Eninge only runs on cylinder no. 3 and 4, Help!!

[Crazy_German]

Hi there guys,

Yesterday in evening the time was there, after nearly two years I fired up the engine of my Beauty for the first time after the total rebuild.
I had some problems before with the carbs cause I got wrong O-Rings and so the fuel was everywhere on the engine, but not in the carbs .

So I got all the little problems fixed and after some trys to start and one big misfire with an 3,0ft long darting fire out of the exhaust the runs... I lett her run for about 10 minutes, in this time I set the idle speed an let her rev about 10 times to 3000 or 4000 rpm. Also I used the time to fill the cooling system step by step to let the system vent.
Then I checked that all four downpipes heat up similar, and there comes my problem, only cylinder number 3 and 4 heat up, number 2 was a little bit hot and number 1 was only "warm". after some minutes I startet the engine again to test it more acurate by spraying water on ever single downpipe and that confirmed my first thougts.
So got anybody an Idea why cylinder 1 and 2 won´t heat up?

Here are the specs of my engine:

-Big Bore Kit 444cc from JE Pistons
-Kent Cams
-Dyno Jet Stage 1 Kit
-GF Racing full SS 4 in 1 System
-Ignitech ECU from GF Racing with HRC mapping
-NGK Iridium Spark Plugs,
-New igniton cables

- Loom is not complete but clocks are connected and everything execpt the ligths and indicators and that stuff.
- fuel pump relay is not fittet but its bypassend with an cable.
- Carbs are not syncronised by now but i´ve done the basic adjustment

So hope somebody could help me out.

Cheers

[tanuki]

Coils or leads.

[Waza4]

Its not coils they run 1-4 and 2-3
Its carbs or head gasket, probaly carbs I take it they are clean and a good base pilot setting (if not 2.5 turns to start with) Then get the vacume gagues on and see if you can bring them in with the screw between 2 and 3.

[Crazy_German]

I also think that it could be the coils cause they fire cylinder 2 and 3, 1 and 4 per coil.

I also guess its are the carbs. I will make the pilot setting again and than have another try. But why could come the problem from the head gasket?
I´m mechanic for engines myself, specialy for diesel engines but i don´t get it why the head gasket could do do the problem?

[thunderace]

I doubt it will be a head gasket problem, it would still run on all four.

Have you got a spark at all four plugs? Are all four plugs wet with fuel?

If you are inclined towards carb issues, don't feck about adjusting mixture screws, get them off and strip and clean them properly. They are more likely blocked than badly adjusted if the bike is not running on one and two.

[stimpy]

Are the carbs seated properly
Are the carb rubbers in good condition,no cracks?
Stimpy

[Crazy_German]

I doubt to that the problem comes from the head gasket. I machined the wholes in the head gasket to 58 mm cause the cylinders got rebored to 58 mm for the bigger pistons.

The carbs where fully disassembled, cleaned and assembled with all new gaskets, only the diaphragms are the old ones but they where in good condition.

The carb rubbers are new too and the carbs where seatet excelent cause I use an special "mounting milk" its like liquid talc powder.
the throttle plates got synchronised by myself, I used a bright LED-Lamp for that,I checked that the light gap on every throttel plate was just closed evenly to the others.

@thunderace: what could be blocked insinde the carbs.

I quess I will make the carb settings again and than I will have look again.

So if anybody got other ideas just please tell me.

Cheers

[thunderace]

Jets and emulsion tubes can easily become blocked, so can the passage under the needle seat.

[tanuki]

Before you start pissing about with carbs check the basics.

Do you have a spark on all 4 plugs?

[gullarm]

At least it runs.

I would be tempted to balance the carbs 1st.
Are the idle screws set to 2 1/2 turns out?
Are the right leads on the right plugs?
Check there is fuel in the float bowels - whilst its running.
Spray some WD-40 round the carb rubbers to see if you have a good connection - mine seemed to run fine but they werent even pushed on fully. Only realised when I tried to put my air box on and it didnt fit.
Get it nice and warm and remove each lead and connect a plug on and see if you get a good spark.