All this talk about stainless lines got me nervous about my own brakes....Ever since the blazing summer heat has started, My front brakes have not been performing as well. I'm not sure of the heat is a factor on o-rings but i know it shouldn't be.

If im coming to a stop I have to quickly pre-pump the lever once or twice to get the pads to bite. And if im at a standstill and hold the front brake lever, it will slowly leak until the lever compresses all the way to the bars. There are no external leaks and the fluid is still nice and clear.

Does this sound like its time for a rebuild? Anyone recommend a good place to get F4i MC rebuild kits? My fluid is only a few months old since the last bleeding.

 

Yes you deffenatley have a problem. Stop riding before it stops working completely and pumping dosen't work when you need it to.

 

Im aware of the problem. And if i stop riding it will not fix itself. So i was asking if anyone has rebuilt their MC before or where i can get a rebuild kit from for a few bucks.

 

Yes you were asking if anyone has rebuilt one before but you also asked if your circumstances were normal which I was replying to but thanks for the attitude and general blow off of my response. Im quite aware it won't fix itself, the suggestion was because I didn't want to see you crashed and dead when you didn't have brakes anymore, which is how master cylinders normally act when they go out. For it to be partly working is very abnormal.

 

When you bled the lines, did you bleed them from the caliper side or MC side? I've read a few times that bleeding the front brakes on an F4i need to be done at the MC to get it right...

As far as a MC rebuild kit, I'm not sure. I haven't had to look for one yet, but I'm sure someone on here has done the rebuild before...

 

It's not possible to bleed the front brakes on an f4(i) from the master cylinder.


To the OP, do you take your bike to the track at all? Instead of rebuilding, I'd suggest getting a 929/954 M/C or even a brembo if you have the money.

 

Believe it or not, these cylinders are not very different from the ones on my 84 ATC250R and I rebuilt mine pretty easily from kits that I got on ebay. As far as bleeding, you might want to invest in a vacuum pump. It makes it easy for one person to bleed the brakes. You can get them at almost any auto parts store.

 

yes you can bleed form the master cylinder
u do it from the banjo bolt instead since it has no nipple to do it

 

Please explain how you bleed the brakes by doing so at the master cylinder? There would be no pressure pushing the fluid up from the calipers.

Edit: I understand that it is possible to bleed the master cylinder by using the method you describe, but that wouldn't be very effective as you are supposed to replace the crush washer everytime you loosen the banjo bolt. Not to mention it'd be almost impossible not to get air in the lines by doing it at the M/C

 

What advantage does the MC bleeding method have over the regular method?? (IE Pump and hold brake lever.,turn caliper bleeder screw to drain, return bleeder screw. pump lever again., etc etc topping off the MC as you go with fresh fluid.)
Taking off the banjo bolts seems like more work than needed unless I'm missing something?

I looked into the 929/954 MC. Seems like a popular upgrade but i'd have to get another shorty style lever because they are a different style than the f4i. I'm on the lookout for an afforable one though.

Thanks boredandstroked and all for the replies

Anyone have that part number for the rebuild kit yet?