Hi guys.
I'm in the process of looking at derestricting my mc28 and starting to gather a few ideas.

I've been looking at the various exhausts available and been told that jha's, jollymoto, tyga or dog fights or those made specifically for the MC28 come recommend.

However looking at the few you see for sale in my opinion nothing comes close to the quality of the original equipment. I'm not doubting they work well but don't look as good. Those that do demand a lot of money.

This has therefore led me to wonder if I should look at buying some originals from Japan auctions and set about having a friend try splitting them and see what restrictions inside can be removed and put back together etc.

It would save having to worry about melting bodywork, trying to make them fit and paying what appears to be a lot for cheap looking items. With limited knowledge of which aftermarket items fit best it's a mine field.

I therefore ask if anyone else has had the same dilemma, or those who have tried it and whether the journey is worth it etc. Anyone split the original end cans? How restrictive are they? And are there alternative cans that will bolt straight onto the OEM expansion chambers?

The added bonus if it works is that it keeps the bike looking as original as possible. Providing the rewelding and spraying is neatly done etc.

Thanks
Graham

You won't find restrictions in the stock pipes at all.

The key elements are volume and length to affect the timing of the exhaust pressure wave back to the cylinder.

Unless you know how you will only buy yourself a headache cutting them open.

A lot of development and knowledge has gone into the aftermarket pipes - I think purchasing a quality set and spending some time improving the finish to your liking is a better option.

My personal opinion.

I have to agree, NSR is not a Moped, there are no plugs or washers in the exhaust, they were limited electronically. from what I understand the standard MC18 pipe makes with in 2 hp of the best aftermarket and has better power in mid-range, I realize it's not MC28 but I suspect not much different.

Mc28 actually does have a stock exhaust restriction - washers in the pipes. If you unbolt the exhaust, you will see them. I spent about three hours per pipe grinding them out over the winter.

Not sure what the actual power gains are, but the bike does have better pep now, and pulls to about 12.5k. Before it felt like it hit a wall at 10k.
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1996 NSR250 SE
1997 CBR900rr
1989 Hawk GT
2000 996

You're flogging a dead horse with the MC28 exhausts! They will never perform as well as the MC18, or even the MC21 exhausts. There's more restriction in them than just the washers in the downpipes, and they weigh the proverbial ton too! While grinding the washers out will liberate a thousand RPM or two, it's quite frankly not worth the time and the effort. You will barely notice the difference, and the feeling you won't get as it gasps asthmatically to the redline, will be rather underwhelming. It's better to have a restricted one and an excuse for poor performance, than a half-heartedly tinkered with one that you hope will reward you for the modifications, but doesn't! The silencers are also hugely restrictive.

Quite simply, there is nothing standard on an MC28 conducive to performance. If you want it to look stock, then it's never going to perform much better than stock, I'm afraid.

As the old addage says, "performance costs". In the MC28's case it not only costs money, but it also costs a little in the aesthetics department too. If done properly and carefully though, there is no reason why you should "melt the fairing". Some pipes have narrower bodies than others, and are easier to fit inside the bodywork. For the most part though, they all perform pretty much the same, despite the different configurations. Not until you start trying to push into the high 60's~low 70's will race pipe choice really start to matter.

Quality-wise, you can't beat any of the stainless steel pipes out of Japan. Value-wise, you cannot beat TYGA's pipes, and they will perform equally as well as any Japanese pipe.
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Andy.
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If you're on a tight budget then you can make noticeable improvements on the 28 pipes.

As has been said, the washer in the header needs grinding out from the strangulated 30mm to the full diameter of the header. Then look through the silencers and you'll see they too have a restriction, but this is harder to deal with and just fitting MC18 or 21 silencers doesn't strictly work as the mounts are in a different place.

We will be revising our pipes very shortly. We're in the process of doing the RGV and Aprilia right now, and will be moving on to the NSR250 once they're done. We're now using full cone technology and not stampings so accuracy is improved and thanks to this we can pretty much get the pipes to go where ever we want without spending a fortune on different stampings. However, the issue on the NSR is that for good performance they like a big belly section which is difficult to route, but we've managed considerably more clearance on the RGV and Aprilia, so I'm optimistic that the NSR can be done too.

