SR250 Cafe build
- Thread starter cosworth
- Start date
stgmngrpro
New Member
Any chance that you still have your stock tank and are willing to sell? I've been looking for that tank forever! If not, that's still a sweet looking ride!
stgmngrpro
New Member
How much would you want for it, plus shipping of course! I'm interested if it's (relatively) clean inside, I can always refinish the outside! I've got less than zero welding skills, and I would love to find something stock!
Mate your bike is mint! Amazing details. How does it ride? Looks like some really nice rear shocks, are you going to do anything with the front ones? I have seen progressive springs available for sale and heard you can insert some emulators from a modern bike too... dont know if there would be any that would fit these forks though?
cosworth
Coast to Coast
It handles quite spectacularly. The rear RFY shocks have about 8mm of preload on them along with 9000kms of use. Holding up steady. I think they are great value.
The front forks have a 30mm brass tubes in the bottom of them with matched and drilled holes for the valving and to lower it 30mm. I also run 30w fork oil in them. It does take a bit to compress the springs down to cap them off but I built a simple tool to get it done solo. I have considered putting a schraeder valve in the caps to add air like my XT225 forks have, but that will be later on once I need to swap out the oil. The mini lathe should make quick work of that but I may have to modify my pretty brass caps. Right now, the front forks seem to work perfectly lowered internally 30mm along with scooting them up 10mm in the triples.
I welded this up last night out of stainless and hope to have it in tomorrow along with a Niche brand 350 Warrior cam. The cam is 1mm higher lift than stock and I'm blissfully unaware of the lobe profile. Cams from 1987-2004 Warrior 350s fit the SR250 easily.
The cam, and going from a double walled exhaust with an internal diameter to a single wall 1.5 inch, should wake it up a little bit on the top end. I expect no real bottom end difference but it would be nice to be able to climb the mountains in full tuck a bit easier and not have to pull over to let a Hyundai pony through.
The front forks have a 30mm brass tubes in the bottom of them with matched and drilled holes for the valving and to lower it 30mm. I also run 30w fork oil in them. It does take a bit to compress the springs down to cap them off but I built a simple tool to get it done solo. I have considered putting a schraeder valve in the caps to add air like my XT225 forks have, but that will be later on once I need to swap out the oil. The mini lathe should make quick work of that but I may have to modify my pretty brass caps. Right now, the front forks seem to work perfectly lowered internally 30mm along with scooting them up 10mm in the triples.
I welded this up last night out of stainless and hope to have it in tomorrow along with a Niche brand 350 Warrior cam. The cam is 1mm higher lift than stock and I'm blissfully unaware of the lobe profile. Cams from 1987-2004 Warrior 350s fit the SR250 easily.
The cam, and going from a double walled exhaust with an internal diameter to a single wall 1.5 inch, should wake it up a little bit on the top end. I expect no real bottom end difference but it would be nice to be able to climb the mountains in full tuck a bit easier and not have to pull over to let a Hyundai pony through.
The header looks great! Good info on the front forks. I might look into something like that myself. I would love to have a mini lathe!
cosworth
Coast to Coast
Thanks zap.
Well. I got the stock camshaft out. I always felt this bike wasn't right. That the age of the motor belied its performance. Performance. Lol
So the stock cam and exhaust tap pet was worn terribly. Like grooved badly. Really badly. The new cam was just light years ahead in the meaty lobes department. And you could see in the wear area the remnants of the stock lobe profile. But mostly on the exhaust side. Hmmmm. The intake was worn but not like the exhaust side. So I probed the exhaust and intake oil feed holes. The exhaust oil feet hole is horribly restricted from the factory. The aftermarket camshaft is not.
Now of course the head bolt doesn't restrict the removal of the intake tappet but you must remove a head bolt to removes the exhaust tappet. Really? I didn't want to pull the head to do the cam shaft. Just swap it and go. Nope. Removing one head bolt is enough torque release for me to never trust the head gasket so I'm pulling the head.
Bottom line is that I think every sr250 owner needs to do this swap and ride yourself of a barely opening exhaust valve due to Yamaha not drilling the feed hole far enough.
