Water cooled 500

[tz375]

This may seem like a completely off the wall question for any normal person, but since that excludes me, I'll ask it anyway.

Has anyone tried to graft a top end from a modern sled onto a T/GT500 bottom end?

We have played with triple-triple sled jugs and cases to see if they could be adapted to work on a GT750 and the answer is NO. Crankcases are almost the same width on a 800 or 900 triple but spacing is all different and there's no room between cylinders to make that work.

But that's not quite the same on a 500 and a 500 doesn't have those twisted ports either. Seems to me that it might be possible without much work (ie small amount of welding and machining etc) to slip say a 600 twin top end onto a 500 bottom end. Why would anyone think of such a devious idea? Partly because that's how my mind works, and because it's possible.

A modern 440 twin makes around 110 - 130HP and a 600 is 120 to 150 and that's with a 2 into 1 pipe! Current Polaris 600RR is 77.25x64 and makes a claimed 120HP. Of course it's case reed and not piston ported, but that's just details, right It might be easier to cast a new block with suitable reed cages and more modern port arrangements and settle for say 125HP.

I have no idea if it's feasible, let alone practical, but it seems it might at least be possible. Anyone game to try it?
It would make a neat TR500 replica in a decent chassis as long as there's a class to run it in. or just as a street bike in a Curtis or Framecrafters chassis.

[diamondj]

TZ,

The T500 does have the twisted transfer ports. Plus the rods are really close together. Something like 98mm center to center versus 110mm c - c on the later snowmobile engines Suzuki built with a 70mm bore. Which is a shame as there's a water cooled 500 cc Suzuki Spirit engine for which parts are fairly easy to get. And there's nothing out there that I know of that has the transfers angled like the T500. Even Suzuki switched to the sides for the transfers on the later TR500 cylinders.

I like the look of the air cooled IT250 Yamaha cylinders but I haven't gotten one yet to see how close one would be to fitting with the fins cut off one side. And even then you'd need to fill the current transfers and stud holes and put in new ones in the T500 crankcase.

I think you would need to find a Nikasil plated bore in order to find something thin enough to fit the T500.....

Jim

[titan performance]

Ooh that sounds like a mission.....

We did discuss a similar proposition with our two stroke guru, Richard......we were pondering the posibility of grafting on a couple of 250 crosser barrells to a T500 bottom end. That must get you to 100 bhp + or so. However, we have never got further than discussion.

[tz375]

I should have done more checking and less "blue skying". I looked at pictures of a TR500MKII barels and base gasket and they had regular , non twisted ports.

I hadn't looked at earlier or street motors, but sure as fate, they were twisted to make it narrow. Looks like Suzuki changed teh crankcase and port design on later TR's.

In that case, it would need TR cases or a new barrel cast from scratch. What is the spacing on Banshee or TZ? The ports would still need to be "straightened" but it might be possible to slide a CPI Cheetah top end on for just as much power with even less work - other than a little (?) crankcase welding and machining.

Though if you were to do that for a street motor, you might as well just build a Banshee/RZ and get 6 speeds in the package.

I wonder if CPI would consider casting a modified Cheetah barrel with GT bore spacing and twisted ports? You could do it as a TR replica with more modern porting or go straight to reeds if there was any conceivable market.

[tgrogan]

IThough if you were to do that for a street motor, you might as well just build a Banshee/RZ and get 6 speeds in the package.

Ah, the real issue! Get your high-powered, high reving cylinders installed on a T500 bottom end - then start working on a replacement for possibly the worst ratioed (for racing) 5 speed transmission ever built. Then we could discuss the chassis. It just makes so much sense to carb, port, and chamber a T500, and then have fun with it. But turning it into a franken-bike doesn't. Back in the day we sawed a GT750 head and barrels into 1/3rds, but gave up quickly trying to put it on a T500. Mainly because it just wasn't worth the effort because a T500 is one of the best air-cooleds ever built. There are so many quirky design parameters at work in a T500. They worked for the street and met a price point of under $1000, but they fight extream modification mightily.

[diamondj]

There are so many quirky design parameters at work in a T500. They worked for the street and met a price point of under $1000, but they fight extreme modification mightily.

Okay that's probably the best summary of what a T500 is I have ever read!

Ya know Teazer if we're going to make some modifications to a Suzuki, let's follow in Barton's footsteps and punch a GT380 out to 500 water cooled cc's. Heck, Graham Dyson was half of Barton along with Barry Hart and is still running Nova racing transmissions. He might even still have the patterns to cast up the cylinders. And since they ran the Barton back in the day, I would think it would be legal for most racing organizations.

Or we could find out where Pedro is with making replicas of the Mk III TR500 barrels and heads. Then see if a GS550 six-speed really will fit into a T500 crankcase (it's got the same shift fork set-up as the T500) and by that point we're just down the road from extending the input shaft on the transmission for a dry clutch.....

Of course for the money you spend, you could just buy this:

http://www.ebay.co.uk/itm/Barton-suzuki ... 19c8028125" onclick="window.open(this.href);return false;

This feels like a similar conversation they had on the cafe board only about T500's rather than CB750's....

Jim

[tz375]

Terry and Jim, You are right. I was just thinking out loud again. Once you start down that line of thought, it quickly hits a reality check (wall).

Why does that replica Sparton look all wrong? Did they make an oversized frame or did the motor shrink in the wash. There are lots of Sparton/Barton pictures on the web and most look great, but that one not so much.

Good point that it should be legal and could shake up the established order. That may be the thread I was stirring up over there. That discussion got hung up on the definition of a Cafe Racer and who had the best bits, so I suggested a slightly more radical approach .

[diamondj]

Pedro,

Have you made any headway on duplicating the Mk III TR500 barrels and head? I do still need a head for mine (and the cases modified and a water pump and etc.....).

Jim

[tz375]

Pedro, is Barry Hart still working on Porches? I read somewhere that he claimed that he didn't much like working on bikes, but that may have been a misquote.

[diamondj]

Hi Jim, nowhere so far, the guy who was going to loan head barrells and pump to me never came across with them and dont answer anyones mails.....Kev Fletcher from tired iron racing, so if anyone knows fletch, get him to give me or spike a buzz.

Sorry to hear this. Don't know Kevin although I have heard his name before in relation to T500 racing.

So... how far would the loan of just a set of water cooled barrels get you?

Jim

[tz375]

I'm not sure if I got the story right but he has an ex Les Trotter bike plus a Harpower reed valve GT750 motor. He's in "Canadia" I think.

They used to be at http://www.tiredironracing.com" onclick="window.open(this.href);return false;, but I'm getting no response from that URL at the moment

[greasemonkey]

I think that some old 250cc honda cr cylinders would work like a charm
they got the reed on the cylinders, and with a filler plate and longer rods you can get some decent runners in the block.

88-94 cr 250 2 stroke

[tz375]

Unfortunately, no modern two stroke top end fits on these old bottom ends - at least none I have looked at so far.

[greasemonkey]

Unfortunately, no modern two stroke top end fits on these old bottom ends - at least none I have looked at so far.

in way that the engine is not wide enough to place 2 cilinders? I've been miss matching cylinders my hole "career"
i will give it a try and post some pics

edit: just find a lead on 2 cylinders like these


250cc rotax 12000rpm non powervalve and 65hp stock.
if this is cheap I'll chop up a engine for it

[Suzukidave]