Miss-fire, rough running, poor starting

[teecee90]

Hi folks


My Fazer has started playing up. Difficult to start but when started it idles ok for a while but miss-fires when revved and the oil light and temperature lights come on simultaneously then go off, ideas rough for a while before settling down. When revved again it miss-fires and then cuts out. When trying to re-start from hot it doesn't want to start but turns over very quickly as iff it has very little compression. Have ordered a compression tester but would welcome any views in the meantime.


Only thing I have done recently is add a bottle of red-line fuel cleaner in an attempt to sort out the rough idle (thinking it was maybe gummed up pilot jets). Probably shouldn't have put the whole bottle in - now thinking I may have fried the effing engine....

[ogri48]

I doubt youve focced it mate. its a tough motor. I suppose you could have loosened carbon deposits in the valves at worst, but id imagine it was something far less worrying.

[unfazed]

How old is the battery?

[teecee90]

How old is the battery?

Less than a year old and kept on an oximiser.

Just changed the spark plugs and tried to start it but no joy..... it fires but won't start and chucks out a fair bit of smoke.

[old son]

I had this once. Turned out I had put diesel in the tank rather than petrol! Exactly the same symptoms as you've got.

[ogri48]

also if its been run on cheap petrol then sat you'll possibly find youve got more water in the bottom of your tank than petrol. A lot of people are making a tank purge a yearly thing now.

[teecee90]

Compression test done, all 4 pots reading 120 psi which is well below spec (210 psi per the service manual). Doesn't look good, but strange that they are all exactly the same value. If i'd fried the pistons/rings surely they wouldn't all come up the same?

[teecee90]

Gauge is obviously suspect (cheap £15 Chinese job from Amazon) - just re-tested pot 1 using an old Halfords gauge and read 170psi - still a bit low but a lot closer to spec.

[unfazed]

Compression test done, all 4 pots reading 120 psi which is well below spec (210 psi per the service manual). Doesn't look good, but strange that they are all exactly the same value. If i'd fried the pistons/rings surely they wouldn't all come up the same?

Did you have the throttle open full when checking the compression, they look like closed throttle readings

[unfazed]

Is your battery definitely fully charged? 
Drain the float bowls, lift the tank, turn off the fuel tap.Remove the fuel line and connect it up to a portable fuel container filled with fresh fuel.
Turn on the ignition and wait until the fuel pump stops ticking, switch off the ignition and switch t one again, keep doing this until the pump stops ticking.
Now start it, let us know how you get on.

[midden]

Compression test done, all 4 pots reading 120 psi which is well below spec (210 psi per the service manual). Doesn't look good, but strange that they are all exactly the same value. If i'd fried the pistons/rings surely they wouldn't all come up the same?

Perhaps the cleaner has cleaned the carbon seal off the valves 

[teecee90]

Did you have the throttle open full when checking the compression, they look like closed throttle readings



Yes - throttle fully open.

[teecee90]

Is your battery definitely fully charged? 
Drain the float bowls, lift the tank, turn off the fuel tap.Remove the fuel line and connect it up to a portable fuel container filled with fresh fuel.
Turn on the ignition and wait until the fuel pump stops ticking, switch off the ignition and switch t one again, keep doing this until the pump stops ticking.
Now start it, let us know how you get on.

Batery is fully charged.


Ok - followed this procedure and still won't start. I think it may well be fuel related though ..... if I hold the throttle fully open while pressing the starter it is definiely trying to fire but doesn't seem to be betting enough fuel to start. Pressing the starter with no throttle or very little throttle there is no sign of life at all. I'm thinking the next step is probably to take the carbs off for a thorough clean and check?

[ogri48]

have you tried brake cleaner in the intake mate? that'll tell you if its fuel starvation

[teecee90]

have you tried brake cleaner in the intake mate? that'll tell you if its fuel starvation

Good idea.... ill give that a try tomorrow. Cheers.

[unfazed]

Open the drain screws a little and see if there is fuel getting in to the bowls.
Is the choke on full and operating the plungers?

[teecee90]

Fired up immediately with brake cleaner...... stopped spraying it after a couple of minutes and it idled smoothly and revved without misfire until it ran out of fuel in the float bowls. So definitely a fuelling issue.


Will put the tank back on and try again to see what happens before deciding whether the carbs need to come off.

[unfazed]

Could even be tight valve clearances. You might as well check the valve clearances when you have the carbs off to check the jets, the slides and the diaphragms.

[ogri48]

glad your getting there bud. I know these old bikes are a pain when they play up but at least they are fixable. And once its running sweet you'll fall in love all over again lol dunno if your near me but if you are gissa shout if you need a hand. I had the carbs in and out about four times afore I got it sorted