Strange Engine Problem Tonight - Opinions???

Hey Gang - My 810 has been running perfectly, pulling better with the Gpz cams than I had ever imagined.

Tonight I had a little problem when I let it rip in the higher rpm's.

The bike cut out on me for a fraction of a second then it backfired out of the pipe - big time! It caught again and was fine. This happened to me twice when I had it on full song above 8-9 grand (maybe even more). I have had the bike up well beyond this range many times and it never happened before. When it cuts out, all cylinders are dead for just a fraction of a second.

Earlier in the ride my battery didn't have enough juice to crank over the starter, luckily my reliable kickstarter is always handy.

I had charged the battery a couple of days ago and it seems to be losing its charge for some reason. The battery is less than a year old, kept in a warm garage and I put the trickle charger on it every couple of weeks. The battery should be fine.

I realize that the backfiring is from unburnt gas building up in the cylinder, this tells me their is a misfire on the complete ignition system.

So, what could be causing my battery to lose its charge and cut out at high rpm.

Plugs are good and wires are new this season. Dyna S ignition and Dyna 4.0 ohm green coils.

So any ideas? I am strong with everything mechanical on the bike but my weakness is in the electrical gremlins.

Cheers-Colin Firth-Ontario Canada

I'd say check the wires around the coils for a bad connection. Also low voltage can cause the ignition to cut out at high RPM's where it needs more juice to keep the sparks up with the RPM's.
Mark

have you checked the charging system, also look at all the grounds on the motorI would even add another one just to keep everything happy

Colin, You state, "battery should be fine"... this is a classic! A little motorcycle battery can sulfate in a matter of no time, regardless of how nice you are to the battery. Either get the battery load tested at an autoparts place or by a small hydrometer and check the cells. If the battery tests good, your charging system has some issue. It is loosing charge and I would be willing to bet that this problem is related to the loss of spark and backfire at higher rpms. If the battery tests good, check connections, as has been noted.

kzrider.com/component/option,com_joomlab...w/catid,2/id,148248/

Had a similar problem but mine happened at lower rpm:(
Still havent found the culprit:angry:

My ZN does this every once in a while too.

The contacts within my ignition switch are worn beyond cleaning and will "kill" power to the bike every once in a while (always when accelerating), which creates a nice loud backfire. :pinch:
Turning the key every so slightly (about 1/16") counter-clockwise returns power to the bike.

I'd buy a new switch if they were still available, but the part# for it only fits the ZN700 and there are none to be found anywhere.

Also check the ignitor and it's connections, as this can cause similar probs.

Post edited by: RetroRiceRocketRider, at: 2007/07/03 22:54

Hey Gang - I had to work a little late tonight and when I was going to take the bike out for a ride with a fully charged battery it started to rain.

I ended up pulling off the points cover and resealed (with electrical tape) the power line to the electronic ignition. I also rechecked the connections and found that the coil wire mod's relay might have had a loose blade connection. I recall this popping sound last summer once before and the connection was loose on the 4 prong relay.

I'll take it out tomorrow night and see if this fixed t he problem. If not, I will check the voltage on the battery and then the igniter and the rest of the wiring to the coils.

I'll keep you posted.

Cheers-Colin Firth-Ontario Canada

Check where the wires from the kill switch run down into the handle bars my 900 wore a small hole in the isulation and would intermitantly ground out on the bars.usually at higher rpm when the 900 buzz was coming on.

RetroRiceRocketRider wrote:

My ZN does this every once in a while too.

The contacts within my ignition switch are worn beyond cleaning and will "kill" power to the bike every once in a while (always when accelerating), which creates a nice loud backfire. :pinch:
Turning the key every so slightly (about 1/16") counter-clockwise returns power to the bike.

I'd buy a new switch if they were still available, but the part# for it only fits the ZN700 and there are none to be found anywhere.

Also check the ignitor and it's connections, as this can cause similar probs.<br><br>Post edited by: RetroRiceRocketRider, at: 2007/07/03 22:54

R4, Ebay has ignition switches for KZ's... It will have a different key, but what else can you do? I think for the most part they are usually a "Universal" type of part.