BACK FIRING AND BLACK SMOKE!! :(

[w00dzy]

Hello everyone..

My mates just aquired a Fzr 400 1988 exup for a bargain of £400 with 7 months tax and mot...

Its got me quite excited seing a 400 as im getting my first bike which is a cbr nc23 tomorrow! :d

However his bike has decided to ...

On hard acceleration around 8 - 11k rpm the bike backfires and spits out black smoke.. and then suddenly accelerates.. - im a bike novice but from doing a little research this sounds like a carb problem? possibly to rich?? is this easy to adjust? any tips?

If left idling for about 5-10 mins the engine gets very hot.. maybe this also indicated a rich mixture?? again im not sure...

Last night the bike kept stalling and now the bike will not start. The starter motor clicks, lights are dull. appears that the battery is drained.. we have been advised it may need a new battery or a new rectifier? any ideas? if so wat rectifier is required? where is it?

We managed to jump start the bike and get it back to his garage for tonight but had to jump it every few hundreed meters for about 2 miles!!! the backfiring was flaming a lot and car alarms were going off!!!

Please advise ladies and gents...

Any help would be appreciated... :)

[Evilchicken0]

I think the two problems could be related.
The altornator cound be knackered so the battery isn't getting charged. That means the bikes sparkplugs are only being supplied by the battery, so as the spark is weaker. When you open the throttle the bike gets a lot more mixture which it can't fire, that then goes onto the exhaust so when the engine does fire it ignites all that as well making it backfire.

You need a replacement alternator, and probably a battery if yours has been damaged by not charging.

[wullvfr]

hello mate-

i think that usually a hot engine is evidence of a lean mixture!!!!!!i know it doesn't sound right but im sure i have heard that before

backfiring and black smoke is however signs of over fueling and unburnt fuel,there could be many reasons for this and as ec say's.....poor spark that is unable to ignite the fuel air mixture.

as for the starting/battery dead issues,get a hold of a multimeter and do a few simple checks.....

i would take the battery off and fully charge it if you can,and then get the bike started..........first of all check the battery charge rate with the bike idling at 5000rpm...........

it should be between 13.5-15 volts.

if your reg rec is goosed then the volts should drop instead of rising.

on the other hand,the volts could be way too high which has caused the battery to have burnt out making it useless....this is because the reg rec is not regulating the voltage as it should from the alternator.

do this first and then go from there.


william


william

[Evilchicken0]

An FZR getting hot in the first few minutes isn't much to worry about. They run hot before the thermostat kicks in.

A week mixture will make an engine hot, that's why you should always get the fueling checked if you change either the can, the air filter, or both, the extra heat can cause the vales to burn

[w00dzy]

Cheers for the advice guys.. My mate charged his battery last night and went out for a small ride with me today.. The bike seemed ok and started fine.. however we do not have a multimeter so will do that soon..

Will keep you informed.. and also post pics of our bikes soon!

[fzrtim]

All above points are valid. I would suspect the rectifier has gone u/s.

[wullvfr]

however we do not have a multimeter so will do that soon..

start the bike and put the lights on,sidelights will do......

rev the bike up and the lights should noticeably get brighter....best to do it when it's darker!!!!

if the reg rec is fine and the battery is getting a charge then the lights should get brighter.if the reg rec is goosed then the lights will not get brighter at all.

i would recommend sourcing a multimeter to do the test but this light test will give you a indication now.



william

[Evilchicken0]

The Bike is running on the stored charge in the battery. As the battery isn't being chared it will go flat again and as it does so the backfiring will start again.

[sharpey]

just a note when you have the multi-meter and are doing the charging check at 5000rpm make sure u have the lights on and on main beam and as stated u shud get 13.5-15volts, if it turns out ur reg/rec or generator is fubar let me no im sure we can come to some arrangement as i have a complete 1988 3en1 that i am looking at breaking some time soon.

[w00dzy]

really appreciate the help peeps.. my mates gona try some of this today and tomorrow.. his spedo is also not working? any ideas of an easy fix?

sharpey, alrite to take ur mob number?? will call when we know wat we need..

right im off to make the most of my day off work!! get the sledge out!

loving this site more everyday!