CB250RS café racer project

[Whata]

The mounting of the ft500 is just like the xl500 exactly the same as the cb250rs engine, you just have to drill the back mounting holes in the frame.

The kickstart conversion is alot of work, you'll need alot of parts from a xl 500 engine and machine the head to fit the decompression lever.
You'd better go for the xl500 engine.
The only optical differences on my engine are a starter-housing and a deeper oilpan , so the xl500 engine will look just as good

Big bore is also an option indeed, you can keep the stock pipes ( but I guess you don't want that)

Received the brake parts today
But the bad news is that the caliper mounting adaptor is wrong.. The wierd thing is that the right caliper mounting on the cb750sc is the same as the bol'dors... but the left one is not

[HenryDorsetCase]

What handling????

Here's my CB250RS, I put an extra cylinder on it and turned the engine 90 degrees in the frame.

http://i692.photobucket.com/albums/v.../smguzzi02.jpg

Oooooh, I see what you did there.

God the more I look at these old Guzzi's the more I want one.

[tychver]

Thread hijack but this is kinda THE cb250rs thread anyway now lol.

Pics of my ratbike CB250RS.
Work so far:
Cycleworks exhaust.
Battery compartment removed and battery replaced with a tiny 1.2Ah SLA up under the seat. Electrics formerly mounted on the comparment are zip tied up to the frame under the seat.
2 hour paint job on tank, seat cowl and fender.
Painted the frame with subframe paint
Painted the engine with engine enamle. It's filthy at the moment though so it looks shit in the pictures and I got petrol on the sprocket cover which stripped the paint off.

Jetting is #130 main with an XL250S needle on the last clip which means it runs richer through the midrange. It seems Honda jetted the midrange quite lean on the CB250RS, probably due to the accelerator pump and to improve economy. Quite a lot of owners seem to be reporting pinging/missing at half throttle? The mid throttle pickup has improved anyway.

I was going to do more performance work on the engine but I think I might just build a functional streetfighter/ratbike out of a 400 4cylinder. Tasteless I know :P

[cave weta]

Here is my Coro Loop Bike- just finished

http://i186.photobucket.com/albums/x...tygroup046.jpg

[francois]

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.

The braking ratio and "feel" is based on the bore ratio of the caliper and master cylinder. The caliper has the same bore (900F versus 250RS). I have not measured the master cylinder and didn't look to see what the diameter marking is, but I was just commenting that it looks exactly the same when I picked it up.

The front caliper mount off a CB900C does NOT fit the CB250RS. The disk does bolt onto the hub but the caliper mount requires you to cut off and reweld a mounting hole. Had I been paying attention and just measured the CB900C in my shed I would have noticed this before ordering a spare setup from the US. I think I would have been better off grafting a dual disk 400 front end on the Yamaha. We'll see how this works out. The rear rim has a different drum stay than the Yamaha, so I need to mill and modify the swing arm to fit the CB250RS rim. hardly seems worth the effort.....

[growlley]

Hi, This is the most knowledgeble thread on the rs I can find so far, I have been donated about 60% of a cb250rs - 1982 from the reg plate.

Unfortunately its missing both wheels `, axels and swing arm. Can any body tell wether I can fit cb250n wheels and axels and brake calipers as a short term measure as its easier to get all the missing parts , ie wheel rims, axle bolts drum brake part calipers etc . At the momen for the genuine parts I have to hope they show up in a blue moon on ebay.


cheers

[dogsnbikes]

Hi, This is the most knowledgeble thread on the rs I can find so far, I have been donated about 60% of a cb250rs - 1982 from the reg plate.

