Jinma Decompression

[Amez]

Can anyone tell me if the decompresion lever on a Jinma 284 causes a noticable difference in cranking speed? I don't think mine works.
I believe the engine should not start with the lever pulled (mine will). The arm on the valve cover is pulled down when the lever is engaged. I think the linkage in the valve cover must be broken. Has anyone had experience with this?

 

[greg_g]

By your description, it's almost certainly not working. If the handle makes the linkage pivot outside the rear of the valve cover, the problem is underneath. Only way to proceed is to remove the valve cover and see what's up

//greg//

 

[Amez]

Thanks greg.Thats what I thought.I'm goiing to inspect under the cover tonight.

 

[RonMar]

My decomp handle actually rotates too far. If I rotate it all the way, the engine will start. As I rotate it around, I can kind of feel a peak, like the peak of a cam lobe when rolling a camshaft over by hand. At this peak, I don't really feel any spring force against the handle and it will almost balance at this point. If I rotate past this, I again feel spring force untill the handle stops. If I only roate it to the peak, the engine will not start and the crank RPM is noticeably higher with a different sound as the engine rotates smoother with no accelerations and decelerations from compression. I had thought about modifying the linkage, or putting a mechanical stop at this point, but have never got around to it.

 

[greg_g]

My decomp handle actually rotates too far. ... I had thought about modifying the linkage, or putting a mechanical stop at this point, but have never got around to it.

My KM454 compression release is a cable pull, and there's none at all on the TS354C. So I'm just going from recall here, trying to remember my old Jinma Y385 decompression levers. But what you describe sounds like either a linkage adjustment is necessary, or that you might possibly be missing a linkage part. I seem to recall both my JM254 handles only rotating 90 degrees to achieve full decompression.

//greg//

 

[Amez]

Ron and greg
Thanks for the tip. It turns out I wasn't turning the decompression handle far enough. It is a fine point at which the handle decompresses or "flops" too far. The linkage seems to give or bend too easily. You saved me a couple of hours of troubleshooting.
Mike

 

[hill]

It's a pretty simple mechanism that will be clear to you if you pull the valve cover. There is an intermediate engaging part that could fall out during a cover removal though, and if not noticed could cause loss of the function entirely.

 

[ToolManRick]

Your correct about the rotating too far. Mine is the same way. Imagine your pushing down a spring with the lever and it's the most resistant spot your looking for. A mechanical stop is a good idea and I may just do that with my tractor too. Do your like yours so far? Mine has been a back-saver and just a good old time saver.