Won't start + Backfire...

1981 KZ1000 CSR Freshly rebuilt engine.

BS34 Carbs with fuel in the bowls and floats set.
Great compression, and new plugs and wires.
Shim gaps are correct.
Timing appears to be set correctly. (Turns over fine).

When I crank the bike with choke in any position, it puffs white vapor 1-2-3-4 out the exhaust then after a few seconds, BOOM a nice afterfire. And of course it doesnt run.
When I check the plugs, they are bone dry! As if they just came out of the package, and no gas smell at all.(All four plugs identical, so I think whats happening is affecting all four cylinders) Its like the engine wont take up the gas?!? just vapor?!?

i'm greatful for any assistance...

Cheers. :dry:

are you getting spark out of all 4 plugs?

if you have compression and spark then it could be the timing advancer locked up in the advanced position. This would cause the plugs to fire late.

Coils plugged in backwards? (left to right)

franknsr wrote:

Coils plugged in backwards? (left to right)

I second that.

Mark

Mark Wing wrote:

franknsr wrote:

Coils plugged in backwards? (left to right)

I second that.

Mark

I would go thirds on that,,,:woohoo:

Thank you for the quick replies guys!

it could be the timing advancer locked up in the advanced position.

I thought that too, but I've checked and lubed it several times now.

Coils plugged in backwards? (left to right)

You know, I hadn't thought of that... Reversing the plug wires for a try wouldnt have any detrimantal impact anyways. I'll deffinately try that, thanks!

Wouldn't the plugs be wet with gas though? They're like new, no brown/black anywhere, just bare metal and dry.

???

YES! Thank you guys, it was incorrectly printed in the clymer manual. Plugs were reversed.

Now shes in the tuning phase... Get the plugs tan, and the carbs balanced.

The road is mine! :laugh:

Cheers!

TeK9iNe wrote:

YES! Thank you guys, it was incorrectly printed in the clymer manual. Plugs were reversed.

Now shes in the tuning phase... Get the plugs tan, and the carbs balanced.

The road is mine! :laugh:

Cheers!

congrats!!! bs34 s.....40/140 3 turns out from lightly seated with k and n s(NOT EMGO) and she ll be a rocket all through the range........emgo s were the root of my problem.....clearancing them didnt help......i tried a few diff combos on jets with emgo s......no go....with wrong jetting, k and n made a huge diff....went back to posted 40/140 and JACKPOT........all 4 plugs a nice dark tan color on first thread ring and its a strong runner......

keith1 wrote:

congrats!!! bs34 s.....40/140 3 turns out from lightly seated with k and n s(NOT EMGO) and she ll be a rocket all through the range........emgo s were the root of my problem.....clearancing them didnt help......i tried a few diff combos on jets with emgo s......no go....with wrong jetting, k and n made a huge diff....went back to posted 40/140 and JACKPOT........all 4 plugs a nice dark tan color on first thread ring and its a strong runner......

Awsome info keith1, and thanks!

My buddy has emgo pods right now, and his bike runs like tar. I've been trying so many different things to help him, but nothing seems to work all throughout the throttle range.

I'm curious though... you say "posted (from where) 40pilot/140main" and "first thread ring (down, looking at ceramic?)". Please enlighten me on these tidbits

Cheers.

TeK9iNe wrote:

keith1 wrote:

congrats!!! bs34 s.....40/140 3 turns out from lightly seated with k and n s(NOT EMGO) and she ll be a rocket all through the range........emgo s were the root of my problem.....clearancing them didnt help......i tried a few diff combos on jets with emgo s......no go....with wrong jetting, k and n made a huge diff....went back to posted 40/140 and JACKPOT........all 4 plugs a nice dark tan color on first thread ring and its a strong runner......

Awsome info keith1, and thanks!

My buddy has emgo pods right now, and his bike runs like tar. I've been trying so many different things to help him, but nothing seems to work all throughout the throttle range.

I'm curious though... you say "posted (from where) 40pilot/140main" and "first thread ring (down, looking at ceramic?)". Please enlighten me on these tidbits

Cheers.

all stuff i read here..search away...read plugs by looking at where ground strap is attached to first thread that goes in engine.......someone posted here not too long ago a link to a page on reading spark plugs....