Crazy broken reeds

pmos

pmos

Location
Richlandtown, PA
I've got a blaster with a stock 61x. I put a SBT rebuild in it, had about 1 hr on, started running really rough. Eventually pulled it apart, found I had a broken reed petal (were stainless steel OEM reeds).

Got a replacement (free of charge, which was nice) from SBT, put it back together and back in with a brand new pair of SBT stainless reed petals. Last Friday, was riding it nice and slow on the break in, everything was going good. Start it up Saturday and it won't idle at all. On a hunch, took my borescope to it and found that the new stainless reeds were broken again!

When I put the 2nd motor in, I OEM cages from JetManiac, and I measured them like 10 times. I'm totally flummoxed as to what could be breaking the reeds.

61x in blaster
Riva Red pipe
Jetting:
145 Main
120 Pilot
High Screw: 1 Turn
Low Screw 1.25 turns
Needle and Seat: 1.5
Spring: 95 grams, but clipped to get popoff to 38 psi
 
D

DualSnSj

Location
KS
Ever figure this out? I just picked a '93 up with a riva red pipe that is on its second set of broken reeds. I haven't torn anything apart yet but I am suspecting jetting is off.
 
pmos

pmos

Location
Richlandtown, PA
I switched from the Stainless Steel stock reeds to Carbon Tech one from JetManiac, seems to have resolved the problem. Don't know what it is the culprit here, but I suspect its a very strong back pulse(?) when the throttle is closed, as both times I've found the broken reed petal sitting on top of the remaining, good reeds. Since the opening in the cages is smaller than the reeds themselves, only way I figure this can happen is some sort of blowback thru the motor...
 
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