Topic: CB 650 eats sparkplugs

[Martox]

Hi everybody!

I started off with my cb650 a few months ago. I bought it in non-driving condition for te price of scrap metal.
There were a lot of small reperations and adjustments to be done ( carb cleaning and restoring, brakes, valves, oil, sparkplugs..) aka the usual when you buy a project like that.
After a few weeks of cursing and swearing-those engineers really did not think about reachability! I managed to get it running... good.
I drove around last summer, did something about 500 km with it, but had to stop because the sparkplugs kept breaking down.
And when I mean breaking down I mean that they just stop working. I could have driven the bike a few KMs and then stop for a drink or so, when i fire it up later 1 or 2 cilinders don't run anymore. if I then changed sparkplugs it would run again until I stopped and let it cool down. This appears with all of the sparkplugs, sometimes it is cil. nr 1, sometimes it is 2 or 3 or 4.
This makes the bike very unreliable so I stopped riding it.
I had some discussions with some people about this thing but nobody understands what the problem could be.
I did all the adjustments according to the shop manual, and it really worked just fine. Only the sparkplug problem keeps coming back.
I am not a hero with electricity but I managed to measure out the resistance of the pulser generators. This was a good value.
The spark plugs I used were new NGK DR8ES-L. I think i bought in total 16 of these sparkplugs but they keep breaking down. Sometimes I tried old ones again after laying around for a few months and then they would fire up but the next time die out again.
I really don't know any explanation for this syndrome. Anybody got a clue?  It's driving me nuts!

THanks'

Martijn

[brooze72]

Maybe pictures would be helpful.  Are they fouled or insulators cracking? Correct heat range? Check plug boots, maybe they have a problem that you are fixing temporarily when you remove then reinsert to plugs. IE poor connection.

[Martox]

I'll take some pictures next week so maybe you can make something out of that. Like I said I tried 4 new sets of plugs and they all stop working.
poor connection would seem unlikely because when a plug brakes down and i try a new one outside the engine it works just fine, when I switch to the old one again it doenst work.
Heat range should be correct according to the shop manual. Insulation is also not cracked.

[Jore]

You've mentioned that you use DR8ES-L plugs, those are resistor plugs, if your caps are also of the resistor type then that may be your problem.

[strynboen]

vas the 650 with same elektronic ignision as later cbx??..with hall sensors..test them ..can you test the plugs in a other mc..or with a megger for isolasion break dovn..often the plugs are just vet of fuel..glassblast or a trip in the oven vith 150 ..sensius vill dry them aut

[grasscutter]

Resistor caps are a known fail point.  The internal resistor short out, giving a misleading fail / work / fail / work scenario.

Put a thin screw driver down in the cap (the end you push down over the plug), and unscrew the screw.
A resistor should fall out.  Usually they are corroded and come out in pieces.

Go buy 4 new NGK plug ends at your local AutoZone, O'Reilly Auto, Napa, etc...

[cb650]

I had a ignition pickup that would get hot and stop working. 

[MiGhost]

Another thing to check is to make sure that the plug wires are seated firmly into the plug caps, and coils. Over time the wires can become loose from heat, and vibration. You can trim approx 1/4" (6mm) from the ends of the wire to allow the plug caps, and coils to get a fresh bite into the plug wire.

[Martox]

Thanks for the replies.
I'll try the new plug caps and keep you guys updated!
The strange thing is that when one sparkplug stops working and I change it with another one it works just fine with the same cap.
I allready trimmed the high tension cables for a better seating of the caps...

[Martox]

Today I Checked the resistor caps.
Unscrewed the resistors and they all look fine! Very fine even.
Can I measure them to see if they are still good? Maybe some WD40for faulty contacts?

[lucky]

You cannot see electrons you can only measure them.
You need to get a real Honda mechanic to help you.
Not one of the kids at the new shops who only know how to plug in a lap top.

[brooze72]

Today I Checked the resistor caps.
Unscrewed the resistors and they all look fine! Very fine even.
Can I measure them to see if they are still good? Maybe some WD40for faulty contacts?

Yes resistors can be measured/tested with a multimeter, & I wouldn't recommend WD40 except for lubrication.
There is nowhere to plug in a laptop on this model (in case you were considering looking for the COM port)

PS Don't be put off by our smart ass remarks, patience Grasshopper, keep posting.