Unfortunately its missing both wheels `, axels and swing arm. Can any body tell wether I can fit cb250n wheels and axels and brake calipers as a short term measure as its easier to get all the missing parts , ie wheel rims, axle bolts drum brake part calipers etc . At the momen for the genuine parts I have to hope they show up in a blue moon on ebay.


cheers

I sold rims wheels etc not long ago and even have a swingarm laying around,you could have if you pay frieght but may be cheaper too buy one there

the wheels should fit at worst you may have too make or turn new wheel spacers but as long as the axle holes are the same it shouldn't be a problem but remember that you can change bearings and dust seals too suit,Iv'e changed the wheels on my CB250RS to 17inch have alook http://www.kiwibiker.co.nz/forums/en...S-the-Creation

[growlley]

I might have to take you up on that swing arm theres none to be had here at the moment.

It seems I can get an rs front wheel rim and disc but not an axle , master cylinder and caliper but cant get a rear rim and nothing in the way of a rear wheel.

One of the chinese import GY 125's the Urban dz125 has a 4.10 x 18 spoked rear tyre on the wheel , I was wondering if would fit as I can get a complete rear wheel for just under £100 new.

[dogsnbikes]

I might have to take you up on that swing arm theres none to be had here at the moment.

It seems I can get an rs front wheel rim and disc but not an axle , master cylinder and caliper but cant get a rear rim and nothing in the way of a rear wheel.

One of the chinese import GY 125's the Urban dz125 has a 4.10 x 18 spoked rear tyre on the wheel , I was wondering if would fit as I can get a complete rear wheel for just under £100 new.

why dont you look at a 79/80 XR/XL rear wheel as they will most likely slot strat in being the honda drum hub....

I will have alook at what else I have next week when I get home I am sure I have the main bolt for the swing arm as well

If you go see a local engineering company they should be able too Make a front axle on the lathe

[growlley]

for an ex mining town there sure is a shortage of engineering workshops in this area, the only place left gave me a snobby brush off of 'we only do precision engineering' I should hope they do but they cant be bothered doing small one of jobs for people or maybe they just hate motorbikes


*Edit well it looks like I can get everything id need off german ebay, though its going to take a while to learn to read German!

[HenryDorsetCase]

for an ex mining town there sure is a shortage of engineering workshops in this area, the only place left gave me a snobby brush off of 'we only do precision engineering' I should hope they do but they cant be bothered doing small one of jobs for people or maybe they just hate motorbikes


*Edit well it looks like I can get everything id need off german ebay, though its going to take a while to learn to read German!

Dont mention the war.

[growlley]

it's not the war you have to worry about it's the cucumbers!

[growlley]

Ok progress managed to get a rear rim and brake drum. Could some one please post the axle bolt diamter and length also the rear spacers so I can try and get some made.

Next up rear swing arm, Ive not decided on a front wheel yet as I intended to flat track it and may go for a 19" front wheel. Does any one know if the xl1250 tanks will fit?

thanks

[dogsnbikes]

Ok progress managed to get a rear rim and brake drum. Could some one please post the axle bolt diamter and length also the rear spacers so I can try and get some made.

Next up rear swing arm, Ive not decided on a front wheel yet as I intended to flat track it and may go for a 19" front wheel. Does any one know if the xl1250 tanks will fit?

thanks

I will measure up complete Axle with spacers I have at home... and post up thrusday morning NZT...Glad you got the rim sorted.......I will get you a price on freight to UK for the swing I have

[dogsnbikes]

I might have to take you up on that swing arm theres none to be had here at the moment.

It seems I can get an rs front wheel rim and disc but not an axle , master cylinder and caliper but cant get a rear rim and nothing in the way of a rear wheel.

One of the chinese import GY 125's the Urban dz125 has a 4.10 x 18 spoked rear tyre on the wheel , I was wondering if would fit as I can get a complete rear wheel for just under £100 new.

here is a couple of links for you...Have a serch on Ebay UK there is a heap of CB250RS Parts

http://cgi.ebay.co.uk/Breaking-Honda...item4840ad4355

http://cgi.ebay.co.uk/HONDA-CB-250-R...item3a65d0c9aa