Vibration problem

[nickwad]

I have an SXR 800 hull with a 750 sxi engine bored to 800cc , Factory dry pipe, ADA head. I have a vibration all through the rev range. The engine was rebuilt about 15 hours ago. The ski has a new solas prop, drive shaft, pump bearings, bulkhead mount and bearing, coupler rubber. the problem has just come now,It was running great before.
I have striped and checked the drive train/ re-aligned it etc.
Could the engine have gone out of balance somehow?

 

[ger87410]

Try to identify where the vibration is coming from. Is it coming from the engine or the pump?

Tighten EVERYTHING and check the bearings.

 

[Scorn800]

Motor to bedplate bolts may be loose

 

[Waternut]

Does it get better or worse when you increase rpms? Idle is usually bad on all engines though.

 

[tor*p*do]

midshaft bearing will do that.
pull midshaft and check i out!

 

[nickwad]

Thank you all for your advise, I have replaced the mid shafrt bearing and housing, Have checked the bedplate bolts, The vibration seems to be coming from the engine not the pump, The vibration starts just above idle all through the rev range but feels worst at mid throttle.

 

[Waternut]

Did you rebuild the engine or did someone else? It is extremely hard to ignore that the vibration issue is present shortly after a rebuild and therefore could be a direct cause of something done improperly during the rebuild. Let's all hope that it isn't this but if the pistons are different or if one is new and one is old, the weight difference could be causing issues.

 

[nickwad]

The crank was re-conditioned here in Thailand by a big shop. The rebore was also done here . I assembled the engine, The pistons were new Kawa 800 parts.
It could be the crank or flywheel although I have been told It would not run if the crank had rotated in itself , And it would not start if the flywheel was loose ??