Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp

sav0r

Member
Looks great!

I probably would have stitched up like Frankenstein's monster anyways. Your fix is much cleaner.
 
And to answer the question about electric vs kick start parts weight... Closer to the beginning of the thread I did a straight comparison of all the components and did not count in the battery, but did include the heavy metal kick start arm from the SR500. And still, a huge weight savings - see image below.

I actually plan to use the base part of the SR500 kick starter and design my own arm to be machined up in 6061-T6. This will of course be much lighter but I am almost forced to do this anyway because of the clearance required by the rear sets, despite the fact that I upgraded to folding ones! I have heard the RD400 kick start lever has good clearance/sticks out further? But then again, that would be heavy, forged steel anyway.
 

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doc_rot

Oh the usual... I bowl, I drive around...
DTT BOTM WINNER
Not sure how it is on the SR, but when I thought about removing the starter clutch from my kz750 I noticed there is an oil journal where the starter clutch rides on the crank. I'm not sure but it may be necessary to have a spacer to replace the starter clutch so that oil pressure is retained.
 

crazypj

Split personality, I fake being smart
In all probability it's to prevent the bronze bearing on starter reduction seizing up?
 
doc_rot said:
Not sure how it is on the SR, but when I thought about removing the starter clutch from my kz750 I noticed there is an oil journal where the starter clutch rides on the crank. I'm not sure but it may be necessary to have a spacer to replace the starter clutch so that oil pressure is retained.
That is correct. That is why I had the drive gear machined down to just it's hub - to maintain any other important functions is might have - like oil flow control. Below you can see what is was and what it became - final image shows the outsourced machine work which included grinding it down properly on a lathe.
 

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teazer

Active Member
DTT BOTM WINNER
CB77 Honda used a similar arrangement with a hole in the crank to lubricate the bush. CL cranks don't use a starter so they don't have that oil hole, but cannot always source a CL crank or crank end, so I used to use a carb needle to block the hole. Cut it short, and "rivet" it into place. Never had one come loose.

You could probably fill it with low temp solder or brass too.
 
After rebuilding the engine and having spent so much time and money on it, I thought it wouldn't hurt to develop a billet magnetic sump plug. One, because the stock one is tiny and the cast alloy is like butter, and two because well a magnetic sump plug is good!

I bought a countersunk neodymium magnet that works with an M4 screw and designed around that. The printed prototype works really well and I will do one further iteration before ordering it in aluminium.
 

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teazer said:
CB77 Honda used a similar arrangement with a hole in the crank to lubricate the bush. CL cranks don't use a starter so they don't have that oil hole, but cannot always source a CL crank or crank end, so I used to use a carb needle to block the hole. Cut it short, and "rivet" it into place. Never had one come loose.

You could probably fill it with low temp solder or brass too.
That's a great idea Teazer. However I was concerned in this case that that oil galley in the crankshaft might feed other important things on the clutch side of the crank case assembly. Oh well, no harm done either way I'm pretty sure. In this form, it will just do it's thing the same way it did in stock form.
 

zap2504

Member
Magnetized sump plug is cool! No other convenient place to strap or epoxy a magnet since the whole bottom of the plug is the installation nut and the oil filter is internal. Neat that you can see how the sump plug/screen actually fit in the case!
 
Received the final versions of these blinker adapters the other day. I think they'll look neat once I blast off the black paint from the mini blinkers and expose the cast aluminium underneath. I'll clear coat them or something to protect the material a little. But everything should look pretty good being most aluminum up front there - headlight brackets included.
 

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Habanero52

The Race......is only with yourself!
JadusMotorcycleParts said:
Received the final versions of these blinker adapters the other day. I think they'll look neat once I blast off the black paint from the mini blinkers and expose the cast aluminium underneath. I'll clear coat them or something to protect the material a little. But everything should look pretty good being most aluminum up front there - headlight brackets included.
Those are cool blinkers. Would you mind sharing where you purchased them?
 
