The XL600 thread

[HeadTrauma]

Originally Posted by Humboldt Brad

ohhh boy I'm in trouble..... I was riding and that noise(see my photobucket) got louder I checked my oil its ugly it wasent before I drained it and took out all the screens and in the screens there are some serious metal flakes... do you guys think I could get more for it parting it out or just selling it. it still runs and drives good I'm just not sure what to do...
talk about depressing I love this bike

You'll almost always get more for a vehicle in parts than in whole but it's also more work and takes a lot longer to disassemble and sell/ship everything piecemeal.

It sounds like your bike lost a rocker and the cam for whatever reason.

[Ghost_Mutant]

Originally Posted by Watcher

That's one of the reasons to look for an alternative.
1989 Rocker Cover from E-bay




The Description when purchased said it was a 1989 Hot Cam, The box it came in said 93 XR650L.
Installed in cylinder head cover with sprocket reversed. Also the sprocket end of the camshaft is larger on the XL600R so to make it work a 1989 XR600 Bearing was ordered. This was my best guess to how it would fit when in the head.




One extra large rocker.




The rocker cover and cam sit on the 1986 head and so far there doesn't appear to be any obvious problems other then the center journal seems a bit off center. The camshaft bearing will be here Wednesday.

Watcher,

Thank you very much for posting on this cam/valve cover swap. I had been wondering what I would do to fix my 83/4 if I had to replace these parts.

Could you take some more photos and elaborate further on the timing chain alignment and cam bearing differences when you get the rest of the parts?

I understand you are using the older timing chain sprocket but mounted on the other side of the cam. Does that cause any centering problems with the camshaft? Is the back of the sprocket flat enough to to match the cam and spin without wobble? How good is the chain alignment with the crank sprocket?

I thought you might have to change cam chain/sprockets to the newer style as well to make this work. Glad to see that appears not to be the case.

Did you plug up the auto decomp oil hole in the cam shaft? Or did the aftermarket cam not have that extra hole?

Lastly, the valve covers on my 83/4 XR does not have the half moon journal for the center of the cam. I think Honda added that in 85? to allow more oil to reach the leftmost two cam lobes. At least I couldn't think of any other good reason to add that journal to the valve cover when the original design didn't appear to need it.

[HeadTrauma]

'88+ Hot Cams don't even have a provision for a decompressor, so there's nothing to plug.

(There are no HCs for pre-'88 engines.)

[Watcher]

Originally Posted by Ghost_Mutant

Could you take some more photos and elaborate further on the timing chain alignment and cam bearing differences when you get the rest of the parts?

I understand you are using the older timing chain sprocket but mounted on the other side of the cam. Does that cause any centering problems with the camshaft? Is the back of the sprocket flat enough to to match the cam and spin without wobble? How good is the chain alignment with the crank sprocket?

I thought you might have to change cam chain/sprockets to the newer style as well to make this work. Glad to see that appears not to be the case.

Did you plug up the auto decomp oil hole in the cam shaft? Or did the aftermarket cam not have that extra hole?

Lastly, the valve covers on my 83/4 XR does not have the half moon journal for the center of the cam. I think Honda added that in 85? to allow more oil to reach the leftmost two cam lobes. At least I couldn't think of any other good reason to add that journal to the valve cover when the original design didn't appear to need it.

This is the Cam in a used E-bay head ( the center journal in the old head was pretty chewed up ) with the sprocket reversed.



A better angle. There is duct tape wrapped around the end of the cam forming a bushing for the original bearing. It's pouching out past the end of the cam some, but I wanted an idea of how well it would all line up too. It looks to me to line up exactly, right on with the original.




The only difference in the bearings seems to be that the sprocket end of the XL600 camshaft is 20mm in diameter with the 1988 and later cams being 18mm. Both are 20mm on the opposite end. The length with bearings against the dowel pins is identical. Perhaps a 1mm bushing would allow using the original bearing though.


The sprocket sits flat on the Hot Cam when reversed and it looks solid. There are shearing forces on the bolts but it's hard to see how they would be any less if mounted traditionally. I don't anticipate any wobble though.

Originally Posted by HeadTrauma

'88+ Hot Cams don't even have a provision for a decompressor, so there's nothing to plug.)

That was a major reason for using a Hot Cam for this project.

I wanted to add that there is a used 1985 XR600 cam currently on E-bay, three day auction, 20 bucks and 0 bids ( so far ), the description says in good condition.

[brucifer]

Originally Posted by mcma111

Brad,

Do the olde screw driver Stethoscope trick. Get the biggest screw driver you have and put the handle to your ear and the tip at different places on the motor to try to locate where the noise is coming from. You can also remove the rocker inspection covers and look at the cam and rockers. Check if one or more rocker arms has a lot of play. That will tell you right there what's wrong.

I'd wash the engine and frame above the engine first to keep dirt from getting into the motor

I don't think Brad's too interested in fixing this bike. Are ya Brad?
http://humboldt.craigslist.org/mcy/2890589560.html

But if you are, my offer still stands to come by and have a look at it for ya. I left a voice mail for you a couple weeks or so ago. Let me know.

[Ghost_Mutant]

Originally Posted by Watcher

A better angle. There is duct tape wrapped around the end of the cam forming a bushing for the original bearing. It's pouching out past the end of the cam some, but I wanted an idea of how well it would all line up too. It looks to me to line up exactly, right on with the original.



