'84 SR250 Garage build.


Gold Coast, Queensland
Gday all. I thought I would start a small thread to show the progress of my SR250. I have been quietly watching other threads and getting ideas. I figured now I am getting close to done I should speak up.

So when I purchased this bike it was a half started project for a friends wife who decided that she would prefer a CB650. I picked it up for a great price with most of the parts needed. It looks like it has been around the block and at one stage someone painted it with cheap spray paint. The rear of the frame had been removed to add a loop and brackets for a bobber seat and all the tabs had been cut off. As I am useless with a welder a friend of mine welded on a rear "loop" which I had pieced together out of an old pallet jack handle that was in the scrap bin at work. After a week of waiting it was done, those side projects in the workshop always seem to take longer. I fabricated a seat pan out of some aluminium tread plate I had laying around and sent it off to the upholsterer. While that was happening I got to work on the rest of the bike re assembling it. I rust proofed and painted the tank and frame. The tank got a does of matt black with the frame getting satin.

Once I had it back together I inspected the chain and rear sprocket. No surprise they were both shagged. The sprocket was so worn its teeth are like knives and the chain has a good 2 inches of play left and right.
The only sprocket my Yamaha dealer had is stock was a 40T so I grabbed it. Down from the 46 standard but might get the bike ever closer to the ton. I also noticed that the rear wheel had a good bit of a wobble in it so I had a look at the bearing which were also shot. I replaced them and all was well until I went to install the new sprocket and one of the studs was so worn that it stripped when I was screwing on the nut.
So I attempted to remove it with no luck. Off to the drill press it was running through all the bits until 7.5mm. After that I grabbed a 8x1.25 tap from the tap and die set and stuck that in the drill press. I found a bolt to suit and stuck it through. I am not entirely happy with it so I have ordered a new hub from CMS. While I was on there I grabbed some tank badges as well since locally they are $45 each.

So there goes my ultra low budget. I have now spent $800 all up. So I am still under the 1k mark I was aiming for. Here are a few pictures of the progress so far.


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Re: 1984 Yamaha SR250 Garage brat/tracker.

And here are the rest. The seat does not sit as flat as I would have liked but the bike will evolve a lot of the next decade or two.


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Re: 1984 Yamaha SR250 Garage brat/tracker.

Looks good man I had hoped to get mine closer to finished today but the bike salvage yard closes early on friday's apparently.... so I missed the boat...Let me know how that rear sprocket works out for ya
Re: 1984 Yamaha SR250 Garage brat/tracker.

Will do DesmoBro, I have been watching your build. A little more work in yours than mine haha. Your bike is what my friend had planned for this one. I like the look of trackers so I decided to head that way a little.

I will get some better pictures once it stops raining. I will let you know how she rides with the longer gearing. I just purchased a ballistic battery 4 cell. Should be easy to hide away under the seat. 135cca in a tiny 6cmx6cmx10cm battery.
Re: 1984 Yamaha SR250 Garage brat/tracker.

Looking good. I like the seat, where did you have it upholstered?

Any more progress yet mate?
Re: 1984 Yamaha SR250 Garage brat/tracker.

Hey Brovok. Only just saw this comment. I have put a new tail light on that is under the rear fender. I pulled it off the Z50 Cafe in my avatar.
Still waiting on parts in the mail. It takes quite a while for things to get to Australia.

I had the seat done by a bloke called Brendan from Bill Payne Motor Trimmer in Southport. I just went in with the plate and gave him a rough idea of what I wanted and the shape and that is what he made for me.

I painted a metallic red stripe down one side of the tank as the flat black just seemed too dull. Still not sure if I am happy with it but it has helped bring the bike to life a bit more.
There is something not quite right about the front end either and I am having trouble figuring out what it is. I am fairly sure it is the height of the gauge and headlight so I will lower them a bit tomorrow.
I removed the battery box as the Ballistic battery should fit well enough under the seat. I am still unsure if I will build a box for it or not. Maybe just a metal tray. A lot of ideas at the moment so I only have the seat sitting on there. It is a little off center in the photos.


