Backfire and won't idle-only running on 2 cylinders-all sorted!

[Deicide]

Update!

[HotelBushranger]

Nice website mate, bookmarked. Wish you posted that up a few days ago though, coudla saved me a tiny bit of hassle

[Deicide]

*****UPDATE***** 16/4/09
Ok, so Duffman and I where going to sync the carbs tonight until I found out that "the cool V-Twin sound" my bike makes is actually because its only running on 2 cylinders!

Cylinders 1 and 3 aren't firing. I get spark, appear to have compression, air but no fuel is getting to the spark plugs (plugs where bone dry)

I have fuel in all of the floats on the carburetor but it dosn't get to cylinders 1 and 3.
Im guessing maybe one of the jets is blocked on 1 and 3????
Would my first course of action be to pull the carbs out again and check the jets???
They where clean when I put them back in, anything else I need to check?

Cheers

Well I pulled the carbs off again last night, cleaned everything

Put them back on this morning, fueled her up and again, only running on 2 cylinders. Purchased some "start ya bastard" today, sprayed some down carbs 1 and 3 and it still dosn't seem to be firing...any one have any idea where to look next?????

[Surly]

Are you sure you have spark?

If it is a two coil wasted spark set up it will probably have one coil for 1 & 3 and another for 2 & 4.

If this is the case try swapping the coils over and see if the problem jumps cylinders.

cheers
Surly

[Deicide]

Pulled no1 and 3 spark plugs out, cranked bike over and grounded plugs to bike-defiantly a spark there. I'll have a check over the leads/coils tonight, is it worth swapping the coils if there is a definite spark?

[g0zer]

done a compression test?

got the leads the right way around?

[duffman]

No need to check coils or leads since there was a strong spark.
In any case cylinders 1 and 3 are are on different coils. (paired 1,4 and 2,3)

Definitely check the leads are the right way round.
Should be a coil with leads going to cylinder 1 and 4, and the other going to 2 and 3.

[Nero Diablo]

I'd say your battery is borked. Most bikes especailly older ones rely on the battery to supply power for the ignition. ie they don't charge at idle when you increase rpm the charging system takes over suppling enough power thus is dying at idle. Your local auto sparky or battery retailer will be able to load test it for you which will definatly tell you one way or the other.

[Deicide]

No need to check coils or leads since there was a strong spark.
In any case cylinders 1 and 3 are are on different coils. (paired 1,4 and 2,3)

Definitely check the leads are the right way round.
Should be a coil with leads going to cylinder 1 and 4, and the other going to 2 and 3.

Duffman, your a frikin legend-I owe you another beer mate! Checked the manual for lead configuration-i just assumed, 2 leads on the left, 2 on the right 1,2,3,4 easy. I changed over the leads to the correct configuration, tapped the starter, after 2 cranks she started up easy and sounds ohhhhh so good!!!!! Running very nicely on all cylinders now!!

Thanks for all the advice guys
Souter

[duffman]

got the leads the right way around?

No worries Souter, but this man deserves the thanks ^^

Hope you arent too disapointed that it doesnt sound like a rumbling twin anymore.

[MuNch]

Was gonna say,

I have trouble idling and backfiring and i only seem to run on 2 cylinders as well