Author Topic: Rd125dx downpipes  (Read 257 times)

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Offline DeadlyBernard

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Rd125dx downpipes
« on: August 09, 2018, 08:59:10 PM »
Hi all. The names Dave. Fed up with tupperware racers and so .......

I've just bought a gungy old 125dx imported from Portugal. I intend to cafe racer it and to that end want to fit spanny boxes. I've looked through a few threads to this end which say the old microns are no good because they use the original downpipes. Whys that? Are they too short?  If so how much longer do they need to be? I intend to hydroform the spanny boxes and was basically intending to copy a micron. I'm quite willing to extend the existing downpipes. Or is it the case the micons are just pants?

Any thoughts much appreciated
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Offline Phil Featherstone

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Re: Rd125dx downpipes
« Reply #1 on: August 10, 2018, 12:36:46 AM »
Hi the comment about using std headers(downpipes) is to do with the benefits 2strokes get from the taper coming away from the cylinder compared with a parallel pipe like the std header. Length has impact aswell. I have been making pipes for 40 yrs and even all them years ago only ever made 3 exhausts with parallel headers before moving onto tapered ones. ;)
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Offline DeadlyBernard

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Re: Rd125dx downpipes
« Reply #2 on: August 10, 2018, 07:45:29 AM »
Thanks Phil. I'd like to have a go at designing my own later but right now have to concentrate on getting the bike working and looking OK. I want spannys for the iconic sound and look of my long gone youth (and the originals are totally knackered and I can make them out of off cuts of stainless so dead cheap). I'm not intending to do any port work other than cleaning and matching and K&N's. If I were to copy microns would they slow it down ?
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Online Johncb500

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Re: Rd125dx downpipes
« Reply #3 on: August 10, 2018, 11:10:47 AM »
Thanks Phil. I'd like to have a go at designing my own later but right now have to concentrate on getting the bike working and looking OK. I want spannys for the iconic sound and look of my long gone youth (and the originals are totally knackered and I can make them out of off cuts of stainless so dead cheap). I'm not intending to do any port work other than cleaning and matching and K&N's. If I were to copy microns would they slow it down ?


  careful fitting "pod" airfilters ,they can cause mixture ,and running problems ,
lifelong rider,laterly with Honda,now a little RD as well

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Offline DeadlyBernard

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Re: Rd125dx downpipes
« Reply #4 on: August 10, 2018, 02:01:13 PM »
Hi John, the airbox and filter housing are already in the bin I'm afraid and I've ground off the mounts I'm afraid so I'll have to persevere. They're important to the look I'm after too. I do fully agree having had such proplems in the past but reliabilty is never going to be an issue.
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Offline Alistair64

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Re: Rd125dx downpipes
« Reply #5 on: August 10, 2018, 05:08:03 PM »
Hi Dave
Regarding the Microns, I wouldn't even try to copy the design if I were you. They look good, sound great, but even with different downpipes I doubt that shape would come close to a set of complete units designed to give a good power increase.
Phil is our resident pipe expert, so I would tend to look at his in another thread on here as he's looking for interest and may make up a few sets from what I understand. Now the pipes he is fabricating are for the 200, so what effect they'd have on a 125 I can't say (or whether they'd fit at the barrels), but I'm sure he would tell you.
By the way Phil, if you're reading, how are things progressing?  ;)
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Offline Levy1982

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Re: Rd125dx downpipes
« Reply #6 on: August 11, 2018, 09:15:56 AM »
Also there are plenty of tuners and pipe builders around these days so you're not struggling for choice. Mine were made by Martin Johnson and were inexpensive. In fact selling my allspeeds paid for the Porting and matching pipes

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Offline DeadlyBernard

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Re: Rd125dx downpipes
« Reply #7 on: August 11, 2018, 10:42:20 AM »
Thanks guys.  A big part of building the bike is to make my own pipes (eventually) and having played around with hydroforming  am at the point where I just want a design to try and copy in the short term. I always found microns to be a look and sound job rather than being a performance improver and a pair certainly slowed my 250lc back in the day. However I have a mate who has a pair I can copy. The biggest prob with hydroforming is small diameter shapes take much more pressure to form and distort more making downpipes the most difficult to make.

Changing the subject. I was gobsmacked to find an MT125 front end bolts straight on to my wee fella ........ looks absolutely crap though !
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Going back to my roots