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Post by marlon on May 20, 2007 11:02:16 GMT -5
Hey Fellas!
I was wondering if anybody has ever had a set of wire spoked and mag SR wheels next to each other. How does the weight compare?
I'm wishing that my SR had more responsive rear brakes, and I don't mind the look of the mag wheels (when they're powdercoated black!) and I'm weighing (pun not intended) up the possibility of swapping the wheels.
Alternately has anyone ever installed a disc brake on the rear? Or are there simpler solutions that I haven't thought of yet?
Cheers in advance fellas!
Marlon
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Post by StewRoss on May 21, 2007 2:44:08 GMT -5
Hi, If you were after the mag wheels the E and F models came with a rear disc as standard. A wire wheel with disc for the rear is a little more problematic, but definitely not impossible. There are a number of disc hubs around that could be adapted depending on the chain alignment problems and so on...I am going through this now and I am trying to track down a suitable hub. My setup is a little different though in that I am looking for a particular style and the swing arm will be manufactured to suit. There was a Yamaha called an RD250CD that was aroung about '76 - '77 or so. These came to here to Aus but were not real common. They had a rear disc and it would undoubtedly suit...however you would possibly have to change the rear sprocket alignment etc. A matter of a sprocket spacer etc.  Talk to you about on the weekend... SR  |
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Post by colinjay on May 24, 2007 17:28:20 GMT -5
Marlon,
This will probably be a sad example of how I spend my time, but you initial question about the difference in weight of wheels for the SR prompted me to do some checking. I borrowed a set of precision scale from work and what follows are the results of an exciting evening at home.
All wheel weights are without tyre and tubes, but include rim tapes on wire wheels.
Front wheels:
STD SR500 19" mag wheel with disc 7.85Kg
XS650 wire wheel, 19" alloy rim with disc 7.21Kg
XS250 18" mag wheel with disc 7.76Kg
SR500 front brake caliper with pads 1.28Kg
Rear Wheels:
STD SR500 mag wheel with disc & sprocket 10.86Kg
XS650 wire wheel, 18" alloy rim with sprocket but no brake plate/shoes 8.70Kg
XT500 wire wheel, 18" alloy rim with sprocket but no brake plate/shoes 8.28Kg
TT500 wire wheel, 18" alloy rim with sprocket but no brake plate/shoes 6.60Kg
SR500 rear brake caliper with pads 1.55Kg
XS650 rear brake plate with with brake shoes and actuating arm 1.78Kg
Therefore:
STD SR500 rear mag wheel with disc, sprocket & rear caliper assy 12.40Kg
XS650 wire wheel, 18" alloy rim with sprocket & brake assy 10.48Kg
I was to lazy to remove wheels from bikes a could not find my spare brake plate assy's for the XT/TT rear wheels to weigh them, but if you add about 1kg to the wheel weights for the brake assy's it should give a ball park figure.
As a side note, I weighed both a SR and TT crankshaft assy's (no main bearings fitted) for the following results;
SR500 crankshaft 7.25Kg
TT500 crankshaft 6.59Kg
CJ
CJ
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Post by fenz on May 24, 2007 19:10:10 GMT -5
Suprised to see that the mag wheels are not that much heavier than the spoked wheels.
Would have thought that there was a lot larger difference.
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Post by canucksr on May 24, 2007 23:36:36 GMT -5
I like the mag wheels that are stock Yamaha. I had two bikes with wire wheels...a 79 GS1000 Suzuki, and a 74 Kawasaki triple. I put mags on both and the difference was amazing. Stability and handling were waaaay better. My SR is an "F" so it's double disc and I find that's plenty of brakes.
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Post by marlon on May 27, 2007 4:47:15 GMT -5
Colinjay, you're a bloody legend mate! Thanks for that - it's greatly appreciated!
I'm with fenz - i would have thought the mags would have been much, much heavier than that. Very interesting. I'm looking at doing the conversion because I really miss a rear disc brake (Though after speaking to people at the KVR it doesn't seem to be an issue for anybody else? Am I the only one who misses it - I do use a lot of rear brake, but this could be because my front end is so soft)
There yas go! Time for a hunt around for some mags. Powdercoat them black and whammo!
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Post by davedunsboro on May 27, 2007 7:16:37 GMT -5
I've got a front mag you can have for the cost of the freight if you cant source one over there ! I've got 3 rears but there all drum/type (bummer) cheers from Dave.
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Post by wizz954 on May 29, 2007 8:13:45 GMT -5
CJ, I'm surprised at the weight of the rear mag you quoted as my racing SR has a rear mag and with cush drive, sprocket, disc and tyre, it weighs 18kgs which is a LOT and that excludes the rear brake caliper! A tyre weighs around 4kgs so that would make mine around 14kgs plus brake caliper.
I'm looking for a wire wheel for the rear to save weight, but if you have a rear mag that weighs so little, I would like to know what year/model it comes off, maybe Yamaha made a different spec wheel at some point
Cheers,
Rick
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Post by colinjay on May 30, 2007 17:25:09 GMT -5
Rick,
The rear mag I weighed was a STD wheel from a 1978 SR500E. It is the wheel that will be fitted to the classic racer that I am currently building. The wheel is a cushdrive type and was fitted with a STD SR rear disc and a 46T XT sprocket. The only thing missing from the STD setup were the sprocket nut and caliper bolt locking tabs (which weigh bugger all) as I normally lock wire these nuts and bolts, due to the outragous cost of the genuine locking tabs, and the fact that I have a couple of rolls of lockwire and lockwire pliers from my navy days.
I will take the scale from here at work home again on the weekend and check it again, and also weigh a tyre or two.
CJ
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Post by colinjay on Jun 3, 2007 22:33:12 GMT -5
I have checked the weight of the rear SR wheel and got a weight 10.83kg, which is very close to the previous weight.
While I was at it, I took the rear wheel out of my stock SR and got a weight of 15.44kg, for the complete wheel fitted with very worn 4.25/85 x 18 Dunlop K81. This wheel is fitted with a drilled brake disc, but a comparison of a undrilled V's a drilled disc gave a weight difference of 0.26kg. The drilled disc weighing 2.16kg V's the undrilled disc at 2.42kg. So the weight of my rear wheel would be about 15.7kg with a std disc fitted.
I also went thru my collection of loose tyre and got the following results.
Near new 4.25/85 x 18 Conti 5.35kg
New 4.10 x 19 Dunlop K81 4.74kg
near new 3.60 x 18 Dunlop K81 3.05kg
near new 3.50 x 19 Bridgestone Mag Mopus (OME tyre) 4.74kg
Rear tube 4.00/4.50 x 18 0.66kg
Front tube 3.50 x 19 0.62kg
CJ
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Post by colinjay on Jun 4, 2007 17:22:26 GMT -5
Apologies,
THe weights I quoted previously for the drilled V's un-drilled disc were for a SR front disc, not a rear disc., however the difference in weight would be similar for the rear disc.
CJ
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Post by wizz954 on Jun 8, 2007 7:40:33 GMT -5
Well, it sounds like I've got 2kgs hiding in my wheel somewhere. I have Bridgestone BT45 120/80x18. Maybe it's a heavy tyre. I am using an XT500 520 rear sprocket (steel) with 44 teeth which is lighter than the 530 sprocket. Plus I am using std disc undrilled.
The only parts of unknown weight are the tyre and inner tube, but hard to imagine an extra 2kgs over any other tyre/inner tube.
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