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topend flutters


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well got a 421 cub on 110 race fuel with a topend flutter not a hard miss that cause's the bike to fall off on power,it use to be a intermitant problem now i can make it happen all the time, i have tried changing stator,flywheel,cdi,plugs,coil,plug caps,jetting up and down 5 sizes as well as the needle position up and down and with a differnt needle completly.have taken wiring harness completly apart and checked it over very carefully,sanded frame to bare metal were ground is and even added more grounds in the front.tried smalller gap on plugs and got the pulsar at 0.15 at the flywheel. any help would be apreciated banshee hq has never let me down these guys on here no there stuff , so thanks in advance!

 

here are my mods

421 cub 68 miill bore

v-force 3 reeds

pro design intakes

18cc domes (cascade)

small bore inframe cpi with cascade siencers

dynatech igntion on position 3

39 pwk

main jet 160

pilot 52

dek needle in the third clip

air mixture at 1.5 turns

dual pingal valve

br8es plugs at 0.26 gap

turbo blue 110 fuel

4milll long rod with tz bearing hotrods

straight cut gears hinson basket

direct drive 3 heavy 3 light springs

toomey radiator with temp gauge

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  • 1 month later...

well got some intersting news for you guys and gals went to winchester bay oregon and still have this flutter nosing over problem butt i brought my cpi silencers with me this time and put them back on from cascade silencers and bike ran great,pulled like crazy for 3 hours out on a ride, reinstalled the cascade silencers and wamo back to the problem now the question is why? any input would be apreciated. oh yea i have checked them for any issues inside the silencers none were found!

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Sounds to me like an exhaust flow issue.

 

Congrats on finding the issue !

 

I bet that 3hr ride felt great !

 

Now find the difference between the silencers that's causing the issue.

 

Just to clarify, are you replacing just the silencer or the pipe and silencer that connects to the header?

Edited by Strm Trpr
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yes i am replacing the stinger tube also do too the cascade silencers are longer and yes it felt great too have my motor back to normal and being able to race again. just need to figure out why, maybee there is a fix were i can still run the cascade silencers.

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yes i am replacing the stinger tube also do too the cascade silencers are longer and yes it felt great too have my motor back to normal and being able to race again. just need to figure out why, maybee there is a fix were i can still run the cascade silencers.

 

anybody got any ideas?

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