780 srxported has 35mm bored yamaha carbs jetted at 170 mains 45 pilots turn and ahalf on screws needles at 4 position one washer over one under. 8bu 10S 4,5 each hole 54/44 helix and have tried a few others with different wraps. take this down to the river 4 wot runs sled pulls to 8400 or so then boggs drops back to 7000 sounds like its loosing spark and sounds like its skipping.or is it getting to much fuel. plugs dont seem to get to the rite color,still lookes a little lean took the 35 carbs off and put 33 back on with 167.5 mj 45 pilot 1 1/2 turns then it goes to 8400 no bogg till ur wot again but then seems to be braking down on top again any ideas 
about had it with this thing about ready to try a different stator need some help on this
about had it with this thing about ready to try a different stator need some help on this
staggs65
Moderator
Ron, where are you venting the carbs? that seems like a lot of main jet.
That sounds like too rich on main jet to me...
Try lifting the throttle to approx 3/4 next time it bogs and see if RPMs pick up.
3/4 throttle normally is the leanest fuel flow through the throttle range...just before main jet starts controlling fuel flow.
Try lifting the throttle to approx 3/4 next time it bogs and see if RPMs pick up.
3/4 throttle normally is the leanest fuel flow through the throttle range...just before main jet starts controlling fuel flow.
Had a similar issue. New spark plug caps fixed my issue.
780srxgeorge
Member
x2 on the jetting.im runing 160 mains in 1 & 2,161 -3rd,w/ hot wires.& the plugs look real good.my sled liks 8100 rpms it pulls 
harder then 8250 or higher after that theres nomoor pull!!!! so im saying try 8100 when jetting is in the right & see.yea i would nock the jetting down a littie & see what the plugs look like.
harder then 8250 or higher after that theres nomoor pull!!!! so im saying try 8100 when jetting is in the right & see.yea i would nock the jetting down a littie & see what the plugs look like.
jetting is awfull big, what I use in 780's is 152.5 mains, needles at 3.5 and 45 pilot jets with the stock carb rack. No cold air kits. No gutted and drilled airbox's.
With the bored carbs I would still use 45 pilots, needles at 3.5 and the mains would be in the area of 157.5, all these jetting specs are based on 93-94 octane fuel.
The fact it goes to 8400 and then falls all the way back to 7000rpm while skipping seems like it could be super rich but still seems like alot of rpm to lose. try going to the differnt specs and see what it does, if still losing rpm and skipping, the sparkplug boots are a good place to start as reccomended and then your idea that the stator is getting weak is also a good place to look. Sometimes if you suspect a weak stator, unplug the headlights and tailight and retry it and see if it runs better.
With the bored carbs I would still use 45 pilots, needles at 3.5 and the mains would be in the area of 157.5, all these jetting specs are based on 93-94 octane fuel.
The fact it goes to 8400 and then falls all the way back to 7000rpm while skipping seems like it could be super rich but still seems like alot of rpm to lose. try going to the differnt specs and see what it does, if still losing rpm and skipping, the sparkplug boots are a good place to start as reccomended and then your idea that the stator is getting weak is also a good place to look. Sometimes if you suspect a weak stator, unplug the headlights and tailight and retry it and see if it runs better.
If your plugs look lean, than it is not running pig rich. Can you post pics of the plugs? What does the piston wash look like? Mine would go to 8,500 RPM and then bog down to 7,000. Cylinder number 3 was cutting out due to bad plug boot.