won't start now ..electrical issue?

[digger650]

Wow ...looks like Spring may be on the way! It got to +3C today!

Had a chance to check the spark situation: using a known-good Honda Civic spark plug, I pulled each plug wire, plugged-in the spark plug, and cranked over the engine (with the fuel turned off). I got a good strong spark on wires #1, #3, and #4 ...but not on #2. I double-checked the wire ...good continuity, but no spark. Does that mean I have a bad coil?

I also checked the pulse generator: the "coil" on the front side had a much larger gap between its "contact" than the one on the back side did, so I moved the front one closer. I cleaned the "contacts" in the process. No change in the spark situation.

I'm kinda running out of ideas here guys ...any other suggestions?

[Rocky]

Continuity at cold does not mean that there would be continuity when the wire heats up. I would replace all the plugs, caps and wires and that should make it fire since you already took care of the pulser coils. And no, it could not be the coils as #1 and #4 fire from one coil (i think left one) and #2 and #3 fire from the other one. So if #3 is firing then #2 should also fire and so either swap wires or buy new ones like I did. Although I am still to test mine. I am not firing on #4 but I had really bad wires, they were all gunked out. Hope this helps. I am pretty sure the problem is minor since it was running before you parked it unless something was sucked in #2 on the day it was parked or something is inside it.

hope this helps. and you are lucky you are getting good weather. over here the rain has not stopped and there was some hail in the afternoon.

[Volker_P]

If you have the original resistive plugs (e.g. NGK DR8-ESL) you might run into trouble with additional resistive caps like you seem to have. In my example D8-ESL would be the non-resistive plugs which should work with caps like yours provided the caps are more or less designed for a motorcycle ignition. In case of any doubt, I would get rid of the resistive caps or bridge the resistor inside with a metal part. In fact the latter would be my next try if I were you. Don't give too much on that it possibly worked that way before somehow. It is not really designed to do that.
For checking sparks outside, always both plugs of one coil must be installed and grounded to the engine (or connected anyhow at their thread side) because of the series arrangement of the coils secondary circuit. However a spark outside does not mean a spark at high pressure, especially when it comes to additional external resistors.

[digger650]

I'll check the plug type later today. Are you saying I should be checking two plugs at a time for spark? ie: take out #1 and #4 and check them, and then do #2 and #3?

Looks like I have OEM stock plug wires and caps etc. What size are the OEM wires (copper core) on these bikes? 7mm or 8mm? I assume it makes a bit of a difference in terms of sealing around the ends to keep moisture out. I think I'll go ahead and put new wires on ..and perhaps bypass the resistors in the spark plug end caps. Does anyone recommend going with the newer graphite core wires? I'm not really concerned about RF noise suppression ...

[digger650]

Okay, Houston ...looks like we have a problem. My bike is running the resistor spark plugs AND the resistor caps. Does that mean there's TOO much resistance going on, and I'm getting a weak spark?? So, hypothetically, I could keep these plugs and go with non-copper spark plug wires and regular connectors, and there would not be an RF issue ...right? Or, I could replace the old copper core wire with new copper core wire (7mm)($1.25 per foot from the local Honda bike dealer) and put in new non-resistor connectors, as long as I use resistor plugs ..
...or, I could put in new non-resistor plugs, and new copper core wire, and keep the resistor connectors ...right?

[Volker_P]

In theory you are right and as your engine did run at least a bit in the present configuration I'd guess it should also be like that in practice.
For checking the spark, no need to take out the second plug of the engine, but it has to be connected to the cable and the thread has to contact the engine (or the plug thread you are checking). This is because the secondary loop of the coil must be closed like:
coil - cable#1 - plug#1 - engine (optional) - plug #4 -cable#4 - back to coil
Any efforts with this circuit interrupted will end up with no spark or other strange results.

[digger650]

Okay, gotcha.

This is just getting weirder and weirder: I tinkered with the plug wires again yesterday ...and re-checked the pulse generator. And then the bike started and ran quite well ..BUT ONLY ON CYLINDER #4 !!! The other cylinders weren't firing at all! I could tell because the exhaust pipes remained stone cold. I'm going to replace the spark plug wires this coming weekend, and see if I can make any progress that way.

