cagimaha Posted April 23, 2009 Report Share Posted April 23, 2009 Right I know that there is a wealth of information out there on the forum... Im modifying a set of swarbrick pipes for my mito 350. Basically to get it all to fit the headers are going to be 2" shorter than Mr.Swarbrick originally intended. The rest of the engine spec is 350LC motor (4L0) with some tuned barrels (allegedly Stan Stephens) that have had a fair bit of work done to them, squish set at 1mm and reed valves opened out a bit (still 4L0 reeds though not the bigger powervalve ones) and keihin pwk 28mm flatslides of a KR1S. What effect is this going to have on the power? and if the effect is going to be really bad then can I alter any other part of the pipe to negate the effect of the shorter headers? The bike was never intended to be practical cos its got no stand, a keyless ignition and is running on premix so im not fussed if its going to be peaky thats the point of having a small light 2stroke but I realise that there is a limit to how many revs an LC crank can take and if the shorter headers moves the power above say 11,000rpm then the crank isnt gonna last long at all. Link to comment Share on other sites More sharing options...
Martin77 Posted April 24, 2009 Report Share Posted April 24, 2009 2" off the header length is a big differance, especially as Swarbrick's are known to be high revving. My advice would be to try adding the 2" to the belly length to keep the overall length as intended. Not ideal, but better that than a too short pipe. Link to comment Share on other sites More sharing options...
cagimaha Posted April 26, 2009 Author Report Share Posted April 26, 2009 Thanks for clearing that one up, the 2" taken out was constant cross section so I'll add 2" into the belly of the pipe (also constant cross section). It'll give me the opportunity to knock some dints out of the pipes anyways... I saw dougon2wheels' bike at the ace cafe today too and the pipes look spot on so I might get back to you towards the back end of this year about a proper set of pipes if the finances allow. Cheers, Ben. Link to comment Share on other sites More sharing options...
willbloke Posted April 30, 2009 Report Share Posted April 30, 2009 As a very rough guide , the length of the front pipe to the chamber controls at what revs it makes peak power : shorter = higher . The angles of the chamber controls how peaky the power is shorter= peakier . So chopping 2 inches off the front pipes will bring max power in at about 13 K at a rough guess ! Rather than funking up some good pipes , try and get some that fit better . Link to comment Share on other sites More sharing options...
cagimaha Posted April 30, 2009 Author Report Share Posted April 30, 2009 The pipes were never mint and have kissed a fair bit of tarmac so I'm gonna have a go at modding these ones. The amount of space between the front of the engine and the front wheel is really limited so theres not much else I can really do with the headers. I realise that this is going to be a massive compromise but if it dosent work out then I'll have to start saving for a bespoke set. So will adding the 2" back into the belly section move peak power back down the rev range or will it just make the powerband come in more progressively? Cheers, Ben. Link to comment Share on other sites More sharing options...
Martin77 Posted May 1, 2009 Report Share Posted May 1, 2009 lengthening the belly will bring the peak rpm down. Though it may not be ideal, with a bit of adjustment later on you should get them peaking where you want it to peak. You can always chop them about a bit once the rest of it's working, and learn about how pipe length effects at the same time... Link to comment Share on other sites More sharing options...
cagimaha Posted May 3, 2009 Author Report Share Posted May 3, 2009 Awesome I'll set to as soon as I get home and let you know how I get on. Cheers, Ben. Link to comment Share on other sites More sharing options...
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