Four into Ones

[Guest]

I have an '81 GS 850G --both mufflers rusted through. If I replace them with a four into one, will that require tweaks elsewhere? I thought about buying used but, chances are they would be as old as the ones I am replacing. Four into one isn't my preference but if it's a matter of taking the old ones off and putting new one on I'm good with it. I'm not looking to rejet if I can help it.
Thanks,
Mike Schuder

[Matchless]

I have an '81 GS 850G --both mufflers rusted through. If I replace them with a four into one, will that require tweaks elsewhere? I thought about buying used but, chances are they would be as old as the ones I am replacing. Four into one isn't my preference but if it's a matter of taking the old ones off and putting new one on I'm good with it. I'm not looking to rejet if I can help it.
Thanks,
Mike Schuder

Not sure what you can get over there, but I recently fitted a 4 into 1 and ordered a street legal baffle (muffler) for it and it still has the OEM jetting and runs beautifully. Apparently the "racing" baffle (muffler) is very much louder and needs rejetting of the carbs. So it seems that if the exhaust is not overly free flowing (and not too loud!) then you should be OK.

[Billy Ricks]

Macs don't flow much better than stock. You may get away with very little or no tweaking.

[marvinsc]

I hear that in many cases there is no need to re jet as long as You stay with the stock airbox. If I keep the GSX1100G for many years I will probably face the same problem, stock system = Unobtanium and very few expensive options for a 4 into 1.

[Steve]

Not sure what brand is on my son's 850, but it's reasonably quiet. Main jets are 120 (stock is 115) and the needles are shimmed a bit, seems to be doing quite nicely. Re-jetting is not that bad, you just need to have an idea which way to go.

With all the help available on this board, I'd say "go for it".

.

[Big T]

You might want to Google "Marshall Deeptone" as several members have given that kudos.

They make an 850 4-1 exhaust

Whether you'll need to rejet remains to be seen. If you do, people here will guide you through it.

[Nessism]

You might want to Google "Marshall Deeptone" as several members have given that kudos.

They make an 850 4-1 exhaust

Whether you'll need to rejet remains to be seen. If you do, people here will guide you through it.

The parent company for Marshall also sells Jama exhaust systems. Reputed to make some nice OE equivalent systems although not easy to find here in the US.