Fuel starvation turned out to be something else - MVAgusta.net
 
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post #1 of 9 (permalink) Old 05-18-2014, 07:54 AM Thread Starter
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Fuel starvation turned out to be something else

Greetings people,

Bike is a 2000 F4 750 15,000 miles.
I was cruising yesterday, went to accelerate and she wouldn't rev, had this once last year. After about 1 mile the problem cleared. This time it took several miles to clear.

When I got off and saw the back wheel, I realised it wasn't fueling. The rear brake pad must of come loose, or the brake jammed on?
Has anyone heard of this problem before, of a brake doing this? In nearly 27yrs of riding, I've never had this one before.

Anyway the rear wheel was covered it brake pad, in lumps in places, along with streaks of metal flake, which must have melted. The paint on the wheel is damaged(must of being the heat of the stuff hitting it?)
Had to use white spirit to clean it it, as hot soapy water wasn't cutting it.

Pain in the butt as I hate the condition of the bike going backwards. The wheel is painted red, the rims polished, so I don't suppose a respray will be cheap? May be not too bad if the paint can be removed with chemicals, rather than the wheel sandblasted, and then the wheels rims re-polished, then masked, then the wheel resprayed.

The rear brake has never being very good, even after bleeding, and the reservoir heat shielded. I had adjusted it to come on sooner, as the lever had to be pushed down until it interfered with the fairing(been like this ever since I got her 4 yrs ago at 8,000 miles).
After the adjustment there was still plenty of free play, I tested it on the paddock stand. The back wheel was out 150 miles ago for a hub service.

Now there is a metal plate gently rattling when I turn the wheel, which I suppose is the brake pad back plate. The brake disk it's self doesn't appear to be groved, hope it isn't warped, although I suppose in my ignorance it's the larger more delicate front disks which are more likely to warp. Also hoping the rear caliper isn't damaged, can it be?

Still a good ride out though, well sort of!

Edit I presume I found the culprit, the bolt at the bottom of the rear brake, which runs through the bottom of both pads was loose/hanging out. So I suppose this allowed the pad/pads to drift and get locked?

Last edited by MVBERT; 05-18-2014 at 04:43 PM.
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post #2 of 9 (permalink) Old 05-20-2014, 04:10 AM
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Hi Bert

I had this problem on my RSV1000R, which has an even less effective rear brake than the MV. I had to use it in winter and adjusted up the rear brake to give a bit more control in dodgy condition. A few weeks later on a decent day the rear brake seized on as I rode along the B660 (cloud of black smoke from it as I rode!). I had to wait for it to cool before it would release then slacken the brake adjustment before I could set off again. The disc went blue but it's not damaged and the brake is back to it's normal level of efficiency again now and hasn't played up again. Something like this combined with a lose pin/bolt probably resulted in worse consequences for you.

I had my first proper run on my F4 on Sunday after a delay in the strip & rebuild due to a big crash in this years first (and last:-() race in March. I'll drop you a PM and arrange a run out soon
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post #3 of 9 (permalink) Old 05-20-2014, 04:37 PM Thread Starter
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Thanks for the input, you may be right.
At the time the free play seemed good to me, as I said, I tested it on the paddock stand.

What's worse is a shop put me on a replacement rear caliper 2 days a go(the seals were fried in mine), and 6 miles from them it locked up at a tricky junction.
An old chap came along and he lent me the tools to set the free play to max.

Despite the grief so far this caliper from a 1000R is pretty good actually!

Where abouts are you, besides being nr Cambridge?
Regarding a run out, I won't race on public roads any more, I put alot of effort into keeping her below 80mph in a 60 limit. I have been stopped twice by unmarked police vehicles, and deliberately followed by police on 2 other occasions. I need my license. Having said that I know some naughty roads in Norfolk, if your doing 70-80mph on them it's quite hairy scary, but rather fun!

Last edited by MVBERT; 05-20-2014 at 05:16 PM.
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post #4 of 9 (permalink) Old 05-21-2014, 03:25 AM
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Mine seemed ok on the RSV, and it was, in cold, wet weather but it clearly needed more slack when used in hotter weather and at higher speed. It now appears to have a lot of free play when on the stand.

Last year I did more track miles than road ones.

