4 replies to this topic

[spudsdad]

any ideas on how the scavenge pipe from the crank case is suposed to work?
runs great disconnected with a little air escaping from crankcase breather, connect it to carb and the bike runs as if the choke is on.
conection to carb is clear. is it building up pressure in the carb? should the pipe have air puffing out of the crankcase breather
cheers guys for any info

[spudsdad]

spudsdad, on 19 January 2012 - 03:18 PM, said:

any ideas on how the scavenge pipe from the crank case is suposed to work?
runs great disconnected with a little air escaping from crankcase breather, connect it to carb and the bike runs as if the choke is on.
conection to carb is clear. is it building up pressure in the carb? should the pipe have air puffing out of the crankcase breather
cheers guys for any info

just had another look at it and the breather from the crankcase has a suck and blow effect coming from the pipe. block the pipe and bike runs ok ,just have to turn the tickover up a bit, connect pipe back to carb and straight away runs like on choke.

[scratt]

IF YOU'VE GOT ROTAX ENGINED APRILIA THE PIPE ORIGINALLY HAD 1 WAY VALVE BETWEEN ENG. + CARB .IDEA WAS
EXCESS/UNBURNT FUEL PUSHED BACK INTO CARB BY ENGINE COMPRESSION HELPING BIKE TO RUN CLEANER + PICK UP BETTER FROM IDLE

[spudsdad]

scratt, on 19 January 2012 - 07:45 PM, said:

IF YOU'VE GOT ROTAX ENGINED APRILIA THE PIPE ORIGINALLY HAD 1 WAY VALVE BETWEEN ENG. + CARB .IDEA WAS
EXCESS/UNBURNT FUEL PUSHED BACK INTO CARB BY ENGINE COMPRESSION HELPING BIKE TO RUN CLEANER + PICK UP BETTER FROM IDLE

cheers fot that scratt , makes a lot of sense as to whats going on

[t-shock 250]

If i remember correctly, we disconnected the scavenge valve & blanked it off. I didn't like the idea of fuel (or more likely, oil that gathers in the bottom) being fed back to the carb.
The best mod though was to raise the barrel 2 or 3mm, on the 240 engine this allowed the exhaust port to be fully uncovered, the bike revved much better after this.