We won't be making specific 21 or 28 pipes. One size will fit both. Once they're done we'll look at fiddling them to fit the MC18 too.

The end cans on an mc28 are indeed very heavy, but most aftermarket ones will bolt on with very little effort.

Andy, is there really any real difference in the chamber between the 21 and 28 except the washer? I have never noticed any difference in the weight for instance, if there is then another option could be to bolt on some mc21 pipes with race cans and keep a more standard appearance.

You can fit 21 exhausts but the "stingers" do come off at a slightly different angle so the silencer mounts wont line up. although this wont be an issue if you are using aftermarket silencers.

I totally get where you are coming from with the stock look but I would go with a set of aftermarket pipes, they just sound so good you definetely wont regret it and make going under bridges and through tunnels a very enjoyable experience

The choice of pipes is down to personal preference but as mentioned before Tygas offer excellent quality and value and are readily available but if you want to go for something a bit more exclusive keep an eye out on yahoo auctions for a jap market set. My personal favourites are the JHA 500V replica , I know someone who has a pair hanging in his shed but he wont sell them not that I can blame him for that.

With regards to the bodywork clearance issues I painted up another r/h lower panel with a bulge to clear the pipe and hammered a small flat on the l/h pipe to clear the l/h panel to clear the Tyga pipes on my mc21. You can now purchase some good quality aftermarket mc28 rothmans decal kits so painting up a second hand panel shouldnt be a big drama.

Matt@TYGA wrote:If you're on a tight budget then you can make noticeable improvements on the 28 pipes.

We'll have to agree to differ on this one then, Matt. I concur, you can certainly improve the stock pipes, but I would say "you can make barely noticeable improvements".

If you want a totally stock [derestricted] look, then you are going to sacrifice power. Simple.

Inside the "belly" of stock MC28 pipes, there's a large section double-skinned, with a perforated inner core, that wrecks their effectiveness. [It's there in MC21 pipes too, but to a lesser degree.] I don't know the chamber dimensions of the MC28, but everything else on it is geared towards making it a great low power street bike. I'm not saying that in a detrimental way, I'm saying it in the way that Honda managed to make it a very [effectively] restricted 40hp 250 2-stroke that can be ridden very quickly amongst 60hp 250/400's and even larger capacity bikes in most "every day" riding scenarios.

At the end of the day, derestricting is really about releasing it's "true [as manufactured] potential". The MC21 was the last model you can do that with and keep it looking stock. The OEM '21 pipes will make well into the high 60's, and we've seen, if I recall correctly, 68hp out of Bill Limbs MC21SP on standard pipes*. You will be lucky to get over 55hp with standard MC28 pipes, so yes, it's a HUGE difference! The true potential in the MC28 stock motor [no porting] is 61~62hp, with race pipes.

*Standard MC21 chambers with Swarbrick carbon cans.
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Andy.
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The other issue is trying to find a decent set of mc28 stock pipes. It took me a good while to find a set for my 28 and with shipping from Greece werent particularly cheap. Even stock 21 pipes are getting harder to come by.

They do come up for sale on Yahoo but the shipping aint gonna be cheap as they are heavy buggers.

You're right! MC21 pipes are heavy enough, but '28 pipes are just crazy! Also, to truly do your best with them, you would need to cut them open and replace the perforated sections with sheet steel, then stitch them back up. And you're never going to get the same finish as Honda, so why bother?

Race pipes... it's the only way to go! You could go for mild steel and paint them black, and use NSR end cans to give it a sort-of stockish look. The least restrictive [stock] end cans are the 1988 MC18, but you would probably need to use MC21 cans to get it to look closer to the MC28. MC21 silencers are still rather restrictive and heavy though, but not as much as the MC28's.

As I said in my first post though, you're flogging a dead horse. Sorry.
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Andy.
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