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Discussion Starter #1
driving my bike yesterday, 14/42 gearing just what i threw on so im in 6th gear real quick
as im 3/4 to full throttle just about ready to let off and blurp the throttle it cut out like i pulled the teather,
at first thoughts fuel? run out ? then electrical ? well tore it down today and there was alot of scuffing on the front exhaust side some gouges on each exhaust port lean ? or cold seizer? thoughts opions 200 main in a 40.5 carb 65 ish degree day drag port cr 250 ign shearer out of frame pipe first time really riding this since i put a 4mm crank, the shearer pipe, and some more porting exhaust bridge removed previous i ran a 190 main 350 cyl on first bore
 

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You saying this is a 350 Pro-x cylinder with the exhaust bridge removed ??.

Have any leaks when you did the presure test ??.
Doughtfull its the CR ignition but might be possible.
200 main still could be lean.
Compression amount, cooling issues maybe with the radiator or water pump, how the dome is cut could cause a spark knock, octaine of gas, & could even be if the exhaust port is to wide & now the bridge is removed allowing the piston to fall into the port more.
Neil
 

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Discussion Starter #3
yes its removed.. i have never had an ign problem i was getting ready to do a comp check it is a race gas set up from ct, it is older gas c 12 good flow for cooling esr gauge said 150 degrees echaust port isnt to wide made sure of it has a good egg shape to it i guess esr removes them for their drag port on the pro x cylinders
i previusly ran a 190 with less porting and a trx 11 center mount jeeting should i have ju,mped to a 210 220? from other their thinking i was lean combo of pipe and porting including exhaust bridge being removed is going to call for more fuel thanks johann morse
You saying this is a 350 Pro-x cylinder with the exhaust bridge removed ??.

Have any leaks when you did the presure test ??.
Doughtfull its the CR ignition but might be possible.
200 main still could be lean.
Compression amount, cooling issues maybe with the radiator or water pump, how the dome is cut could cause a spark knock, octaine of gas, & could even be if the exhaust port is to wide & now the bridge is removed allowing the piston to fall into the port more.
Neil
 

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Might be the bridge hasnt been removed if it was a drag engine to start with. There is a oval exhaust port Pro-x cylinder, looks just like a p/v cylinder.

Lets hope that old C12 gas didnt hurt anything.
Neil
 

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My '87 isn't near as extreme as his drag quad, but the sixth gear cut-out and subsequent scratching/gouging near the exhaust port sound identical to my piston failure. My floats were set all wrong, my fuel level in the bowl was low, the carb couldn't keep up with the demand for fuel from the engine, and my jets went airbound just after I hit sixth gear. The result wasn't simply running lean, but a complete state of fuel starvation...no fuel means no oil...my piston said "Screw this, I'm done".
 
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