SV650S master cylinder suit 4 pot Tokico calipers?

Hello all !

I'm having some braking issues since I've done a fork conversion on my sv650s.

I'm running some 4 pot Tokico calipers from a k2 gsxr 750 but the lever is constantly spongy, the calipers have had new seals all round but the lever travel is awful and only starts to apply the brakes when the levers about 50% pulled in.

I'm running a standard sv650s master cylinder and wondered if it would help to use a Gsxr one from a k1 k2 model, are the internals different ?

Me and my friend have bled the lines which are goodridge ones many times, used over a full bottle of dot 4.

Any info any knowledge on the matter would be awesome.

I love the feel of the forks but just need that accurate brake to go with it

Thanks

[Bibio]

there is more brake bleeding than just pouring brake fluid into system and pumping the lever.

if you have not tried it i would suggest first you take the bleed nipples out and wrap them with PTFE plumbers tape remembering to stay away from the bleed holes. next get yourself a large syringe and back bleed the system. cracking the banjo bolts open a little then giving the syringe a little squirt then while still squirting tighten the banjo again usually gets rid of little air bubbles.

have you done the pump/open/close/repeat type bleed?

have the pads been bedded in? i dont do a final bleed till i have bedded the pads in (2-300 miles) that way i know for sure that the pads are in full contact.

your M/C might be on its last legs.

when you stripped the callipers did you clean out the seal recesses and assemble with RRG?

Thanks for the speedy reply.

I will try the plumbers tape on the nipples, I was given new nipples with the seal kit to so I think that will be the next port of call.

We did the pump/open/close/repeat bleed, with the calipers on the disc, with the calipers off the disc and without any brake pads in at all, the pistons moved perfectly.

We have tried a vacuum bleeder to remove any possible air in the lines.

I cleaned the seal recesses but didn't use red rubber grease, so guess I need to take them apart again ?

Currently looking at Gsxr master cylinders but unsure if it will be different, the master cylinder was fine before with the 2 pot calipers.

Done around 200 miles but not using the front brake as it feels horrible, guess this is an issue, but the feel is so awful, don't know when it will bite, feels inconsistent.

[Bibio]

so what did you use to assemble the pistons in the callipers?

for a final bleed you must bed the pads into the discs.

what have you been using to stop the bike?

You still have air in your system. Once you get it out, your brakes will work fine and you'll not need to bleed them again until you need to replace the brake fluid.
For very stubborn problems with air in front brake systems, I've had good results removing the lever/master cylinder assembly from the bar and tilting it so the air can rise out of the upper banjo fitting, where it's most likely trapped.

I had a completely standard front brake that went spongey, exactly as you say, 50% in before a slight bite. My dad has a 2010 gsxr 1000 and he recently changed his lines and master cylinder so I have put his standard lines on the bike, aswell as his old master cylinder. I also upgraded the pads to ebc hh sintered pads. The first 30 miles were brilliant, as I posted on my thread on here, now, I'm back to spongey ness! This makes me believe I have something wrong with my calipers? It's a pain in the a#$e.

[Sid Squid]

Worn discs and new pads? If yes, then the pads may be flexing - wait until they're bedded in properly before looking for a further problem.

If the discs are worn hollow this can take a while.

We just used some brake fluid for the pistons, obvious to me now it was not the best idea, the pistons had been cleaned to.

As for stopping the bike, I just didn't go fast, rear brake and engine braking has been enough for 30mph roads plus a bit of judgement.

I shall try the master cylinder tilted trick, we did open the top banjo bolt as the braided hoses were not in the correct position and bled them after but guessing if the air is trapped at the top it can just sit there.

The discs are almost new, but starting to get surface rust due to little use. :P