spb expansion chamber mods??

J

jasonpadilla

New Member
is there any modifications you can do to the sbp expansion chamber? like in the silencer part? i know in the stock muffler you could drill holes or cut the inner pipe? anyone tried things??
 
Yeah i was going to make a post about increasing the length of the silencer, but i found this one !

Here is a threat that kinda goes into it but I still had more questions.
http://motorbicycling.com/showthread.php?t=19070

I should just dive in and remove the rivets but , heh little paranoid.

Think i would like to do just what BarelyAWake did and double the length of the glasspack.
 
One of the things I do to the SBP pipes is to 'port match' it to the exaust port of the engine. (better flow) ;)

The other thing I do is to throw away the rubber sleeves & weld all the parts together for a custom fit; Like this...
vmbbtr12-1.jpg
 
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Are you able to get the expansion chamber to pass under the bike like that with the stock parts the send with the kit?
 
ivan H said:
Hi Rocksolidperson, where in the rev range did a 14.5" header lenght put your power band. Cheers
Click to expand...


Hi Ivan, At about 14.5" i find the power to come on well at around 2/3 or 3/4 throttle all the way through to full throttle, i have reed valves and a dellorto carb on my build but my low-end is very poor, it all is in the mid-high end, if i where to get a new header i would have it on about 18-20" in fact so power comes on nicely at 1/4-3/4 then my jetting takes care of the 4/4 throttle, the reed valves defiantly give as much pulling power as the expansion chamber after 1/4 throttle to 2/3 throttle anything below 1/4 is very dodgy and it struggles to go smooth.
 
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Hi Rocksolidperson, thanks 4 shareing that. I have rocksolid head, mild port massaging (widening/ramping), VM16 mikuni,,,, & with sbp shift kit the power is at the moment too high in the range to really make use of 7th & 8th gear (shimano hyperglide cassette), so I might have a play round with lengthening the header to better suit i'm just about to order a pullstart & coupler from rocksolid,,, I might grab a reed block &' cage in a week or 2. Cheers
 
Venice Motor Bikes said:
One of the things I do to the SBP pipes is to 'port match' it to the exaust port of the engine. (better flow) ;)

The other thing I do is to throw away the rubber sleeves & weld all the parts together for a custom fit; Like this...
vmbbtr12-1.jpg
Click to expand...

That is sweet! I wish I wasn't so far away from your shop!
I may have to have a buddy twist me up something like that.
 
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G'day Rocksolidperson, how ya goin mate. Well its raining again here (sunshine coast) but I just got 1/2 hour blast in. I've got a few different lengths I've been experimenting with & with 2 & 5/16" length plus 45 degree bend & stock pipe & chamber I just got it up to 67 kph, or 41.5 mph in 6th of 8 gears. Its just starting to run out of pipe on wind out so I might knock 1/16" off & see how it goes.i'll check the plug again when cold,,, I think its still a shade richer than optimum, but no 4 stroking. Cheers
 
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Yes, & thats what I've got now that I added a little length to the header. It had been a darker tan than I like but now its probably a touch light. I'll file a tiny bit off the header til it stays on the power a little up top & check it again,,, maybe drop the c clip on the needle a notch if it needs but hopefully it wont. Perth,,, I've heard good things about the west coast, I'll have to get over there one day. Cheers
 
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