1981 Yamaha SR250 Cafe Racer

lunar_c

New Member
Hi guys and girls,
This is my bike, a 1981 Yamaha SR250. It was basically given to me, and when I dragged it home, it was a pretty sorry sight ..



Initially I didn't have any grand plans for the bike, I intended just to clean it up and use it to get my license as I've always ridden offroad since I was a kid, but have never had my road license.

Then, as I got into cleaning it up I was inspired by some of the amazing work Deus Ex Machina (www.deus.com.au) in the eastern states (I live in Western Australia) do with the humble Yamaha SR and decided since I have always loved 60's race bikes such as the Manx Norton's and British cafe racers, that I'd turn it into a cafe racer.
I played around with the stance of the bike by slipping the forks through the stanchions 2 inches, raising the rear shocks, lowering the bars and removed the seat in order to measure it up and fabricate a cafe seat, I also repainted the tank and shaved the badges (what a mission that was, that tank has so much filler in it, it was junk, but my "budget" dictated I save it!) and the bike began to look like this ..



And here's a couple of photo's of the tank before and after painting, I shaved the badges also hence all the filler ..



After about a zillion coats of high build primer it finally started to look straight ..



I had a friend who is a spray painter paint the tank for me (but still using rattle cans) and I think we made a pretty good purse out of a sows ear..



I then decided to clean up the rear end of the bike, so I gutted the middle section by removing the side panels, airbox, battery box, inner guard and tool box (for want of a better description, you could probably only fit a 10mm spanner and some loose change in there) deciding to relocate the battery, run a pod filter on the carburettor, and hide the electrics. At this point I stripped the bike ..



I then decided to go solo, and remove the loops that mount the pillion pegs, sidestand and muffler from the rear downtubes. I also removed any superfluous mounting tabs and brackets for a cleaner look, and welded plates over the holes where the loops were.

Here's the frame before modifications ..



And after a lengthy session with the grinder (actually 3, two of the ones I borrowed from the workshop died on me before I bought a good one!) and wire wheeling the paint off ..



And after all the grinding, cutting and welding here it is with a coat of paint and the rubbers back on. As you can see I still need to fabricate a clamp/bolt on muffler mount and sidestand, but I am waiting until the bike is a rolling chassis again ..

 

lunar_c

New Member
More..

I used gloss black RustKill epoxy enamel which gives a very tough finish, but creates an immense ammount of overspray which unlike most paints, is extremely sticky! Wear a mask and long sleeve clothing and do it in an open area or a booth if you can! Here's a pic of the frame with the tank on ..



Once the frame was done I started on the myriad of other things that needed detailing and painting. Every nut and bolt has been wire wheeled and polished, after all it only takes is time and patience so why not do it to the best standard you can, right? ..



The forks are a little pitted at the top where they slide through the triple clamps, but they are fine in the travel area, so they will simply get new fork seals and oil. After wire wheeling ..



The engine mounts, all removeable brackets and sprockets were all stripped down and painted ..



As with the frame and everything else, the swingarm was taken to bare metal before being painted to ensure a good finish ..



And finally here it is painted ..



The triple clamps turned out especially nicely after painting and polishing the bolts, and there's two spare tapped holes for when I get around to ditching the speedometer housing and running a nicer gauge and making an alloy panel for the idiot lights ..



Speaking of the speedometer, I am keeping it for now (as this bike is being built on a very small budget over time) so I decided to shave off the raised white lettering for the idiot lights and then masked it and sprayed it using K&H bumper and trim paint, which has a slightly speckled finish and is weather resistant. I polished the chrome trim piece and reassembled it after painting it's mounting bracket with the same epoxy enamel I used on the frame.



The headlight got the same treatment ..



With regard to the wiring, it was mostly pretty good so I simply labelled everything, layed it out on the bench, cleaned it thoroughly ..



Unwrapped it checking for any faults, and replaced any corroded or crumbly connectors and plugs ..



Then rewrapped it in a quality black electrical tape, here it is ready to go back on the bike ..



The last things to do styling wise, are the fabrication of the seat and hump, and the front fender, which I've cut to the right dimensions, it still needs shaping and blending though ..



The engine is a SOHC, 2 valve 239cc single, running 8.9:1 compression. It's listed as producing 20hp from the factory. I'm fabricating a new exhaust that matches the diameter of the exhaust port (the standard one flares down sharply inside the cosmetic outer pipe) with a BSA gold star style silencer. I am also running a pod filter on the 34mm Mikuni carb and it will be rejetted to suit, but as it's pretty healthy that will be it for now. If I decide to continue on with the bike, I will rebuild the motor, raise the compression and so on later on.

Here is the engine as it is now ..

