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Replacing Cam (Timing) Chain

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The bike's due for a new cam chain.  I've poked around in the manual and on here and haven't had a clear answer on a couple things.  I've checked valves in the past, so this isn't new territory, I just want to make sure I have all the tools before I start into it.

 

1) Do I have to pull the flywheel?

2) Will any flywheel puller work?  (I know Honda's require a special one or you will screw up an oil feed orifice)

3) Any other tools required to loosen the flywheel other than the one nut on the crank?

 

General procedure:

1) Remove cam chain tensioner

2) Remove intake/exhaust cams

3) Remove flywheel

4) Remove anything else????

5) Replace chain and reassemble at TDC

 

Is there anything I'm missing/over-doing in the disassembly?

 

Thanks!

 

 

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Replace the cam chain tensioner as well. I picked up a flywheel puller off eBay for something like $20 I think. Yes you will need to pull flywheel off. I am by no means an expert on this, but I did just do a complete top end and in the process, replaced the timing chain. Members on here helped out a lot in my whole learning curve. (Ronbuell, SUnruh)

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SPUD,

I think you have experience enough to get the job done.

>>Get the manual out and read that section and refer to the exploded views of top end and bottom end.

1) Do I have to pull the flywheel?     YES

>>2) Will any flywheel puller work?  NO, has to be for the YZ250F

(I know Honda's require a specialicon1.png one or you will screw up an oil feed orifice)

Anything that goes thru the vent holes in the flywheel with chew up the coils.

3) Any other tools required to loosen the flywheel other than the one nut on the crank?

>>NO

 

procedure:

remove the seat and tank and pressure wash to get rid of dirt and use the leaf blower to blow it all dry.

then remove the valve cover

1) Remove cam chain tensioner

2) Remove intake/exhaust cams

remove the left side cover

3) Remove flywheel

remove the rear cam chain slider

4) Remove anything else????

5) Replace chain and reassemble at TDC

>>reinstall the tensioner and then reconfirm proper timing AND rotate the engine thru to make sure nothing is jammed up

... sometimes it easier to remove the sparkplug and drop a long wooden dowl in the hole to verify TDC (I have used a long screwdriver... carefully   shhhh don't tell Sunruh)

>>>You may need to replace the gasket for the side cover, but if you're careful when you remove it, you can save it.

 

Is there anything I'm missing/over-doing in the disassembly?

 

Yes, since you haven't done this before, work slowly and carefully.  Give yourself plenty of time.... 30 min until the next moto is not a good time.

Keep clean rags handy, and get some Brake Cleaner (spray can) on hand to clean off the side cover and all mating surfaces.

Don't loose the locator pins.

 

When I do this at home, I locate the bike outside and lean it over and let the right handlebar rest on a short wall about 3 ft high.  That way I don't loose the oil in the crankcase.  The drawback to this is anything that gets dropped CAN go down into the bottom end.....so be careful if you decide to do it that way.  Just thought I'd mention the shortcut.

 

Allow at least 2 hrs and be happy if you can do it 1.  Most of us can change it out in about 45 min or less but thats with experience.

If the engine is out on the bench, 30 min tops.

If you don't have the flywheel puller, invest in one, you will use it later.

Good luck

L8tr, Ron

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Thanks for the tips Ron.  That's what I was looking for.

 

 

yes

 

reading the manual

 

The manual goes in depth on a full rebuild with the cylinder head pulled off, which makes replacing the chain pretty straight forward at that point.  I'm not planning on tearing that much apart.

 

I even searched TT and youtube and didn't find much!  :jawdrop:

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