Front brake firming up by itself

[twinlovin]

Hi everyone,
After a couple of months running around with the standard TRX master cylinder mated to the R1 goldspots I decided to get off my lazy arse and fit an R1 master cylinder. I have Braided lines and the TRX master cylinder had no feeling it was just like a light switch. Anyway I fitted up the R1 master master cylinder and bled both lines. I was pumping up the lever and bled a few more times just to make sure there was no air. The lever [pumped up firmly so I took it out for a test.
I got to the end of my street (about 800 meters) and the lever felt a bit firmer still. Then in the next 100 meters the brakes came on themselves. I pulled in the clutch and came to a very abrupt stop. The lever was extremely firm and I couldn't push the bike at all. I had to undo one of the bleed nipples and push some fluid through to release the brakes. I decided best to go straight back home. The same thing happened on the way back (not cool getting stuck in the middle of your own street and bleeding brakes).

I'm thinking I might have air trapped in the system somewhere. I haven't used any fancy techniques to put the fluid in to the system, just bled the brakes the old fashioned way. I might give it another bleed and see if that's the case.

Any thoughts on what might be happening here ?
Dirt, air, leaking brake line, dodgy master cylinder from the wreckers ?

[HansJ]

It's most certainly the brake lever. If You're using the TRX, (or even a 3rd party supplier for R1), You'll have to take some material off the lever where it is in contact with the piston. The lever is slightly different in shape/size, and does not allow the piston to back off completely, so pressure is not decreasing. But be careful, the lever's material is pretty soft...

It's happened for me twice, once at the race-track after my spill. I had just fitted a brand new lever from a guy selling spares at the track (f***ing vulture ), and it was a 3rd party lever for the R1. I was feeling quite stupid, standing still on the track in the middle, unable to move the bike. Scary moments Lucky it didn't lock up in a curve or that someone hit me...

[twinlovin]

Thanks Hans, I'm glad it's something simple.
I vaguely remember the lever being mentioned before when upgrading to the R1 brake system but couldn't remember the significance. Thankfully the Yam toolkit has an 8mm spanner in it. Other wise a 6 foot spanner would have looked even stupider stuck out on the street.

[JL]

It's most certainly the brake lever.

^^^^ What he said ^^^^

If you can, try and find out exactly what year R1 your mc came off before going to buy a lever for it. A mate had his front brakes lock up on his 2000 R1 because a replacement lever was from a different year. I would be checking that the lever came from a company that made different levers for different years, I think they were the same from '99 - '01, and then different for '02-'03. Some companies say their lever is for '99 - '03 which I would be dubious of, but that's just me. Probably get more info about it on an R1 forum...