Jump to content

Arrg, shavings and a bad rocker. How far should I go?


Recommended Posts

Well, got the FCR on and it started right up. Oil looked OK but had a little more noise than the sewing machine should have. The DG pipe sounds good ๐Ÿ˜

So I run the valves and it sounds the same. So I think rockers or cam pull the cover off

Off with the cover on the bike (neighbor with 600 said you can't do it in the bike) and right away I see a bad rocker and some shavings on the cams center race. I see no shavings floating around and plenty of oil up top. Chain looks good as do the guides.

So simple, I already have a new rocker set and needed to put the S1 cam in anyway. Will open up some oiling holes too.

I guess this is a good time to go just a little farther and up the compression some. I have a JE 10.5 piston I could drop in if it doesn't need a bore. If it does I would probably go for the 600 piston.

If I use the 10.5 JE should I machine a dish in the center to lower the comp just a little. I can turn it easy on my lathe, just wondering how much to remove for around 9.5:1?? Another option is a thicker copper head gasket.

If I pull the head I think I will get the big fins added, do a slight port cleanup and I should be good for another 25K or so.

Any input??

Link to comment
Share on other sites

69nthx.jpg

oh you mean like this???

lol, just banged mine together today. was gonna wait for the new cam chain to arrive but i got impatient.

took it for a quick run in down the street but haven had the chance to give it a hiding yet.

its a 628cc je, stage 1 cam, cleaned out ports, thick copper head gasket.

not too hard to start either.

Link to comment
Share on other sites

1.) Off with the cover on the bike (neighbor with 600 said you can't do it in the bike)

If I use the 10.5 JE should I machine a dish in the center to lower the comp just a little. I can turn it easy on my lathe, just wondering how much to remove for around 9.5:1?? Another option is a thicker copper head gasket

1.) Inform that neighbor that only XL600s have that problem. The rest will allow the head cover to come off without pulling the engine. ๐Ÿ˜

I would be concerned with why the engine started eating the valvetrain.

2.) I don't know how thick the JE's crown is, but I would leave it alone anyway. You wouldn't have to take much off to get 9.5:1 if you did put a dish in the top; that piston only makes ~9.7:1 with a stock bore anyway.

Say, do you still have the box for the JE? Does it have the compression height listed on the label?

Link to comment
Share on other sites

Depending on their condition, the head and head cover gaskets can be reused a few times. The head gasket in my engine is on its second tour and the head cover on number three. Both are the laminated steel type with a black rubber coating. I skinned the head cover gasket with Yamabond 4 and put a little around the cam chain passage on the head gasket.

That one in your photo still looks good.

Link to comment
Share on other sites

I am going to check the oiling system and clean out the screen for sure. Only the exhaust rockers show damage. One was toast, one was starting to show scuffing.

Piston is a flat top, 4 valve reliefs showing a 1.234 comp height, stock bore. Mic'd the face and it is 4.5mm thick.

JE# 130682 shows it as the 10.5:1 but I remember reading here it was lower.

Link to comment
Share on other sites

All the bolts came out clean, but 2 were tuff. 1 was a 6mm that I was sure was going to break, but I worked it back and forth and pored a little ATF in the hole (ATF wicks great and cleans!)

The jug should not be hard pull from here and I can look at the chain too. Only issue from there is if it needs a bore, then I need another piston too.

Any obvious way to tell if the chain need replacing? I have no idea on the miles of the bike.

When it goes together I will use ARP bolt prep on everything. I never hear of anyone using this or anti-seize but always hear about stripped threads.

Link to comment
Share on other sites

1.) Any obvious way to tell if the chain need replacing? I have no idea on the miles of the bike.

2.) When it goes together I will use ARP bolt prep on everything. I never hear of anyone using this or anti-seize but always hear about stripped threads.

1.) The rule-of-thumb check is to pull up on the section of chain wrapped around the cam sprocket while the tensioner is still installed. If you can pull the chain away from the sprocket, then it's worn.

2.) Don't use anything with moly(like ARP bolt prep) or it will be a lot easier to pull the aluminum threads out unless you compensate by applying less torque. How much less is up for debate. A little engine oil is quite adequate. Something else that will make it easier to pull the small threads out is using a foot-pound torque wrench on fasteners smaller than M8. The increments are too big and the feel too vague IMO, so I suggest using an inch-pound wrench on the 6mm bolts or calibrating your wrist. 7ft-lbs is not much, especially when aiming between 5 and 10ft-lbs with an 18" long wrench.

And 83-84 XR500.

I was wondering about that. ๐Ÿ˜ I guess I should say "all the XR600s and 650s." Do the XL600s and XR500s share the same frame?

Link to comment
Share on other sites

ARP bolt prep is designed just for stuff like this. Much better than engine oil.

I have an in torque wrench but probably would do it by hand using a 1/4 ratchet. Snug is close enough on those little buggers.

Thanks for the advice on the chain, seems easy enough.

Link to comment
Share on other sites

I was wondering about that. ๐Ÿ˜ I guess I should say "all the XR600s and 650s." Do the XL600s and XR500s share the same frame?

Thinking they have the same basic dimensions. Wouldn't go so far as to say they are the same. XL rear frame rails have a bunch of brackets that XRs don't. Tank mounts are different of course. Pegs are different but might mount in the same relative position. No shock res mounts on XL and wider swingarm. I only know the clearance over the head is about 3/4" less than 85 up XR600s. You can feel the difference in seating position when riding the 2 back to back. Horri may know more. I've got both, I'll have to check it out closer some time.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

ร—
ร—
  • Create New...