Can you help a brother out ...(my brother's XR600 just died)

[Mid_Life_Crisis]

Hi All

I normally hang out on the DRZ forum, but my brother has an '97 XR600 and slow internet access, so here it goes.

He was out riding, took a good fall (going over a log), and his bike wouldn't start (doesn't know if the motor breaking contributed to his fall).

Anyway, back at the house, he says he's got lots of spark, but it kicks over funny, and feels like the valve timing is off.

Anyone got any suggestions (even on which manual to buy).

I got to help him get it running again (he own's the truck ?).

Either post here, or email me at dsc353@gmail.com

Thanks

Don ?

[fishbone1]

Buy an oem manual. Any Honda XR600 manual 1988 and newer will work. There are several on Ebay.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7929996040&category=34237

If you want to check the timing you will need to pull the valve cover, the spark plug, the center cap on the flywheel cover(so you can get a socket on the flywheel bolt and turn the crank) and the top viewing cap from flywheel cover(so you can see the "T" on the flywheel for setting timing.)

The cam timing will be on when the piston is at TDC on the compression stroke, and all the valves are closed (like when you do a valve clearance adjustment. With everything set right, the two little hash marks on the camshaft sprocket will align with the top of the cylinder head, with the piston at TDC on the compression stroke.

Make sure when you are roating the engine to find the "T" mark that you turn it in a CCW direction. When you get the T mark lined up with the notch in the flywheel cover and the piston is at TDC the two lines on the cam gear should be parallel with the surface of the head. If they are not. The bike has jumped time or severely stretched the chain.

[Mid_Life_Crisis]

Thanks Fishbone ?, I'll pass the information onto my brother tonight.

Couple questions:

Does the XR have an automatic cam chain tensioner?

Is cam chain skipping a common problem?

From what I remember his bike didn't have any cam chain noise, but I know he hasn't adjusted it in the 2 years he's had the bike.

I'm not trusting enough for ebay, but I'll put a WTB ad on TT (why didn't I think of that earlier ?).

[HeadTrauma]

Couple questions:

Does the XR have an automatic cam chain tensioner?

Is cam chain skipping a common problem?

- Yes

- No

The chain is only really prone to skip if its stretched beyond the service limit. If that happens, however, you risk having both the piston and some valves try to occupy the space in this plane of reality. Also make sure the manual decompressor isnt sticking the valves open if he crashed it.

[minioutlaw]

Also make sure the manual decompressor isnt sticking the valves open if he crashed it.

I found out recently that when the previous owner of my bike removed the auto decompression mechanism from the cam, he did not plug the oil holes that are normally underneath it. This meant that nearly all the oil that entered into my cam was dumped out before it reached the lobes/rockers/journal, and for almost 4 years I had a nearly unlubed top end. That I made it 4 years is a real testament to the durability of the XR motor. But anyway, just something to think about if you tinker with the auto decompression.

[Mid_Life_Crisis]

Thanks for the reply's.

It might be the auto-decompressor. When he fell, he knows that he jammed the decompressor lever back into his fingers.

He said that the decompressor level still feels like it is functioning normally. What is the symptom when it sticks (does the autodecompressor no longer work?).

Going to try to look at it tonight.

[Mid_Life_Crisis]

Had a look at it last night. The valve adjustment was fine.

Couldn't check the timing (have to buy some 3/8 drive hex sockets). But when you kick it over it doesn't feel right (it doesn't seem to kick thought the stroke) and every so often you get a small backfire, so we're thinking its probably that the cam chain has skipped.

The owners manual says not to pull the decompressor while the motor is running. Anyone know what what happens when you do?

I'm off the net for the weekend, but will try to update what we've done on Monday.

[TimBrp]

The owners manual says not to pull the decompressor while the motor is running. Anyone know what what happens when you do?

I'm off the net for the weekend, but will try to update what we've done on Monday.

The valve will whack the piston.

[97xr400r]

The valve will whack the piston.

heh.. Does it? I thought pulling it with the bike on caused the cam to 'click back' because the bikes internals want to keep rocking the cam.. and the decompresser forces the cam to push down.

If it really hits the piston, I hope my bike is fine from the couple times I've done it.(97' xr400, believe it or not.. It doesn't even have 600 miles on it).

[don87xr600]

if you pull the decompression lever while the engine is running it will stop, that's all

[Mid_Life_Crisis]

Well he took it to a friends shop and pulled the head off He said that one of the exhaust valves was not sealing. Re-lapped the valves, and made it so that the auto-decompressor would no longer function (as it looked like it was responsible for holding the valve open.

Anyway, he said it feels better than before, and he now needs to use the manual decompressor when starting it.

Thanks for the replys everyone. ?