Master cylinder troubles CB250RSA

[Howling TerrorOutOfOffice]

Hi, gave the 250 a once over, ready to pickup my daughter at 4pm...not good found this
https://i104.photobucket.com/albums/m174/howlingterror_2006/DSCF1266.jpg

https://i104.photobucket.com/albums/m174/howlingterror_2006/DSCF1269.jpg

Its obviously leaked/been spilt before as the paint is stripped off the main body. Looking at the haynes there isn't a seal between the plastic reservoir and main body, or is the O-ring the only seal?

Haynes isn't helpful in how i would split the reservoir from the main body to check this O-ring and replace it.
Also i can't find where to get a replacement O-ring if that is the problem. Wemoto & David Silvers offer the Piston assembly, diaphram, infact everything but the O-ring.

Help appreciated.

Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[Kickstart]

Hi

Not sure that you can legitimately separate the plastic section from the alloy section. Is it actually leaking now?

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Howling TerrorOutOfOffice]

Hi Kickstart, yes the plastic reservoir can be separated. I've not done so, the diagram in haynes shows all the parts separated and parts are still available except for the alloy body.

Looks like 4 screws that go through the cap and reservoir also thread into the alloy body.
I really tightened them up(more than necessary IMO) and after a 30mile ride got back and no leak.
Makes me think the O-ring has come to the end of its life. Shame i can't find one off the shelf, or at least i can't locate one unless i buy a master cyclinder repair kit at silly money.

I saw some O-ring seals in Aldi t'other day. Hopefully a rubber washer will work.

Thanks

Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[Kickstart]

Hi

Concern that some random rubber O ring or washer would not be brake fluid proof. Although being unpressurised it isn't quite so important.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Howling TerrorOutOfOffice]

Yep i share your concern, i like proper parts...especially for brakes.
Sods law says i'll end up buying a box full of tap washers that don't fit, or start melting.

Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[Howling TerrorOutOfOffice]

If anybody else has suffered the same problem, you can get a genuine replacement from David Silvers. The part isn't shown on their website, so give them a phone call. 01728 833020


Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[Howling TerrorOutOfOffice]

Little heads up: Don't over tighten the four cap screws.
As after i'd replaced the O-ring and reservoir i thought abit of extra torque would stop any future leaking. It doesn't, all it does is distort the reservoir again. Which led to more drips Loosening the screws has sorted this.

Brute force isn't always required it seems.

Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[Vincent]

I'd consider using a more recent M/C. Just make sure it has the same bore piston.

[Howling TerrorOutOfOffice]

If it fails, then yes i'll probably do that.
I'm only renewing things that are broken/worn.

I heard it was possible to put a CB500 disc and brakes on the 250RSA, but i like things original, even if that means i can't stop.


Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project

[virus]

Superdream 250 commstars fit front and back, using spacers for the superdream as they used basically the same swing arm as the 250rs just a bit longer (as I found out when I fitted a 250rs swingarm to my mates superdream, actually made it possible to wheelie the bugger).

Gives you 50% extra brake shoe width on the back, a larger disk on the front and wheels that wont suffer alloy rot and eat themselves from the inside out.



Better looking than rusty spokes aswell.

Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[Howling TerrorOutOfOffice]

It would make sense to uprgrade my brakes, but commstars on my RSA. There's still plenty of wheels about and a respoke isn't a bank breaker.
As for the discs/brakes, i'll just have to look furthur ahead.
I feel i owe it to this great little bike to keep it original. But if i trash it i'll be back to this post. Ta virus

Pat
____________________
Diabolical homemade music Bandcamp and Soundcloud
Singer songwriter, Artist and allround good bloke Listen to Andrew Susan Johnston here
The Harry Turner Project