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Broken Butterfly Shaft

5K views 17 replies 11 participants last post by  rbabos 
#1 ·
Well, finally took the 1350 up to the dyno this weekend to figure out what gains I'd gotten over last winter..ya ya I know it's damn near this winter but was just having to much fun with it during the summer to take it up to them. Well everything went okay on the ride up, after they got done with warm ups they guys came to give me the results. 132hp an 90lbs not bad but not what I was expecting but then they tell me the bike is idling weird and that I should replace my twin tech with the Race tuner. :banghead:

I gladly declined but wondered with what they mean that the bike was idling weird. On the way home the first stop like the bike wouldn't come down from 2k thought that was weird, second stop light the bike wouldn't come down from 3.3k....hmm, 4th stop light same as the third and I made it home. To really pissed at the dealer to think straight I just put the bike away. Well today I go out to figure out whats wrong since it hit 70 here today, and wanted to go for a ride. I pull the air filter off and start checking stuff and I notice the the back half of the rear cylinder butterfly shaft is missing. :barf:

My heart sinks thinking that it went in the engine, so I tear off the airbox pull the TB's and sure as shit it's gone. Split right at the screw, thinking all crap I break out the flash light and look down the intake, both valves are open and I can't see any damage, so I stuff some towels down it and look around in the valley of the engine and fine the missing half. Oh thank you god! :notworth: :dance:

Here are some pics of the shaft and the dyno sheet.
 

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#7 ·
Ok so it was a 53mm bored to 58mm with the bolts welded? If that's the case, at least the screw remained in place so welding it worked!!! That's why I had the shaft upgrade by Scott in my last engine work, tried to bulletproof as much as possible at once.
 
#8 ·
Sorry to hear this Kris.

You are lucky for sure.

That could of caused some serious damage.

I am sure Scott will get you back on the road soon.

Good Luck on the next one
 
#10 ·
Is Scott still making the model with the redesigned shafts?
 
#11 ·
Yes we make two types of 58mm throttle bodies.

1) Bore out stock unit re-install stock shafts and add half shafts on top of the butterfly blades, insert new screws, and then tig weld them into place.

2) Bore out stock unit install (2) new stainless steel shafts and add half shafts to the blades, insert new screws, and then tig weld them into place.

Option 1) is a 50/50 on whether or not the original shafts dont break. They always break where the tapped hole is in the shaft. Ultimately the shaft is too small but making a bigger one is not a option at this time seeing you would have to re-engineer the entire setup.

Option 2) is rock solid as of right now but nothing is guaranteed in the high performance sector. Welding the screws is the best bet to insure nothing falls down into the motor. Unfortunately this option is pricey each shaft is hand made by one of our skilled precision toolmakers.
 
#14 ·
Scott,

Wanna shoot me a PM on what the cost of option two would be? Hopefully not as bad as normal since it's already bored out and everything lol but gotta do what you gotta do.
Does this thing have a warranty?

:hidesbeh:

:angeldev:
 
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