Best DT1/RT1 weight savings

[Tahitian_Red]

I just weighed a stock front wheel vs. a hub, Excel rim and HD stainless spokes and nipples.  The savings is a little over 1.25 pounds.  The back rim is bigger, so the same setup should saves around 1.5 pounds.  That's just under a 3 pound saving of un-sprung weight.  I was hoping for a little more than that, but with the rules forcing me to keep the stock hubs it's gonna be hard to turn my RT-1 racer into a "Lightweight".

Stock hubs, forks, triple-clamps and frame must be retained and replacing the tank would defeat the purpose of the class (stock looking bikes from 68-71), so what are my smartest choices for putting this pig on a diet? I'm planning to use as much aluminum as I can, but don't want to go crazy and spent big money on Titanium.
 

[Iain Cameron]

Are you allowed to cut off all the brackets on the frame . the bolt in the middle under the motor . air box ,oil tank and pump ,can you run the alloy fork sliders ? seat try a DT2MX glass base . chain guards alloy then paint black . When you say era hubs can you use other hubs from the era or only Yamaha ones . Iain

[Tahitian_Red]

Oil Tank, pump and Air box are already tossed.  The skid plate is gone also.  It's a '71, so it has the aluminum sliders and the seat needs to look stock.  Hubs must be the stock ones that came with the model ('68-'71 DT1/RT1).

[Iain Cameron]

Drilling brake shoes in the webs and mill work saves a bit (bugger all ) change the brake stay arm to alloy . mud guards ? original as well or after market aloud ? front hub a AT or CT one is much smaller also Ive run a CT rear hub . can you get away with that .

[firko]

Jay, I think you're pretty much going to have to rely on your riding brilliance as you've done pretty much everything without replacing axles and bolts with titanium. You could use an MX250 style rear hub and hope nobody notices but the ounces you save are miniscule. What tyres are you using. Take your bathroom scales along to your local bike tyre outlet and weigh all of the different tyres. I believe there's quite a difference in weight between the various brands.

[jerry]

Only run enough fuel for the race distance instead of running around with a full fuel tank. Lightweight tubes or tubeless. There was an article years ago in one of the old American mags maybe Cycle World about a blokes effort to build the ultimate lightweight Yamaha. I think Firkov may know about it. Cheers Jerry

[firko]

I think Firkov may know about it

http://ozvmx.com/community/index.php?topic=28129.0

[Iain Cameron]

Jay how about the TY250 alloy tank its period as well .

[firko]

Jay how about the TY250 alloy tank its period as well . 

Iain I got the impression that he has to run the stock tank to keep the stock appearance of the bike....but I might be mistaken. There is a holy grail tank made by Maely (the speedway steel shoe guy) back in the day that is basically a 'glass replica of a DT1 tank, only a tad narrower. Don Jones also made one and I think those hippy surfer fibreglass tank guys in Santa Cruz (can't remember the company name) made a glass DT1 replica tank as well. Of course I haven't seen any of them up for sale for as long as I've been scanning eBay and the Swapmeet. I recall seeing an exact replica aluminium DT1 tank on the shelf at Vintage Iron back in the mid 90's. Doughty wouldn't sell it to me.
Here's a poor shot of the Jones tank (right)
                                                                                               

[Davey Crocket]

Hollow chrome moly axles and swingarm bolt...stronger and way lighter....you don't need titainiun, can you use alloy triple trees?....those std cast iron ones weigh as much as a new chinesse chinka pitbike....put holes in everything like a YZ A......or you could dip the whole sucker in an acid bath like they did with the drag cars in the 60"s to get rid of weight. .....I reckon theres a few kilo's in a YZ A clutch/gearbox aswell....."Cycle World" magazine article from back in the day did a good job.

[KB171]

DT diet tips the cycle world mag.

[Tahitian_Red]

Pretty much going to follow that recipe when I put together my RT2MX.  I have most of the items except a Boyd and Stellings swingarm.

 

[Iain Cameron]

bit of a weight save but a cool bit of kit http://www.ebay.com/itm/NOS-Yamaha-DT1-Torque-Engineering-Exhaust-Pipe-DT2-DT3-AHRMA-/300901456481?pt=Motorcycles_Parts_Accessories&hash=item460f1fda61&vxp=mtr

[Tahitian_Red]

Got a Hooker pipe on her already and it's a weight savings over the stock "Boat Anchor". 

I'm looking at using as many YZa parts as I can find that fit on the RT and do not break the spirit of the class.  A fiberglass seat-base or an alloy or fiberglass DT1/RT1 tank would be nice, but I'm sure I'm just dreaming.  Looks like the rear wheel, swingarm and pipe are where most of the fat is.  LOL

[vandy010]

Looks like the rear wheel, swingarm and pipe are where most of the fat is.  LOL

and the frame...
 i think they rolled the frame tubes up from an old bulldozer blade...