XB stock tuned pipe mods

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phreerider

phreerider

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looking at the stock setup on the XB 30.5 cc , carb/pipe combo


here's a thought...by listening to it, looking inside it, and the carb backpush of fuel. It SEEMS too much back pressure..making carb adjustments futile and unstable through power band unless dialed very lean. at reasonable rich setting it just won't take it. adding MORE air in the mix from the low end helps but still drowning from its on tight exhaust, anyway.


the arrestor/baffle thing. i'm gonna put MORE holes in it..try to get it breathe better. maybe one 1/2" in the center or 1/4" x 2. or until resonance and snappy flow is found.


and if not, some new pipe and some walbro help will rescue the lame hardware, but in the meantime. custom is the only way to go.


pipes for this thing of decent build are not so common but the ghost for baja SS at kingmotors is a fair design Al alloy is a fail for sure. this has to be a common issue though , right?
 
Yep. The 2strokes need a good tuned pipe to perform their best. It's not just back pressure, the tuned pipe creates a resinating frequency that actually pushes some of the unspent fuel back into the engine.

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although small, it can flow better AND its eating too much recycled exhaust ATM. practically roasting itself the plug and everything ,,,carbon build up has to be a problem running this pipe, if not fry the pipe right off!
 
You can get a good indication of your mixture by looking at the plug.

Do a few full throttle passes then shut it down.

Pull the spark plug. The tip should be a brown paper bag color.

Black is too rich and grey is too lean.

It is safer to stay on the rich side .

The alloy pipes do not handle the heat well.
 
a drill and 5 minutes and things have changed! basically drilled out about 80%

we have flow! now theres more noise from the exhaust than from the carburetor! which is seems so much better.

definitely take a richer settings and snaps right up in throttle response

..man that was drilling a beer can, soft and tedious. don't know how long it will last but got a few more ponies kickin' fo sho. it rips, even with a fat setting right of the line
 
yep, small hole plugged with set screw. dropped it for tuned pipe. currently in the "harvested" pile.
 
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