I bought a Firebolt XB9R (2004 Reg) about a month ago - it had been standing for approx 2 years but started and run OK at time of viewing.

I gave it a thorough service, new front tyre and new EBC brake pads fitted, caliper and pistons were perfectly free.

Time came for MOT on Tuesday so I decided to take it for a short run prior to taking by trailer to MOT centre. After about a mile front brake came on hard with no application of lever by me!!

It remained full on until bleed nipple was slackened which relieved pressure buildup and brake remained free throughout the MOT.

Following day after approx one mile the performance was repeated.

Same again today.

Whenever brakes have been applied intentionally there has been no problem.

Am now scratching my head for a solution - any point in re-fitting old pads which do have some meat on them just in case the new pads are expanding to the extent of braking?

Anyone have any similar experience or suggestions please?

Does the bike have it's OEM brake lever ?.......if so, you need to check the small bleed back drilling in the reservoir.

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Wrong front brake lever? The levers from Buells up to 2002 have a longer heel than the XBs...

In any case, I would be stripping the master cylinder to get rid of any dirt as even if the pads did expand (this is a new one on me - but the fluid could), the master cylinder should allow fluid to pass the face of piston into the reservoir through a small hole. If the piston is already partially depressed (wrong lever), the fluid will have no return path. If there is dirt in the hole, potentially the same story.

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08 Specialized Langster

Thanks both.

Looks like OEM lever in situ - could you give me a pointer to position of the hole in the resrrvoir please (will I need my specs?).

Yes, you will need your specs.........take the lid off the reservoir, drain the fluid and you'll see 2 drillings in the base over the piston.
The larger one is the fluid feed to the piston, the very much smaller one is the bleed back, if this gets blocked then the hot/expanded fluid is trapped and will then push the caliper pistons out to apply the brake.
Also make sure there is clearance when the lever is released ie. with the reservoir full of fluid, if you pull the lever the smaller drilling will 'squirt' fluid for the 1st couple of mm movement.

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Thanks Maz will do that soon - first I must put new caliper on OH's jeep's front wheel, check transmission fluid and one or two other tasks on the vehicle.

Thanks people - now sorted.

Checked master cylinder - both holes clear; bled brake; tried bike - brake came on after nearly a mile.

Bleed nipple slackened, bike returned to shed and threatened with arson, my huff arrived and I departed in it!

A couple of days later I remembered that I had been given a bag containing parts of broken footrest plus other small bits. I re-examined brake master cylinder and on removing brake lever realised that piston was not returning fully. I recalled the query re OEM brake lever so checked the pieces in the bag and found another essential part of brake lever ?heel part?.

Reassembled lever using the heel piece from the bag.

Piston now returning fully; bike tried and brakes OK - problem solved thanks to forum
(lever on bike looked old, had some scratches and other marks therefore I assumed it was the OEM and had not been previously replaced).