DO THE TON

Blood Sweat Tears and Grease => Projects => Restorations => Topic started by: VintageMBike on Jun 10, 2018, 15:21:44

Title: Restoring a 1982 Honda CB 900F - Pics
Post by: VintageMBike on Jun 10, 2018, 15:21:44
This bike is pretty much finished except for brake work and tying up a few loose ends.

I encountered the following problem yesterday:

While racing on my 1982 CB900F, at high speed, the engine sputters and dies, as if its run out of fuel. The fuel cap vents are clear, Im pretty sure the carbs are clean, so Im thinking it might be the AFV - Automatic Fuel Valve, though I will double-check the carbs. I really *HOPE* its not the carbs.

A friend advised that I bypass the AFV, but I have read some ppl have had the experience of their motor hydrolocking when a float got stuck, and the AFV had been removed: so fuel flowed right into the engine.

Im pretty sure this problem isnt electrical, but is related to fuel delivery. Has anyone had this issue, or an experience like it?

Thanks!
Title: Re: Restoring a 1982 Honda CB 900F - Pics
Post by: cxman on Jun 10, 2018, 17:05:20
check your charging voltage

then check you voltage at the coils while running consider doing the coil relay mod sparckmoto has a plug and play relay solution for this

look at the potting compound on your igniters iff it burnt and melting out i would get a set of procom engineering  igniters they are a great upgrade

also do a ohms check on your coils make sure they are good

i have the same color 900f great bike
Title: Re: Restoring a 1982 Honda CB 900F - Pics
Post by: VintageMBike on Jun 10, 2018, 19:25:36
check your charging voltage

then check you voltage at the coils while running consider doing the coil relay mod sparckmoto has a plug and play relay solution for this

look at the potting compound on your igniters iff it burnt and melting out i would get a set of procom engineering  igniters they are a great upgrade

also do a ohms check on your coils make sure they are good

i have the same color 900f great bike

Thanks.

Im pretty sure this isnt an electrical issue. Bike is fine when choked, but when unchoked, this happens. Its fuel related, but Im not sure how.
Title: Re: Restoring a 1982 Honda CB 900F - Pics
Post by: cxman on Jun 13, 2018, 11:21:09
plugged idle passages
Title: Re: Restoring a 1982 Honda CB 900F - Pics
Post by: Maritime on Jun 13, 2018, 13:41:35
By AFV do you mean Vacuum petcock? is there a line from the intakes to the valve that doesn't pass fuel? If so and that is cracked or leaking it will not allow the valve to fully open when you need it too. Removing it and changing to a regular petcock valve just takes the discipline everyone had to have before Vacuum ones to shut your fuel off when you park. everyone before 1980 had to do it. That prevents hydro lock and you always have full fuel flow. FINE-C as the MSF folks say.

F= Fuel valve on or off
I= Ignition switch
N= Neutral
E= engine kill switch

C = Choke on cold motor.

Anyway replace the hoses and clamps for the vacuum and check the diaphram in the valve for dry rot cracks if you want to keep it.