Hi all, new to CBRs and the forums. I recently bought an 88 Hurricane 600 and and am trying to diagnose an issue I am having with the front brakes. I originally rode the bike back 250 miles with no issues, only to struggle here in town with my brakes seeming to heat lock. It only takes a few blocks for them to start self applying and getting very hot.

As I did not struggle with this issue on the way home, that makes me believe that it is not the brake lever, and that it is properly adjusted. I did find a seized piston in the front right caliper, replaced it, and am still having this issue. After R&R the caliper, I took it out to test and the same issue occurred. The fluid is obviously over pressurized, as when I cracked the bleeder screw, it shot fluid out. The caliper is very hard to compress, and I am unable to do it by hand. To me (very green to bikes so would love some help), that leaves two possible causes:

A) The compensating port in my master cylinder is bad and not allowing fluid to return to the reservoir to reduce pressure while fluid expands from getting hot.
B) My brake line is splintering internally and acting as a check valve, allowing fluid to run towards the caliper but not back

Before I order parts, is there a way I could test to see if it was either of those, and if not, which one would you all think most likely to be the culprit here?

 

Welcome to the forum, my two penneth, I have never heard of an issue with the brake line deteriorating internally rather the other way getting weak and over expanding when used. That would leave the pistons and / or the Master Cylinder

Ensure that the pistons are clean and move freely within the caliper. When you say they are very hard to compress you should be able to move them relatively easily.

I would start with stripping and cleaning the calipers, replace the seals and go from there. Would be worthwhile changing the brake lines when you have it apart as the originals will be getting past their best.

 

I've got some brake lines and a new splitter joint for them on order. It only affects the right caliper, even after swapping it out with a known working caliper.

 

That being the case then, if still the same after replacing the lines it is still the same only leaves the MC.

 

Yeah, I'd agree with that, fit the new lines and the splitter when they arrive change out the Master cylinder bleed it all up and see what happens bud.

 

Hopefully you got this sorted out. Adding in from my personal experience from recently. When the caliper starts dragging, does the brake lever get harder to pull? IE- pressure trapped all the way back to the MC piston? Or is it only down lower in the system? You could try removing the brake lever when it's locking to see if it releases the pressure and unlocks the caliper.

If you have access to a heat gun, please don't ride the bike to test it. You can carefully heat up the calipers and lines with the front wheel in the air to test it. Keep it moving and don't hold the heat gun in one spot. The consequence can be severe of the front wheel locking up at speed on the road.

Different bike, but they all work the same - ​I recently had a problem with installing an incorrect brake lever. It pushed in the MC piston too far and pressure was not able to escape back into the reservoir through the return port, return port was blocked. Removing the lever in my case instantly released the pressure and the calipers unlocked.