[Carrera12003]

I have an '05 M620 on which I am performing the 24k mile service. While checking the valve clearances, I've noticed the engine is extremely difficult to rotate. Having done this service myself every 6K miles, I've never noticed the engine to be this tight. For comparison, in the past I could rotate the engine wth one hand on the rear wheel while I watched the flywheel through the opening. Now I have to get behind the bike and exert a great amount of force with both hands just to get the engine to rotate. To rotate the engine, I've put the bike in 6th gear and removed the spark plugs. The engine actually feels as if it is binding as it nears TDC. Also, the valve clearances have always been within spec and I have not removed nor adjusted anything on the engine.

Any ideas what may be causing it?

Thanks...

 

[Norm]

Try taking the belts off & see if it's still tight. Don't forget to be sure the valves are closed on both cylinders.

 

[ducman851]

It seems on the newer engines they get a whole lot of crank preload.

 

[chipazzo]

First I'd like to say you're a little over my head with this. Second 24k miles!? [clap]

 

[Aguacate]

I just changed my belts today and I'm getting the same thing.

Did my valves a few weeks ago, and it was tight then but it seems like it's tighter now. I had to bump the rear wheel in short increments to get tdc.

So is it bad to be tight?

The bike seems to be running fine (well the only glitches I presume will be fixed with my carb sync).