[Rocky]

Dude. Just change all your wires, plugs and caps and it should get all the cylinders firing. stop driving yourself crazy. do the easiest first. and don't worry about copper wires or anything. Just go to any store that sells equipments for boats and they should be carrying the plug wire, buy in bulk and use whenever you want. Buy the plug caps from oldbikebarn.com others have said that they have had problems with shipping but I have not.

[digger650]

Okay. Now I've gone from impatient to frustrated.

I took Rocky's advice (which is GOOD advice) and replaced the spark plugs with NGK DR8ESL's (gapped at 28), replaced the resistor caps with new NGK resistor caps, replaced the plug wires with new 7mm copper-core wire ($1.75 per foot). I then re-checked the spark at each plug separately (good), then checked 1 & 4 together (good), then checked 2 & 3 together (good), then repeated the double-plug check by shorting across the pulse generator (good). On the pulse generator test I noticed that the spark on 2 & 3 appeared to be stronger than the spark on 1 & 4.

So ...I fired up the bike ...and STILL ...only #4 cylinder is firing! It's amazing that the bike will run on only one cylinder, but it does. I pulled the plugs again (EVERYONE knows how frustrating a process that is!!) and 1, 2, & 3 were wet with gas, so I know they're getting fuel ...but the not firing! What the hell??????? Its a good thing I already have quite a bit of grey hair!!!

[Rocky]

Ok so now you have made some progress. #1, #2 and #3 are getting gas so that means that gas is getting to them somehow. Could the carbs be somehow plugged? How long ago did you clean the carbs? I mean do you run seafoam every now and then?

Do you have a compression guage? maybe check compression on the 3 cylinders not firing. If you do not have the guage then check cranking the engine over with hand and you should feel the difference in pressure. If you do not then all is not lost you can do a dirty test, take out the plugs and turn the engine by hand but at the same time plugging the spark plug hole with your finger, no matter how hard you try if there is compression you should not be able to plug the hole with your finger. Also did you check the tappet clearence? It could be possible that you have no play in the tappets and that is why you have no firing in the cylinders.

again this an amateur guess. the big guns here should be able to help you here if these ideas do not work. If it was firing on all 4 before you parked then you can get to fire it again on all 4.

[digger650]

Okay ...did the quick and dirty "finger test" for compression, and the compression WAS down on 1,2,3 as compared to #4. So (...and why didn't I think of this before??????????????) ...I checked the cylinder head bolts (at least the ones I could access) and a couple of the bolts in the #1 and #2 cylinder area were actually LOOSE ...yes! One of them took a half-turn to snug up, and three others took at least a quarter-turn! So, according to the tech manual, I re-torqued all the cylinder head bolts I could reach to just over 20 lbs (manual says 17 to 22). While I was messing around down there, I did notice that the head-gasket was wet in quite a few places, so it was obvious that it had been leaking. Anyway, I was so excited about the possibility of this being THE solution to my problems, that I didn't even bother to re-check the compression: I just replaced all the plugs, wired it back up, and ...FIRED it up. I runs really good now ...on ALL four cylinders!! Its amazing (to me, at least) that a lack of compression would have prevented the cylinders from firing ...even when there was gas and spark. But ....that was definitely the problem: loose cylinder head bolts. I doubt they'd ever been checked since the bike was new. Is it common for them to vibrate loose like that??
I'll keep an eye on the gasket to see if it springs any more leaks. Perhaps a replacement is due.

Anyway, guys ...it looks like I'm going to be ready for Spring, after all. I really appreciate all the feedback and suggestions I received, and hopefull I won't be monopolizing the forum for the next few months!!

[Volker_P]

Interesting. It is not normal that head bolts come out. As many of them were affected, possibly the P.O. applied very insufficient torque or used a quite excellent lubricant. In the latter case they might come out again and then it is time to clean all the threads. Or did you have a look on the threads? Maybe a location mark on an outer bolt would be a good idea.
Let's hope your head did not get warped from warming up and cooling down again under that quite undefined tension.

[digger650]

Well ...this whole issue was anything but "normal", so I guess I should have been looking for the "unusual" all along! The bike seemed to be running fine when I stored it last fall ..perhaps the -40C temps had something to do with the gasket shrinkage, and resulting compression leakage. I did not remove the bolts all the way to check the threads ..so I can't comment on that part of it. I just torqued them down. I'll have to keep and eye on the head gasket to see if the leakage re-occurs. I've ordered a compression testing kit, so I'll do a "real" test when it comes to see if there is still an issue. Right now, I'm just happy to know what the problem was!!