#4 cylinder not firing

Hi to everyone....

I rebuilt my engine after it had been idle for 18 months and fired her up. I found a lack of power which turned out to be #1 and #4 cylinders not firing. I swapped the coils round but same thing. #1 then started working and I rode her hoping #4 would start. She never did.
Is there a way of checking if fuel is getting to the cylinder without taking the carbs off?....

Any other ideas on my problem would be welcomed.

Grandadbob.....in the UK

'83 kz550 C4

'06 VFR800 vtec

do you have a multimeter if you do i'd check the resistance of the no.4 plug cap if it checks out fine cut the end of the lead where the cap screws in back about 1/4" and reinstall the cap you should be getting around 5k ohm resistance on the plug cap. while your at it check no1 as well

do you mean take the complete lead of and measure resistance end tn end thro cap

I think he means unscrew the sparkplug cap and measure from the spike that screws into the lead to where it secures to the sparkplug. On the caps that came with the bike from the factory, they push onto the sparkplug threads at the top of the insulator.

Yeah that figures but I don't think the problem lies there as I've swapped plug leads between #3 and #4, and #4 still not firing.. But i'll try anyway.

Thanks

Might be a coil failure you're seeing. Do you have good compression,valve clearances been checked,and good fuel flow?

You could drop the carb float bowls looking for crud in the jets. This way it's possible to see if fuel is getting to the carbs.

I'm no real mechanic...but after you do a compression check, make sure that carb didnt com out of sync., then i would check valve clearence..and just for shit and giggles recheck your count on the timing chain to make sure u didnt have a little slack caught up somewhere and then after a turn over or two it came off count

grandadbob wrote:

Hi to everyone....

I rebuilt my engine after it had been idle for 18 months and fired her up. I found a lack of power which turned out to be #1 and #4 cylinders not firing. I swapped the coils round but same thing. #1 then started working and I rode her hoping #4 would start. She never did.
Is there a way of checking if fuel is getting to the cylinder without taking the carbs off?....

Any other ideas on my problem would be welcomed.

Grandadbob.....in the UK

'83 kz550 C4

'06 VFR800 vtec

If not already done, would first check for visible fat blue spark using brand new NGKB7ES plugs connected to caps and removed from outside cylinders with plug bases held grounded against the head.

As known, absent decent spark, a cylinder won't fire regardless of incoming fuel mixture.

Good Luck!

I have a spark but not a fat blue one. I get a good kick thro my hand from the other plugs and having swapped the coils round but still have the problem. I'm now checking resistances in the IC igniter.

I'll keep posting.

grandadbob wrote:

I have a spark but not a fat blue one....

What is visible spark quality on the other plugs?

Am thinking maybe weak battery voltage to coils (a common issue).

With ignition switched ON, could use a voltmeter to measure voltage feeding into coil (often from red/yellow wires).

Btw, please don't be put off by responses including simple stuff already known, as it's there to possibly help an interested third party viewer.

Good Luck!

grandadbob wrote:

...Is there a way of checking if fuel is getting to the cylinder without taking the carbs off....

I usually just remove the spark plug and check for any fuel residue (wetness)or gasoline odor.

Would suggest assuring spark quality and compression before further addressing carbs.

Good Luck!

Have you switched spark plugs between cylinders? (i.e. take the plug out of #3 and connect it to the #4 plug wire and test the spark quality again). You might have a bad spark plug.