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Re: 1984 Yamaha SR250 Garage brat/tracker.

Alright I have been slack with updates. I have not progressed to far with the bike since the last. I have been having troubles with the rear wheel seeming to be unbalanced. After replacing all the bearings, the sprocket, the clutch hub and taking the wheel to be balanced it is still off. I have a feeling that the shop where I took the wheel to be balanced just spun it once or twice and called it fine. I will take it to be looked at by a tyre shop rather than a mech next time.

Anyway the new battery arrived which is a hell of a lot better than the old one. It hides fairly well under the seat but still need to make up a tray for the rest electrics. I decided to drop the oil yesterday as I had a feeling that my mate had filled the case to the top for storage. Sure enough 3L of oil came out. While I was at it I attempted to look at the oil filter. The two top bolts for the oil filter were well beyond worn and I had to use the rattle gun to remove one.
The other required a bit more. I had to cut a slit into it so I could fit a drill bit to remove it. So it is off to the bolt shop again today.

After I looked at the oil filter I think it might be the original, so I will order a K&N high flow for it today. I also need to replace the flasher relay as that burnt out when one of the signal wires from the rear indicators hit the rear guard. I have ordered a replacement with a fuse in it which should arrive by monday. As for new pictures I have none yet as the tank is off for the relay replacement.
Re: 1984 Yamaha SR250 Garage brat/tracker.

I have been quite slack with updating this thread so here is another small update.

I have the rear wheel sorted now, it only has a small amount of play but it is not noticeable when riding. I would like to assume it is because the bike was sitting so long with half inflated tyres but I have a feeling the rim needs a good sort out.
I have replaced the relay with a 3 pin type and run a ground over to the coil mount bolts and all is well for indicators. I have replaced the oil filter and refilled the bike. Now all I need is to make a bracket for the number plate and wiring in the lights for it. I have purchased bolts with LED in the top to light up the plate as well as fasten it. Should work well enough and they will be here next week. The only other thing I need to fit is the horn. I plan to mount it under the tank away from view. It is more for the safety cert than use.

This afternoon I was adjusting the controls when I managed to break the front brake lever mount. So it looks like I am up for another unless I can find any spares laying around. I have a set of bar end mirrors on it now and still have not created a final design for the battery box. I will be working on that this weekend.


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Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

The bike is on the road now. But I have not had a chance to ride it yet. It has been raining here for quite some time and now it has stopped my riding buddy has dropped his bike breaking the rearset mount and bending the gear lever. Once Kawasaki send the part over it will be fixed in no time.

I have been looking at getting a few more parts for the bike just to clean up a few things like the license plate mount which is currently right on top of the rear fender. I don't the po po will appreciate the angle it is on.
I have also been looking at replacing the clutch cable as it has some fraying to it. Whilst I was searching I came across a hydraulic conversion kit which looks like a good deal for the $50 it will be. The problem with living in Australia is you often end up paying more for postage than the item its self. I also need a new front tyre as you can see in the pictures. I have been looking at something along the lines of a Dunlop K460, I have never been a fan of dunlop though as the only two I ever had slid around more than a deer on ice.

Does any one have any opinions on hydro vs cable for the clutch setup?

Anyway here is a picture of the clutch kit I was thinking of getting.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Sweet build man, Diggin the seat.

If you're looking for some cable perches I've got a flat black universal set that fit 7/8 bars, Would be willing to either sell on the cheap, or barter.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Thanks Relax. All good now though I grabbed a few from the wreckers a while back.