The TSB for installing the roll pin in the crankshaft to feed the cam with more oil wasn't enough. It was a .5 hour of labour and a 10 cent pin fix. Re and re of a camshaft and tappet for a TSB would have been prohibitive.
Looking forward to getting this on the road and possibly rejetted in a few days before the weekend.
Well. I got the stock camshaft out. I always felt this bike wasn't right. That the age of the motor belied its performance. Performance. Lol
So the stock cam and exhaust tap pet was worn terribly. Like grooved badly. Really badly. The new cam was just light years ahead in the meaty lobes department. And you could see in the wear area the remnants of the stock lobe profile. But mostly on the exhaust side. Hmmmm. The intake was worn but not like the exhaust side. So I probed the exhaust and intake oil feed holes. The exhaust oil feet hole is horribly restricted from the factory. The aftermarket camshaft is not.
Now of course the head bolt doesn't restrict the removal of the intake tappet but you must remove a head bolt to removes the exhaust tappet. Really? I didn't want to pull the head to do the cam shaft. Just swap it and go. Nope. Removing one head bolt is enough torque release for me to never trust the head gasket so I'm pulling the head.
Bottom line is that I think every sr250 owner needs to do this swap and ride yourself of a barely opening exhaust valve due to Yamaha not drilling the feed hole far enough.
The TSB for installing the roll pin in the crankshaft to feed the cam with more oil wasn't enough. It was a .5 hour of labour and a 10 cent pin fix. Re and re of a camshaft and tappet for a TSB would have been prohibitive.
Looking forward to getting this on the road and possibly rejetted in a few days before the weekend.
Also looking forward to hearing how the cam swap performs.
I did read somewhere about an official Yamaha statement about a lack of oil feed to the top end on the SR250. You seen that? It had instructions on how to remedy the issue I believe.
Hey that exhaust came up really nice man!
I did read somewhere about an official Yamaha statement about a lack of oil feed to the top end on the SR250. You seen that? It had instructions on how to remedy the issue I believe.
Hey that exhaust came up really nice man!
cosworth
Coast to Coast
Yep. The TSB had a small roll pin installed in the crank to force more oil into the top end to save the camshaft. It was a cheaper solution than replacing the camshaft.
I personally think every sr250 owner should replace the stock camshaft in order to get the true performance from the motor. They are all worn down from oil starvation
I personally think every sr250 owner should replace the stock camshaft in order to get the true performance from the motor. They are all worn down from oil starvation
cosworth said:
Good tips. I will look into doing this too. Btw, what made you go with the big bear cam? Did you know about/consider these two options of cam re-grind? Would you still recommend a new cam over a re-grind?
http://www.webcamshafts.com/mobile/motorcycle/yamaha/yamaha_xt_250_(80-83)_sohc_2v.html
cosworth
Coast to Coast
I went with a stage I Niche cam because I didn't want to mess with springs. It's a 250, it will never ride like my GSX-100R did. But it should run and start well enough to match its looks.
Plus the cam was $80 USD and pops in. I was lucky I have a spare motor here to pinch a good tappet from. Should have it together tonight. Butt dyno results to come. Either holy shit or meh. We'll see.
Plus the cam was $80 USD and pops in. I was lucky I have a spare motor here to pinch a good tappet from. Should have it together tonight. Butt dyno results to come. Either holy shit or meh. We'll see.
Barkingmadspeedshop
Sell the many to fund the few
Waiting to see how this goes. I have a feeling I am going to have to step up my 250 game with you next time we ride
Barkingmadspeedshop
Sell the many to fund the few
Yup almost scared to look 
There apparently were a couple TSBs regarding oiling of the cam area. The one you describe is M83-005 IIRC. There is one in the microscopic image file I have that looks something like M80-029 that describes how a major oil passage in the crankcase cover behind the filter may not be drilled through and how you are supposed to use a #10 drill bit to ensure a 47mm-deep hole in the crankcase cover. And another one that prescribes replacing some of the oil pump items as well as checking for the passage: http://yamahaclub.com/forums/topic/38530-1981-xt250-rocker-a-weak-point/cosworth said:
