July 2010 8

I recently purchased most of an 86 honda shadow vt500. As it was missing some of the parts and I was pretty lost in the wiring I just decided to pull the harness and start over. After I had done that however I realized that model has a pulse generator and an ignition control module. Do you have any advice/simple diagrams to wire that system from scratch? I’m bobbering it out so won’t need much past the ignition headlight and blinkers but really just need help with the ignition. I know nothing of this system and this is my first motorcycle so even the coils are a bit funny to me. I tried wiring the coil from a kz440 just to see if I could get the engine to start and failed. I don’t know if that is due to the fact I was trying to wire straight from the wire coming from what I hope is the pulse generator and thought was the points, or if I’m wiring the coil wrong in general even if those were points wires. the diagrams I find online don’t really seem to represent the coils with the correct location and number of terminals. Thanks for your help.

The Honda VT500 does have a pulse generator. It’s a pretty simple and very reliable system. The pulse generator on the flywheel sends pulses to the ignition control unit which then sends a plus to the ignition coils and the spark sparks.

Just use a wiring diagram for your bike and trim off whatever you don’t need. If you have the old harness just use it as a guide. Follow the wires from the pulse generator to the ICU and make sure you match them up properly. Do the same with the coil and you should be fine.

I wouldn’t recommend swapping coils with any other bike. You could easily end up with a non-optimal spark which could over time cause problems in your cylinders.

Cheers.

Great article on carb cleaning….very explicit. I am a first time owner (not so new rider) of 81 honda cb650 custom. It was reasonably well maintained. has 55000 km. It appears I may have carb issues, but would like your opinion before I follow your advice on cleaning. Fuel is leaking out the bottoms of the carbs (in line 4). However this only started to happen following full choke for extended period of time while cold idling. while tightening exhaust from replacing copper o rings at manifold. Also had noticed I left the petcock in the open position for a couple of days after riding. Which by the way i noticed does not fully prevent fuel from entering carbs ( petcock not shutting fuel off completely) as it still drips regardless of setting to off position. Could the carbs have over fillled due to petcock and choke issues….or are the floats likely in need of cleaning. And yes there had been a fair bit of rust in the tank, although I was pretty diligent at removing prior to this fuel leaking issue as I removed for mantenance. There is also an in-line fuel filter reccommended and installed by previous owner due to rust in tank. It seems to capture any residues. Can you offer sugestionsor advice on how to proceed. The bike was running very well and in spite of fuel dripping from base of carbs was still running and idling good. I appreciate your time and efforts in anything you can offer….happy trails….take care.

Thanks for the post.

Leaky petcocks are very common on older bikes. Over time the gas will dry out the rubber diaphragms inside the petcock. It’s easy to replace the rubbers inside the petcock. Rebuild kits can be bought all over the place for under $15.

As for your #4 carb leaking through the overflow – also common. You could have a couple minor problems causing that. Your float level might need to be adjusted, the float pin might be dirty and sticking, and your float needle might be worn and leaking. All three are easy to take care of, you’ll just need to remove the carbs and inspect them.

Cheers
Evan

I’m building a barstool racer with an 78 xs1100 engine. I need help with the wiring. I dont want it to be a total loss system. I need Inginition and charging short cut from t.c.i./ rectifier throuhg on / off switch and start button everthing else will run off the fuse block and switchs. If you could help it would be great . Thanks Fred

Hi Fred,

I don’t know exactly what help you are looking for aside from me coming over and wiring it for you.

Start with the full wiring harness on an XS1100. Cut back all the sheaths to expose the wires. Then go through things one piece and one wire at a time. If you don’t need the part, take it out, then remove the related wires. If you do need it, leave it in. Use a volt meter to trace current. Sounds like all you are looking to do is replace the ignition switch with a keyless switch, and remove all the lights. Most everything else you will be keeping.

Take your time and you can whittle that harness down to nothing.

Cheers,
Evan

Installed a Dakar baja kit on my newly purchased 00 XR650R, when bought ran but dumped fuel out carb o-flow. Removed carb found float level way high, adjusted, reassembled now no start, compression not completely gone but now kicks like my old XL125. Put OE kill switch back and 2 other ignition related wires back to OE connectors. New spark plug pulled and old 1 back in just to eliminate possibility. Confused, any ideas?

Your XR650R should have WAY more kicking compression then your XL125.

Compression won’t be effected (significantly) by your float adjustment, or electrics. Compression is mechanical and inherent to the motor itself. If compression dropped suddenly I would wager that your auto decompression mechanism has become stuck. Or the manual decompression cable is pinched. I would inspect the manual decompression system very closely. If nothing is found to be off then pull your valve cover and have a look at the auto decompression mechanism. It has been known to cause problems from time to time.

Hi Evan. My v65 is leaking oil from the right rear exhaust pipe and smoking at start up. Once it has warmed up and ran for a mile or two the smoking is not really noticable. I adjusted the valves 2000 miles ago and the cold compression for that cylinder is 175 psi.I took the exhaust collar loose and started the bike and saw the oil come from the pipe. I took off the valve cover and everything including the valve lash looks great. I’m also running some lucas through and changed the oil 3 days ago.The smoke is blue and heavy like a predrag burnout. I’m thinking maybe the valve seals. Any ideas and suggestions would be greatly appreciated. Dave

Hi Dave

It almost has to be valve seals. You can have worn seals and seats and still have good compression. I bet if you did a leakdown test on that cylinder it would perform poorly. Sounds like it needs a valve job. How many miles are on the beast?

It has almost 25000, but I know it was ridden really hard before I got it.I was thinking the valve seals also,because it sat for at least 3 years without being ran or maintained. Is it possible to replace the seals without removing the cams or engine?

Hey Dave – I believe the front head can be removed with the bike in the frame, but you’ll have to pull the motor to get the rear head off.

It could also be the valve guides.

Either way – sounds like you need to be opening that baby up. I’d love to know what you find! A v65 is worth the effort of fixing IMHO.

Hi Evan, you wont believe what the problem was. I opened up the carb and the slow idle jet fell out of the carb with the trouble cylinder. Tightened it up and checked the others, bike runs like a sewing machine. I guess what i was seeing as oil was the raw fuel pulling from the valves and cylinder walls. Never seen anything like it though.

Hey Gil – Great to hear you got the problem sorted. I’m glad you didn’t have head damage.

I’ve seen pilot jets drop out more than a couple times. It’s actually fairly common in off-road bikes because of the extreme vibration.

Enjoy that Honda v65, it’s a great bike. I miss mine.

Thats a good looking V65. Mine needs some paint, maybe this winter. I love the bike, the performance is amazing, especially for an 83.I’m gonna ride her til she quits. Take em easy Evan, and thanks for all the advice.

Hi. I just picked up a 1987 Cavalcade with 15000 original miles from the original owner. The bike starts great, idles great, doesn’t miss, choke, cough or anything. Just wont go past 72MPH at WOT. I changed the fule and air filters. Only thing I noticed is that the fuel filter only gets about half filled with fuel. DOn’t know if that’s the Norm. It almost feels that there’s a governor that limits the fuel flow.

When at top speed note the RPMs you are turning.

When in 2nd or 3rd gear are you able to sustain RPMs higher than when in 5th gear at top speed? Does the bike rev out cleanly in 1st/2nd/3rd?

I have a 78 Honda CX500 that Has been sitting for at least 10 years. Put 12V to it via jump starter and all lights, horn and directionals work. When hitting the start button the magnetic start just clicks. I have pulled the starter and it works fine. Bought a new magnetic starter and same thing. What should I look at next? Thanks for any and all suggestions.
Keith

Is the motor seized up?

Put the bike in 5th gear and try to roll it forward. The motor should turn over.

I will try that. Thanks for the quick reply. It is my son’s bike and he was wondering the same thing.
Thank You.

No problem. If the motor is seized then the wheel won’t spin.  You can also do it on the center stand. If the bike is up on the center stand with the rear wheel off the ground you can put the bike in 5th and try to turn the wheel by hand. You should be able to. Pull out the spark plugs to make it easier.

If it’s stuck I generally pour a little oil into the spark plug holes and let it sit a day or two. Or spray in some WD40. Then see if you can rock the wheel back and forth to get the pistons to free up. If they are just lightly stuck due to some minor rust you can generally break them free and have no other issues. If they are rusted up good you’ll never get them free, and if you do the cylinders would likely be too pitted to use.