Hi All

I keep hearing that the standard exhaust is very restrictive. Is it just the washers next to the barrel or are there also restricters in the expansion boxes ? Also are the end cans too restrictive ?

Thanks in advance

Headman

You need to get shot of the restrictors in the downpipes, and junk the silencers. You could probably replace the internals with some straight-through baffle tube, and repack them, but the outlet is a rather small diameter too... I suspect you'd need to fabricate a decent end-cap.

The problem with the MC28 is that everything is a bit (or a lot) restricted, so we've never had the opportunity to run a properly delimited bike (i.e. with HRC card, modified airbox, HRC needles etc.) with stock pipes to see just how bad they are... there's just no point. My best guess would be that the expansion chamber part of the exhaust isn't too bad, although it's never going to be perfect. I imagine they are fairly similar to the MC21 chambers inside (that can actually perform well on a delimited bike), it's just that everything else is stifled so much.

I would guess that a properly delimited MC28 running standard pipes [with downpipe washers removed, and MFactoryWest/TYGA/Swarbrick type silencers] would make about 57~58hp. As I say though, unless you are hell-bent on keeping it looking as standard as possible, I don't see the point. A set of used race chambers can be picked up for only a couple hundred pounds, sometimes far less for mild steel, and they are well worth it in terms of added performance, lower weight, and ease of maintenance.
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Andy.
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If you want to retain the standard look I believe Tyga still do mild steel pipes. We've had a number of these professionally painted black. They then look very original with all the gains Andy talks about.
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If I have to take the carbs off once more...

Thanks for the replies.
I have already shaped the washers to the exhaust ports but am considering a decent race system.

Headman