Cold header pipe

[Bisley96]

First post ever! So its for a good reason;

My Kat is running on 3 cylinders, started back when it rained while i was riding. I waited for a clear day and took it for a ride and the symptom was intermittent. cleared out at high RPMs, idles on 3 Cylinders. Pops when I give some light throttle turns.

Things that I have done prior to posting.
-Identified that #3 Header pipe is cold;
-Changed the spark plug for a brand new one. Old one which was near new (less than 1k) showed some rust around the bolt and had some whiteness (oxidization)developing just above and on the bolt.
- ensured the drain hole was clean;
- removed 1cm of spark plug wire at the cap end. tested the ohms approx 9.6k ohm reading. Waiting for 4 X water proof NGK 5k ohm caps to arrive in mail;
- swapped #3 wire and cap with #1 - no change;
- swapped the dynatek coils around both reading 3.2 ohms (3 Years old and wires) - no change;
- checked carbs and checked floats (4 years old as well as seats) height - 14.6mm;
- changed both fuel lines, T's carb vent lines and T's with OEM parts;
- carbs were cleaned and sync'd floats checked this season prior to this issue and floats rechecked before posting;
- new main jets 112 and pilot jets 32.5 (mikuni);
- needles set at P3.5 (W/ spacer);
- checked diaphragm (4 years old) for damage and ensured new o ring for vac port still in place;
- fuel / air screws all the same 2 turns;
- choke plungers working correctly;
- New seals on header pipes this season, rechecked tightness;
- Header pipes # 1,2 & 4 temps quickly rise to 300c, #3 50c;
- all vent caps installed & Petcock vac tube installed #4 carb;
- Valve rockers adjusted less than 10k kms.

I am out of options and have not been able to find similar posts with well maintained carbs.

Only thing left I can think of is dead animal plugging header pipe, valves adjustment??

J

[92xjunker]

Clogged pilot jet..

[Bisley96]

I will pull the carbs out and remove the pilot jet and use compressed air on er. Thanks for the reply. Any thoughts on the spark plug oxidization and rust? Its only on that plug.

[92xjunker]

Drain hole clogged and the rain cap over the plug not in place.

[arsenic]

You just said you'll take a jet out and spray air at it. Good luck with that.

[92xjunker]

[Bisley96]

Clogged pilot jet..

It was a clogged pilot jet thanks for your assistance.


Arsenic - I sprayed carb cleaner through it first and dried it out with compressed air.

Drain hole clogged and the rain cap over the plug not in place.

Drain hole is clean and the rain cap is on the spark plug cap. Would it be a sign of arcing? Bad spark plug cap?

[92xjunker]

No