GT750 Drag Bike

Retro, Wild, Cafe, etc. The stuff only your imagination can come up with.

Moderators: oldjapanesebikes, H2RICK, Suzsmokeyallan

Post Reply
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

GT750 Drag Bike

Post by water cooled »

Hey,

It's great to see the site back up and running. Great job to those involved in capturing and archiving the old data and posts. Thanks !!!

Well, since my last post on the bike build, I got a lot accomplished and made it out to the AMA Norwalk Fall Nationals during October 10-12.

My GT750 made it past tech inspection and I made several passes. Here are a few pics of the GT750 (the way it looked that weekend). I continue to make modifications to further reduce weight. Between the front rotor/caliper and battery change, I saved 21 lbs. I am starting a serious effort converting the head to a "squish" design. I made 3 passes, each one slightly better than the prior with the best pass at 12.83 sec/104.3 mph. I know thats not fast but it was a great shake down run and I had a blasts.


Image

Image

Image
Last edited by water cooled on Tue Nov 18, 2008 8:47 am, edited 1 time in total.
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

AMA Super Eliminator

Post by water cooled »

Here are some pictures that were taken of all the two stroke bikes at Norwalk. I hope it is ok that I clipped it from the Kawasaki Board but these bikes are all awesome and should be seen. There is a wave of two stroke drag bikes making their way to Norwalk. Please click on "PLAY" to see all the bikes...

The first pic is me :shock: needing to lean out the carbs.

http://www.shutterfly.com/progal/slides ... 5c8&idx=20

....but I was there and went as fast as I could....
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

Another side view of the GT

Post by water cooled »

Image
Last edited by water cooled on Tue Nov 18, 2008 8:48 am, edited 1 time in total.
muzza
Supreme UFOB
Posts: 218
Joined: Wed Oct 15, 2008 2:21 am
Location: Western Australia
Contact:

Post by muzza »

great bike Water......I have sent you a PM.

Muzza
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

Battery Upgrade

Post by water cooled »

In an ongoing effort to shave pounds off the bike, I found a replacement battery that I will try out. Its a 12V 3Ah. I need to experiment to a large degree and determine if I can get 2-3 full runs from this battery without degrading the output of the ignition.

Anyway, the weight is about 3 lbs and saves considerable weight compared to my existing YUASA 12V - 14Ah battery.

[/img]Image
Barry S.
To the on ramp
Posts: 444
Joined: Mon Oct 20, 2008 5:31 am
Location: Killen Alabama, USA

Post by Barry S. »

You could probably save 5 pounds by getting those big slabs of metal called brake rotors off the front and putting GS rotors on there that are much thinner and full of slots. One front brake would do on a drag bike, or none.
GT Tim
Yeah Man, the Interstate
Posts: 732
Joined: Tue Oct 14, 2008 9:41 pm

Post by GT Tim »

Barry S. wrote:You could probably save 5 pounds by getting those big slabs of metal called brake rotors off the front and putting GS rotors on there that are much thinner and full of slots. One front brake would do on a drag bike, or none.
*Measure your run-off area first! :lol:
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

Brakes

Post by water cooled »

Barry,

I agree with you. I took one off after getting back from Norwalk and weighed it along with the caliper, hose and bolts. The weight reduction is 11.4 lbs. I am sending one rotor out to have it drilled and expect to get that rotor down to about 5 lbs. and run with one only.

There are lots of places I can pull weight from...

Buchanan has some suitable aluminum rims. I'll drop the front down to 18" and use an MTT-3210 front tire which weighs about 6 lbs. (v. 11 lbs for the Bridgestone BT-45). I'm not sure yet how much weight can be saved switching to the aluminum rim.

There's several lbs I can drop from the engine, I still have most of the starter clutch gearing etc left in there when I switched from points to MSD. I just ran out of time. The cylinder head bolts can save some weight when I cut them down. The cooling system can be reduced, the seat is bulky...etc.

The rear swing arm is no light weight either...and the rear rim needs to be replaced to allow a 5.5 x 18" slick. I might build the rear wheel up from a 1978 GS750 spoked hub and replace the rim through Buchanan again.
User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Post by tz375 »

Kevin,

Great result for a first time run. The bike is looking great.

