Finished the top end

[prairieboy]

Sorry for the long post, but I'm hoping one of you more experienced mechanics can tell me what's going on.

Finally had a chance to finish buttoning up the top end on my speedster. Had to go 0.5mm over. I aligned the cylinders to the exhaust manifold and torqued everything down to spec. Before I put the head back on I thought I'd better check to see if it spins freely by hand. Added 30ml of 30 weight to the counterbalance as well.

It turned over real nice for a good half dozen turns then would just find a spot and not turn. If I back off a bit and try turning again it would spin. I tried both directions and same thing but not in the same spot as far as where the pistons were in the cylinders.

I know for a fact nothing went down the crank and when I had everything apart it spun freely.

There's no clunk or metal on metal, more of a softer stop and it would take a lot of effort to finish the rotation.

At this point I figured WTH and buttoned everything else up.

With the plugs out, I hit the starter a couple of quick times and no smashing apart - haha. So I put the compression gauge on and 150 on both cylinders. K - so I'm starting to smile a bit.

I hooked up the water hose and put the plugs in to prime the oil pump and she fired right up.

Ran it a good couple of minutes on the hose and it idled real smooth and no harsh noises, but I guess I'm a little gun shy at this point.

I was hesitant to post thinking I would hear the truth about something bad, but I figured I gotta figure this out before it drives me nuts.

So, good or bad? Haven't obviously had a chance to do a water run as winter is settling in real quick here. At 3000 rpm out of the water and it ran and sounded ok - should I still be concerned or should I expect the worst next time I put it in the water and perform break in duty.

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[howie099]

Did you get the raves cut down to match the larger cylinders? You can catch the rings and by by engine.

 

[prairieboy]

Yep - the machine shop that did the re-boring were very particular about that and ensured that I brought the raves in at the same time.

 

[Sportster-2001-951C-Stock]

I wonder if the machine shop chamfered the intake and exhaust port windows on the inside of the cylinder sleeves, might have been noticing a ring hanging in the port window?

One kind of a clue is after the fist startup or within the 1st half hour riding around there shouldn't be scratches above the ports. If the ports aren't chamfered, the ring might catch or if not chamfered correctly the oil can be wiped off the ring face as it passes by the edge of the port and cause cylinder scratches just above the ports.

Otherwise, maybe rotating before torquing the head the bearing journals aren't really aligned until the case is stressed to it's final position. Some engines (not seadoo specifically but in general) that aren't machined correctly can develop a tight bearing once the heads are torqued, which is why all machining really should be done with torque plates in place of the heads.

Just tossing out a couple ideas.

 

[prairieboy]

Yes, those both seem like plausible causes - however on the ports being chamfered, I confirmed and re-confirmed with them that they chamfered the ports.

I'm more in favor of the cylinders or head not being torqued to spec while rotating the crank. Maybe a completely newb thing to do while the cylinders were in place, I thought I would check to see if things rotated freely before torquing things down. The cylinders were tightened down, just not to spec.

After cranking and running the engine on the hose, it sounded good and there wasn't any grinding, clunking or smashing sound. So maybe with things not completely lined up straightened itself out one I torqued everything down.

I didn't have an alignment plate for the cylinders, but used the alternative method of the exhaust.

If I wasn't supposed to rotate the crank while everything was put together and not completely tightened down, my bad, and hopefully it didn't mess anything up - the machine shop that did the work were very thorough and ensured everything was done accordingly.

 

[Sportster-2001-951C-Stock]

I doubt you would've caused damage by rotating before final torquing, but I can imagine you might notice tight spots. Sounds like you're good to go.