Author Topic: 1984 Honda Nighthawk 450cc back after 7 year break  (Read 5731 times)

Offline danyboy

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1984 Honda Nighthawk 450cc back after 7 year break
« on: July 09, 2016, 02:20:49 PM »
I could use some advice . Bought this 1984 Honda Nighthawk 450cc (Canada version) after it sat for 7 years. Friend of mine cleaned the carbs and told me I should get new pilot (slow jets) jets cause the old ones were too hard to get the small holes cleaned up. Took it for a ride yesterday on the highway. After a 6 mile stretch, took the next exit. When the street light turned green, it stalled on me. Waited 5 minutes, started the engine again, drove another mile back on the highway and it stalled again. Did this 6 times. At the seventh, it wouldn't start anymore. Pushed the bike for about 2 miles back home.
 I have no idea as to what might happened. Any help would be welcome.
Thanks.
Dan

Offline murdo

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #1 on: July 09, 2016, 10:48:40 PM »
Have you cleaned inside the tank and the fuel tap? Sounds like it is not getting the fuel through to the carbs. How old are the fuel lines? These sometimes break up from the inside blocking fuel flow. Take the hoses of the carbs and see if you have fuel flowing. If yes then there may be a blockage in the carbs themselves.

Offline danyboy

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #2 on: July 10, 2016, 07:55:26 PM »
Murdo,
 That was  the problem. Petcock was packed. Cleaned it up good. Started the bike. Only problem I have now is backfires (both at the same time). Don't recall having backfires before I changed the pilot jets.
 Thanks for your help, I appreciate.
Dan

Offline murdo

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #3 on: July 10, 2016, 11:17:02 PM »
You may need to richen the mixture a little with the idle mixture screw. On some American/Canadain carbs they are under a cap that has to be removed first. Try adjusting them 1/2 turn at a time (out/anticlockwise to richen).
Did you use the same size of pilot  jet? These may be blocked again from the crap from your fuel tap. Do you have filters in the lines to carbs? Might be a good idea to fit some.
Maybe check for any air leaks around the intake rubbers with the engine running and a spray can of WD40 or similar, spray around the joins of carb to rubber and rubber to head. If you hear a rise in the revs then you have a leak.

Offline danyboy

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #4 on: July 11, 2016, 10:29:40 AM »
Murdo,
 Pilot jets are thé same size. I looked in the carbs for dirt and fortunetly it looked clean. Pilot jets are OK. I will install  an inline fuel  filtre. As for the idle screw, thé guy  who initially helped me out with this carb job went by ear cause I didn't have the  shop manual back then. It says 2 1/4 turns out to start with and there seems to be an adjustment technic in the book. I will start by following your advices first and will let you know.
Thanks
« Last Edit: July 11, 2016, 10:31:48 AM by danyboy »

Offline danyboy

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #5 on: July 11, 2016, 11:48:34 PM »
No leaks after wd40 on carb rubbers test. Player with iddle screws ans backfiring almost disappeared. After turning engine off and a 5 minute wait, checked spark plus. I could pick up thé right  one  by hand (not too hot). Left one was too hot. So, I assume, one side heats up more. Plugs colour looked normal, according to shop manual. Considering checking ignition cables. Plugs are new and well gapped.

Offline murdo

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #6 on: July 13, 2016, 08:40:47 AM »
Both plugs should be getting the same heat.
(Do you have a multi meter to test electrical circuts? They are cheap and can help find a lot of electrical faults.) Try unscrewing the plug caps from the ends of the plug wires, snip about 1/4" from the wires and reattach the plug caps. This gives the caps a clean bit of wire to grip to, clean path for spark. Check the coils are getting the same voltage when the engine running. Check the coils have the same resistance (primary and secondary), are making a good earth to the frame, and check you plug caps too. Try swapping the spark plugs to other side. Are they still one warm one hot? Don't discount a faulty new plug.
Have you balanced the carbs together? If one is open more than the other then one cylinder will be burning more fuel (and getting hotter) than the other side.
Hope this helps.

Offline danyboy

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #7 on: July 13, 2016, 02:24:42 PM »
Murdo,
 Yesterday, I removed  the carb assembly and took it to a bike mechanic, who has a good rep, to get the carbs cleaned up (hé uses ultra sound device to do it). He'll make sure all parts look OK, make basic adjustment. I'll go pick thèm up, pût them back on thé bike. Then, I'll take care of synchronisation, ignition check ups like you suggested ans will get back with results.
 Your tips sûre help and give me a good idea as to where to start.
Thanks,
Dan
P.S. Your  name must be Murdoch, like the detective TV serie.

Offline danyboy

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Re: 1984 Honda Nighthawk 450cc back after 7 year break
« Reply #8 on: July 16, 2016, 12:23:52 PM »
Picked up thé rebuilt carbs et my mechanic, put them on. Runs like a new one. Took it back to get them adjusted. Ready for pick up. Pissing rain out. Can't wait to try it out.