• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

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    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

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    Thanks for your patience and support!

SM610 Cold Starting Issues?

B

bacon

Husqvarna
Hi All

Not sure if I have an issue or not so I just wanted to ask the group - Are these FI SM610s cold blooded?

Background:
I got a 2008 SM610 last fall that was non-running. I fixed a host of electrical issues and had it running last fall. It seemed to run strong although I didnt run it long. I know they can be noisy motors, but I thought I heard a ticking sound so I checked the valves. Im 99% sure I was at TDC compression and found the front valves to have a huge clearance - something like .080". It was so much that the little swivel cap on the end of the rocker could almost come off. I figured that was the source of my ticking, so I adjusted to the spec .002". The rears were measuring right at .002".

Fast forward to now, I put the bike back together yesterday and tried to start it up without much luck. It turns over fine and seems to pop and fire every now and again, but just doesnt take off. If I open the throttle a bit while it's cranking it will fire and run for a second until I leg go of the throttle.

It's about 30F here right now. With that thick oil in there are is it just too cold to start? Did I somehow muck up the exhaust valves? Note I tried the little enrichener lever on the clutch handle with no change. I did a compression and leak-down test prior to starting any work on this bike and it checked out great. Seems like I still have spark so I guess im down to valve issues or just being a cold blooded monster.

Since I didnt intend to ride I didnt work very hard to get it to stay running - figured I'd ask here first.

Thanks!
 
I would take the spark plug out and then turn the engine over by hand until the follower comes off the lobe onto the base circle and measure again.

Widest valve clearance discovered during 1st valve adjustment?

I am seriously considering checking my valves at 300 miles instead of waiting to the 620 mile mark. It is a 2009 SM610. Engine seems to be noisier since I started the break in process. I am at the 300 mile mark. Anyone else do this based on what they felt was a noisy engine? I have read a few...
www.cafehusky.com
 
havent had a chance to pull things back apart again, but I had a thought. Could the decompressor be interfering with my valve adjustment? How much does the decompression shaft open the valves? If the last owner adjusted the exhaust valve while on top of that, could that give the excessive play that I found? Or, did I somehow set them in a weird position thats now causing poor compression?

Assuming I had clearance between the valve stem and rocker, is there a way to set the valves so tight that they never close fully? There shouldnt really be a spot in the cam lobe that would be lower than it would be at TDC should there? I'll try to check compression and see if it's dropped off - if it has I'll know the exhaust isnt closing properly. Prior to all of this I did a compression and leak down test and everything looked good. I never heard any valves hit the piston when I was cranking so I hope I didnt bend a valve.
 
Started a little investigation last night since it was warmer. Pulled the tank and moved the rad tanks and checked the valves. Still had clearance at TDC even though it was a little snug. Tested compression and it was real low - like 45psi. Rolled the engine a few times and noticed that even though I had clearance at TDC, when the intake valves were half open, the exhaust valve rocker was snug like it had pressure on the stems. I loosened the valves up a bit and compression went up, but not as high as it should I think I have about 60-70psi now.

Prior to me messing with the valves it had really high compression - something like 150psi. The exhaust valves had massive clearance which is why I adjusted them but I now wonder if someone adjusted the valves on the decompressor lobe essentially deleting the decomp feature. I'm going to do a leak down again tonight and loosen the intakes a hair and see where I end up.

Before I throw the tank and whatnot back on to test it, what would you say is the MINIMUM compression required to start? What should I expect when the decomp is working? I know the manual says 113psi, but I just dont see how i'll get there with it sitting so low right now. Will it start with pressure around 70psi and then the decomp will deactivate?
 
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