Suzuki 2 Strokes

Found this somewhere on the ‘net. Wondering if this is the jetting instructions for the JEMCO 3-1 pipe for the GT750? If so, is this with airbox or pod filters? Any insight greatly appreciated.

I can't speak for the Jemco pipe and 750s, but the Piper 3-1 made my 380 run a little rich throughout the rpm range (standard airbox & air filter). If you still have the stock airbox/filter, I'd be very surprised if a jetting change was required.

The Piper also stopped the engine revving above 7,000: it would get up there fine but would then stop at 7K like it had hit a rev limiter, because of the breathing limitations.

Did the GT380 with the Piper 3-into-1 make good power up to 7k rpm?

Not JEmco. The headers on a Jemco are welded to the collector. Might be for a Strader which came with separate headers.

...Yes it's a Strader and that was on a new late design with multi-tube baffles.

tz375 wrote:Not JEmco. The headers on a Jemco are welded to the collector. Might be for a Strader which came with separate headers.

...Yes it's a Strader and that was on a new late design with multi-tube baffles.

Great info tz- much appreciated. I’m still waiting for my JEMCO from the chrome shop. Going with the jetting specs on it you recommended with 112.5 mains, 45 pilots, anti surge jets installed, and stock needles in 4th groove position. Air screw 1 turn out also. I just finished my first cleaning and overhaul of the stock BS40/ CV carbs- pretty time consuming job compared to the Mikuni VMs I’m used to. I went with all new brass inside the carbs including new float needles/ seats. Float level was way off by PO so I adjusted to 27mm with the tool bought from Baz. I’m also running stock airbox and bought a second used centerstand to see if there might be anyway to modify it/ reshape and re weld to use with the JEMCO.

jabcb wrote:Did the GT380 with the Piper 3-into-1 make good power up to 7k rpm?

It was comparable to the stock bike up to about 6,000/6,500, but the top-end was stifled. Because it wouldn't pull more than 7K, it meant the practical top speed was about 85mph ... however, it sounded glorious

I don't believe the Piper was ever designed with any consideration for power etc, it was purely for looks, weight saving and offering a cheap alternative replacement to the stock exhaust for owners who had crashed their bikes

The GT380 needs the revs a lot more than the GT750 & GT550. I’m fine with the 3-into-1 on my GT750. But I’ve wondered about the 3-into-1 on the GT380.

Aftermarket pipes don’t have the dents for the side stand. Cornering clearance with the 3-into-3s on my 72 GT380 was rather skimpy with the stock stand. I thought about switching to a 3-into-1. But I came up with a mix-n-match parts bin side stand that works without dragging.

jabcb wrote: Aftermarket pipes don’t have the dents for the side stand. Cornering clearance with the 3-into-3s on my 72 GT380 was rather skimpy with the stock stand. I thought about switching to a 3-into-1. But I came up with a mix-n-match parts bin side stand that works without dragging.

Mine was an M model, which had the later, higher exhaust mounts so the side stand tucked away fine. Fitting the centre J&R chamber on it so that it didn't fret against the center stand lugs was the big challenge, it needed careful mounting and the correct number of washers on the mounting bolt