schumi
L plate rider.
Posts: 12 
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Post by schumi on Oct 3, 2013 18:23:37 GMT 1
Wonder how to decoke a RD125LC MK1 pipe? Because the baffle is welded into the pipe and I don't want to damage/destroy the stuffing...
I read about the caustic soda thing, anybody tried that on that pipe?
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Post by billy on Oct 6, 2013 17:26:27 GMT 1
I have no idea how to decoke it mate, but I know one thing, and that is that Mk1 pipes has a layer of, thin, dense padding around the inside edges of the baffle, so it's not just the actual silencer part that acts as a silencer. I know this as I cut an Mk1 pipe apart when I built a custom pipe for my RD/CR hybrid (I removed ALL of the padding, leaving me with a completely empty chamber). imageshack.us/a/img811/7195/expansionchamber.pngimageshack.us/a/img837/1592/kopiaavdsci0001.jpgOh and if anyone wonder how it runs: |
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Post by ozzy on Oct 7, 2013 0:23:46 GMT 1
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Post by mudguts on Oct 13, 2013 10:39:07 GMT 1
just get a allspeed easy to take to bits
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 14, 2013 22:11:10 GMT 1
Not that easy to get one here in Germany  There's also the problem that you have to go to Germany's TÜV to register that pipe, I heard that this isn't possible... Another thing I noticed recently is that there's a restriction washer in the downpipe, therefore the bike is driving like the late versions of '85 UK-non-YPVS models with 12BHP@7,500rpm, although it should have 17BHP@9,000rpm; it has also stamped "12A-14711" on it. What if I remove the washer, will it have 17BHP or the full unrestricted 21BHP? |
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Post by billy on Oct 14, 2013 23:38:00 GMT 1
Not that easy to get one here in Germany There's also the problem that you have to go to Germany's TÜV to register that pipe, I heard that this isn't possible... Another thing I noticed recently is that there's a restriction washer in the downpipe, therefore the bike is driving like the late versions of '85 UK-non-YPVS models with 12BHP@7,500rpm, although it should have 17BHP@9,000rpm; it has also stamped "12A-14711" on it. What if I remove the washer, will it have 17BHP or the full unrestricted 21BHP? Try it. Unrestricted pipes has no visible washer in the downpipe. Another thing worth looking at is the very end of the exhaust - how big is the hole at the end of the pipe? I know there are some pipes that has a smaller hole at the end. I think the full power exhausts should have an 18 mm ID hole. Restricted pipes might have smaller, something like 16 mm which is pretty f**king tiny. |
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Post by looey on Oct 15, 2013 9:18:18 GMT 1
The 12A pipe has a short tube welded in at the top of the downpipe help in by two 1cm welds that are directly opposite each other.
I removed one from a 12A pipe a couple of years ago (I have pictures somewhere doing it) but the bike still went cr*p compared to any aftermarket pipe (Micron or Allspeed)
My advice would be to get yours decoked if it's an unrestricted pipe, or lookout for another that's not blocked up.
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 18, 2013 21:49:46 GMT 1
Just found out that the 12A pipe is the wrong one for the German 11Y model... So I'm hoping somebody can help me out: Anybody has a 11Y pipe that he doesn't need anymore? Please send me a PM if someone has one!
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Post by looey on Oct 18, 2013 22:32:17 GMT 1
I've got a matching numbers 10W bike which I believe was imported from Germany at some point in its life.
It has an 11Y carb fitted (which I've found to be better than a 12A or 10W carb) but thought it would've had a 10W exhaust as standard, or was there an 11Y exhaust also ?.
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 19, 2013 0:43:32 GMT 1
Yes, there is actually an 11Y exhaust, I found that one in the parts catalogue for that model. It may has a restriction washer like the 12A pipe I have at the moment, but it can be that the inner diameter of the washer is bigger; not sure about that, just read about it having one too...
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Post by looey on Oct 19, 2013 8:48:49 GMT 1
Well like you've said before, the 12A pipe will restrict the bike to 12hp, sounds like the 11Y pipe will restrict it to 17hp ?, so the best to do is find a 10W pipe which should give you 21hp, as there's no other restrictions on the bike  |
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Post by ozzy on Oct 19, 2013 11:10:00 GMT 1
one on ebay 21hp pipe
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 19, 2013 14:35:02 GMT 1
Yeah, saw that one. But the seller doesn't offer delivery to Germany; I aksed him, but he didn't reply yet... Or is it yours?
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Post by billy on Oct 19, 2013 18:17:02 GMT 1
I put an 11Y pipe on my dads Mk1 once (the 11Y is the pipe with the tiny hole at the end of the pipe), it went like crrrrraaaap. The 10W ipe makes it run MUCH stronger.
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 19, 2013 20:21:07 GMT 1
Do you know if there was a washer in the downpipe or not, maybe the diameter too? Just to be sure...
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Post by billy on Oct 20, 2013 18:11:53 GMT 1
Do you know if there was a washer in the downpipe or not, maybe the diameter too? Just to be sure... I can't recall having found a washer in the downpipe of the 11Y pipe (not saying my memory is correct but I think I would have notied, and remembered it), but I know the hole at the end of the pipe was smaller than on a 10W pipe. I could have a look today if I remember it when I'm in the basement, I still have the 11Y pipe laying around. Oh btw, with the 11Y pipe, the compression of the engine was VERY, very poor. I thought my engine (although it had a fresh bore and a new piston) was bored to the wrong specs, or that it needed to bed in, or it had a leak or whatever. You almost couldn't feel any resistance in the kick starter with the 11Y pipe. When I put the 10W pipe on (and bare in mind, I changed NOTHING other than the pipe), you could clearly feel the compression in the engine by moving the kick starter. |
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Post by billy on Oct 21, 2013 21:45:05 GMT 1
I checked the 11Y pipe and you're right, there should be a washer in the header/downpipe. This washer was removed on mine, but I could see the remains of three weld dabs inside there if I looked more closely. The 11Y pipe also have a washer-like restriction at the back as I mentioned. You might be able to pop up the power if you grind the hole up so that the hole becomes as large as the perforated tube on the inside. If doing this however, you have to clean the exhaust really really careful to get any steel burrs out. I think the best way to do it is to dump some petrol in there (the more the better), shake it around and empty it (through the back of the pipe) into a plastic box of some kind. Then use the petrol again (the steel burr crap will just sink to the bottom) until you feel it's clean enough. |
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schumi
L plate rider.
Posts: 12
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Post by schumi on Oct 21, 2013 22:49:20 GMT 1
Thanks for that billy, appreciate it I removed the washer from my 12A pipe and wow, I'm stunned... I didn't expect that high increase of power! I made a comparison of engine's power with and without the washer seen in the diagram I attached, quite a big difference. I think I leave the bike like that, because the diagram shows that it's very close to the German 17HP version (diagram shows torque and power at the rear wheel, so it's a bit less than the real engine's power). Oh, and if you wonder how I made the diagram: It's done with a program called GSF Dyno, you can find and download it here: atom007.heimat.eu/tmt/gsf_dyno.htmlAttachments:
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Post by ozzy on Oct 22, 2013 0:08:30 GMT 1
Yeah, saw that one. But the seller doesn't offer delivery to Germany; I aksed him, but he didn't reply yet... Or is it yours? no not mine sorry mate. |
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There's also the problem that you have to go to Germany's TÜV to register that pipe, I heard that this isn't possible...
