch cover and head?
New one way bearing.
Wheel puller (for centrifugal clutch?)

I think I replaced the centrifugal clutches a while back when I rode it more. But I didn't touch the disk clutches, should I plan to replace those while I'm in there for the bearing, or wait and inspect them?

How much of the top end will I need to remove to replace the chain guides? Just the very top "head" section? I don't really want to mess with the cylinder and rings.

I pulled the clutch cover this evening, looks daunting but I take it that it's not so bad.

Thanks for any help, tips, and assistance. I've never dug this deep into an ATC before. I am searching through old threads, but given I'm doing 2-3 things at once I want to see if I can't get some logic checking before I get in too deep.

[jabhonda]

I would check the guides but you shouldn't have to remove the jug and if your taking the centrifugal off then your pretty much right there at the crank pulley you might have to remove the oil pump and a line but its not to bad to do the chain. The 250sx manual should be the same for your machine.

[tri again]

try the search key?
Lots of people have tried , I mean done chains. d.i.d is the choice of chains.
I would LOVE to see a measurement of tensioners as in, how deep is it to the guide rail
when it needs to be changed. Maybe measure yours before and after?
I'm next this winter for sure.

[Airmapper]

Thanks for the responses.

tri again, best I can measure, the tensioner shaft is extended 19.5mm from the very bottom of the part it slides into. I'm not sure of the accuracy on that, I had it open and have been moving the chain by turning the crankshaft, so it may not be the setting it was at when I first removed it. Kinda hard to lock that spring then pull it out to measure. I may get a direct measurement from the mounting face to the rail before I close it up, didn't have a lot of time to work this evening.

I'll try to remember to get the same measurements with the new chain as well.

I found the D.I.D chain, looks good. I cannot find new guides, only used. Guess I'll check the old ones out and see how bad it is.

Right now I've hit a wall getting the centrifugal clutch off. That nut is tight. And I am trying to take it off clockwise. My impact wrench won't budge it. (I suspect it's a piece of junk...) I found a 1-1/16" Socket fits it well, but tomorrow I think I'm going to get some Metric sockets and see if I can't get the exact size and try it again, by trying to tap it off with some controlled hits on a ratchet.

Anything in there a pen torch will hurt? I'm not talking red hot but warming it up just a bit to get the metal to expand some?

[Airmapper]

Well I ended up getting a cordless impact at Harbor Freight, thought what the heck I'll use it to rotate my tires, and I was surprised, it works pretty good.

I got everything off okay. I can't really tell that the timing chain guides look very worn, I don't think I'll replace them.

Actually most everything looked good. All the clutch wear parts seemed fine, in both sets.

The one way bearing definitely allows travel in both directions, it will catch and slip, works for a bit but if you jiggle it breaks loose. I assume it's bad since it allows reverse rotation, but it doesn't look worn, guess it's even wear.

[tri again]

Thanks for the pix. Looks like I'm next for this project

[Airmapper]

Well I got it all back together today.

Put a new D.I.D chain on it, nice and tight now.

New one way bearing does it's job, kick start will turn over the engine now.

But once I got everything hooked back up......It won't hit a lick.

But since I've worked on darn near every system, it could be anything....carb, timing, fuel, who knows....