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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: PaulP on November 02, 2017, 06:29:38 PM

Title: K100 Exhaust Back Pressure
Post by: PaulP on November 02, 2017, 06:29:38 PM

Morning / Afternoon / Evening.

I'm going to be indulging in a little jiggery-pokery with the exhaust system on my K100.

Are there any issues regarding back pressure (either too much or too little) which might cause a problem if the engine>silencer distances are altered?

Is the K. engine particularly susceptible to such alterations, or is it robust enough to laugh in the face of untuned pressure waves?

Cheers

Title: Re: K100 Exhaust Back Pressure
Post by: Martin on November 02, 2017, 09:15:01 PM

Various exhaust have been tried on Bricks. And from the reports that I have seen there is nothing to be gained performance wise. The only advantages are weight reduction and noisier if that's an advantage.
Regards Martin.

Title: Re: K100 Exhaust Back Pressure
Post by: PaulP on November 02, 2017, 10:18:20 PM

Thanks for that.

I seek no performance or noise gains, it's just that I want to reposition the exhaust for aesthetic purposes and get rid of the fairly ugly (IMHO) silencer.

In order to achieve this I need to add some length to the manifold pipes, and I was concerned it may have an adverse effect on valves/stems and such like.

Title: Re: K100 Exhaust Back Pressure
Post by: Chaos on November 02, 2017, 10:27:17 PM

I have run a Luftmeister and now a MAC pipe for decades with no ill effects.  I think  the FI brain compensates for backpressure up to a point.  When the baffle blew out of the luftmeister and it became an open cone the engine was not a happy camper. 

Title: Re: K100 Exhaust Back Pressure
Post by: Martin on November 02, 2017, 10:35:48 PM

If that is the case I would try and find one of the made for replacement ones. Try looking for a Luftmeister, MAC or Staintune, that way you know that the state of tune will not be adversely effected.
Regards Martin.

Title: Re: K100 Exhaust Back Pressure
Post by: PaulP on November 02, 2017, 10:57:03 PM

Thank you both.

I've a couple of nice Pan European stainless silencers which I intend to 'make fit', but as mentioned I'll also need to add a few inches to the manifold pipes to get 'em to where I want 'em.

Satisfied that I can make a modest change without the lump exploding into a fiery ball of shrapnel, I shall crack on....

Title: Re: K100 Exhaust Back Pressure
Post by: billday on November 04, 2017, 07:05:48 AM

Never knew that MAC made a K system. Just looked it up at Dime City Cycles. They say that carburetor rejetting may be necessary. So factor that in to your budget.

Title: Re: K100 Exhaust Back Pressure
Post by: Chaos on November 04, 2017, 09:31:42 AM

Quote from: billday on November 04, 2017, 07:05:48 AM

They say that carburetor rejetting may be necessary.

Yes, that would be difficult on a K  :hehehe

Title: Re: K100 Exhaust Back Pressure
Post by: Martin on November 04, 2017, 03:09:46 PM

No Chaos, it means that in order to run the exhaust you must fit carbies.  :hehehe
Regards Martin.