Other weight savings in no particular order:

Frame - It's very heavy. Contact Randy Illg at framecrafters.net for a light chrome moly frame

Swingarm: Incredibly heavy and not much use. Randy can make you a replacement at a reasonable price.

Starter clutch: can be reduced considerably as long as you aren't using the stock starter that is!

Starter motor, wiring and solenoid.

Front Disk: get a modern disk with aluminum carrier and almost any twin piston, sliding type caliper say SV650 or EX500. You will have great brakes that weigh very little.

Rear wheel: That one is probably very heavy. Spoked stock type wheel with fat rim would look great but isn't as light as a modern wheel. If you can use modern wheels in that class, I'd go with say GS500 or katana rear wheel.

Wheels (Both): Replace teh bearing spacer tubes with aluminum ones but make then .020" longer to allow for crush.

Axles: replace with Titanium if money is no object or get them drilled through from one end to the other. That goes for the swingarm spindle too.

That battery is a good start. We use small batteries on our road race bike and connect them with simple two pin connectors. After a run, pull the plug and plug in the charger using a matching 2 pin plug.

A single charge should last all day, but this way you are always sure that you have a full charge.

Forks: Billet triples could be lighter than stock and use an aluminum fork stem. It seems to me that stock forks are very heavy (thick walls) and a later model bike may have lighter forks - look at a GS500 for example- or even a 250 street bike or cut down a set of 125 motocross forks.

Crank: That could be lighter, but this is getting out of hand :roll:
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Post by Suzsmokeyallan »

You could dump the complete stock front legs and fit some from an 81 GS 850 into your triple trees. It uses the thinner and lighter GS slotted rotors and the calipers as well that mount behind the stancion legs that are also much lighter.
The front wheel/hub from the Buffalo can be reused and you should save at least 20 lbs with this retrofit.
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
User avatar
water cooled
Yeah Man, the Interstate
Posts: 704
Joined: Thu Oct 23, 2008 3:23 pm
Country: USA
Suzuki 2-Strokes: 1974 Suzuki GT750
Location: Medina OH

weight reduction

Post by water cooled »

You guys are giving me enough to keep me busy all winter....I love it. Theses are great mods. I'm going to tackle the wheels first. Drop the front down to an 18" aluminum rim. Dave helped me find a hub for the rear from a 1978 GS1000. Buchanan spokes has a 4.25" x 18" aluminum rim to accept either a Goodyear Eagle or Mickey Thompson slick.

Then, I'd like to finish removing and lightening the starter clutch assembly, switch to the 3Ah battery and make a new bracket and finish off a few small engine mods to increase the compression just a bit.

I'll start looking into the GS850 fork mod and see what I can find on ebay.
20 lbs is a fantastic reduction....and a needed one.

Thanks Richard for the web link to "framecrafters" I studied it closely. Some nice bikes in there and a couple of TR750's in the bunch. I wont be able to do a frame this year but if I sort a number of other things out, it might make sense for 2010. A lighter swingarm might be in the cards though.

Thanks guys. All this is really helpful.

Kevin
markj
To the on ramp
Posts: 341
Joined: Sat Oct 18, 2008 10:01 am
Location: Hudson Valley, NY

Post by markj »

I'm really diggin' that bike. 8)
So many Projects - So little time
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Post by Suzukidave »

Besides going thru the disassembly lighting the starter clutch is pretty easy , remove the three peened over screws on the face and you can remove all the guts from inside the clutch and then just screw it back together .. Dave
the older i get the faster i was
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Post by Suzukidave »

markj wrote:I'm really diggin' that bike. 8)
Yep .. looks low and mean :shock:
the older i get the faster i was
User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Post by tz375 »

Take the starter clutch and as Dave said, dump the contents, then machine it down so that all that's left are three mounting tabs and the hub.

Drill the living daylights out of the gear and bolt what's left of those two pieces together.

The one I modified, dropped just over 600 grams on just that part. That's a pound of steel you don't need to carry.
Post Reply