 

jay_kent

1979 cb650
wicked build,

I just finished getting one done for my wife. It was an ebay buy for $160, sat in the barn for 2 years. The manual says the top speed is 83 km/hr but I had it up to 115 and I'm 220lbs. Poor thing was screaming. It was a surprise for her, and if she didn't like it i was going to cafe it.
 

lunar_c

New Member
Thanks guys!
They're a pretty unassuming bike, but the SR400 and SR500 in particular lend themselves very nicely toward the cafe treatment. Definitely take a look at www.deus.com.au they have a couple of cafe racer and manx inspired designs based on the SR400 that are simply brilliant! Personally I love the look of drum brakes (I grew up reading my grandfathers old motorcycle books!) so I like the SR250 for that reason.. I'd like to switch the front end out for something with a bigger TLS drum later, which would of course invite me to give it some more power to match ;)

The manual I downloaded online says 89mph.. or 146km/h in the metric money. With a tail wind perhaps .. So far I've ditched about 12kg of stuff from the bike, so I am hoping it'll be pretty nippy for an old 250 with the lower weight and engine breathing modifications.
 

lunar_c

New Member
I got a little work done on the bike today. I cleaned and polished the drums, gear shift lever and brake lever, started on the carb and did a few other little jobs.

Here's a pic of the drums and levers ..

 

Ease

83 XJ650RK, 77 TS-250
You're doin a great job on that bike!

Lookin forward to what you come up with for a seat.
 

lunar_c

New Member
Thanks for all the encouragement, guys! It makes my day.
Got the front end together today!

Head stem bearings in with Castrol HTB grease ..



Here's the frame on the floor of the garage with the front end installed and head stem tensioned. The swingarm is sitting next to the bike because I've lost one of the cup washers that hold the sleeve inside the swingarm pivot and have to order one tomorrow.. otherwise it'd be on there.. D'oh!



Tomorrow I will go and get the few replacement nuts and bolts I need to finish the frame assembly and order a few things. I'm also replacing all of the phillips head screws on the engine with hex head set screws. Then it's onto detailing the wheels so I can make it a roller ..
 

lunar_c

New Member
Hey!
I got heaps done today and I'm totally digging the look of the bike now, I have renewed enthusiasm and I'm eager to finish it!

Last night I sprayed the underside of the tank with black chip guard paint to protect it, I mocked up the bars today, and also put the brake pedal and foot pegs on

I also fashioned a small clip to hold the tank on it's rear mount out of some scrap metal, and filed down a bolt to match as it was MIA when I got the bike ..



This is an exciting picture for me! I am a university student (read: broke) so I decided to play around with the stock bars (usually lame results apply) but when I inverted them and cut 20mm off of the ends, they looked quite nice. I will heat them up and sharpen the angle at which they come in towards the tank to narrow them a little, but they can stay for now! It'll look sweet with rear sets but it feels reasonable now .. they could use to be about an inch or two further back, as I have size 14 feet.. I will fabricate some rear sets soon enough .. probably using some from a GSXR or similar bike, and making aluminium brackets to mount them from the standard peg mounts further back.



I also put on the headlight .. his face is back on!



I hope you all like it!
Cheers,
Ben
 

MBS

Live, breath, sleep HONDA!
Nice work, looking really good. I am impressed with the paint job on the fuel tank. Could you give us a step by step method of getting the same results?
 

lunar_c

New Member
Hey guys and girls, Here's another update. I stripped the top end of the motor the other day, here's a pic :



It has no excessive side play in the crank, the small end is in pretty good nick, the bore is just a little glazed and it's remarkably clean inside the cases.



The piston is a little scuffed and has plenty of carbon on it, I will probably replace it. The head and valves are in good nick, and will only require cleaning and de-coking.

I've rewired the bike and taken the time to run the loom so it is least visible. I've hidden as much as possible underneath the tank, and the starter solenoid underneath where the seat will be.



Here's the refinished clocks and headlight from the cockpit view..



Hopefully I will have the engine cleaned, detailed and ready to go back in the frame soon .. and the wheel's cleaned up then I will start on the seat.

Regards,
Ben
 

lunar_c

New Member
Hey all,
The rear end is back together and torqued up! Many thanks to the guys at McCully Yamaha, Perth who gave me an exploded diagram to make sure I had everything right.





The wiring is completed, the battery now relocated underneath where the hump will be .. I need to build a bracket for it which I will get around to soon. The solenoid etc has been relocated and new cables run in preperation though. I also chose a round brake light with license plate light to recess into the fibreglass hump when I fibreglass the seat.



I also disassembled and painted/detailed the starter motor, painting the centre section black and polishing the end caps, and finally assembled the detailed levers ..





