FZRSupport: the FZROnline Archive

YAY it's my turn.
Was running Wed night, then wasn't Thur morning. It tried to start but all I got was backfiring through the carbs. I checked the plugs and they were black. Today went out and got new hotter plugs (CR8E). I installed the plugs, almost started and still backfiring through the carbs. Tool carbs off and found pools of gas in the valve areas. Completely took apart carbs and cleaned them. I Then drained drained the battery trying to start it. I Also got the same result. Almost started and baxkfiring through the carbs. The battery is charging now and I'm posting this plea for help. I would check the resistance on my coils but the Multimeter is AWOL

You prolly already wet the new plugs. I would pull them, and clean them off now that the carbs have been dealt with plus air out the cylinders (crank-no plugs-let sit a few, reinstall plugs).

Then try to start it.

This is odd. I've been doing a bit of research and it seems backfiring through the carb is caused by a lean condition. This would be interesting as my plugs are foulded.
Here's what I can remeber of my carb setup
D&D full exhaust with no baffle(WAY LOUD)
Stock airbox.
Factory Pro springs.
Factory Pro needles clip position #2.
Float Height 24 or 22 mm.
mixture screws 2.25 or maybe a bit more(3) turns out.
Stock jets 107.5 main

Backfiring thru carb while running is a symptom of a lean condition.

Backfiring thru the carb while flooded won't happen on an engine that isn't 'waste spark' like ours are. Since our plugs fire on both TDC on the power stroke and TDC on the waste stroke. What happens is the engine misfires at tdc and a little kernel of combustion happens..but since the mix is so lean it can't fully ignite until it gets more air,so the engine keeps rotating on the starter. Then the exhaust valve opens as the piston comes up on the waste(exhaust) stroke..it gets more air but it is hot stale air with some of the flood fuel in it and the kernel of flame grows a little....then the intake valve opens..nice clean cool air and !bang! the mix goes off.

And you have a backfire thru the carb.

I let everything dry out overnight, I tried again this afternoon and it started for a bit. It ran rough, couldn't get above 4kRPM, had backfires through the carbs and flaming backfires through the exhaust. I also noticed that the backfires coming through the carbs are only on 1 and 4. I really wish I could find my VOM

davephipps wrote:I let everything dry out overnight, I tried again this afternoon and it started for a bit. It ran rough, couldn't get above 4kRPM, had backfires through the carbs and flaming backfires through the exhaust. I also noticed that the backfires coming through the carbs are only on 1 and 4. I really wish I could find my VOM

my bike used to backfire with flames at high rpms...it stopped once I found that my main and pilot jets were switched....not saying yours are switched, but there is a small possibility

my mixture screws are a whole 1 1/2 turns out.

Rechecked the carbs and I didn't switch the jets. I didn't think I did but it never hurts to doublecheck.
I've ransacked my house and still can't find my multimeter. I should be getting my spare multimeter back in a few days (friend had car electrical issues). After that the real testing can begin.
Does anyone have the test procedure for the CDI? I saw one a long time ago but can't seem to find it now.

Update.

I got my multimeter back and the coils are way out of spec.
First my stator went then the VR. Now the coils. I'm wondering if I should get a spare CDI just in case. With my luck it will go out next month.

davephipps wrote:Update.

I got my multimeter back and the coils are way out of spec.
First my stator went then the VR. Now the coils. I'm wondering if I should get a spare CDI just in case. With my luck it will go out next month.

There's a Vance and Hines Powerpak ending soon on Ebay!

reelrazor wrote:

There's a Vance and Hines Powerpak ending soon on Ebay!

you mean this?
http://cgi.ebay.com/ebaymotors/FZR-600- ... ccessories

you can get the stock fzr600 CDI for $20 shipped
http://cgi.ebay.com/ebaymotors/_Motorcy ... 240%3A1318

Thanks for the links guys, but I can't get them right now. I'm so broke right now I won't be getting parts till after the New Year

davephipps wrote:Thanks for the links guys, but I can't get them right now. I'm so broke right now I won't be getting parts till after the New Year

same here!

!!!!!
I went out to the pole barn and was looking through boxes and found a spare set of coils that I got 2 years ago. I got the multimeter out and they spec out fine
Now I just have to wait for all the ice to melt and get them on the bike.