Xl600r 1983 cam chain slack opionions, see video

The bike is a 1983 XL600r with 12 k miles on it. It jumped time on the previous owner who said it was the tensioner. I just reasemebled the motor with the old parts and some new parts. Cam gears look good, chain looks good, tensioner seamed to be working. I just tore it back down due to back fireing, popping, no idle, high idle, hard starting and at WOT it would pop, and stall until I let up. Great power when no symptoms show.  I purchased a new wiesco cam chain, and have a newer tensioner. In addition, I noticed that the exhaust lobes were pitted and am finding out how hard it its is find 1983 cams. I could have it hard welded and ground but that is a future plan if this does not work. I used a diamond hone and removed .003 from the lobes and then buffed them out. The lobes are still with in spec at 1.216 and spec is 1.213 for ex. I was care full to keep the same profile . Take a look at the video of the chain fit the the upper gear and the lobes and give me some thoughts. this is my first bike other than a hodaka 80 in 1984. 

 

You really need to install the chain along with the tensioner and try to lift the chain off of the cam sprocket.  If you can lift the chain at all you may have to replace the chain along with the guides, upper, and lower sprockets.

 

ME

 

DSCF0002a.jpg

Edited by kmequint

Well the chain doesn't look too bad to me..I take it that's the old one is it???,,Put a new one in it anyway and certainly replace the tensioner spring. What's the bottom sprocket look like,,It's the one that suffers the most abuse and seems to be the jumper favourite.

 

What with the crazy throttle and idle thing it sounds like a carb problem..maybe an air leak around the manifold??

 

Cam looks ok,,If it's in spec it should be fine..I'd be happy running it in my bike.,but then I'm no engineer..

Edited by Horri

Well the chain doesn't look too bad to me..I take it that's the old one is it???,,Put a new one in it anyway and certainly replace the tensioner spring. What's the bottom sprocket look like,,It's the one that suffers the most abuse and seems to be the jumper favourite.

 

What with the crazy throttle and idle thing it sounds like a carb problem..maybe an air leak around the manifold??

 

Cam looks ok,,If it's in spec it should be fine..I'd be happy running it in my bike.,but then I'm no engineer..

The cam chain is the original and it also lighly binds in the joints as each plate passes each other. The bottom sprocket looks like 95% of the upper. 

How I got to the point of tearing appart the motor was by going playing around with jetting. its cold in Oct and Nov in Vermont 20-45 deg F so I suspected lean from the popping at WOT and dieing at low idle. I scoured net looking for simptoms like mine. Did the wd40 thing around the manifold, head, carb and the kitchen sink, no leaks. New exhaust gaskets and stock exhaust. I even tried thicker more resistant to air flow home made air filtes from open cell foam and two stroke oil. Then I got a 6sigma stage 2 kit (127.5, 130, 132.5,  135, 137.5 and 140.  and and some pilot jets 60 and 65 from jets are us? It then ran to rich with jets above 132.5 and the exhaust was sooty and it would 8 stroke and pop and back fire. All the same time it still had little to no reliable idle and wild high idle. When I would turn the idle ajust it would bring the idle down fast with little turning.  The idle set wheel was useless, and modulated the idle very little. I did remove the air screw, and cleaned that and tried any veriation of jetting and scew setting. It did have an amazing low and mid for power. It has new honda 100mm rings, if I did not mention that. I have cleaned the carb with guitar wire, brake cleaner and air. 

 

i know that if the timing is advanced or retarded on you can get higher idle or lower idle rpm dending on what direction you go. If the tensioner was faulty and the chain was elongated then it might be possible that the idle might be all over the map because the chain lash was causing the timing to be advanced or retared depeing on were you were on the throttle, and engine drag. I could brake the hight idle if I brought the engine down threw the drive line via brakeing. Just a thought. 

