CB250RS café racer project

**dandandan** · 2nd June 2010, 14:10

Originally Posted by maybegunnadoo

Hmmmm,

Been a while, so mine is up to this point. Could'nt believe the amount of filler that was on the duck tail and mudguard, plus 4 coats of paint. This bike will be heaps lighter. Don't know if I mentioned it but got approval from MVR for the 500 engine so I'll document it as I go.

What speedo are you using? Love the look of your dash.

**maybegunnadoo** · 26th June 2010, 13:49

The Win.
lots of progress so here goes. As you can see i went and got a battery and built a battery box behind the newly covered seat (pretty cool hey) the next job was then to wire up all the electrics so that they were all hidden away and install the round headlight. Al;so the indicators and taillight went on plus the sharp rear end and then I had to test if it would all work......it did'nt.........of course..... so lots of effing round later I now have a full working elec system. I;m still not happy with the rear duck tail so will continue work on it. The motor is now on the bench and is next for the raping prcocess.

The Loss
whilst buying the battery my Great Dane managed to jump out the car window (HOW?) and was killed by a car/trailer......it was an expensive battery

**NordieBoy** · 26th June 2010, 20:59

Looking good...

And bugger mate

**tychver** · 27th June 2010, 02:34

Originally Posted by maybegunnadoo

The Loss
whilst buying the battery my Great Dane managed to jump out the car window (HOW?) and was killed by a car/trailer......it was an expensive battery

Wow dude that must seriously suck

Must have been a bloody big car window though? :|

**tychver** · 27th June 2010, 02:38

Does anyone know the dimensions of the CB250RS front master cylinder or alternative/upgrade?

Mines going to take more to repair than it's probably worth the hassle and I can't get my hands on an original right now. I'm looking at a KTM 525 EXC brembo master cylinder at the moment but I'm unsure if it has the microswitch for the brake light or if it's going to be too big.

**maybegunnadoo** · 2nd July 2010, 17:54

Hey tychver, I took my thoroughly seized master cylinder down to me local wreaker and he managed to free the cylinder by using backpressure on a hydraulic rig. did not cost to much and the I'm going to try to clean up the bore myself. one thing I have discovered is that a good bearing/seals shop do all the seals at a lot lower price than the originals.

**maybegunnadoo** · 7th November 2010, 22:35

Well folks, massive progress with the ol’girl so bear with me and I’ll get it all down. Had a hiatus for awhile as I got busy but I was really unhappy with the look with the original tank and awful tailpiece. One of my main places to get stuff is the local tip shop and it didn’t let me down. Hidden was a 1972? CB350 tank. Badly dented but all the badges and fuel cap all intact. It fitted beautifully over the front grommets but needed extensive modification to fit at the back. After a lot of discussion and angst, I finally went at it with an angle grinder. The local welder did a fabulous job and it now fits beautifully. This of course ruined the seat so now that has to be redone. The tip shop came thru again for the tail piece, which was Taiwanese steam cleaner suitably modified. I then found a wrecked VFR750 to add some more bits and a ZX650 provided a lovely brake master cylinder. Unfortunately my original brake calliper was US so whilst down the local wrecker (rip off merchant) I found a CB750F calliper mounting bracket….So THANK YOU JESTER…I now have your plug’n’play 270mm disc, twin calliper brakes…utterly fukin’ brilliant. The best bit so far is most of the parts I am using could easily be bought new and quick over the web, but I’m having so much more fun finding and using stuff that keeps the costs right down (the noo) and challenges your ingenuity to make it all go together as an attractive cohesive whole. Hope you enjoy the photos…Oh yes I now have a 9 wk old Boerboel…he’s lovely and will be nice and huge.

Now of course I have no excuses not to put the 500 engine in….

**T.W.R** · 8th November 2010, 08:22

Cool project

Played with the idea of doing something similar too.

**francois** · 22nd February 2011, 10:58

Originally Posted by jester_parks

I bought and fitted CB400n-forks, which have the same diameter (33mm) and give you the option of double-disc 240mm or - with CBX750, CB900F (or FT500?)-calipers - 276mm brake-disc....and this combo does work!

I purchased a CB250RS front and rear to graft onto a Yamaha, hence why I found this thread. A CB900F caliper will bolt onto the front (as I have one) but the single pot version is EXACTLY the same as the CB250, so you gain nothing. You'd need a double pot upgrade, like the CB900C had. The master cylinder on the CB250RS is EXACTLY the same as my 900. This is pretty odd since the 900 has double disks. I could be why people on here are complaining about the braking being poor, the master cylinder may not be the best choice for the caliper.

**maybegunnadoo** · 1st March 2011, 12:13

Francois,

The CB900 caliper is the same, however the diameter of the piston that creates the brake px is larger and its a more complex design. This allows for the twin disc set up. I've finally gotton the piston out of the brake caliper and am hunting for some new seals. I also have now fitted a VF1000F master cylinder which is also exactly the same as the CB900F. So that combined with braided lines on a 278mm disc will be HEAPS of stopping power. Also as the plus, the weight of the brake cylinder and disc is nearly half that of the original CB250RS. So a lot less unsprung weight.

Out of interest its all a bit slow up here. We've have a record 'wet' of over 2500mm including 700mm in 3 days so getting to the shed is a bit hard, hence ther lack of progress.

**Whata** · 3rd March 2011, 08:32

Hey guys, just registered.
I'm Wouter, 18 years old studying mechinal engineering and living in Holland

Maybegunnadoo, remember the first video you posted about a guy kicking a CB250RS with a 500cc engine ?
That's my bike now !

The owner got demotivated in finishing the bike, so he sold it too me

He has done alot of work allready, the engine is from a FT500, which he converted to kickstart, and installed a compression release lever.

When I bought the bike I noticed alot of rust near the swing arm. I decided to take the whole bike apart and repaint it. I had to reweld a part of the frametube near the swingarm because of the rust.

I've just finished the front and swingarm, starting to assemble the bike to fit the new parts.

http://www.mijnalbum.nl/Foto-P73OZH4Z-D.jpg

Your project is nice mate, a very different style than mine

If you need any info about the conversion, just ask

By the way.. Big thanks Jester for that brake information ! Just ordered a cb750sc caliper and a cb900f disc

**maybegunnadoo** · 3rd March 2011, 12:42

Wouter,

Nice looking bike,

especially the FT engine. It gives a really different look compared to the Xl500 engine. I found a bloke who was offering a 305 big bore kit but unfortunately no stock and none coming in. So i'm going to hunt Jap websites in the hope of tracking it down.
Can you send some images of the mounting and the kickstart?

**NordieBoy** · 3rd March 2011, 15:07

Originally Posted by maybegunnadoo

I found a bloke who was offering a 305 big bore kit but unfortunately no stock and none coming in. So i'm going to hunt Jap websites in the hope of tracking it down.

Ask around the VMX guys.