Uncle Bob's new hot rod

[excess11]

XS1100 turbo

I have seen XS1100 turbo set ups on ebay. I don't remember who made them, they were aftermarket kits

[excess11]

Valves

Originally posted by MAXIMAN
There's a world of difference between a GS1100E and an XS Eleven. It's called 4 valves per cylinder.

An engine can only draw so much air when naturaly asperated. Once you reach maximum flow it does not matter if it has 2,4 0r 6 valves per cylinder. I think a 78' XS1100 large valve head that is ported would flow as well as a 4 valve head.

[TomB]

4 valve heads were also used because the valve size is obviously a lot smaller resulting in needing a lot smaller valve spring pressure, even the pressure of 4 smaller springs is a lot less than 2 big springs so the HP losses in driving the cams is a lot less.

in short, smaller valves - more horses.

[excess11]

Valves

So smaller is better, sounds strange?? But it does makes sense!! 4 valve good, 2 valve not so good!!! So Xs1100 is a slug and needs 4 valve technology??

[50gary]

Another item that drove the "over square" bore/stroke ratio is the need for more valve area I.E. 4 valves per cylinder. Higher rpm ranges also spurred on four valve technology. 2 valves make pretty good low end torque but high end rpm favors four valves in general. To be honest, if I could have found a GS1100e for the right price at the right time I would have bought it instead of the XS11.
Cheers, 50gary

[MacMcMacmac]

If the bike is everything he says it is, it might be interesting to see what it would top out at with the XS750/850 final drive mod.

[MAXIMAN]

My bike has been dynoe'd at 95 rwhp and 69 RW ft-lbs of torque.

Of course I'm pushing a fairng and bags...and I've seen 127 -128 out of mine. I think it might actually 145 or 150 naked. The calculated speed with an XS750 drive at redline is 151 mph.

I'm just not sure that mine could actually get there even naked because of the power to weight ratio. In this case 565 lbs / 95 rwhp.

My ZRX1200 is putting 126 rwhp to the pavement. It weighs 498 lbs soaking wet and has a much higher power to weight ratio. It is also geared even taller than the XS750 mod.

The fastest I've ever seen on the speedometer is 162 mph indicated and that is optimistic...I was probably doing 155 - 160 mph actual.

So I doubt an Eleven....even hopped up and putting 125 hp to the rear wheel would do more than 150 mph even with the XS750 mod.

One last thing...concerning speed and power. The mathematical relationship is not proportional....it's exponential. In lay terms simply put this means it takes huge gains in horsepower to realize a small gain in speed.

[HobbyMan]

i think it is 4x the power to double the velocity, not factoring wind resistance. I also thing that having 4 valves is to bring the mass of each valve down. I guess so you can run at a higher rpm and have less power required to move the cams. I saw an article on electrically operated valves. They just had an engine and placed solenoids on top of the valves. That way they were able to electonically push the valves open and pull them closed with a spring assist much faster than mechanical action. As a bonus, they had a computer controlling the valve timing. I am not sure if they got it working correctly or not but I do think the engine actually ran. Has anyone seen this article?

[excess11]

Drag bikes

Most people would have to agree that the Kawasaki KZ900 is just about the greatest drag bike there ever was!!!!!! It has just a 2 valve head design but modified can make enormous horsepower.

[MacMcMacmac]

International is putting electric valves into its engines. Some might already have them, I'm not sure.

Electric Valves for Navisater


The KZ was indeed a rock-solid drag bike, but was superseded by the four valve Suzuki. Of course, if valves was all there was to it, the drag series would be dominated by FZRs.

F1 engines use pneumatic valve springs which allow them to hit 22,000 rpm without valve float.

[50gary]

excess 11, the Hayabusa is the current drag racing boss with four valves per. and that's the whole point of this. the four valve layourt is (all other things being equal) preferable to two valves. Time and technology marches on, although Peugeot had four valves per cylinder way back in the 1930s. Yamaha even uses five valves per cylinder.
Cheers, 50gary

[excess11]

What?

I thought this post was about classic motorcycles, I would hope technology has advanced since the 1970's. How about a GT750 or Kaw H2, It had no valve technology but was king of the dragstrip!!!!! Unbeatable in their day!!!

[mainlylinux]

Electric valves

That's the ticket - where do I sign up?

[TomB]

Hey don't forget Rudge did 4 valve heads in the 30's

I also thing that having 4 valves is to bring the mass of each valve down

Yep, less weight makes them easily movable = more revs and less spring strength to move them = less horses used up turning the cams.

Click Rudge head

[pggg]

All you do is bung in an extra 2 valve holes preferably with something better than an electric drill but see that A.P.E outfit fits twin sparkplugs for couple hundred dollars, even slamming on a GSX head I suppose, but the GSX's and GS's, 1100 & 1000 I rode, the 1000 was more like an XS than the 4valve GSX, compared, the 2 valves still give screaming top-end it's only 9000revs, the 4 valve one I rode was mushy down low and peaky, even though dyno sheets show otherwise, compared to the XS longstroke 2 valve is torque everywhere, riding it only can tell.