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'79 Suzuki GS550E w/ Mac 4-1 Exhaust stock box jetting question

C

charlie27

Forum Apprentice
hi, I am in the process of getting the bike running. I bought it with this set up. I will be doing a deep clean on the carbs with new O-rings, gaskets, berrymans, etc.

what is the recommendation for main jet and pilot jet? does removing the top of the airbox w/ jetting add any notable performance?

TIA
 
With a stock air box and only an exhaust change, I wouldn't do anything with the pilot jet. You may up the main one size but in reality the MAC 4-1 isn't noted for massive air flow improvements over stock.
 
If you take the airbox lid off you should bump the main. I'd buy a few sets of mains so you can experiment. I'm not sure how to do it on the VM carbs but you may also investigate lifting the needle a smig too.
 
Nessism said:
If you take the airbox lid off you should bump the main. I'd buy a few sets of mains so you can experiment. I'm not sure how to do it on the VM carbs but you may also investigate lifting the needle a smig too.
Click to expand...

Lifting the needle is as simple as moving the clip down one slot. There are five slots, the stock position is the middle one. Removing the airbox lid adds a little airflow, useful to combat the effects of high elevations a little bit. Might give a touch more power if you jetted it for the change, but I just found out something interesting. The airbox left intact as it comes from Suzuki seems to make the VM carbs work OK at a much wider range of elevations without the need to change jets or even feather the throttle or any of that crap. My 750 works much better in the mountains than any of the VM bikes I've had since I have lived here.
Not anywhere near as well as the same engine with CVs but a whole lot better than VMs with pods.
Since charlie27 didn't list a location I don't know if that matters to him, but it sure does for me.
 
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