CB250RS café racer project

[AllanB]

Found one (by chance) that better shows the 'look' applied to a cafe style.

Friday night - excellent for searching the net for cool bike stuff

[jester_parks]

far too technical, modern for my taste!

[Wobbles]

I'm bowled over by the compliments for my litttle project - thanks guys!

I took some pics this morning.
One of them might help some ideas for the speedo/tacho... took alot of fiddling to get the tacho as low as you probably want Xwhatsit, but those cruiser plates look well neat & may do the job.

Talking of budget - we found the original bike in my sister's barn when she bought her house near Bristol and assumed ownership of the bike. Cost zero$$$.

BTW - this is the most valuable thread i've every read on caffing up an RS

You all rock

[jester_parks]

This bike is just perfect!
I must admit I did not put as much TLC into my little thumper jet and it definitely shows on the triple-clamp.
BUT: this forum is very motivating and my next sample of "RS-Coffee-Racer" will close the gap to the UK-machine!!
btw: cheap gauges are CB200 on ebay - nobody wants them and I guess they fit:

[Wobbles]

Getting rid of all that plastics is straight forward!
Airbox & -batterie-holder is one unit and can be taken off - replace the batterie with that small one I show below /12V - 0,8A) - it is so small that it fits right behind the frame-tubes under the seat! Add a bell-mouth and you are done.

Hey Jester,
Is that you bike in this post?
Now that's sweeeeet!

[xwhatsit]

Wobbles -- what did you do to your top yoke? Seeing as grinding the bar mounts off would leave holes. Did you weld some plate in to fill the hole?

Jester -- is that a stock German top yoke? Interesting the number of differences in the German RS's compared to what the rest of the world had. P.S. you must tell me about the bottom-end work you did on your 330cc conversion when you have a chance

[xwhatsit]

I'm going to post up some of the pics of modified CB250RSs that I've collected (mostly Japanese, many from Yahoo Japan Auctions, they come up for sale very often and at ridiculously cheap prices).

I have more shots of certain bikes.

[xwhatsit]

The first two photos are of the most stunning conversion, this is very CR77. Interesting how the pipes look stock but are seemingly stretched out flat and straightened (obviously not as the stock pipes are made up of conical sections). This was my favourite -- but I think after seeing Wobble's bike I've changed my mind He had a website somewhere, just a list of the bikes he'd had over the years, I used Google Translate to get it from Japanese but there were bits I didn't get. His site disappeared now

How good is the last image of a Ducati 250 knockoff?

[jester_parks]

I certainly will forward a photo-documentation about the 340cc-conversion
, but at the moment my Yamaha-engine is on the bench due to road-worthy!
I will be gone on top of it for a week to enjoy italian food (and wines), but I suppose it is not all that urgent, is it?

[Wobbles]

OOOF!
Those picture are unbeeeelieveable! Thank you so much Xwhatsit

'specially lurve this one(attached).

Also the pastiche of the Laverda[?] is cool as you like.

Jester - what sort of power/torque benefits are you looking at for the 340cc?
Is there alot of work involved?



Cheers guys

[Wobbles]

Forgot to attach the pics.
Those pipes are how I'd do it if the pipes already on the bike were't so pretty.
I'll wait til they rust or drop off as an excuse to get some made

[xwhatsit]

OOOF!
Those picture are unbeeeelieveable! Thank you so much Xwhatsit

'specially lurve this one(attached).

Also the pastiche of the Laverda[?] is cool as you like.

Jester - what sort of power/torque benefits are you looking at for the 330cc?
Is there alot of work involved?



Cheers guys

Do you mean the red bike (well there's a few), the MV Agusta pastiche? I've seen a few bikes with that tank/seat combination so they might've made a kit in Japan for them.

