Exhausted!

[twelveport]

Hello, just joined the group. Was wondering why the GZ 250 has duel exhaust on a single cylinder and then it is reduced to less than an inch at the end of the muffler? I'm sure the duel pipes is due to multiple exhaust valves. Any ideas here?

[5th_bike]

Welcome to the forum twelveport!! :2tup:

You're absolutely right, it has the dual exhaust pipes at the cylinder because of the two exhaust valves. And I assume it reduces to less than an inch at the end of the muffler, um, well, to muffle the sound.

People here have tried to imitate the Harley and Ducati/Moto Guzzi sounds by drilling two large holes in the muffler plate (at 22.5° and 90°, respectively) but that somehow never works out as planned, no idea why.

PS - twelveport - I can't keep from guessing - you are riding a three cylinder with four valves each cylinder (Triumph?), or a four cylinder with three valves each (no clue), right?
:rawk:

[mole2]

Welcome to the forum from South Carolina. You are correct, there are two exhaust valves. Ride safe.


:)

[twelveport]

I took the handle "twelveport" from the news letter of our inline engine club. The "12Port News" is published by "Inliners International." I built a hot GMC inline six cylinder. Took a 302 GMC out of a bus or dump truck of the era and bored it .125" to a 320 CID, custom Ross 10:1 pistons, balanced/blue printed block, sent the stock head to Sissel's Automotive in CA & done a port & polish, lump porting, and stainless SB Chevy 160/194 valves, 3 Holley/Webers, McGurk cam 270 in/ex duration w/530 lift. Makes just over 300 HP. Not bad for a little six banger.........hahahaha.

[Water Warrior 2]

What did you drop the engine into?

[twelveport]

I put the engine in a 1954 GMC 1/2 ton, mustang II IFS, Chassis Engineering rear suspension, 9' Ford w/3:50 Limited Slip, Ram clutch, 3000 lb. static, anti sway bars all around, traction bars, Richmond 6 speed manual w/od, stainless brake lines w/line lock, custom built 2.5" dual exhaust by me...mandrel bends cut and welded...ceramic coated inside & out, electric exhaust cut-outs. Then it went to the body shop and the night mare began.... enough said on that, I get mad thinking about it.

[Water Warrior 2]

I put the engine in a 1954 GMC 1/2 ton, mustang II IFS, Chassis Engineering rear suspension, 9' Ford w/3:50 Limited Slip, Ram clutch, 3000 lb. static, anti sway bars all around, traction bars, Richmond 6 speed manual w/od, stainless brake lines w/line lock, custom built 2.5" dual exhaust by me...mandrel bends cut and welded...ceramic coated inside & out, electric exhaust cut-outs. Then it went to the body shop and the night mare began.... enough said on that, I get mad thinking about it.
Sounds like a neat ride. Also sounds like you found the wrong body shop. Hang in there, things will work out in time. Goes without saying that we what pics sometime in the future.

[Goose51683]

Twelve port- I think you stated in one post more than I know about engines, vehicles and engineering in general. Good to have you around.

[twelveport]

Thanks! Nice to meet all of you folks and it is really nice to have this Forum.

[Goose51683]

Twelve port- Have you ever built a bike before?

[twelveport]

Goose, I have only put rings, bearings etc. Mainly just maintenance. If I had a fast bike when I was in my 20's I would be dead by now. I rode with "THROTTLE WIDE OPEN ." Like a lot of dumb know it all kids.

[Goose51683]

I understand perfectly. Thank goodness I was a poor in my twenties (and now haha) or else I would have been wrapped around a pole somewhere.

[Water Warrior 2]

Building a bike would be a real challenge. Might be fun to try a custom made bike along the lines of a S-40 Suzuki. Basically a big GZ. Keep it simple and you have less moving parts.

[twelveport]

Right now I'm committed to finishing the old GMC and that takes all my spare money. I could not afford to build a pedal unicycle. Hahahaha.

[twelveport]

I found this little GZ for my son to learn on. I think it is the perfect size for that. He finished the safety course a week ago Sunday and got his motorcycle license last Wednesday. He is going good on it, and is using a helmet and wears a green/yellow shirt. Cars can see those construction shirts a mile away. Leaving the headlight on does very little to make you visible. I have noticed a lot of bikers in this area (Quad-Cities, IA/IL) wearing them. Just makes sense to be seen instead of laid out.