MR-1 Timing Chain Tensioner Replacement

[Someguy]

New to the forum as I picked up a SR 230 this summer. Have found some great content and help here. Hoping that holds true now. I pulled my timing chain tensioner and reinstalled it. Now the engine won’t start. It cranks fine, just won’t catch. Starboard engine starts fine. I’m wondering if the chain slipped a cog while the tensioner was out and now the timings off? I wouldn’t have thought removing the tensioner would create enough slack for that to happen? I’m thinking gravity would have keep the chain seated on the cams and when the chain was re-tensioned it should re-engage in its original position on the bottom cog? Am I off base? And is there any way to check timing without removing the valve cover?

 

[Neutron]

New to the forum as I picked up a SR 230 this summer. Have found some great content and help here. Hoping that holds true now. I pulled my timing chain tensioner and reinstalled it. Now the engine won’t start. It cranks fine, just won’t catch. Starboard engine starts fine. I’m wondering if the chain slipped a cog while the tensioner was out and now the timings off? I wouldn’t have thought removing the tensioner would create enough slack for that to happen? I’m thinking gravity would have keep the chain seated on the cams and when the chain was re-tensioned it should re-engage in its original position on the bottom cog? Am I off base? And is there any way to check timing without removing the valve cover?

You will have to remove the valve cover. Do you have the manual to see how to verify the cam marks? If not i have seen it online with a google search

No amount of gravity will prevent a cam from jumping if there was enough spring tension from the a bunch of valves

What was the reason to remove the tensioner to begin with?

 

[Someguy]

Thanks, I was afraid of that, and I have seen the cam marking video online.

Good point! I wasn’t thinking of the spring tension.

Apparently stupidity was the reason for removing the tensioner.

 

[BumbleBee255]

I have seen this happen on motorcycle motors all the time. I have not had a Yamaha marine motor apart, but I assume they would be very similar design in this aspect. It's not a difficult fix, just time consuming.

 

[Someguy]

Thanks for reaffirming and the encouragement, not sure it’s something I have time to mess around with now, but may reach out to the forum if I feel inspired.