If you're interested in the XT350-in-a-CB250RS thing, there's a thread I started a while ago here http://www.kiwibiker.co.nz/forums/sh...ad.php?t=75655 . It's not very clear though, but the general gist of it is to take an XT350 piston (86mm vs. 74mm, so 12mm oversize -- 336cc) as it has the same 19mm piston pin diameter, and fit an oversize cylinder liner to accommodate it -- which then requires machining out the top half of the crankcase to allow it to fit.

Jester seems to be going for a complete monster, cylinder head porting, oversize valves, big carb -- it sounds like it's going to go like a rocket! As I commute on mine, I'm leaving it mostly standard with ordinary 250cc-level intakes and exhaust specs, so in my eye that'll give good low-end torque and tractability even if it won't rev like a lunatic.

I've also got an XR250R 6-speed gearbox set and the single gear-driven balancer to go in it. One thing I'm sure you hate about maintaining the RS (aside from the lack of oil filter with corresponding frequent oil changes) is adjusting the bloody balancer chain. The XR250R went 6-speed and also did away with the twin chain balancers, using a single larger gear-driven balancer, so that will make life a lot easier.

[Wobbles]

Wobbles -- what did you do to your top yoke? Seeing as grinding the bar mounts off would leave holes. Did you weld some plate in to fill the hole?

Hi Xwhatsit,
Yes, I just got fed up with the bar mounts mocking me and ground them off. You're right, there were holes left so I just filled them with weld and ground them down. If I ever decided to build it to show, I'd have to smooth these right off as you can still see the grinder marks!!

At one point in it's evolution it had ace bars which looked horrible as all the instrumentation was way too high. When these got binned, I used the mounts just to hold the original headlamp bracket in place along with the digi speedo mounting onto it.
Never felt right and modded the bracket, dropped everything down which left the mounts looking a bit redundant.
Btw, the original brackets are nice as they keep the stanchions unclutterd.

Like you mentioned earlier, i too intended to keep all lugs etc so I could always convert it back, but after a while, realized this was never going to happen. It's amazing how therapeutic an angle grinder can feel when taken to a perfectly good bike!!!

Thanks for the link on the XT350.

Jester's 340 sounds awesome. Look fwd to seeing more.

[Buddha#81:Me]

A year or two back I post classic raced a CB250RS. Not a bad wee bike just with 18" sport deamon tyres. Seeing the relative ease these wee bikes convert to and how they look I'm kicking myself for selling it for $200.
I found the gearbox weak when thrashed, which effectively is the same gearbox as the 500, as a 500 they must be like a grenade with the pin pulled. A FT500 (6speed) cafe project appeals, they look like crap but using some of the ideas on here could look as good with the 500 boogie. Bombing out a 250 to 350ish could be more rewarding.

[xwhatsit]

A year or two back I post classic raced a CB250RS. Not a bad wee bike just with 18" sport deamon tyres. Seeing the relative ease these wee bikes convert to and how they look I'm kicking myself for selling it for $200.
I found the gearbox weak when thrashed, which effectively is the same gearbox as the 500, as a 500 they must be like a grenade with the pin pulled. A FT500 (6speed) cafe project appeals, they look like crap but using some of the ideas on here could look as good with the 500 boogie. Bombing out a 250 to 350ish could be more rewarding.

Yes, my first gear likes to pop out then jump back in of its own accord after the engine near reaches redline. Not a nice way to lift the front wheel.

I think it was you who said that with the extra weight of the 500 lump the handling would probably suffer. With the 6 speed I'm putting in (supposedly more reliable) and the nil extra weight of the 336cc conversion -- although mine won't pull massive horsepower, Jester's sounds like it will at least match the 500 (which were fairly mildly tuned) albeit at higher RPM -- I think there could be very good results.

Did that racer you had go to TygerTung? I remember you said you sold it and he was complaining about 2nd gear troubles.

As I type this my front end is in about a million pieces. Fork seals (lasted ~20,000kms, not happy ) and putting some tapered headset bearings in. Got to wait until my old man gets here with some heavy-duty equipment to get the old ball races out.