New Moby carb, question on exhaust and performace

Steve Peterson /

I'm putting a Dellorto 15 on my 77 Moby 50v as well as the corresponding jet.

It came with the newer style blunderbuss exhaust that is a tad more difficult to derestrict.

I was wondering how much of a difference having a restricted exhaust will be with the new carb.

Is it enough to make me consider buying a better exhaust or surgery on my current one?

If it's only a few mph I can live with it, but I'm looking to get as much out of it without getting into porting and big money stuff......for now.

Re: New Moby carb, question on exhaust and performace

On a well tuned stock cylinder with a SHA15:15 it needs the extra exit volume from either getting a better perfrorming pipe or at least derestricting the stock blunderbuss. Easiest way to derestrict the later blunderbuss is to dispense with the end cap and just put on a blank with a hole about 11mm (7/16 inch) and give it a try. If the noise is an issue and neighbours are hating you then you can stuff in a 1mm ID pipe with an end cap on the portion on the inside of the exhause and turn it into a piccolo baffle by cross drilling a bunch of 2 or 3mm holes.

On a tight budget there is always a SIM cheapy pipe which will run you $50 plus shipping (or less if you find a previously enjoyed one on Buy/Sell). For $59 1977Mopeds has the very nice AV88 cashew replica pipe which was the best stock Moby pipe ever!

Re: New Moby carb, question on exhaust and performace

Steve Peterson /

What about drilling some holes in the current exhausts exit tube? Will that do anything at all?

Ive already accepted that I'm going to need an upgraded exhaust, just trying to do what i can till i can really afford it.

Re: New Moby carb, question on exhaust and performace

You need to shift volume of charge out of the exhause while having some containment of exhause so you can get some reversion to stuff the combustion chamber. On a super tight budget try replacing the entire ass end big ass assembly with just a metal plate with the 11mm hole drilled in it.

Turning the existing exit tube into a piccolo tube will releave some of the pressure but the pea shooter size exit pipe will be giving you unrequired restriction.

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