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85 KLR600, cam chain jumped @ 1700 mis..

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I just bought this bike, '85 KLR600, with the intention of getting it running. It is in nearly new condition, with only 1700 miles showing, and a previous reg sticker from 1990. Presumably it has been stiing since then. I have an 84 motor for parts to replace the damaged items. The guide around the crank is bent, and the piston hit the valves. It looks like it happened at low rpm, as the damage is minor. Cam chain tensioner appears to function prpoerly, so its still a mustery as to how the chain managed to jump at the crank. I do have a good tensioner from the 84, which is pawl/rathchet design,whch is different than the 85 screw style tensioner. Does anybody have a resonable guess as to why it derailed, and is the ratchet type tensioner better. I may just get a manual tensioner.

Edited by mjg15

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other than an obvious failure of the tensioner itself (which I have not seen), I have seen:

 

failed balancer shaft bearing causing loose parts to fall into the cam chain drive area (probably not that.... low miles).

 

broken "doohicky" lever/spring parts loose & get into the chain. (balancer chain tensioner)(seen one broke with1200 miles)

 

a paper towel left in the chain tunnel during a valve check... derailed the chain & made it jump. 

 

other things it could be maybe.... is the rubber chain guides.... haven't actually seen that but it's possible

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while you are in there get an Eagle Mike doo lever. I have not been able to make the "torsion" spring he sells work in a 600. he's a really good guy and a wealth of knowlege so maybe ping him

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All of the balancer components seem to be intact, and the "doohickey" was aslo intact. Camchain tensioner and guides (except the one around crank, that was damaged) seem to be fine. I did send an email to Eagle Mike about a week, but no response so far. I'm waiting for a manual, and couple gaskets, and then it's going back together using the "84 parts, which are from a motor that I roadraced a few times ( so I know that the parts work...)

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I got it back together and running, but...

 

When it first started, the starter stayed engaged for a few seconds.  When i revved it above idle for the first time (3000 rpm or so) the starter re-engaged and stalled the motor. I started it few more times, and at best, the starter is slightly reluctant to disengage, takes a second or two, and it has re-engaged a couple times at the slightly higher rpm. I did let it sit and idle at 1000-1500 rpm for 15 minutes or so without out it doing it again. I'm quite sure it's not an electrical issue, and it appears that I have everyhing assembled correctly. I didn't fully tghten the bolts that hold the stator to the bendix mechanism until the flywheel was tight.

 

I have only run it on the bench, and haven't tried to ride it.

 

Any ideas?

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the starter is always engaged to the starter gears. the gears couple straight to the rotor through a sprague clutch. this clutch is like a needle bearing that slips on direction but not the other. it grips when the starter is turning faster than the crank, and slips when the crank is faster than the starter.

 

grabbing in  & out is not something that normally happens with a sprague clutch. if you hit the starter with the engine running at 3000 rpm a normal response would be.... nothing... the sprague will slip. no slowing down, no extra noise except the starter turning (if you could hear it over the engine). maybe there is something in the needles of the sprague. maybe it's something else... you sure its in the starter system?

 

my other guess is loose parts in the works, or possibly... the rotor torque is too tight. I remember stories of rotor problems on 600s and early 650s. mething when the rotor bolt is too tight.  I cant remember the exact problems but that might be it. apparently on some, 135 lbs is too much. I remember reading someone's procedrure to go to 90, check rotation, then add 10 & check, add 10 & check, repeat until the rotor drags or you make 110-120. if you get that it's,ok... stop.  or go all the way up & see if it binds. if it does, back it off, pull the rotor & torque to the highest value that still worked

 

what torque did you use on the rotor bolt?

 

Kawi doo parts are shit. I've replaced dozens of broken ones. I've seen a couple engines destroyed by oem parts breaking. one was my friend's 600... locked the rear wheel 150 miles from home.  it's a terrible design built with crappy parts. buy an Eagle replacement

Edited by Beezerboy

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Beezerboy, thanks for the lengthy and informed reply.

I am going to admit to not knowing what the torque on the nut is.. I put it is on with my electric impact. I "carefully" watch it while tightening, but admittedly, it's not science. Later today I'll pop off the cover and rotor, and do it as you suggest. Hopefully my issue is something so simple.

I reassembled the doo using the spring from my '84 motor, which was same length, but slightly stiffer. I put a loop of safety wire thru it, so it can't escape. I also used the '84 can chain tensioner, which is a ratchet type.

I'll post results of reassembly/torquing later

Thanks

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Did a quick test-fix, and it seems that you were dead-on!! I pulled inspection plug out at rotor bolt, removed bolt, heated inner part of rotor and hit it with the puller a little. I put moderate pressure on the puller (thread- in type), but not enough to fully pop it off. After that, I reinstalled the bolt, and lightly tightened it. It starts smooth and quietly, and doesn't engage when it shouldn't. I'll take it apart and do it correctly when I get a chance.

Good call. !!

Edited by mjg15

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A friend has an 86 KLR 600 that has jumped timing. We are trying to figure out what has failed so we can replace it thus insuring the problem doesn't repeat. It has about 8300 miles on it. He just bought it so we aren't sure of the history. The oil level was too high so we drained it to proper level and a small piece (pencil eraser size) dropped into the drain pan that appears to be from the rear cam tensioner as we removed the valve cover and looked down into the cam chain tower and it appears to have split off from there.

 It stopped suddenly as he was riding so we checked for gas and spark which checked out. We thought it might be the automatic compression release was stuck and checked that. It was ok. While we had the valve cover off we checked the cam timing and found out that the marks on the cam sprockets and the "T" mark on the flywheel don't match when performing a timing check. When the "T" mark is in the proper location the cam sprocket marks are off and vice versa.

 When rotating the engine by hand it stops suddenly near the "F" mark, assuming the piston is hitting a valve. (We performed a compresssion check and there is 0 psi.) After looking thru the Kawasaki service manual we were wondering if the cam chain will need to be replaced as it might have stretched or if the chain tensioners are at fault and will the engine need to be removed and disassembled to replace the cam chain?

Thanks in advance for any help.

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the cam chain tensioner is a "T" shaped casting on the back left side of the engine.... it is held on to the case with 2 bolts that have 10mm heads, in the middle is a bolt with a 12 mm head. this is all on the outside of the engine. if you want to check it, crack the 12mm before you remove the housing because it's a bitch to do once it's off the engine. you have to remove that bolt (12) and then the spring underneith in order to re-set the tensioner plunger. that needs to be done any time the chain is off, loosened or moved. the plunger has a one way ratchet devise... it is easy to understand once you have it off.

 

I suspect you are looking at & having problems with the balancer system. parts break off or fail & they can fall into the cam chain & cause it to jump. the old style balancer weights had springs & rollers in them... the springs wear & the rollers fall out. or.... you lose tension due to the "doohicky" breaking. there are also cases where the bearings in the balancer shafts fail.  at any rate you need to pull the side cover(s) off the engine to inspect what going on. much of that can be fixed in frame

 

the lack of movement & loss of compression indicates possible bent valves.

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Everybody seems to recommend this Eagle Mike and his fantastic doo whatever . I have and I see others have tried to get in touch with him , And he does not reply , says a lot for anything he sells on the aftermarket service side does it not ?.

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