Exhaust Resonance

[MikeH101]

A previous owner of my '93 R80GS has replaced the exhaust collector box with a Y piece probably Keihan. While I don't mind the sound levels, I don't like the resonance it creates between about 3,400-4,000 revs, right in the max torque range. Has anyone found a way of taming the resonance? I don't know if a db killer would do much or it if there is any device to fit in mid-exhaust.
I don't have the original collector box, so can't go back to that without purchasing new.

 

[GB.]

I have one on my 100gs and haven’t had that problem. I prefer the noise and the look of the Y piece. Apart from the volume I haven’t noticed any major performance differences.


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[scooter paul]

Do you have the standard silencer? You could try a baffle insert into the end pipe. This will increase to back pressure a little which might compensate for the removal of the collector box. Plenty of universal ‘db killers’ available. You just need to match the id of the end pipe to the od of the db killer. A sell tapper or pop rivet should suffice to hold it in.

 

[GB.]

Might seem obvious but have you balanced the carbs recently?


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[MikeH101]

Do you have the standard silencer? You could try a baffle insert into the end pipe. This will increase to back pressure a little which might compensate for the removal of the collector box. Plenty of universal ‘db killers’ available. You just need to match the id of the end pipe to the od of the db killer. A sell tapper or pop rivet should suffice to hold it in.

This is what I was thinking. Seem to be plenty around so will give it a try.

 

[MikeH101]

Might seem obvious but have you balanced the carbs recently?


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Yes,this was done just last week at Rainbow Workshop. Made a huge improvement to engine running but resonance remains .
Like you said, the exhaust sounds good but the resonance is really loud/ annoying.

 

[Mad Hatter]

Sounds like you may have a loose baffle in the silencer rather than it being a problem with the y piece

 

[MikeH101]

Sounds like you may have a loose baffle in the silencer rather than it being a problem with the y piece

That sounds expensive!

 

[Wierpig]

I found my R100R engine harsh and rough with the y piece. I rejetted the carbs, as it was running weak, but it still felt and sounded horrible.
I found a used centre box and fitted that. Massive improvement in running ( i put the original jets back) and doesnt sound rough anymore.

 

[barny]

I tried lifting the carburetor needle 1 notch and then re-adjusted the idle jet and my bike ran better, worth a try at no cost apart from time.

 

[nicholsonj2252]

Used OEM collector box up for sale on eBay (I’ve no connection to seller ) https://ebay.us/m/ywlJH0


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[The Other PaulG]

Sounds like you may have a loose baffle in the silencer rather than it being a problem with the y piece

That was my thought. I had a CB900F that had exactly that issue. The culprit was indeed a loose baffle which made the MOT man unhappy. .

Thing is, on the CB it sounded fabulous!

 

[MikeH101]

Closing this one off. I fitted a cheap db killer to see what difference it would make. There is an improvement and the resonance is reduced to an acceptable level. So I intend purchasing a decent quality device from Pipe Worx and fit that. Finally solution might be to go back to a collector box but that can wait.