rear shock problem

[C COOPER]

Excellent suggestion on flushing the brake system. One of my riding buddys bought a '99 650 BMW a while back. We were way back up in the hills over Kernville, CA. Long, steep, snowy, wet, gravelly down hill grade. Lots of rear brake action. About 2/3 of the way down the grade his rear brake went out completely. He managed to get the bike stopped, and got off. After he calmed down a bit he got back on the bike.... and the rear brake worked. We surmised that there was some moisture in the caliper - doesn't take much. When the temp got to boiling point for water it vaporized and... no brake. As soon as it cooled down again, brake worked. Very scary. We flushed the brakes last week, and the stuff that came out was pretty nasty looking. Moral of the story: Flush your brakes every year. Chuck

On 9/3/07, Michael Nelson wrote: > > On Mon, Sep 03, 2007 at 08:34:05PM -0000, zeemanscience wrote: > > > Next day, still would not idle when starting with choke. > > Disconnected the fuel line to make sure fuel was flowing to carb, and > > it was (petcock seemed to work), as I thought it was fuel starvation. > > This is an A12 I bought used, have no idea if valves were ever > > adjusted, 2426 miles on this bike > > With that low mileage on a bike that old, the carb is almost certainly > gummed up, and that would also explain all the symptoms you are seeing. I > would strip and rebuild the carb, drain the tank and petcock, and flush > the > brake fluid and coolant, hoping that the corrosion hasn't set in too badly > in the cooling system and brakes. > > You *might* clear the carb with Seafoam, but don't neglect the brake > system. > If the brake fluid has been sitting in there and never changed, it will > have > turned dark and absorbed a LOT of water. Water in your brake system is bad > news, and can cause lots of corrosion. > > Low mileage older bikes are a far worse buy than one that has maybe 5-10K > miles per year with good maintenance. > > Michael > > -- > "Do you think that when they asked George Washington for ID he just > whipped > out a quarter?" --Steven Wright > > San Francisco, CA > > [Non-text portions of this message have been removed]

[Michael Nelson]

On Tue, Sep 04, 2007 at 04:15:46PM -0700, c cooper wrote:

> We flushed the brakes last week, and the stuff that came out was pretty > nasty looking. Moral of the story: Flush your brakes every year.

When I got laid off and was "between assignments" in the computer biz, I did a year and a half as the sole mechanic in a small bike shop. The owner never met a neglected ratbike he could resist, so I ended up rebuilding LOTS of carburetors (70s GL1000 Goldwings were a real pleasure... NOT) and brake master cylinders and calipers (hydraulic clutch master & slave too). We had a commercial grade ultrasonic cleaner and even that had trouble removing some of the clogs in the carbs. I have seen many calipers and master cylinders where the aluminum in the bore was actually eaten away so much by the corrosion created by water in the system that new seals wouldn't seal well enough to work, so that meant "buy new a$$embly" time. For most motorcycle owners IME maintenance of brake systems consists of putting in new pads when they get down to metal to metal and have ruined the rotor too. One guy came in and hadn't even noticed a problem with his rear brake, but when I pulled the pads out all that was left was the metal carrier, and the carrier had been worn clear through in some spots. The rotor was toast. How unaware can you be? Changing the fluid? Almost never, unless I was able to convince them. The corroded, eaten up parts I kept for demonstration often convinced them that a brake fluid flush & refill was a good idea. Open up your master cylinders and look at the brake fluid. If it is darker than very light amber (and you don't know for SURE that it was changed in the last year), flush it and refill the system. If pump the old stuff out while keeping the master cylinder filled up, you can do the job without even having to bleed them afterwards. Michael, who hates working on neglected motorcycles. -- "Do you think that when they asked George Washington for ID he just whipped out a quarter?" --Steven Wright San Francisco, CA

[John Kokola]

There's some frou-frou stuff in the Griot's Garage catalog, but their "Brake Fluid Extractor" is about the best $70 I've ever spent. http://www.griotsgarage.com/catalog.jsp?&SKU=85700 --John Kokola Michael Nelson wrote:

> On Tue, Sep 04, 2007 at 04:15:46PM -0700, c cooper wrote: > > >> We flushed the brakes last week, and the stuff that came out was pretty >> nasty looking. Moral of the story: Flush your brakes every year. >> > > When I got laid off and was "between assignments" in the computer biz, I did > a year and a half as the sole mechanic in a small bike shop. The owner > never met a neglected ratbike he could resist, so I ended up rebuilding LOTS > of carburetors (70s GL1000 Goldwings were a real pleasure... NOT) and brake > master cylinders and calipers (hydraulic clutch master & slave too).

[Michael Martin]

After I had three of the four carb diaphragms fail on my ST1100 last year (at 144,000 miles), someone asked me if I had ever used spray carb cleaner on the carbs. I had used Gumout choke cleaner in the past, spraying it up into the jet passageways with the jets removed. I was told that that stuff can be death to rubber parts. I don't know that for a fact, just take it as a precaution. Mike Martin, Louisville, KY --- Jeff Saline wrote:

> > I think it's easier to try to clean the pilot jet by blowing carb cleaner > through the pilot screw hole and seeing if that works. If it doesn't > then removing the pilot jet and cleaning the passage and jet orifice is > probably the only remaining procedure. >

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[Jeff Saline]

On Tue, 4 Sep 2007 19:29:35 -0700 (PDT) Michael Martin writes:

> After I had three of the four carb diaphragms fail on my ST1100 last > year (at > 144,000 miles), someone asked me if I had ever used spray carb > cleaner on the > carbs. I had used Gumout choke cleaner in the past, spraying it up > into the > jet passageways with the jets removed. I was told that that stuff > can be death > to rubber parts. I don't know that for a fact, just take it as a > precaution. > > Mike Martin, > Louisville, KY

<><><><><><><><> <><><><><><><><> Mike, I'd agree that dipping carb with rubber parts still installed would be a very good way to ruin the rubber parts. But I think a bit of reasonable spraying jets to clean them would be ok. I've done a few jets that way to side step a rebuild. I also use the least expensive carb cleaner spray I can find. Usually I don't pay more than $1 for a 12 oz can. And if I use it I normally start the engine almost immediately upon finishing the cleaning. I think to get carb cleaner on the diaphragm would take a lot of spraying into the throat of the carb and on the slide. Spraying it into the orifice that leads to the top of the diaphragm wouldn't be a good idea either. : ) Thanks for sharing your experience and the caution when using carb cleaner around rubber parts. That's a caution well worth heeding. Best, Jeff Saline ABC # 4412 South Dakota Airmarshal Airheads Beemer Club www.airheads.org The Beautiful Black Hills of South Dakota 75 R90/6, 03 KLR650, 79 R100RT

[Michael Nelson]

On Tue, Sep 04, 2007 at 07:29:35PM -0700, Michael Martin wrote:

> I was told that that stuff can be death to rubber parts. I don't know that > for a fact, just take it as a precaution.

It can, and often so states it right on the can. I would only use spray carb cleaner on disassembled carbs, and only on the metal parts. Michael -- "Do you think that when they asked George Washington for ID he just whipped out a quarter?" --Steven Wright San Francisco, CA

[clint lee jin yew]

my new stock rear shock was working fine for nearly a year on my 1988 A2 till last week. suddenly , the bike lost its height and was soft. i checked for oil leaks , none. BTW i had custom raising links , shorter by 6mm install for about 6 months ago. did i loose some or all of the nitorgen gas packed in the rear shock or am i looking at the wrong place? clint