twinsted crank, or oddly failed MSD enhancer?

[Matt_E]

Did you check that bdc and tdc are 180 apart? It's a five minute check, if that long.

 

[Big Kahuna]

it doesnt "just happen" there has to be a reason



never heard about this happening to a yamaha twin....







now, a polaris triple...maybe..

It does "Just Happen". It can happen if you jump out of the water with the motor pinned and the re-entry can act like a brake. Rare for this to happen but possible. It can happen from sudden water injestion just to one cylinder. I have seen it happen on 550's before. You could even have a violent sudden seizure and the sudden stop could do it and have the piston unstick it self.

 

[Mouthfulloflake]

I do not think the starter is bad.

and I have not had time to check BDC and TDC yet.

the engine turns over freely by hand with the plugs out, and the coupler disengaged.
no odd noises like that, and it feels as smooth as any other yamaha twin ive touched.

 

[Matt_E]

So did the triple I worked on.

 

[Mouthfulloflake]

was it twisted, or had a bad bearing?

I cant imagine that the bearing could be so bad that the starter could spin it, but the engine couldnt spin its self?

 

[Matt_E]

It was twisted about sixty degrees between the first and second rod. Perfect other than that, a real shame.

 

[Mouthfulloflake]

60 degrees?! holy crap, yeah I think that would prevent a twin from running.

thats my bet at this point, I should know by this evening, leave work, grab beer, drive to lake, and play yamaha mechanic on the rocky shore!

 

[Matt_E]

You don't need to drive to the lake to do that check, but if it makes ya feel better....:biggrin:

 

[Mouthfulloflake]

Actually I do, since thats where the ski is.

( sitting on the rocky bank, all alone, and sun faded, its even got algea growing on it)
:dead1:

 

[yamaslut]

It does "Just Happen". It can happen if you jump out of the water with the motor pinned and the re-entry can act like a brake. Rare for this to happen but possible. It can happen from sudden water injestion just to one cylinder. I have seen it happen on 550's before. You could even have a violent sudden seizure and the sudden stop could do it and have the piston unstick it self.

I think you just proved Idok correct... "just happen" would be riding along and it just happening, not jumping and landing wide open causing it to happen, right?

he he, sorry, but I could not resist.

 

[Mouthfulloflake]

Videos coming soon

no difference In tdc and Bdc that I can eyeball
forgot the damn vernier of course

 

[Mouthfulloflake]

Ok fleeting thought
what if there is an obstruction in the exhaust
would it exhibit these symptoms ?

Maybe a baffle in my stock water box broke?

 

[Matt_E]

Then how are you checking it?

 

[OCD Solutions]

Definately a possiblity, better check for a rats nest or a couple snakes making a home up there.

 

[Mouthfulloflake]

spark video

 

[Mouthfulloflake]

in2,

check Exhaust, its flowing, I held my hand on the starter and the output at rear of hull, its flowing alot of air to NOT be running..

Matt-E,

T handled allen wrench ( that I adjust b pipe screws with)
I bottomeed each one out, and the topped each one out, the look same, or very close by eye.. within a mm or so at least... ( given my old ass eyes)

 

[chriselmore_1]

must be the waterbox bearings then

 

[Mouthfulloflake]

here is the odd nearly lock up noise... it happens once or twice in this video.. once after I touch the throttle.

 

[Mouthfulloflake]

more likely the damn GM fuel pump.

fawker!

 

[chriselmore_1]

more likely the damn GM fuel pump.

fawker!

ouch,,,,