Howzit from South Africa

[impi]

I've just become the owner of a 1990 Bros 400, this little bike has been standing in someones garage for about 5 years, I was asked if I would like to have it and see if I can get it running.
On a positive note I have eventually sorted out the wiring as it was a nightmare of corroded terminals and brittle wire, on the down side the carbs were left with fuel in them, this left a load of brown gunk in all the jets etc. I have cleaned them once but I don't seem to have got them clean enough to get the bike to run, the other big problem I have is the fuel pump and its relay are both dead.
I will be asking for advice from the forum to help sort these issues, and look forward to chatting to other owners

[The Cheese]

Welcome. Good luck. Well done with the free bike.

With past experience in mind. Until you take the carbs apart and do the job right, it will never run well. Be careful of using carb cleaner with rubber o rings still in them. They don't mix well together.

I have no experience with the Hawk yet, but if both relay and pump are dead, hang a temp fuel tank. Just to see if it runs.

[Captain 80s]

Be sure you realize what kind of relay these bikes have. They dot not start to pump when the key is turned on. They only pump when the bike is being cranked or running. If you haven't already tried, you can bypass the relay by connecting 2 of the three wires on the harness side (can't rememeber which right now, black and blue?) and a good pump would operate when the key is turned on.

Good luck!

[Ziggy]

Be sure you realize what kind of relay these bikes have. They dot not start to pump when the key is turned on. They only pump when the bike is being cranked or running. If you haven't already tried, you can bypass the relay by connecting 2 of the three wires on the harness side (can't rememeber which right now, black and blue?) and a good pump would operate when the key is turned on.

Good luck!

Yes, jumping the black wire and black/blue wire will bypass the relay.

[impi]

Thanks guys. I have bypassed the relay and I fitted a generic fuel pump, I may fit a cutout switch to stop the pump running constantly so I don't have it pumping while I'm doing other things with the ignition on( a bit of trial and error will be involved).
As for the carb I only use petrol to clean carbs as I know that it can't hurt any of the seals, now I found a diagram of the carbs I realized that the choke mechanism was missing a couple of items and there must still be gunk in there. 20210810_152352.jpg this was the needle when I first opened the carbs

[Yoshihns]

yuck

[Captain 80s]

I can smell it from here...

[Captain 80s]

Thanks guys. I have bypassed the relay and I fitted a generic fuel pump, I may fit a cutout switch to stop the pump running constantly so I don't have it pumping while I'm doing other things with the ignition on( a bit of trial and error will be involved).

I do retain my fuel cut relays, but I install a parallel toggle switch so I can prime the system, like after winter storage when I drain the carbs. And to get me home WHEN the fuel cut relay fails out on the road.

[jspeed53]

Welcome! We like pictures ... they say thousands of words that posts can’t.

[flyinelvis]

A proven electric fuel pump replacement is that of a Mukuni vacuum pump that receives pulses from the sync port on one of the carbs. Plenty of info to be found here in the forums.

As a side note, I replaced the dead, Chinesium OEM style electric fuel pump on my CB-1 (CB400F) with a Facet 40171 electronic fuel pump. These are used in lightweight aircraft and I figured if they can keep a plane aloft, they can keep my bike running. Would require some creative plumbing but we're all into mods here, anyway...

Fuel pump.jpg

[sfdownhill]

Nice find, impi. Hope it’s running soon and we get to see photos.

[Yoshihns]

I'm pretty sure the Honda OEM pumps are made by Mitsubishi, which is Japan.

You can also run gravity feed. Just don't leave out the inline fuel filter.

[Toxicwst]

I do retain my fuel cut relays, but I install a parallel toggle switch so I can prime the system, like after winter storage when I drain the carbs. And to get me home WHEN the fuel cut relay fails out on the road.

This happened to me on my YZF750, I did the same thing and "poof" problem solved. I eventually replaced the faulty relay but retained the switch. Ya never know.

[sfdownhill]

It’s great to see all the support for the revival of another brother.