Phat Trakka

[tz375]

That's true Ian, but I would also have to go back to a stock airbox and ports to get a meaningful comparison.. The ports are close to stock but compression is raised on this motor.

To do a valid back to back test on the same dyno, I'd have to swap back to a 100% stock set of barrels and head with a stock airbox. If we can find someone with a stock bike in north East Illinois or south east Wisconsin, we could test that bike and declare it the baseline. Then we either tweak that one to get the optimum results and then test say a change to filters and see if that makes any difference.

We could try the two other sets of pipes on that bike of course to see the "pipe only" effect.

Then we drag that bike off the dyno, and throw the new one on and declare the difference to have come from known changes to CR and exhaust ports.

If I had started with a complete running bike I might have done things in steps, but we started with a pile of rusty bits, so that was never a realistic option - might have been fun though.

[oldjapanesebikes]

I was thinking more along the lines of different pipes on the one engine - the assumption being that if you hold everything else constant, then any differences are due to just the pipes, and that difference could then be quantified. I realise it is a lot of work though.

Which carburettors are you using by the way ?

[tz375]

Ian, That was the original plan, but I need to lower the back end to allow stock pipes to fit. It would also be nice to compare a stock bike plus each and every combination of parts, but that probably isn't going to happen in this lifetime. That's why starting with a completely stock bike would be a good place to work from.

Carbs:
BS40 with a selection of needle jets, main jets, pilot jets, and needles to fine tune things if necessary. We have others to try in another series of tests. TM39s, TMX34s, Lectrons, Power jet Mikunis, as long as I can borrow enough carbs and jets, anything is possible. I do have a set of TMX34s I'd like to try but no alternative needles yet and they don't have replaceable needle jets. Cables have to be made up, but that's not a major task. And at this stage I'm not sure if they will clear the clutch housing.

I was planning to use a 3mm spacer plate like Lane Rngdng and I figured it would provide adequate clearance, but I need to run this first set of tests and see what works and what doesn't and then I'll work out if different carbs and a spacer will help or hurt it.

This bike is not supposed to be a 9000rpm missile. It's more of an overweight urban assault vehicle so low down grunt is more important than top end, so I need to be a little cautious to avoid mission creep. That's the problem with running on a dyno. They suck you in to the search for more.

[MazerRackham]

I have been stalking your blog for a minute now. I just wanted to say excellent work sir. I'm currently building a T500 of my own, and your bike(s) have been a true source of inspiration.

[tz375]

Thanks.

Managed to drag it's heavy ass up onto a set of scales today to check the weight. Full of oil but only half a gallon of gas, it weighed in 442Pounds. 211 on the front wheel and 231 on the rear. Stock exhausts weigh around 40# and the Strader must be less than 5, no electric starter, clutch, gears or solenoid. No fenders to speak of and no heavy stock gauges. Rear axle, and footpeg bolts were drilled out too It all adds up.

At the old 7# per HP that's an improvement equal to 12HP

The scales I used are more "indicative" than "accurate" but at least we have an idea where we are now.

To put that in perspective, that's similar to a stock H2, 90# more than an RZ (or a 2008 GSXR750 "dry weight"), close to an SV650, but only 50 more than an 85 GSXR. All that work and it's not even close to a modern bike and still is basically an old heavy relic. Would someone please remind me why we do this.

[Fritz500]

Thanks.

Would someone please remind me why we do this.

Because we can
Because it's fun
Because you only live once
Because you're not taking your meds...or you're taking too many.

[water cooled]

R, 442 lbs is a huge reduction from 550 lbs stock. At the beginning of your thread, you were hoping to get below 500. I cant see what you have for wheels, rotors and tire but there is a lot of weight tied up in rotating mass. The alternator rotor is also a big adder but I think you have a modified setup. The battery is the other killer. A 4 amp AGM is a lot lighter than 14 amp for same cost but only you know what is required for your particular electrical setup. Center stand could go unless you really want/need it.

Something tells me you have something special going on there with your wheels. I cant find any pics that show them. Brocks Performance CF wheels?? http://www.brocksperformance.com/

[tz375]

Fritz,
It's OK to pour all the meds into a bowl and scarf them like candy isn't it?

Kevin,
Both wheels have DID alloy rims. The rear axle is gun drilled and the front wheel has light CBR600F something disks in place of the steel boat anchors that Suzuki fitted. Calipers are SV and they are probably similar in mass to stock. of course the forks weigh a ton and if I have to add more trail, that might entail different triples with less offset - good excuse for some nice billet triples, but why do that for stock bendy forks ......And so it goes ........

Anyone know how long SRAD 600 forks are?

[ja-moo]

OWCH! I didn't know they were that heavy, definately working the "underdog" moniker!

I thought my 500 Kawi was a pig at 375 with a full tank. I feel beter....LOL.

[Suzukidave]

I hope my GT custom fully loaded with fuel and oil should be around the 400lb mark .. they quote the dry weight of the stock GSXR at 366lb but i really dont know how much more the GT engine weighs over the GSXR engine .

[tz375]

Dave that would be fantastic if you can get it below 400. I'm on the lookout of a lighter fuel and to use less pounds of air in the tires OK so that was a joke.

And on my frame I removed the lower radiator mounts completely and lightened those heavy front motor mounts. Short of grinding the frame tubes thinner (joke) or replacing them with thin wall Chrome-Moly tubes, there's not a lot left to cut, drill or grind. Maybe it's time for a light Dresda or Framecrafters frame. Not on this bike though.

Aftermarket carbs might save half a pound I guess and the lower triple clamp is around 4 pounds.

Talk about porkers. Still it's lighter an a Hardly Dontwantone.

Dave, since you mentioned a certain GSXR framed GT beast, how is that coming along?

[MazerRackham]

Two questions.

1) Can I use any 32mm-40mm Carburetors?

2) Who still makes frames for these bikes? Can you suggest a couple people to me?

When I was reading Ozebook, a "Jada" frame in particular struck my eye.

[tz375]

Some carbs will just fit but others are slightly too tall and need more space. With a spacer plate, they are OK or cut a clearance hole in the clutch cover part of the crankcase and have a concave piece of aluminum welded in.

VM34 are one size up from stock and work well - not too large. Anything larger and you won't see any benefits unless/until the bike is ported and has decent pipes and even then you will tend to lose bottom end. TM or TMX flatslides can be made to work too. You could try a set of Keihin flats but I have no experience with them.

TR750 style Frames are available from Dennis Curtis in Canada and PEDRO on this board in the UK. If you want a custom frame in the US, Randy and Karsten Illg in Illinois are the go to guys. They can make it any shape you want that's feasible but they do have a preferred shape. Tell Randy what you want and he'll make it.

[MazerRackham]

Some carbs will just fit but others are slightly too tall and need more space. With a spacer plate, they are OK or cut a clearance hole in the clutch cover part of the crankcase and have a concave piece of aluminum welded in.

VM34 are one size up from stock and work well - not too large. Anything larger and you won't see any benefits unless/until the bike is ported and has decent pipes and even then you will tend to lose bottom end. TM or TMX flatslides can be made to work too. You could try a set of Keihin flats but I have no experience with them.

TR750 style Frames are available from Dennis Curtis in Canada and PEDRO on this board in the UK. If you want a custom frame in the US, Randy and Karsten Illg in Illinois are the go to guys. They can make it any shape you want that's feasible but they do have a preferred shape. Tell Randy what you want and he'll make it.

Thank you for all of the information tz!

[MazerRackham]

So how does the GSXR fork size up to the original?

Feel better? Lighter?