As for the bike I have finally achieved the exhaust tone that I wanted. The muffler is a little too restrictive for my liking but as I still have the stock head pipe it is not that big of an issue. I filled one of the megaphone mufflers that a friend of mine gave me with steel wool and cut the old baffle that it had to make it less restrictive.
After the different concept baffles that were made and blow to bits I went back to the one that it had to begin with. I welded it in there as the first time I gave it a good rev it ended up a few meters away.
Once I get a custom header made I will consider opening up the baffle some to relieve the restriction a bit. Anyway here is a picture of the new setup.


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Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Alright so after a bit of test riding and tuning I seem to have a flat spot after 3/4 throttle. Now I know that I will need a larger jet because of the pod filter but I have decided to go another route and get a new carb all together. The current carb has a few issues and needs a rebuild but since it is old tech I am going to grab something a bit more modern. I have been looking at the Mikuni TM36 or the Oko K-104 36mm and cannot decided. The Oko is a reproduction of a Keihin PWK36 and is closer to my budget than the Mikuni.

Decisions decisions.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Just get a few jet sizes....don't you have a stock mikuni?
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Yeah have the stock one. I guess I am just looking for excuses to stick a flatslide on it.

I should just grab some jets and work it out. I think the stock is a 125 so I guess a 127.5 and 130 would be the next two to try. What kind of info do you have on the carb Desmo. From what I know it is a Mikuni BS34. Just having trouble trying to find jets that don't have shipping on them more than the price. Australia is good like that.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Not really sure where is good place to order them down unda... Jetsrus.com may have them but not sure about shipping
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

I pulled apart the carb and now I remember why I wanted a new one. A few screws are stuck but nothing a hacksaw and a flatblade screwdriver won't fix. I can't get at the top side of the carb because of the stripped screw heads. Anyway I stuck it it a tub of "General purpose degreaser" as it seems to strip everything away where as the carb cleaner I had did bugger all. This stuff is stripping the crappy paint off the carb that the cleaner did not.

The main jet is a 122.5 and the pilot 47.5. So not far off that 125 and 50 I thought they were. I ended up giving in and grabbing two main jets a 127.5 and 130 but they will be a way off yet as postage from the US takes around 3 weeks. See how she goes after this harsher chem bath.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Finally got into the top. There was a fair bit of debris up there and I discovered another jet. After finding a better breakdown of the carb http://www.boats.net/parts/search/Yamaha/Motorcycle/1981/SR250TH/CARBURETOR/parts.html I found that is the Main jet and what I had though was the main appears to be a smaller main jet. So that would explain why it was choking at 3/4. I have to give the larger main a good clean but I cannot seem to find a size written on it yet. Back to it and once it is dry I will give it a go and come back with the results. Learning about new carbs is fun once you pass the "god I hope I don't fuck it" stage.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

Alright after all that it is a lot better but there is still a slight splutter. Seems to pick up a bit quicker and it is spluttering well after when it was. So I will be assuming that a size bigger jet is needed. I still don't know the size of the primary main but from what I can find it seems to be 140. I am thinking a 145 would be the go but I will wait and see. To bad for me that I already ordered those jets in 127.5 and 130. Ohh well that is the price I pay for being impatient.
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

All this talk about jets makes me want to ride this little beast!
Re: '84 SR250 Garage build. Solo Tracker now, Cafe later.

I have been giving the carb another clean today and found this guide which showed me a few thing I didn't know about the carb. http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf . The guide is for a gs1000 which has 4 BS34s so obviously a few things don't apply. I grabbed some heavy duty carb cleaner today and the stuff works to well it cleans the skin off my hand. Sadly it eats rubber so I need a new oring for the float valve seat which should be easy enough.

It also managed to clean the primary main jet away enough that I can make out it is a 160. So it looks like something else might be the problem. I did a bit of research and came across Crazypj's post about Emgo pods and CV carbs. Sure enough the boot was slightly covering the vacuum port and by my guess not allowing the slide to open far enough at full throttle. I am also having a problem with fuel leaking from the air intake but I will raise the float needle and see if that stops it.


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