I generally keep under the speed limit + 30mph on the open road and have done for years as then it's unlikely to lose a licience if caught. 6k rpm equates to about 84mph and that seems ok so we aren't far appart; I'm far more interested in corners!
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post #5 of 9 (permalink) Old 05-21-2014, 04:57 PM Thread Starter
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Quote:
Originally Posted by Graveltrap View Post
Mine seemed ok on the RSV, and it was, in cold, wet weather but it clearly needed more slack when used in hotter weather and at higher speed. It now appears to have a lot of free play when on the stand.

Last year I did more track miles than road ones.

I generally keep under the speed limit + 30mph on the open road and have done for years as then it's unlikely to lose a licience if caught. 6k rpm equates to about 84mph and that seems ok so we aren't far appart; I'm far more interested in corners!
That's interesting about hot weather and higher speed, more expansion and friction. Not sure if my new brake has enough freeplay, I have it to max, whilst it still allows the brake light to stay off. When I first adjusted it to get home, and actually checked it when back home, the brake light was on all the time, so I backed off on the freeplay a tad.

The rear disk still has a little of the old pads stuck on it, so in time this will go, and should help. I also spent ages getting the tough almost carbonized old brake pad out of all the drilled holes in the disk thinking it will help with the cooling?

I hear what you say about being far more interested in the corners!
I saw an Yam R1 recently with a worn rear tyre with inch wide chicken strips. I found this quite odd because I thought anyone with that type of machine would want to corner. Perhaps he/she could do with a track day to boost confidence?
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post #6 of 9 (permalink) Old 06-11-2014, 04:03 PM Thread Starter
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This situation is now fully resolved, and I am posting this incase it helps anyone else. Graveltrap was indeed correct.
Not everyone on this forum is very technically savy, so please don't laugh too hard at my expense!

My old rear brake which had too much travel was probably suffering from the usual heat fade(I'm now adding additional heat shielding to cover the master cylinder as well, and possibly later a high boiling point brake fluid).

By my ignorant action of screwing the rod into the master cylinder to far(even though after adjustment I had tonnes of freeplay at the lever) I blocked the fluid return hole in the master cylinder thus causing a gradual increase in pressure until the brake locked on(25 miles).
I am so ignorant I didn't even know the master cylinder had a fluid return hole which you could block.
I should not of even being messing with that rod to remove excessive freeplay, rather the old caliper should of being properly re-bled yet again and more steps taken to reduce heat fade.

Dave at Xbikes was very patient with me despite me causing him some stress, he is the consummate professional and a true gentlemen. He explained in detail my error and even showed me a master cylinder with a cut out in it showing the return hole's position, and it's relation to the rod position.

The bolt that runs through the bottom of the brake pads came out with the extreme heat and stress of a locked brake being dragged several miles by an idiot thinking he had fuel starvation(brake locked as I went to accelerate and felt just like a fueling problem) the bolt worked it's way loose at some point, and I can't say I can blame it looking at my back wheel afterwards, the fried caliper and what was left of the pads

Thanks once again Xbikes for sorting me out, and a very reasonable bill!

Cheers peeps!

Last edited by MVBERT; 06-11-2014 at 06:57 PM.
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post #7 of 9 (permalink) Old 06-13-2014, 09:25 AM
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Don't worry Bert, there is currently a thread running on RSVZone stating exactly the problem with another RSV100R, which also destroyed the pads, melted the caliper seals and wrecked the disc.

It's a fairly fine line between trying to make the best of a pretty poor rear brake and destruction of the caliper, pads and disc and I doubt you will be the last to suffer this fate!
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post #8 of 9 (permalink) Old 06-13-2014, 09:52 AM Thread Starter
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Thanks Graveltrap,

My disc seems to have survived, the paint on the rear wheel got hot stuff and brake fluid chucked at it.
I have done a semi reasonable job at touching it up, but it won't stand a hand and knee close scrutiny, but other wise it's not bad, if I can be bothered it needs a 3rd attempt at it.

Is the RSV another bike with the rear brake close to the pipes?
So I take it all master cylinders are the same, in that they all have a fluid return hole?

Last edited by MVBERT; 06-13-2014 at 10:08 AM.
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post #9 of 9 (permalink) Old 06-13-2014, 03:10 PM
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RSVR has an amazingly similar set up with the master cylinder next to the exhaust and it doesn't even have a heat shield. The reservoir is placed in the cool unlike the MV decision to sit it behind the motor to keep it cosy.
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