Suzuki 2 Strokes

I'd like to hear from those that have eliminated the SRIS system. Any ill effects etc.

Different subject. I wonder why those miserable cross overs were maintained on the GT550 through all production years? I read somewhere the the later GT550's had no cross overs on the European market. Why there and not in the USA?. I only ask because they are a little bit hard seal well, not to mention quite unsightly. They shucked them on the Buffalo here. Why not the 550?

I eliminated the SRIS system on my GT550 about 2 yrs ago during some major engine work. I can't tell any difference in it's operation or performance. It smokes some when its warming up, but once up to temperature it doesn't smoke unless I REALLY crank the throttle, or go in excess of 70 MPH. Neither condition is where the SRIS was designed to reduce smoke, which is when accelerating AFTER extended idling or closed throttle operation such as when coming down a long hill. Those conditions are where excess oil might accumulate in the bottom of the crank, then be consumed by the increased action of the acceleration. In my mind, the SRIS probably served some minimal function at best, but seems to address a problem that didn't exist in any significant level. I would NOT pay any $$ to replace the little valves. Just remove them & plug the front holes with suitable hardware. As for the rear inlet nipples, I just capped them off with some bits of tubing which I then plugged with RTV. No muss, no fuss, no problems.

As for the exhaust cross-overs, I agree with you. Again, seems un-necessary complexity to address some (imagined?) minimal issue..... but I'm sure there's some 2-Stroke Gurus out there that will insist they are absoutely essential or the engine will explode & your wheels will grow square corners due to misdirected air flow vortices affecting traction or some such nonsense. I would eliminate them too if there were an easy way to do it. Maybe a simple extension of the center pipe "Y" such that each branch would smoothly clamp into the two outer pipes. Then the two center cans could also be eliminated too.

Good Luck

CBWELLS wrote: As for the exhaust cross-overs, I agree with you. Again, seems un-necessary complexity to address some (imagined?) minimal issue..... but I'm sure there's some 2-Stroke Gurus out there that will insist they are absoutely essential or the engine will explode & your wheels will grow square corners due to misdirected air flow vortices affecting traction ..........

That is the answer. You are right

SRIS I would cap off and have done on the last three GT750 motors though I am still having nightmares that I may have forgotten to cap off the one to the left intake on the last motor I built.....

For the crossovers, the only good reason I can see is to share the volume to make the exhaust quieter, but that isn't an issue on later 750's so I'd just remove the cross pipes and cap the "ports" with welch plugs.

A 32mm OD core plug in metal will close off any unwanted GT550 cross-over holes if you want. I know this as I obtained a spare right pipe for my UK 550B and that spare was from a US bike, with a cross-over.

I had read somewhere that the cross overs increase the low speed torque and accompany cylinders ported for this effect, and both porting and pipes were altered on later machines. No idea if actually true, or noticeable.

Agree that the SRIS is a pain in the backside. Just more stuff to go wrong. I'm pretty sure they're responsible for a good deal of the angst occasionally posted here (including from me ) on 'why is only one pipe smoking?' or 'why is one of my pipes NOT smoking?'. We fear its the oil pump, or lines / check valves and, while these can go wrong, pooling in the crankcase from poorly functioning SRIS can certainly make itself known.

Mike

Suzuki made more GT380s & GT750s then GT550s.
The GT750s were the flagship model & its shortcomings were more of an issue.
As-is the GT550 was good enough to win bike magazine comparison tests.

Suzuki probably did little to update the GT550 because they thought it was good enough.
They were too busy wasting money on the RE5 & then later salvaging the company with the GS-series.

I have to remove the SRIS valves to drain out any junk / funk on my current project. They will me replaced with bolts. I have enough problems as it is. I put new valves in my last 550, but no filter screens. Why no filter screens? Try to find even one. I dare you! Last one I saw on ebay went for $45!

On my GT750 one of those little screens came off in the right crankcase and destroyed the dreaded middle crank seal. Game over. I removed them and capped it all off. Problem solved and looks a bit tidier without hoses going everywhere.