Staggered jetting GP760/oem 44's?

[Pablo]

Is it standard practice on the GP 760's to have staggered jetting? I bought this ski used a few years back and am finally getting around to rebuilding carbs. Found the mains to be 132.5 on PTO/front cylinder and 130 on rear. N/S, springs and pilots are equal. Ski is completely stock.


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[Captain PegLeg]

yes... I re did a set of these carbs earlier this year. They are staggered. And set the screws like this:

Front:
HS 1/2 turn
LS 2 1/2 turns

Rear:
HS 3/8 turn
LS 1 5/8 turns

 

[akok74]

The carbs that I took off my GP760 were staggered the same way, Yamaha staggers them from the factory for whatever reason.

 

[yamabro]

It was Yamahas answer to the rear cylinder taking the most abuse from the torque and twist of the crank when the pump comes unhooked and hooked back up from wave or heavy chop jumping.
They thought richening up the rear cylinder would keep it cooler and lubricate it more.

 

[akok74]

But the rear has the smaller jet

 

[yamabro]

 

[Freakrider]

Is it standard practice on the GP 760's to have staggered jetting? I bought this ski used a few years back and am finally getting around to rebuilding carbs. Found the mains to be 132.5 on PTO/front cylinder and 130 on rear. N/S, springs and pilots are equal. Ski is completely stock.


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Should be 130 front cylinder and 132.5 rear...thinking you reported it backwards ? Rear cylinder is also 5 psi lower compression and the rear cyl timing is retarded 3 degrees to compensate for crankshaft twist due to load.

 

[akok74]

I just rechecked my thread the rear is the bigger jet, my bad

 

[Pablo]

Thanks for the help and replies fellas. Good job catching my slip up.
I ended up having to be at 2-1/2 turns out on both LS screws and at 5/8 turn on both highs. Running well. Slight hesitation off idle to WFO so may play with that LS adjustment some more. This ski has been bullet proof reliable for company to use. I hated even fooling with the carbs but glad I did they were full of trash in the internal filters. If it ain't broke...


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