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Freezeman

2005 Kaw KUF 650D no start issue

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Well I came on here hoping to read a manual about the quad but found that I have to make some posts before that can happen, so here is one. 

I work on peoples stuff. Had this well used unit come to me with a no start issue. I found it had fuel  and spark was good but it only had 30 pounds of compression. I put each cylinder to TDC and feed the plug hole with a small amount of air pressure and could hear the escaping air coming out the carb openings. I then checked the valves lash at TDC and found that booth cylinders had 0 lash for the intake valves. I reset the lash to .003 for all the intake valves and reapplied a small amount of air pressure and the leaking of air was gone. I then spent a few hours screwing all the parts I had to take off, back together and then drove it out of the shop.

The lash was only 1/4- 1/2 a turn too tight that caused the valve to stay open just enough to make it not start. IMO the heads could use an overhaul some time soon as the valves and seats have become a bit warn.

These ATV's just have too much crap stuffed into a small space, I wounder how many fasteners are used to hold 1 ATV together?

Later, 

Edited by Freezeman
add some stuff
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Well this unit came back after it ran well for some time, This time it died while riding and will not restart.

This time I looked back into the valve operation and to my surprise I have no rocker arm movement of either the front or rear cylinder when rotating the crank, The pistons are moving up and down, I can turn it over by hand rather easily with the spark plugs out as there is no valve spring pressure resistance because the rocker arms are not moving.

 

I am rather puzzled... How could the two timing chains on each end of the crank running the two over head cams stop working at the same time?? 

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Something snapped, weather it be a shaft or the chains (doubtful that both chains would snap though.  So the chains have tension on them ? If so then it’s the cam chain drive shaft that snapped or the key way that holds that sprocket in place on the lower end.   

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Behind the flywheel, there's a chain from the crank to a shaft that the cam chains are connected to.  This shaft drives both cams.  I'd venture a guess that lower chain broke.  You've probably got some bent valves now also.

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Agreed on the bent valves.  As soon as that shaft or sprocket went the valves and the piston collided.  So the piston is prob damaged also.  Start with pulling the head off and see what all that looks like.  There will def be a mark on the piston noticeable if the valves hit the piston.   

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Thanks for the tips. A separate shaft that turns booth cam chains... I am no longer puzzled as that has to be the heart of the problem. Tear it down.

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very interesting!  I didnt know that just a small amount of play could cause loss of compression.  I would have been interested to know what caused the valve clearance to change.....enough to lose compression

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Jacob, Any time a valve or valves in this case do not close when they are supposed to you will have a loss of compression.

In my case with this unit it now makes sense that when I first found that the intake lash was too tight on booth cylinders   while checking it at TDC, The valve timing had changed some how. I originally thought it must be that the seats had receded a bit from wear and was happy that just a simple adjustment made it run again.

But now it came back with the lower chain that drives booth timing chains broken..  So the intake valves not closing all the way at TDC the first time I worked on it was from that lower chain stretching a bit causing all the cams timing events to be late or retarded.

Below is my attempt to post a picture of the broken chain. I now need to make or buy the "special tool" to pull the flywheel off the crank end. I hoard crap yet I can't find a 35MM 1.5 pitch nut to make my puller.  

 

https://www.facebook.com/photo.php?fbid=10215975557754824&set=a.1422066704716&type=3&eid=ARDFrorzbNPZWvb62q6P6YdhQm1uoEqedU7lHkNXVFWi_OG3Hx_s-hOTkj88wRYe0d-x776rjbyDpbga

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I am wondering about pulling the heads. With the rockers off the valves both cylinders are equal and have just 10% leak down at BDC which isn't too bad with my cheap gauge. I have tested new motors at 8%.  So no hole in piston and if a valve is damaged it's not really noticeable.  

I got my flywheel puller ordered now I need to order the clutch puller bolt,

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On 3/18/2019 at 8:26 AM, Freezeman said:

I am wondering about pulling the heads. With the rockers off the valves both cylinders are equal and have just 10% leak down at BDC which isn't too bad with my cheap gauge. I have tested new motors at 8%.  So no hole in piston and if a valve is damaged it's not really noticeable.  

I got my flywheel puller ordered now I need to order the clutch puller bolt,

If you have just 10% leakage, I wouldn't bother pulling the heads.  It's a p.i.t.a. anyway.  If any of the valves were bent, you'd have 100% leakage.

I think I'd just replace the chain.  Retime the cams and call it good.

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I see now- it jumped time and he was measuring valve clearance without the cam at TDC.  how bad was it off?  if it stretched the timing chain, you probably want to order another one, and if it jumped a tooth, I would check the tensioner- be a pain if that happened again!

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During his test on the valves he seen that there was a minimal loss. So #1 piston had not collided with the valves and not making a hole in the piston.  Secondly if the piston and valve collided that valve would be bent and not seat back in the head correctly leaving a gap for air to escape. 

The drive shaft that turns the sprocket that turns the timing chains has somehow someplace broken.  Not the chain it’s self.  Although the chain should be changed during this process it’s most likely fine. 

Basically he may have dodged a bullet here and wind up only replacing the broken part on the lower half of the engine instead of the  top end as well.  “Hopefully” 🙏🏻

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Yes The owner did dodge a bullet. If you look closely at my facebook pic you will see the sprocket and broken chain that is on the end of the drive shaft that turns the two cam chain sprockets above the flywheel.  There is 3 chains and three tensioners that operate the 2 OHC's there is also a 4th chain and tensioner in this area operating the oil pump.

I am replacing all 3 cam chains while I have it torn down this far. 

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