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Author Topic: Fire during warm up 2  (Read 262 times)
RVFRick
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« on: February 25, 2019, 12:46:22 AM »

Add'l post to add more photos


* CB-1 fire 20190224 6.jpg (48.55 KB, 332x244 - viewed 64 times.)

* CB-1 fire 20190224 7.jpg (39.24 KB, 212x245 - viewed 52 times.)

* CB-1 fire 20190224 9.jpg (48.69 KB, 223x324 - viewed 52 times.)
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You meet the nicest people on a Honda.
RVF400, CB-1, C70, C70, C70
RVFRick
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« Reply #1 on: March 08, 2019, 03:41:09 AM »

With the left side cover off I can see mostly what happened. There is melted plastic from a large cover shield just below the tank.  Flames from below melted it. The fuel pump points appear to be the origin since it is the most damaged area. The burnt plastic cover around the points is carbonized and crumbles under pressure. Damaged plastic elsewhere has more integrity and still flexes. I figure the points over heated and flames spread from there.

Luckily the tank looks fine except for scorched paint on its dangling flange. It was right in the path of the flames.

To do list - buy fuel pump, points, large and small plastic shields (both NLA but found large one on Japaese auction which I won. $10). Probably get new battery. Why risk an acid leak. The cables look decent and I think a layer of heat shrink will make them good as new. Replace any dubious crimps. New fuel line(s) and maybe filter (bought $50 fuel kit from Japan, too). I will drain the tank and remove it to get an even better diagnosis. So far it all seems doable.


* CB-1 fire 1 side cvr removed copy.jpg (112.26 KB, 1703x1277 - viewed 28 times.)
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« Reply #2 on: March 09, 2019, 08:12:45 PM »

Hi Rick, your horror story prompted me to order and install the fuel pump replacement contacts from David Silver Spares, just to make sure mine weren't going bad. At 14,800 miles my originals looked just fine and ran with just the faintest arc with the pump powered up on the bench. I installed the new set anyway. But I'm puzzled how they can get hot enough to start a fire. The fuel pump relay power is protected by a 10A fuse, it seems like the fuse would blow if there was excessive current flowing through the pump contacts. And there is really nothing flammable inside the contacts cover that would ignite easily from sub-fuse blowing current. Or could it be that the normal minimal points arcing could ignite gas fumes that might be present in the points area due to the 30 year old pump diaphragm seeping some fumes? But this theory seems sketchy because the contacts are under a rubber cap the limits oxygen for burning. Anyone have an idea how these fuel pump fires are happening?

Also Rick I didn't even know about the two plastic shields you are replacing. What function do they serve? Thanks,

-Bill
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1975 Honda CB125S2, 1989 Honda NX250, 1989 Honda GB500, 1989 Honda CB-1
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