Habanero52 said:
Those are cool blinkers. Would you mind sharing where you purchased them?
Yeah they are pretty decent quality and don't cost too much. I got them from Biltema here in Sweden - a motorists grocery store pretty much. But they sell under other names at a few different places. Found them here on Amazon and I am sure they could be found on ebay too:

https://www.amazon.co.uk/Devil-Eyes-Micro-Mini-indicator-Motorcycle/dp/B00RQ3U1MG

https://chop-it.de/en/lights/turnsignals/20-mm-led-turnsignals-black

https://www.conrad.si/devil-eyes-led-smernik-za-stirikolesnike,-mikro

Looks like they're called Devil Eyes hahaha
 
With the engine half buttoned up and wrapped up in a sheet, it was time to trim the frame. Pretty decent weight savings here. I'll weld up a couple patches (steering lock hole in the neck for example) and then blast and paint it.

This may sound strange, but I really want to hand paint the frame - yes, with a brush. I want sort of a rough old vintage bike look. I read somewhere in an issue of Classic Bike that one of the editors has done this and I though it looked cool. It also lends itself well to patching up scratches down the road haha

However, I don't know what kind of paint to use. Any suggestions? I would really like to know what paint is used to restore all the metal frames and rails on bridges for example - because that is applied by brush and is extremely tough and weather resistant. Thinking it must be oil based but what exactly? And would it need an undercoat?
 

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spotty

Vmax...why,yes i think i will
thats impressive, a 9kg frame, perhaps you could pop down to australia and perform similar surgery on my vmax, mind you the rear wheel is still going to weigh more than your engine so probably not worth the effort and i'm a fat bastard anyway so a couple of kilos off the frame wouldn't really be noticed

as for paint, from memory the vintage guys use a basic enamel thinned down to avoid too many streaks and lines, you'd use an enamel undercoat and thinners ( turpentine ?) and use long even strokes, these memories come from reading classic and motorcycle mechanics way back when
also has the advantage that its unlikely to react with anything if you're using the same basic formula all the way through and its easy to touch up with enamels later on as they're easy to get anywhere
 

3DogNate

"You Meet the Nicest People on a Honda"
JadusMotorcycleParts said:
However, I don't know what kind of paint to use. Any suggestions? I would really like to know what paint is used to restore all the metal frames and rails on bridges for example - because that is applied by brush and is extremely tough and weather resistant. Thinking it must be oil based but what exactly? And would it need an undercoat?
VHT Epoxy Paint Gloss Black... Applies beautifully and is pretty darned tough.
 

Maritime

Active Member
3DogNate said:
VHT Epoxy Paint Gloss Black... Applies beautifully and is pretty darned tough.
+1 this is good stuff, I've used it 2-3 times and it turns out pretty nice. poor mans powder coat if you lay it on in the right conditions. i.e. watch humidity, 70% or less I think and it really makes a difference.
 
Thanks for the input. The thing is I have the possibility to powder coat - I have my own set up. So for me, powder coating will beat a rattle can any day of the week. However, to achieve this brushed on look, I would like to try an alternative. For me to buy a spray can, spray it in the cap or something similar and then paint that on with a brush just doesn't make sense.

It must be possible to buy like steel fence paint in a bucket right? Something like the attached? Just wondering if anyone had some suggestions and/or experience with such a method and the paint used.
 

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spotty said:
as for paint, from memory the vintage guys use a basic enamel thinned down to avoid too many streaks and lines, you'd use an enamel undercoat and thinners ( turpentine ?) and use long even strokes, these memories come from reading classic and motorcycle mechanics way back when
also has the advantage that its unlikely to react with anything if you're using the same basic formula all the way through and its easy to touch up with enamels later on as they're easy to get anywhere
Thanks for the tip. Makes sense. Glad someone else remembers the magazine article/s!
 
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