just supposing i wanted to run the pipes from my r5k up under the seat unit and out of the holes where the rear lights are. does it matter what length the long pipes after the expansion chamber are ,as far as exhaust performace is concerned??
there was a mc21 track bike 4sale here in australia last week on e-bay way expensive but it had under seat exaust on it if it goes back on you could ask him
cheers mate, managed to copy the pictures from the expired listing.
that's kinda what i was thinking of doing as i have a single sided swingarm to go on to!
the total length of the exhaust does affect the timing of the return pressure waves that stop fresh fuel charge from going straight out the exhaust ports.
I remember reading that Tyga pipes have a tuned length that specifically suits the 250cc motor - therefore they are not the ideal length/size for use with the 300cc kit. Though i have no idea just how much of a difference an increase in stinger length would cause to your r5k's power output. My 300 certainly pulls hard enough - even if the pipes aren't specifcally tuned to the motor's capacity. _________________ After years of moaning about immigrants now i am one...
I have to say, the engineer in me screams at the thought of form over function on such a critical part of a two stroke engine... _________________ MC21SP Plaything
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Unless you are running back to front cylinders I'd leave it as is. Unless your gonna put a 4 pot in there somehow! _________________ More **** two strokes than you can shake a **** stick at.
Thats one cool bike.. rothmans colours, a747 bottle for a catch tank, small plate and buggered plastics. Happy days! _________________ More **** two strokes than you can shake a **** stick at.
Haha, the A747 bottle is full of..........A747, just left there for when I need to mix up fuel at the petrol station......every 50 miles!
And there was me thinking most of the damage was hidden in that picture . Then again you must be very knowledgable about these things if you can spot from that angle that its a A747 bottle! I think you get the idea of the underseat exhausts though....on a 4 pot engine
Nice and economical then? Looks good, nice to see something like that 'used' as it were _________________ More **** two strokes than you can shake a **** stick at.
the reason i asked about the length of the pipe ,from the expansion chamber to the stinger affecting performance, is that the ones on my mc18 r5k are already alot longer than on any other nsr and the r5k isn't know for being down on power?????
and that 4 pot is pure sex, any one got a tissue?? lol
The stinger is the small diameter pipe between the expansion chamber and the silencer - sorry im not tryin to be a smart-arse i jus wanna clarify the bit im on about!
Anyroad - if you look at a set of tyga exhausts you can see that the stinger on the left hand side exhaust is alot longer than the right hand side one. Its not just a case of how long the stinger part of the exhaust is but more about its total tuned length and the sizes and pitches of the cones in the expansion chamber part - which gives you the characteristics of your power curve.
On the MZ race bike we were running at uni, the first exhaust we made had a longer front cone with a shallower pitch, no straight section and a much shorter, steeply pitched reverse cone. I don't think we paid much attention to the stinger length or the length of the silencer, we were just copying other bikes we'd taken photos of at previous races. That exhaust became the benchmark for us and we ran it for three races.
The second exhaust had a much shorter, steeper front cone, no straight section and the same reverse cone and stinger as before. The silencer was the same length but much bigger in diameter because we'd been moaned at by scrutineering for being too loud. Overall the exhaust was shorter but we were only interested in the expansion chamber's profile (becuase we didnt know any better). We had also chopped the header pipe down as much as the rules allowed.
This exhaust had the affect of letting the engine rev higher and it made significantly more power in this new, higher rev range. It also had a pronounced 'power band' whereas previously power had felt linear.
The Burwins bike (arguably the fastest and most developed) had a MUCH shorter exhaust, with a fat, stubby silencer and virtually no stinger section. So he'd found by years of trial and error that that total length gave good power, or perhaps it just gave the characteristics he was after as a rider.
Your MC18's exhaust will be sized and shaped to give certain characteristics, so changing JUST the length of the stinger (and so, the total length) will spoil that design's performance. By how much i don't know. _________________ After years of moaning about immigrants now i am one...
Martin and or Elegy (both on this forum very occasionally) are the men to ask, but as far as I recall;
Longer stingers (and shorter headers) move the power further up the rev range.
Dave (Elegy) did suggest putting a small spacer (a couple of cm) between the header and the cylinder, as my racebike pipes (from an RS) were probably designed to rev too much for the NSR cylinders they were attached to. _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
The stinger diameter is more important than length, but making the stingers long will have a similar effect to using a slightly smaller diameter. I would suggest if you were going to do this, make sure the tube you use is a larger diameter than the original stinger, so that it doesn't have much of an effect, something like 24mm or so.
If they're too restrictive you run the risk of melting a piston...
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. Then again you must be very knowledgable about these things if you can spot from that angle that its a A747 bottle! I think you get the idea of the underseat exhausts though....on a 4 pot engine 