No power, but idle good (after rebuild)

[Paul_Dublin]

I did a full rebuild of my Yam 60. Rebored and replaced pistons rings etc.<br />Motor started great and idles good and can rev to 3000+ in neutral, but has no power when I put it in forward. Will not get any more than 1600rpm.<br />Heres what I have tried (and no improvement)<br />Just rebored so compression should be good.<br /><br />Pumped fuel line to make sure it's not the fuel pump<br /><br />Swopped Complete Carbs from identical motor to make sure it's not the Carbs<br /><br />Put in new Sparks<br /><br />I havn't checked timing (how do I do this?)<br />I havn't confirmed compression (I am assuming it is OK and feels good when manually turning the flywheel)<br /><br />Any ideas what is causing it to be down on power?<br /><br />As you guys have said.. It's Suck-Squash-Bang-Blow...And I think I have taken care of these!

 

[jim dozier]

Re: No power, but idle good (after rebuild)

Check to make sure your carb linkage and ignition advance linkage are synchronized propoerly. I'm betting you are not getting full throttle, full advance, or some combination of both.

 

[Paul_Dublin]

Re: No power, but idle good (after rebuild)

Is the ignition advance linkage the Electronic box with the I and II setting? <br />This stays at 'I' for the idle, and moves to 'II' when put into forward. Does this sound correct?<br />I have 2 identical motors, so I made sure it acts the same as the good motor.<br />I also tried to manually open the throttle but it still had no power.<br /><br />Any other possibilities?

 

[jim dozier]

Re: No power, but idle good (after rebuild)

Begin at the beginning. Verify that you have spark on both cylinders. You may be not be running on all cylinders. Verify that you have fuel going in both cylinders. Verify that the engine is receiving full ignition advance. I don't know the specifics on that particular engine. Is its ignition advanced electronically or manually. Hook up a timing light. Do you have a manual? If not get one at the bottom of this web page.

 

[Paul_Dublin]

Re: No power, but idle good (after rebuild)

Jimd<br />Thanks for the Advice. Got to the boat over the weekend and checked for spark. It wasn't sparking on number 1. Turned out that one of the cables to the coil wasn't tied down and got cut through by the flywheel. fixed the cable and shes working well now.<br />By the way. Compression in 125/125/110 so maybe should have gone for a slightly larget piston on lower cyl.<br />It is still down on power compared to the identical other motor. I'd assume due to the slightly lower compression on number 3.<br /><br />Thanks again for the help