PB1 Posted April 6, 2012 Share Posted April 6, 2012 Hi - I'm after some help regarding interchangeabilty between the RD and RS 200's exhaust systems. The worst parts of my newly aquired RS200 are the exhausts - the headers are not that bad but the silencers are very badly rusted. Do RD200 silencers fit okay, both in terms of physical fit and performance/backpressure etc? These seem much easier to get hold of, and seem a bit cheaper. Are they, in fact, the same thing with identical part numbers? I've found a previous posting saying that the RD headers won't fit the RS barrels but it's not clear if RD silencers will fit RS headers or not? I'm okay with making up adapter rings if required. Anybody know anything about this, or have done this? Any help or info would be very much appreciated. Mike Link to comment Share on other sites More sharing options...
blackhat250 Posted April 6, 2012 Share Posted April 6, 2012 Hi PB , [ chemical term for lead ] my mate has a RD200 1976. i will measure the leanth of silencers, [ front to mounting point, ] and diameter of joint area,,, and may photo, ... Link to comment Share on other sites More sharing options...
Moderator mervin Posted April 7, 2012 Moderator Share Posted April 7, 2012 most likely the best way top find out is to go to http://www.aircooledrdclub.org.uk/forum/default.asp and ask in the under 250 help section, all aircooled yam 2 strokes are welcome the RS is just a derivative of the RD Link to comment Share on other sites More sharing options...
PB1 Posted April 7, 2012 Author Share Posted April 7, 2012 Hi PB , [ chemical term for lead ] my mate has a RD200 1976. i will measure the leanth of silencers, [ front to mounting point, ] and diameter of joint area,,, and may photo, ... Thanks, that would be great. Link to comment Share on other sites More sharing options...
blackhat250 Posted April 11, 2012 Share Posted April 11, 2012 Rite P.B.. RD200 exhaust measurments,,= joint to mounting bracket,,, 240 mm. [ double bolt bracket, 50mm between bolts, ] thats it , nowt farther back,,, Link to comment Share on other sites More sharing options...
PB1 Posted April 11, 2012 Author Share Posted April 11, 2012 Rite P.B.. RD200 exhaust measurments,,= joint to mounting bracket,,, 240 mm. [ double bolt bracket, 50mm between bolts, ] thats it , nowt farther back,,, Excellent - thanks very much for this. If there was a slight mismatch in this positioning, it probably wouldn't take much to fabricate some new brackets, or extensions to the original ones. Link to comment Share on other sites More sharing options...
PB1 Posted April 19, 2012 Author Share Posted April 19, 2012 So, £80 lighter and a pair of pretty good RD200 exhausts have turned up from an eBay seller. They are in good condition and will polish up well enough for me, without the expense of re-chroming. That's the good news. Not so good is that they don't fit the RS200's downpipes. The RS ones are 35mm ID at the collar and the RD ones are smaller at 32mm. This means that RD200 have smaller downpipes than the RS200, which was a surprise. See pic below They physically fit exactly the same on the frame though, so I shall modify the collars to fit my existing downpipes. I can't use RD downpipes as I'm told the angle of the bend is different between RS and RD (strange - I thought RD barrels would fit an RS? Maybe not.). I'm lucky to own a lathe so I can cut off the threaded collars from the old RS silencers, which are scrap anyway, and bore them out a bit. I'll then grind down the new collar to make a stub spigot with just enough left to weld them on from the inside. A bit of trimming of the downpipe ends should allow me to fit them without altering the brackets. Part numbers are the same on both types except for the RS ones starting with YAMAHA 3L2 and the RD ones starting with 1E8. Numbers are 14711 and 14712 (Left and Right). Link to comment Share on other sites More sharing options...
blackhat250 Posted April 21, 2012 Share Posted April 21, 2012 Well done PB , thats a good bit of usfull knowlege for future Rd / RS owners,,, Link to comment Share on other sites More sharing options...
PB1 Posted May 15, 2012 Author Share Posted May 15, 2012 Well, I’ve now modified the RD200 exhausts so that they fit onto my RS200 and use the existing RS200 downpipes. The picture a couple of posts above shows the difference in size between the RD’s smaller threaded end (left), and the larger RS’s one (right). This is only a few mm but enough to make modification necessary. Firstly, I cut these ends off the RS200 exhausts so that I could use them to make an adaptor collar: I then parted this off in the lathe, very close to the weld line, and counter-bored into the collar to a depth of 8mm and a diameter enough to get rid of the remaining bit of downpipe inside . This would be difficult to do with hand tools, although a hacksaw and die-grinder in a drill could possibly be used with some care. I then trimmed off the threaded part of the RD200 exhaust so that 10mm remained as a stub, and filed the threads down until it was an interference fit with the bored out collar. The new adaptor collars fit really tightly onto the trimmed down RD exhausts. I was planning to weld it all the way round inside, but was worried about to much heat ruining the chrome. As these fitted so well, I used exhaust assembly paste on the join, hammered the adapters on with a rubber mallet, and put four small tack-welds on the inside. Luckily, the chrome has remained intact okay. There’s also now a step in the end that is the same size as the downpipe’s wall thickness, which means there’s minimal gas-flow interruption. I’m not sure what the effect on performance will be from the slightly smaller diameter of the exhaust at this end, but it soon reaches the same diameter as the RS one within an inch or so. I’ll no doubt find out when I ride it if has decreased performance! As said before, the rest of the exhaust silencer part fits the bike perfectly, and the baffles are the same too. The only downside is that with the modified adapter collar on, the exhaust is now 15mm or so longer than standard, so 15mm needs to be cut off the end of the downpipes so that it all lines up properly and fits into the barrels okay. This is easy with a hacksaw. When fitted on the bike, they almost look standard and don’t look bad in my opinion. Sorry If I’ve taken too much space up with all this, but I thought I’d put it up on here in case anyone’s interested, or is thinking of doing similar. RD200 exhausts are far easier and cheaper to get hold of than RS200 ones, and it might just be of help to somebody at some point to know that this can be done. Link to comment Share on other sites More sharing options...
PB1 Posted May 16, 2012 Author Share Posted May 16, 2012 Putting these RD200 exhausts on has certainly not blunted the bike's performance as far as I can tell. I took it for a ride up and down a twisty country lane near where I live and it goes really well. I can't get over how tiny it is compared to my Honda and previous Aprillia Pegaso, very nippy and great round the twisty bits. Also, I don't remember small two-stroke twins being so quick and such great fun as this is - it's brilliant! It feels a bit like you are sitting astride an angry wasp... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 16, 2012 Moderator Share Posted May 16, 2012 Thats a proper nice job you made of those silencers Link to comment Share on other sites More sharing options...
blackhat250 Posted May 16, 2012 Share Posted May 16, 2012 Well done PB1" Them small twins sound Ace... Turn up at our stroker meet , Sept 1st ,,, Link to comment Share on other sites More sharing options...
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