Hi guys, I'll introduce myself (after posting my first posts just now). I'll go by UnderAssumedName and I have a little problem with my lovely F4.

I was riding today and suddenly felt the engine bogging on me when on low revs (idle and take off). It even died on me when taking off from a light. I parked on the side of the road I did a little walk around and didn't see anything out of the ordinary. I tried to take off again and it stuttered on me again (like starting a cold engine before giving it some choke).

I went home and parked it until I had to go out at night. It bogged a bit but thought it was just the cold engine. It then died on me in the middle of the road and I had to push the damn bike across a pedestrian crossing onto the sidewalk. All the gauges were off and the bike wasn't getting any power at all..

Now comes the annoying part. I was just around the corner of my gym so I pushed it over, locked it up and left my helmet, jacket etc at the front desk just so I could figure out what was going on. I replaced the main 30a fuse with the spare and it seemed to work. I popped it in first gear and gave it a mild take off just to see if it would stutter again. F*CK!! In all my frustration I forgot to remove my disk lock!! Ahhh, I've been fine for months without the reminder cable and now this happens!! I inspected the front right caliper and disk and couldn't see any real damage but when sitting on the bike and engaging the front brake lever there was no pressure! The lever went straight to the handlebar. After riding home very slowly I checked the front right brake disk and it seems a bit warped! I can pump the front brake lever to get some pressure but after giving the front wheel a bit of a spin it loses all it's pressure. I can't see any leeks but I guess I'll have to bleed the brakes to check everything.. So annoying!!!!

I've seen two other posts of stuttering F4's. Does anyone know what is going on? I don't feel comfortable testing it out with the 'new' fuse without the front brakes. Will bleeding them at least sort that out? (I'm just wondering how a thump of the disk lock will make the calipers lose pressure..)

Sorry for the long post!

 

Not a single reply?

 

hi... nobody seems ta want to help on this site... nooby myself.. i also posted ...... and no reply.....

well here goes(i'm no expert).. if the disc(rotor) is warped then it will force the brake pistons into the caliper, so ya have to pump the brake... ya need ta replace the disc.....

 

Ide pull the front wheel off, pull the caliper and take both disks off.

Verify both disks are perfectly flat, and verify your piston/pads are in good shape.

Whats most likely happening is what herbal said, the warped disk is pushing the piston in on every revolution, but that doesnt really explain ZERO braking pressure.

Hows your fluid level? Still sure you have no leaks?

 

Thanks for reply guys. The disk was so warped that there was indeed no pressure at all at the lever. I finally just removed the front right caliper and tried to un-warp the rotor with a wrench (spinning the wheel by pushing the front up with my *** against the headlight). The first time was ok but I still didn't feel very comfortable on the bike with only slight pressure on the lever. The second un-warping session made the rotor surprisingly straight. Not perfect but enough for plenty of leverage and stopping power. Now off to look for a used right rotor. I can't splurge now so I'll get some new Nissin rotors and braided line in a few months.