high rpm surging

mopar1rules said:
is it something wierd w/the servo motor for the valves?? where like they open properly @ 1st (rpms come up fine) and then they close (rpms drop/go flat) and then re-open again (rpms come back)?? if the valves were closing for some reason, that would make sense that the engine drops in rpms, as the duration of the exhaust port and time area would be too small for that higher rpms?? then when the valves come back open, you get enough duration and time/area to allow the engine to turn the higher rpms??
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Good thinking, but there are no issues with the valves. We were thinking the same thing, so we even locked them open for a few runs, with no change in regards to the surging issue.
 
Not sure Dan, I would have to look at the schematic. We are using the 98/99 electrical package which I believe is DC and the wiring is per the Yamaha schematic without all the bells and whistles. The only thing we have wired in are the coils, on/off, servo, and a high rpm cdi. I can fax you the schematic if you need it

What are you using for a CDI box?

Josh, Josh, Josh,,,,,,,where is the love?? :WayCool:
 
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dave you have made me a bitter man with your stinky cheeseman antics...LOL

Dan sleds look nice, love that 600.
 
Wouldn't mind having a copy of the schematic.. Let me know when you can fax it and I'll set my fax to answer.. (I use my house line for fax..) I have 3 high rpm cdi's 99,2000,and a 2001.. All are moddified yamaha cdi's..
 
We could always bolt on my MSD coils and wires to test....

Although, I use the smaller SX coils on my 1136, and had no issues at 9400 rpm.
 
By the way, the surging issue with my quad was fuel related.....way too rich. I picked up 10 mph by jetting it properly :) ....LOL. So, this does not help you at all since your A/F is all good.
 
valin said:
Good thinking, but there are no issues with the valves. We were thinking the same thing, so we even locked them open for a few runs, with no change in regards to the surging issue.
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huh, i wonder what the heck is going on then. i'll keep thinking/brainstorming....
 
jabber800 said:
Wouldn't mind having a copy of the schematic.. Let me know when you can fax it and I'll set my fax to answer.. (I use my house line for fax..) I have 3 high rpm cdi's 99,2000,and a 2001.. All are moddified yamaha cdi's..
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Dano, pm me your phone number, havn't talked to you in awhile so I will give you a call
 
jminor1 said:
dave you have made me a bitter man with your stinky cheeseman antics...LOL

Dan sleds look nice, love that 600.
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Josh, I will send you a pound of limberger to throw in your kitchen. I'll send it the slowest way possible and wait for some 95 degree weather.

Hope you guys have a great 4th, talk to you soon
 
Surge is gone!! Made quite a few changes but it looks like a combination of issues might have been the problem.. Changed fuel pump and carbs and porting specs.. Engine pulls great power right up to around 10,000 rpm's... Thx for everyones input!! Wish I had a more definate explanation to the solution but we made quite a few changes before heading off to the dyno this time.. Now hopefully we can get thing organized here to make Syracuse next weekend..
 
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