Kawasaki KLR 650 Forum - Reply to Topic
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

Thread: Bike won't start, low compression, 83% leakage Reply to Thread
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  Topic Review (Newest First)
09-17-2016 05:20 PM
pdwestman Glad to hear that it is up and running again.
'Break-in' has very little to do with tappet clearances. Proper lapping after light cutting of the seat, does tho!

I would suggest that you acquire the proper shims to set the Intake tappets at .007"-.008" and the Exhaust tappets at .009"-.010". (I hate trying to use Metric numbers on tappet clearances. I can't purchase a metric feeler gauge in .025mm increments! Only .050mm increments, which I find to 'coarse'!)

Always try to get as close to Maximum Spec of tappet clearance as possible. They only get tighter with mileage!
09-17-2016 03:30 PM
colemans11 The bike is running again! I rode maybe 70 miles since the new valves went in and the head was cleaned out and reconditioned. Bout time I should check my valve clearances again... Well, I checked them and everything seems a bit tight. Exhaust valve clearances are .051mm (left) and .038mm (right) and they should be .15mm-.25mm. The Intake valve clearances are similar. I was gonna go ahead and get the proper shims to get back to spec, but it just seemed like a huge adjustment. I thought I would check with some of the greater KLR minds here and get any opinions. Should I go ahead and get the shims that will take me back to spec now, or did I just not ride or "break-in" the new head and valves long enough? Should I put a few more miles on before I switch anything out...? Thanks!
07-14-2016 08:58 PM
650Stew
Quote:
Originally Posted by colemans11 View Post
Thanks all! Cover and head removed and a chipped exhaust valve was discovered. Time to get to work. Looks like I have been running too lean for a while... I will have to adjust carb as well then.
Good to hear that you got it figured out, I suspected a broken exhaust valve since it died in the same manner as Daves. If I recall, his broken valve did no damage to the bore. He just did the overbore because he was using lots of oil anyway. If there's no other damage it should be a relatively easy fix for you!
07-14-2016 10:28 AM
colemans11 Thanks all! Cover and head removed and a chipped exhaust valve was discovered. Time to get to work. Looks like I have been running too lean for a while... I will have to adjust carb as well then.
06-14-2016 07:17 PM
650Stew The thing that kind of made me think of David's bike was that his broke down in the same fashion. He was just riding along and everything was fine, then all of a sudden it ran crappy and died... To lose compression suddenly and not over a long period of time usually points to parts breakage.

I wish I could find a thread on it so you could check it out, but I think it was mostly on the KLR Owners forum on Facebook. I know he did start a thread here when it initially broke down looking for ideas, but he wasn't too impressed with the 15 post's to put up a pic so I think he just kind of let the thread die out.
06-13-2016 08:24 PM
pdwestman
Quote:
Originally Posted by Ian H View Post
Hi, did you disable the decompressor when doing the compression test.
Thanks

Ian
Ian,
The spec. of 77-124 PSI in the manuals is with an Active KACR.
These bikes must start from cold, be that +20F. or +125F. with an active KACR or something else is wrong.
Disabling the KACR actually gives a 'False' reading because there is no specification for a dis-abled KACR. Tom Schmitz has measured about 175-185 psi with a disabled KACR, but that is just his engine. What could be the maximum standard sea-level compression?
What might be the minimum start-able compression with a dis-abled KACR? I'd like to suggest 90-100 psi, but I don't know!

Anyways, leakdown test tells us all that something is a-miss!
06-13-2016 07:50 PM
Ian H It could be as simple as a valve clearance not been too tight. Have you had the rocker cover off and checked anything yet?
I'm guessing the spark plugs good and still tight! lol.
06-13-2016 07:16 PM
650Stew
Quote:
Originally Posted by Ian H View Post
Hi, did you disable the decompressor when doing the compression test.
Thanks

Ian
Yeah, the KACR could be messing up the compression readings. But I'm thinking something is amiss when it does so poorly on the leakdown test. Unless somehow the KACR packed up and is holding the exhaust valve open? I have no idea, just throwing it out there...
Hopefully it's not too big of a fix, I remember on David's bike he did the 685 while he was fixing it as it was oil burning anyway. Can't remember where he got his rebuilt head from though... Wymann maybe? Bah, my memory sucks!
06-13-2016 06:53 PM
Ian H Hi, did you disable the decompressor when doing the compression test.
Thanks

Ian
06-13-2016 08:41 AM
colemans11
Quote:
Originally Posted by 650Stew View Post
When you guys did the leakdown test, where was the air escaping? Exhaust? Just curious, David Nichols (admin of KLR Owners Facebook page) had a very similar thing happen on his gen 1 when he was out riding in Texas. After many suggestions and head scratching he ended up tearing it down to find that a part of the exhaust valve had broken off, hence almost no compression. Maybe something similar in your case? Especially if all the air was coming out of the exhaust when you guys did the leakdown test.
Yes there was leakage out of the exhaust. Busted exhaust valve was one possibility we thought of. Looks like its time to dive in a bit... Thanks for the info, 650Stew
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