At wits end...87 VFR with no spark

New to VFR World here and need some help.

I've had this bike for 10 years now. In 05 I broke a chain while riding @ 60 and it broke/bent all sorts of things in the gear shifter area. I tried to repair it but it never ran the same. In 07 I bought a used 86 motor and am now finally getting around to replacing it.

I've gotten almost everything back together and tried to fire it up and have no spark. It has 12v to the CDI box with the ignition switch on. It has 12v at the black wire on the coils. Accessories seem to be working ok.

Any help would be a godsend before my wife makes me get rid of it!

 

Since you have loosened a lof of stuff, with the first engine & then replacing it, I would be sure the ground wire is tightly grounded & remove any corrosion.

 

Honda bible for 86vfr700f: weak or no spark:
1. faulty spark plugs.
2. fouled spark plugs
3. faulty spark unit
4. broken or shorted spark plug wires.
5. faulty ignition coils.
6. faulty engine stop switch.
7. faulty ignition switch
8. faulty pulse generator.
9. faulty cam pulse generator.

I would first be sure the battery has a good charge. Try to start it. Then check the negative battery cable , both ends for corrosion and tightness. (another words the ground). On my 86 there is also another ground wire on the right side of the cycle, just where the upper part of the radiator hose makes a 90 degree downward turn. It is the rear attach point for the front fairing . Its a green wire.

Others on this forum have had trouble with the engine stop switch on the right handlebar. Be sure its in run position. To check it honda bible says: for the engine stop switch when in the run position, continuity should exist between the color coded wires in the chart below: Then it shows BL, BL/W. Remember this is from my 86vfr700f book. Some of the other posts mention contacts within the run switch assembly.

Seems to me low battery or poor grounding could degrade the system to provide no spark, & the stop/run switch is designed to do just that in stop.

I am also concerned about what all got damaged from the chain on your first engine, that could not be repaired or diagnosed.

 

YOU need the wiring harness and CDI box from an '86 due to the differences between the 2 models, namely the cam pulse generator on the '86 system.

 

ok I have the same darn problem. a horse and no spark. got a test light and checked the plug leading to the right hand run/off switch. here's the results

black/r no light
y/r no light
blue/w nno light
g/y dim light
brown/w dim
brown/blue bright
white/green bright
black white dim
black bright

 

Is this on your 1985 vf700f?

 

I found this post on this board but cannot download the vf700f wiring diagram. You might try finding the live post to attempt a download or contact the member for help.

07-09-2010 01:00 PM #1
hoobatech
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1st / 2nd Gen Service manual Download links
Since this comes up pretty frequently, maybe we could sticky this post.
Im hosting these files purely for vfr world
so its a safe bet they will be up for a very long time
1983-1985 VF 700 - 750 Service manual - Honda Shop manual
1983 VF wiring diagram
1984 - 1985 VF Wiring diagram
VF 700 - 1100 v4s - Haynes manual
1986 VF750 Owners manual
1986 VF750 Service manual - Honda Shop manual
VF500 - Clymer manual

Edit:

This is just a link i was given i have no idea if these work all the time or if you need a user/passwordLink to all sorts of v45 manuals

 

yeah 85 vf700f.