And started on the polishing .. what a messy and tedious job! Still, I'm getting there ..





And for the last pic .. I just wanted to show you the cap head set screws (or bolts in laymans terms) I'm using all over the engine instead of the horrid phillips head screws Yamaha used originally that I've had to remove since with an impact driver, or worse .. drill out .. These are high tensile steel and I like how they play against the polished cases.



I also started rebuilding my forks but the dust seals refuse to come out .. so they'll need replacing as well now (I already have the oil seals) .. if I can ever get them out!
 

lunar_c

New Member
Hey all,
Here's some more pics of todays progress .. I've been working on detailing the engine, while I'm waiting for the parts to finish off the forks. Basically getting it ready to put back together with a new piston, new rings and seals.

After about an hour of scrubbing and cleaning with D-10 degreaser (an Australian product, very good on aluminium!) I had the engine clean enough to paint. I then masked it off, as I haven't split the cases on this rebuild - just done the top end.



And here it is with a shot of black. I've used Dupicolor black gloss enamel hi temp engine paint on all engine parts .



Here's the barrel after painting, the bore is in good shape so only requires a hone.



Here's the cam cover .. I've sanded the paint off of the ends of the fins and polished them for contrast. It breaks up the black, as will the polished side covers, and valve inspection plates. Lots of extra work, but it looks sweet though!



And finally I threw everything together quickly just to see what it looked like (I decided to polish the fins after seeing all the black parts needed breaking up)



Looks good to me so far.. has anyone noticed my side cover had a small chunk missing over the gear shift spline? I smoothed it out with a grinder today so it's less visible! It's all in the details ;)

I started polishing the other side of the motor today - I've also filed off all of the raised lettering (oil capacity is written on the side of the crankcase, oil filter cover is labeled etc) and smoothed it out for a cleaner look.

More pics soon!

Regards,
Ben
 

lunar_c

New Member
Hey,
Cheers man! I appreciate the complements. Wait til you see the other side cover though, it looks so sweet! I'm getting some new polishing wheels tomorrow so I can finish it off. I will start doing the rest of the fins tomorrow too.

I am using a pressure pack hi-temp engine enamel, the brand is Duplicolor .. I prefer to use VHT, but this is all I had in stock at work in a gloss black last weekend. However I'm getting good results and this stuff dries REALLY quickly so I'm quite happy overall.

The best tip I can give you for painting aluminium engines is to clean, clean, clean. It's quite a porous metal and tends to soak up every last bit of oil, chain lube and dirt and crap so you need to really scrub every bit you can get to with a wire brush, using a good degreaser in a pressure gun if you can, like D-10, or carby cleaner works well too.. use tooth brushes and scourer pads on the fiddly areas, allow it to dry once it's really clean then wipe over with thinners before painting.

I am getting so impatient to finish the bike .. argh! I want to ride it!
 

Maritime

Active Member
Great work, isn't polishing fun :'(. I am going for the exact same look on my CM400T, I have the engine side covers almost done, they are still on the bike as I am riding it until snow flys, then I am tearing it down and moving into the basement to polish, paint, then more polish etc..... I was wondering how the Duplicolor engine paint went on. Good to see your results. I am going to use it on the tank and side covers as welll because it is supposed to be fuel resistant after the 5 day cure. I will post pics when I get it done. They have a clear as well I am going ot try out, If it doesn't look good I will strip it and redo.

Great job on the bike.

Mike
 

lunar_c

New Member
Thanks Maritime,
The duplicolor seems to be a good product.. but I wouldn't recommend engine enamel on panels, it's far too thick and gluggy (I think it's based on an epoxy enamel) and it'll orange peel and look ugly. I'm lucky living in Western Australia, we don't have snow .. anywhere .. though it's been a pretty long, cold and wet winter (well, to me cold is anything under 18 degree's c, I went to New Zealand a few months ago and it was -7 there and snow everywhere, I was freezing!) So I don't have to worry about salt on the roads and stuff. That'd suck on your aluminium and paint. Still, the red dust gets into EVERYTHING here, inside all of the fins etc and once it's there .. you can't get it out this side of a sandblaster!
Good luck and I will look out for your project!
Regards,
Ben
 

lunar_c

New Member
Hey,
Today I got a new 3 step polishing kit from work and went nuts. The results were so much better than the kit I originally tried on my side covers and forks that I had to re-do them, creating twice as much work (I still have to final polish the clutch cover, do the forks again and the fins once I sand them down) but the results are incredible!





Here is a quick look at the newly refurbished starter motor on the motor - I know being a cafe bike I should have a kick start but this looks pretty sweet :)



More polishing to come .. geez it's messy work!
 

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