Experiencing random & unpredictable engine stalling on my Bullet 350

The engine of my Royal Enfield was opened a few months ago but I am pretty sure this problem has nothing to do with that.

BHPian that_sedate_guy recently shared this with other enthusiasts.

Guys, please, a little help!

So, my Bullet 350 has been on a continuous upgrade & pamper spree. New shocks, new tyres, new mirrors, windshield and whatnot. The engine is butter smooth with satisfying gear clicks.

However, I'm experiencing very random, unpredictable engine stalling. It doesn't stop the bike. The stalling occurs for one or two engine strokes and that's it; resumes like nothing happened. It seems to recur when accelerating hard when in a higher gear but this problem never happened before. Sometimes it also occurs when normally riding; just a split-second stall but enough to scare me wits out. Imagine stalling when doing a calculated overtake!

Tried checking the sparks but the sparks are firing fine. I did notice that the larger spark plug was getting slightly lethargic sparks, missing one or two. Replaced the spark plugs and the new ones seemed to work fine but I can't help but suspect the plug wiring.

Thoroughly cleaned the fuel and air filters. I've also fully cleaned the carburettor. All these combined, reduced the frequency quite a bit but it still occurs very randomly and occasionally. I thought of even replacing the carb before cleaning it but dropped the idea because after cleaning the carb, the performance was much better and I did not want to waste 3.2K over possible placebo effects. However, if need be, I can replace the carb too.

The engine was opened a few months ago for buffing the cylinder head but the unanimous feedback was that my engine was almost factory-fresh so I'm pretty sure it has nothing to do with the health of the engine. Same with the crankcase and drivetrain. I keep these clean and maintained properly always.

Any idea why my buddy is starting these tantrums? He's barely 8.5 years & 40K kms old now.

Here's what BHPian jeeva had to say about the matter:

Assuming it's a UCE, try switching the TCI unit from a different bike and see if the problem persists. Looks like an electrical issue related to ignition.

Here's what BHPian Anz1979 had to say about the matter:

Check your primary ignition coil and replace if faulty. Hope it will solve the issue.

Here's what BHPian Geo_Ipe had to say about the matter:

Fuel quality could be a possible culprit. Have you been feeling at random bunks? Stick to one particular company (I usually fill up only at Indian Oil) and choose a bunk known for quality.

Empty the fuel tank fully and look for rust inside as well. Always keep a quarter tank of fuel minimum in the tank, opt against refueling only when you start running on fumes.

Here's what BHPian Balaji31582 had to say about the matter:

After a long gap, I did a water wash for my TBTS 350 and unfortunately, I didn't realize that the men at the water service station didn't dry the bike properly (almost after sunset it was). Eventually, there was water or wetness in all touch points from the battery, rectifier, spark plug, charging coil assembly, etc. I had to take it to my mechanic 3 days later as it was stalling without any symptoms and asked my mechanic to spray air on all the touch points. He opened up the connectors throughout the wiring line including the ignition switch. Post that no stalling happened.

I am narrating this whole incident because by any chance if you think your buddy was done with water wash, that act could be the source of the trigger and it will simply require you to spray the air in all touch points opening up connectors, etc. If not, the circuit closing battery with the rectifier that will keep the charging from charging coil should be checked as you have ruled out the spark plug, carb.

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