Engine problem?

[Miokoukou]

Hi guys nice to meet you.

Hi i am from a small isalnd in greece. Unfortunately no engineering for harley here . Ι am engineer for boats I know some thing about engines . So I have a sporster 883 hugger 1996. I have a problem with my rear cyclinder (under the seat) makes less burnings from the front. For example the front one burning 3 times instead of back cylinder burns 1 time.

I have clean the carb many times with factory adjustment and i have put new manifold o-rings.
Exchausts 2 on 2 without contact with the pipe under the carb with straigt muflers with light silencers(nice sound).
I have some backfires when i close the throtlle for example without push the clunth on street, when i open the throtle i take one backfire 1-2 times in 20 km(i don't care so much for thisi know that this cause it the mufflers).
New genuine harley spark plugs.
I have change rocker box gaskets from both cylinders.
And a custom hopper with an 90 deggre inox angle.

Many Greek engineers says that's how harley works so i don't think that this is how the harley engine works.

Sorry for my bad english hope to find a solution to this problem.

[NRHS Sales]

does not sound right to me either. Do you have a way to check the compression of the cylinders?

[Miokoukou]

i am going right now to take from my friend a pressure cloack i don't how excactly it named.

[A 4 liter V8 eater]

pressure cloack is good enough. pressure cloack = compression gauge

[Miokoukou]

Both cylinders have 150 psi without loosing any pressure. I don't know what happening after all it's the first time i have a problem like this on an engine. I am w8ing for a ignition coil from my friends sporster to try it in mine sporster. I have good spark but i can't think anything else.

[Bob s hog]

check for intake leak ,your rolling compression is good have you put in new plugs might have a spark plug wire going bad too .

[Miokoukou]

I have new silicon wires and few hours ago i bought new spark plugs. I am w8ing to change the ignition coil with my friends we have same ignition coils to check if something change.
But i have already put the fronts spark plug wire in the rear spark plug and the rear in front without change the wire in ignition coil (I think you understand what i mean) so the engine start up like ever without any change so i thought that it's not from ignition coil (the spark plugs works the same time).
Intake leak u mean from manifold o-rings ? ( i have put already new, one or two months ago. Nothing changed. I have also new manifold from a crashed sporster.

O and while the engine is idling i pulled the spark plug wire from the front cylinder, the engine worn off, i did the same with the front one cylinder i pulled the rear and the egine still keep idling with the front cylinder working perfectly.

Why it can't work in idle with the rear to different timings???????

Pffff big headache

[steelworker]

Try removing both plugs, fit the plug caps to them and rest the threaded part of the plugs on the cylinder heads, then turn on the ignition and spin the engine over. Look to see that you have a spark at both plugs. Does one appear weaker than the other?

Your stock ignition should be "wasted spark" type, where both plugs fire at the same time, regardless of which cylinder is on compression stroke, so it seems strange that one cylinder only should have a problem.

Do you know whether your bike has the stock ignition module?

Can you try swapping ignition modules with your friend's Sportster?

Which island are you on? Anywhere near Koroni (Peloponnese)? I'll be there for a week from Saturday.

[norseXL]

This engines by the design run fatter on the rear cylinder so if your carburator is set up a litle to fat then the rear spark plug are going to get bad first.
Try one step hotter spark plugs and maybe one step smaller pilot jet.

Tore

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[BWP 5p]

Miokoukou........ to THE FORUM! No need to apologize for your English either! We have English speaking people on here that can't use it either!

Keep posting and I know there are enough folks on here that have had your problem.....and will help you get it sorted out!