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Author Topic: Fire during warm up 2  (Read 573 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 105 times.)

* CB-1 fire 20190224 7.jpg (39.24 KB, 212x245 - viewed 97 times.)

* CB-1 fire 20190224 9.jpg (48.69 KB, 223x324 - viewed 97 times.)
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You meet the nicest people on a Honda.
'90 CB-1, '95 NC35, '94 MC28, '82 C70, '09 Odyssey
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 66 times.)
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You meet the nicest people on a Honda.
'90 CB-1, '95 NC35, '94 MC28, '82 C70, '09 Odyssey
Spurlock
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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
RVFRick
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« Reply #3 on: April 20, 2019, 04:37:02 AM »

Hi Bill,

Sorry for the delayed reply. I don't come on here much.

I picked up a complete fuel line kit and and shield (plus some fender stuff I didn't need (sold as set) from Japan. Posted about it on the facebook CB-1 group: https://www.facebook.com/photo.php?fbid=10157350112460854&set=pcb.2372623069465851&type=3&theater&ifg=1

The function of the shields? I don' t know to be honest. Maybe heat, fire or dirt deflectors. I never found the smaller on in the parts fiche. Your bike doesn't have them?

Also got points from eBay https://www.facebook.com/photo.php?fbid=10157350291165854&set=pcb.2372734732788018&type=3&theater&ifg=1

I had the same thoughts how could the points start a fire? I never detected or since smelled fumes.

I've been too busy to do the repair. Further, I'm thinking a new pump might be wise. I'll try to make time to diagnose this weekend.

-Rick

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You meet the nicest people on a Honda.
'90 CB-1, '95 NC35, '94 MC28, '82 C70, '09 Odyssey
Spurlock
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« Reply #4 on: April 20, 2019, 11:43:27 PM »

Hi Bill,

Sorry for the delayed reply. I don't come on here much.

I picked up a complete fuel line kit and and shield (plus some fender stuff I didn't need (sold as set) from Japan. Posted about it on the facebook CB-1 group: https://www.facebook.com/photo.php?fbid=10157350112460854&set=pcb.2372623069465851&type=3&theater&ifg=1

The function of the shields? I don' t know to be honest. Maybe heat, fire or dirt deflectors. I never found the smaller on in the parts fiche. Your bike doesn't have them?

Also got points from eBay https://www.facebook.com/photo.php?fbid=10157350291165854&set=pcb.2372734732788018&type=3&theater&ifg=1

I had the same thoughts how could the points start a fire? I never detected or since smelled fumes.

I've been too busy to do the repair. Further, I'm thinking a new pump might be wise. I'll try to make time to diagnose this weekend.

-Rick



Hi Rick, no my bikes does not have the shields. I guess I'm happy not to know what I'm missing! Can't be very important.
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1975 Honda CB125S2, 1989 Honda NX250, 1989 Honda GB500, 1989 Honda CB-1
RVFRick
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« Reply #5 on: April 21, 2019, 12:41:01 AM »

Got tank off today. I now know there is supposed to be only one shield not two as I initially believed. The fire burned mine into two pieces.  Roll Eyes

I would ideally buy a new pump since my wiring is damaged and the contact breaker cover is mostly missing (what's left has been carbonized). I hesitate because google search results show generic pumps of dubious quality (several folks report mixed results).

If I go the repair route does anyone have suggestions on how to evaluate my pump's condition? I assume I can run it directly off 12VDC and run IPA or water through it with a flush of gasoline before reinstallation. I have new points I can install and perhaps buy a generic pump to scavenge a contact breaker cover.

My fb post here https://m.facebook.com/groups/1119747858086718?view=permalink&id=2414794988581992
« Last Edit: May 13, 2019, 02:34:57 AM by RVFRick » Logged

You meet the nicest people on a Honda.
'90 CB-1, '95 NC35, '94 MC28, '82 C70, '09 Odyssey
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