The sprocket sits flat on the Hot Cam when reversed and it looks solid. There are shearing forces on the bolts but it's hard to see how they would be any less if mounted traditionally. I don't anticipate any wobble though.

Cool.

To sum up what I've learned:

1) New style cams take bearings with smaller ID requiring a new bearing.

2) Old style cam chain can be retained if the chain sprocket is reversed and mounted on opposite side of cam chain mounting flange on new cam.


More questions:

Is the hot cam a requirement to do it this way due to the sprocket mounting flange? I see that the hot cam is machined flat on both sides of the mounting flange. I don't think the stock Honda cam is that way, at least my old style cams are cast with only one side machined. Best close up photo I could find of my mounting flange:


I suppose one downside to mounting the sprocket in reverse is that the alignment marks aren't visible in the normal fashion, making gauging cam chain stretch harder?

[HeadTrauma]

Here's something to look at until I take a better-aligned photo in a little while.

[mcma111]

Anyone looking for XL600 parts. I have a bunch of XL600 stuff that I am tired of looking at and would like to see it leave.

Various engine bits, rear wheel complete, wiring harness complete, almost a full set of 83 plastic.

No cam, front wheel, seat or exhaust.

A couple sets of later XR600 forks.

PM me if your looking for something.

[ricnepalm]

Originally Posted by mcma111

Anyone looking for XL600 parts. I have a bunch of XL600 stuff that I am tired of looking at and would like to see it leave.

Various engine bits, rear wheel complete, wiring harness complete, almost a full set of 83 plastic.

No cam, front wheel, seat or exhaust.

A couple sets of later XR600 forks.

PM me if your looking for something.

Looking for a front brake caliper. Also, if anyone knows what years the front brake caliper was used.

[mcma111]

I have two calipers but both are stick. I can compare it to a later XR600/XR650l caliper.

[Humboldt Brad]

Originally Posted by brucifer

I don't think Brad's too interested in fixing this bike. Are ya Brad?
http://humboldt.craigslist.org/mcy/2890589560.html

But if you are, my offer still stands to come by and have a look at it for ya. I left a voice mail for you a couple weeks or so ago. Let me know.

I don't know. I think at this point I need to fix it so I'm pulling the engine this week and starting the tear down i know im wishy washy about it but I just like the bike so much I have to fix it and I'll never hear the end of it from my wife if I dont.

so where is the best place to get parts(gaskets and such) and I'm going to need to seriously clean out the oil system any suggestions

[Watcher]

Originally Posted by Ghost_Mutant

Cool.

To sum up what I've learned:

1) New style cams take bearings with smaller ID requiring a new bearing.

2) Old style cam chain can be retained if the chain sprocket is reversed and mounted on opposite side of cam chain mounting flange on new cam.


More questions:

Is the hot cam a requirement to do it this way due to the sprocket mounting flange? I see that the hot cam is machined flat on both sides of the mounting flange. I don't think the stock Honda cam is that way, at least my old style cams are cast with only one side machined...

I suppose one downside to mounting the sprocket in reverse is that the alignment marks aren't visible in the normal fashion, making gauging cam chain stretch harder?

Here are the two cams, the one on the left (with the duct tape) is the Hot Cam, the other is the original XL600 cam. They both have a similar profile just reversed.




The sprocket mounted on the Hot Cam the way it seems to be on the 1988+ cams. Mounted this way the chain alignment is moved to far towards the center of the engine.




With the sprocket turned around the alignment is spot on.




The sprocket on the XL600R Cam for comparison.



I went with the Hot Cam because it was specifically mentioned in one of the two references found when researching this mod. Not having a 1988+ cam to compare to the original from the XL600 made it a bit safer bet from the stand point of keeping the original timing chain.

In this post from HeadTrauma the 1988+ cam looks similar to the profile of the Hot Cam. The same 1988+ sprocket bolts to the camshaft of both the Stock and the Hot Cam. The XL600 camshaft bolts to the Hot Cam. Without actually having a stock cam to compare it's impossible to say with absolute certainty, but at this point I am planning on pulling the engine out of my 83 XL600 and going with a stock 1988+ cam.

Originally Posted by HeadTrauma

Here's something to look at until I take a better-aligned photo in a little while.

The reversed nature of the the Hot Cam and sprocket offset each other so that the timing marks are visible in their normal position.

[cynicwanderer]

PM sent.

Originally Posted by mcma111

Anyone looking for XL600 parts. I have a bunch of XL600 stuff that I am tired of looking at and would like to see it leave.

Various engine bits, rear wheel complete, wiring harness complete, almost a full set of 83 plastic.

No cam, front wheel, seat or exhaust.

A couple sets of later XR600 forks.

PM me if your looking for something.

[randylahee]

i finally got back to work on my 83 XL... it had a leaky rocker cover gasket and it was cutting out at high rpms

did a compression test 175 psi!



pulled the beast of a motor



cam chain looks stretched, bearings were replaced at one point



looks like it was getting lube



can you tell if the tensioners maxed out?

[randylahee]

old rocker box, one of thems badly worn. i have a 85 rocker box that looks like it will work the only difference i can see is that the kickstart decomp thing works differently, doesnt matter for me though i took off the kickstart decomp.

anyone know what would cause this damageÉ





83 and 85