Force120 miss cyl. New development

[Beno]

no I meant the tops of the cylinders where it meets the head gasket….

[Beno]

ok for anyone following,

I scuffed the gasket lightly in a circular pattern, as well as the cylinder block top.. I wiped down the tops then polished them with isopropyl, then another light scuff, then a final polish.
same with the head, it got a circular scuff and then acetone/isopropyl rub.
Dryed and installed, 225 Inch pounds in circular pattern.

my pre-rebuild psi was:123/150+/150+/150+

my new numbers are: 144/163/151/157

I’m calculating a 11.7% range from highest pressure to lowest
((163-144)/163)=11.7%

regardless. cyls were DRY. so with a little oil I bet it’s going to skate by with the kids on the water tube

all thats left is a sea test..
I really wish I would have gotten 155,155,155,155 but it is what it is.

[Beno]

Took it out on the water. IDLES STRONG. Different feel to it.

Unfortunately.. the high end just isnt there.

Under heavy accell the power just falters and feels sickly.

Feels like missing cyl.

But On the.good note:  no more greasy water on plug spark face!

Plotting my next move

[Steve A W]

Have you sinked the carb to the ignition?

Member of the MOB chapter.
I live in Northwest Indiana

[joecb]

Beno, through all that , had you had a look at the rings thru the Ex or intake ports? Maybe stuck rings on #1 from the excessive carbon gunk

Joe B

[Beno]

both good ideas,

I have tried various timing adjustments from the trigger to the carb. so I will try some more.
My experience is that off timing causes consistent engine low performance. This one kind of cuts out and in and sickly meanders at high throttle…

I will try to get into the intake inspection ports and look at the rings… but for me stuck or broken rings mean, replace engine… :<

not to worry, I have extensive boat motor parts / resources, this problem will be identified.
I have extra flywheels triggers and stators, even tho these all check out with the tester I’ve heard that some stators can test out well yet not really be working right. updates soon

[joecb]

If you encounter stuck rings, don’t lose hope, a good insitu soaking with OMC “de-carb” cleaner may help…. especially if you can get to the rings through a side port. Pretty strong stuff for attacking carbon gunk.

Joe B

[Beno]

Ok checking, If it’s that bad I’ll just disassemble the block and replace the piston/Or part it out.

I learned long ago that my mechanical skills are ..ok to passable.. but! my disassembly and re-selling skills are EXCELLENT along with my locating new engines skills.

[Beno]

Powerhead pulled.  Exhaust manifold removed.  (Fyi. Exhaust manifold on a sportjet is a very interesting beast)

It appears that the exhaust manifold has been compromised.   As shown by the area circled in yellow.

This part is very expensive I have it on order now.

Question now is would this create water signs in JUST cylinder number 2 and a cyl miss  at high rpm?

Could water be sucked out of the water jacket in the exhaust area, then get pulled into the cylinders? (water pushing backwards into running engine???).

I understand that a two-cycle engine doesn’t completely clear the cylinder of combusted fumes but I didn’t think they would find their way back in.. much less find their way back in mixed with water?

[Author]

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