 

anyways bring on your thoughts. I will solve it and I hope soon, its getting very cold in VT to be riding

 

Now back to the timing chain, when I get the new one I will compair the old and new. I will put the new one in regardless. Regarding the tensioner, they appear to have clutching mechanism that restricts or supposted to restrict backwards movement. Its not a ratchet with detents but rather a mutiple point binding system with shoes that press agains the smooth suface of the tensioner axel? Is this this spring loaded shoe clutch that fails or as mentioned is it the spring. I know that springs loose strenght with heat and this bike was over heated at one point. 

Regards the auto tensioner mechanism..I have never seen the actual mechanism fail,,though there is one over on ADV that snapped in half. I just reccomend a new spring because when I had a few 600 engines I noticed the end that sat against the case was worn away quite noticebly from new so I figure,,new spring if someones doing some work in there.

 

That jetting seems pretty large in mains..Pretty sure when I had my XLs I didn't go above 128 mains in each carb..The Pilot I'll have to have a look around and see if I have any info on it. I did have a CRF250X Muffler on those bikes so they weren't totally stock..Nah.info on the PIlot is lost..I say a 65 is what it was..

 

What's the numbers stamped on the RH side of the RH carb just above the float bowl..???

 

All that up down idle popping farting carry on sounds similar to an ignition coil failure..that's if you have to use the accelerator all over the show just to keep the bike running..I am not saying it is the problem,,just that the symptons are alike..

Edited by Horri

That chain and cam sprocket look FINE. That's how I test a chain and I'd run that one in my bike.  I doubt the new one will be any tighter.

 

As for pitting in the cam,  that can wear your rockers, so keep an eye on your valve adjustment.  It's caused by lack of lubrication at high RPM.

 

Can you trade the new chain for a new cam?

 

Edit: The PITTING is caused by lack of lubrication at high RPM.

Edited by Baja Rambler

Slight lifting of the chain at the tops is fine.....if the new chain is tighter then use the new chain,,why not right???????

 

I`ve seen guys sand/polish cams before and have no issues........if a new cam isn`t available i`d run it,,but keep an eye on it in case it decides to frag more pieces of it...

 

B

Edited by brianhare

Update, 

 

I split the case because I had a small leak between the case halve. I found that the non tensioner side cam chain guide was broken in two at about 2" from the top. I found some guides on ebay and they are coming. I also found on the net a dude who did a back up fix to a unreliable tensior by putting a M6 screw threw the case just behind the tensioner arm with a set screw. I am going to do this as well. I can't wait for a normal performing bike. 

Replace the countershaft seal while you're in there.  $4 part from Honda.  Also make sure the shaft has a nice polish where the seal touches it.

Just did another video to show the old chain and the new timing chain. There was a slight difference in length, flexibility, plate thickness, joint lash and width, from old to new. The new fits much tighter on the gears and is much more fluid feeling in hand.   

 

http://youtu.be/pafr38R_Gc4

Cool. The old chain looks worse in the second video. 

Did you wrap the new chain around the lower gear to check it?

Cool. The old chain looks worse in the second video. 

Did you wrap the new chain around the lower gear to check it?

not yet but its in the other room and I will and report back. 

Ok, I am new at this, so the ring that I thought was the lower cam chain sprocket turned out to be and oiler gear. I did find the lower cam sprocket and it has some wear on it. Divets on only a few teath and none of 3/4 of the sprocket. I found a new one online and ordered it. Also, since I was into the motor again. I checked the bore dimensions at 6 points, top mid, and low at two differnt axis. I had, 002" taper and .001 out of round. It also was .0075 gap between piston and cylinder, .004 over service limit. I orginally compensated by getting new set of Over sized rings it filed ring gaps. It did not smoke, no slap noise and made good compression power when it ran ok. Anyways, i found a new 100mm sleave on xronly and with the new parts I should not be into the bike like this for what I hope is 20k or more. The transmission shifts like new, the crank, ballancer seals and bearings are tight. My "Free Xl600r" is no longer withing my $500 budget and approaching $700. Blue book is $1200. I can find these on craigs list from 700 - 800 but they will need work. This one has been gone threw top to bottom now. 

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