Yamaha SR 250 rebuild

[grandwarrior]

Hi peoples, I love bikes, but i have never owned one. I have also always wanted to do a rebuild of something. Now, after 20 years of working, i am unemployed and am finding it hard to find work due to an injury.
So, i asked for a freebie motorbike to rebuild. I was kindly given this 1984 Yamaha SR250. I was told it ran 2 years ago. The guy i got it off of was going to 'get it running' but lost interest in it due to other things.
It needs a new seat base and i need to break the lock on the tank to be able to fill it, but they will be sorted later.
I poured petrol into the carb and have had it running. It sounds pretty good, not seized at all, although the revs stick high when i let go of the throttle. The butterfly seems to be moving freely. Any guesses ?
Im also hoping to change the front brake to a disc later too.
The frame i going to take back to bare metal, prime it and thinking of painting it a red of some shade. Red headlight surround, red forks at the bottom and maybe a black tank.
Apart from those changes, it will be a stock bike.
Ill put updates on here as i go.

[brethren22]

great pick up mate. just the thing for keeping you out of trouble whilst you are on the hunt for work!

if the throttle isn't sticking but it's holding revs it could be a lean mix problem. this tends to only result in the revs taking a moment to drop back down though. does this sound like the problem or is it genuinely sticking at high revs?

[grandwarrior]

thanks Brethren, That could be the trouble. Once ive rebuilt it, ill look into that first. The revs do go back down, just very slowly.

[Desmo]

Definitely an air leak somewhere. Get some ¨Start ya bastard¨ and spray it around the inlet tract (carbs and manifolds, stay away from the carb mouths.
If you find a place where the revs rise, that´s where your air leak is.
All hoses on the carbs OK?

[grandwarrior]

cheers Desmogod, ill be trying that once the rebuild is done. Im trying to find a cheapish sandblaster and painter at the moment. Either that or sand it down myself using a angle grinder with wire brush attachment. But thats going to be a lot of fiddly work. And im thinking the paint finish wont be the best from cans. But saying that, im not after a show bike, just something neat and tidy. Im in Adelaide if anyone knows of someone that can help with the sanding and painting side of it.

[lunar_c]

These are a great bike to learn the ins and outs of motorcycles on, and pretty forgiving!
I have lots of spare parts from my SR 250 build so pm me if you get stuck, I'd rather it goes to some use than sit in my shed.

[Tbird tracker]

Just another thought on the carby, being that it is a CV (Constant Velocity) carby and quite old and neglected, it could be "Definitely an air leak somewhere" but I suggest you carefully check the rubber diaphram at the top of the slide for perishing and small holes as this will also cause the symptom you discribed. If the diaphram is torn, holed or perishing, replace it, this usually means replacing the slide as well because they usually dont come as seperate parts, if the slide is worn this will also improve carburation when it's replaced.

[Weapon_X]

i'd say T-Bird is on the money. diaphragms will cause it to "stick" if they are worn or old and brittle as they wont give like they should.

[grandwarrior]

cheers fellas, ill have a look at that

[manxman]

Perthite SR250 man here, mine's just bit the bullet. Have to recon starter, & replace cam chain and slippers, clutch plates.and most cables. I WILL have a kickstarter!!!!! Of course, there's no petty cash to do it with just now, so it will have to wait. Pity it didn't go just another 3 weeks, when my ute will be running again.

New carb slide is same as XS650-just make sure you get it with or without the cutaway, as needed. ebay usa usual source, around $US80- typical, comp carb sometimes, but will need recon. leaky diaphragms won't rev up, and jitter up and down whilst running. Backfires usually kill them.

GT250 front end seems to work, there an orange and black chopper version at Jandacott airport-beautiful, if just a tiddler. Pick the tank lock if you can, or just drill the tumblers out until it opens. comp key sets are ALWAYS expensive. generic ign switch only avail. most parts stores. Adapt wiring if necessary. bkperformance.com.au useful for new bits.