Honda Shadow Forums banner
1 - 10 of 10 Posts

· Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
I have taken up a hobby of repairing and restoring older bikes. My current project is a 1986 VT500C. I detailed the bike and replaced rusted screws and bolts and just finished cleaning and lining the tank and cleaning the carbs. The bike starts and runs, but backfires when I rev it up and let off the gas and when driving, hesitates and loses power when accelerating at driving speed. The exhaust smells strongly of unburned fuel. I have the service manual and have gone thru most of the checks there, The ignition primary coils test out at 2.6 and 2.4 ohms, but are supposed to be at 2.0 Ohms and the secondaries test out within the specs. The pulse generators test out at 396 and 406 Ohms, outside of the 432-528 Ohm spec window. It has a weak spark at the two plugs I have checked. The Tachometer also goes on and off, which according to the manual, runs off of the CDI. I suspect it has a faulty Capacitor Discharge Ignition (CDI).I have only found one place that sells aftermarket CDI's. They want about $400 for one, which is about one third of the current value of the bike. I am almost considering doing this. Because there are no specs from Honda on how to test them, the only way to do so is to install it in another bike that is working and see if works. I am considering "surgery" on my CDI to check and replace any obviously bad components. I have replaced popped capacitors in other electronic before, but this might end up being more of an "autopsy". I could use any help you might be able to supply to get this old beauty back on the road and running strong.
 

· Registered
Joined
·
177 Posts
I have the same bike.
I was having trouble with mine and it turned out to be the pulse generators, one of the pair (rear cylinder) would go flaky and lose spark off and on. My pulse generators, when cold tested within spec so testing cold is a guide but not a guarantee of what's what.

The tach runs off the yellow wire that goes to the coil for the rear cylinder.
The bike has a TCI not a CDI box.

Coils are a major failure point on these bikes and if original are probably in the process of failing. Read up about symptoms of coil failure. Coils can be cracked and still test good--they are not.

Plugs, wires, plug caps and wire connectors in general are all sources of problems.

Coils are still made by Honda, around $85 each. Shop around.
Pulse generator: your ONLY choice is a used one. Try ebay.
TCI box: New aftermarket as mentioned or again ebay.

TCI box is particular to 1985-1986 only.
Pulse generator is 1983-1986
Coils are all years.

Remember each cylinder has 2 spark plugs. Check them all.

Get your 3 posts up and post a picture of the bike.
 

· Registered
Joined
·
20 Posts
Discussion Starter · #4 ·
'86 VT500 Help

Thanks for the help. I have been looking for all these parts on Ebay, and even bought coils there. One of my coils was bad and one of theirs was bad, but I got better spark plug wires with their coils. I found pulse generators for $75, but do not look forward to tearing off the exhaust, emptying the oil, and removing the crankcase cover and subframe to replace something that might, or might not be bad, so I am holding off on that for now and hoping my PGs and CDI are good and I just need to run some sea foam through the carbs. The Czech place looks promising for a CDI (TDI) replacement if it comes to that, and maybe I still need new coils and PGs. I will keep plugging away at it.
 

· Registered
Joined
·
177 Posts
Used TCI Box on eBay right now.
Used coils are not worth it. Shop around, new Honda brand coils can be found for $75-$85 each--change both.

If you need to change the pulse generator, order the right side case gasket which is still available, about $8.

I put off changing the pulse generator until I was positive that it was bad--too much work for a maybe fix.

If you do decide to open the case, the only way that you can get the exhaust system off is to remove everything--pipes, power chamber and mufflers--all at once. Having a second pair of hands is helpful. If you end up needing specifics PM me.
 

· Registered
Joined
·
20 Posts
Discussion Starter · #6 ·
Update: The pulse generators were bad. One of the coils had a short just inside the coil case. The ohm reading would fluctuate when I held the coil and pulled on the wire. Found a used one that works on Ebay. I found that one of the boots from the air box to the right carb intake was not fully seating over the back of the intake. From the outside it looked good, but the rubber boot was caught on the edge of the lip of the carb intake. I used a small crow bar to pry it down from the opposite side and now it is on tight. Started it up and the choke doesn't seem work as good as it did before I cleaned the carbs. It takes a while to get warmed up and it runs a little better, but still hesitates when given more throttle, but not as bad as it did before. Its not reliable enough for a road trip just yet. Now the tach, which was working intermittently has stopped working completely.
 

· Registered
Joined
·
20 Posts
Discussion Starter · #7 ·
New Additions to My Shadow Family

Shortly after changing out my pulse generator and going through another carb cleaning on my original '86 VT500C in August I bought another '85 for $600. It only has 24k miles on it and the owner couldn't get it running. Lucky for me it only needed a battery! This one has become my reliable daily rider. By the way it is the California model, with all the anti smog tubes and canisters (three hose connections to the fuel tank!!)

Just last week I bought my third VT500 an 86 with 24k miles for a "parts bike" for $250. It is missing one side cover, the battery, kill/run switch, keys and title (it was repossessed by a tow company). It has three broken turn signals, bald front tire, but a fresh looking back tire with good tread that is only 7 years old according to the code on it. The tank and fenders were repainted and look very good, except for the dent in the tank, and it needs a seat cover.
My wife says, "why do you need another bike?" She thinks I'm crazy. Maybe I am...
I say to myself, "this is a pretty nice bike and with just a little help could live again".

Does anybody know where I can get keys for a '86 Honda Shadow VT500C??>:)
Pictures are of my "California Red Rider" and my other two: the red 86 "Problem Child" sitting next to the "Purple Orphan".
 

Attachments

· Registered
1983 Honda vt750 Shadow
Joined
·
20,586 Posts
Do you mean get them cut? If you have the blanks do you have an original to copy? I had to go to a locksmith to get blanks and have them duplicated.
 
1 - 10 of 10 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top