Fuel, Spark, Not Starting.

A few days ago while riding the HK4 around the yard, the fuel line split at one of the nipples for the carburetor. There was plenty of slack (in both lines) so I trimmed the offending line and slipped it back on and continued doing laps around the house. 5 minutes later, same story. 10 minutes later the line developed a 2 inch split and I called it quits for the night. Looking at the fuel lines, they were shot, so yesterday I picked up some new fuel line as well as some Valvoline 20W-50 (not knowing what the previous owner used and hoping that the proper fresh oil would take care of the rough shifting).

Fast forward to this evening, I got home from work, and planned on replacing the fuel lines, warming the bike up and then changing the oil. I replaced the fuel lines without a problem and then went to fire the bike up, NOTHING. I tried and tried and tried for 2 hours before I finally called it a night. The carburetor is getting fuel - I cracked the drain line and had a steady flow of fuel. I am getting spark - pulled the plug and cranked it over, plenty of spark. I even removed the air filter, just in case. But nothing. Any where else I should look?

I really should search before I post! I will clean the carburetor tomorrow, and check the make sure nothing is clogging a jet. If that doesn't work I will check compression.

Try adding a few drops of gasoline down the carb slide, or via the spark plug hole. If it fires, then dies a few seconds later, the carb is clogged. Replacing the fuel lines may have stirred up garbage that had been resting quietly inside the fuel system.

I had a similar issue with my K 1. Rebuilt the carb and it ran flawlessly for weeks on end with one kick on a cold start and no choke. Then one day on a low speed cruise it started sputtering and cutting out. I had plenty of gas in the tank but had to add some choke to get it home before it died. turned out to be the # 35 idle jet was completely clogged. Replaced it with a spare new one and it fired right up like new again. Check that idle jet.

Make sure the fuel lines are ethanol resistant. Check if the inside of the lines are solid and the ethanol don't deteriorate the rubber.

I would say that if your fuel line was that deteriorated then it could very well have gotten fuel line bits in the float bowl, and then the jets of the carb. You gotta clean those little buggers.

Oh, the K4 wasn't an H-model as the "H" designates the 4-speed model.

racerx said:

Try adding a few drops of gasoline down the carb slide, or via the spark plug hole. If it fires, then dies a few seconds later, the carb is clogged. Replacing the fuel lines may have stirred up garbage that had been resting quietly inside the fuel system.

Click to expand...

Tried and didn't work. Looking at this with fresh non-tired eyes, the spark looks really weak IMO. I discovered last night when I pulled the plug that the previous owner stripped the &#$@ out of the plug, I'll grab a new one tomorrow. I cleaned the carb, didn't see anything in it, but I will try firing it again once I get a new plug.

If I have to, what is the best way to get to the Ignition Coil? From above, or dropping the engine?

KC4YIN said:

I had a similar issue with my K 1. Rebuilt the carb and it ran flawlessly for weeks on end with one kick on a cold start and no choke. Then one day on a low speed cruise it started sputtering and cutting out. I had plenty of gas in the tank but had to add some choke to get it home before it died. turned out to be the # 35 idle jet was completely clogged. Replaced it with a spare new one and it fired right up like new again. Check that idle jet.

Click to expand...

It looked good, but I cleaned it out anyway.

kcjones33 said:

Make sure the fuel lines are ethanol resistant. Check if the inside of the lines are solid and the ethanol don't deteriorate the rubber.

Click to expand...

They are. I double checked by looking at some line trimming that got dropped in a bucket of fuel and sat there for ~24 hours, no gelling or any other deterioration.

steampick said:

Oh, the K4 wasn't an H-model as the "H" designates the 4-speed model.

Click to expand...

The bike is a K4 with a 1970 H heart.

Thanks for all the help guys!

The coil can be R&Rd either way. It's usually easier to drop the motor. Save yourself that p.i.t.a., it's not the problem.

The most likely source of your weak spark is the breaker points or the plug itself. Of course, you want to try a new plug...it's too easy to NOT try. My guess is that your points are lightly fouled, it doesn't take much. Verify the gap, give `em a few swipes with clean 600-grit sandpaper, followed by a good shot of contact cleaner. You can also wipe the contacts with a solvent-soaked rag, if you don't have contact cleaner. Brakleen is preferred, it leaves no residue.

The simple fact that you have any spark, at all, rules-out the coils. They either work or they don't. There is a chance that your condenser is dying. However, that is far less likely than a fouled plug or breaker points.

If you were referring to the plug cap being stripped, it's probably just the end of the HT lead. In that case, I'd simply clip 1/4-1/2" off the end...the shortest amount that will give you clean end, then screw the cap back on. It takes very little force, so take care not to strip the wire again. HT ignition leads don't grow back after trimming.

Thank for the tips! I also noticed last night that the plug wire has a poorly done splice, I might pull a coil from one of the other bikes and replace this one just to rule that out. Hadn't planned on cleaning the points, but wouldn't be hard.

racerx said:

If you were referring to the plug cap being stripped, it's probably just the end of the HT lead. In that case, I'd simply clip 1/4-1/2" off the end...the shortest amount that will give you clean end, then screw the cap back on. It takes very little force, so take care not to strip the wire again. HT ignition leads don't grow back after trimming.

Click to expand...

I wish I was! The plug itself has a few threads stripped so I am assuming the case is stripped as well, I didn't have the heart to look the other night. :2: If that is the case, I might just part out this H, as I already need a flywheel cover and the left case is missing a chunk where the stator wires exits the case. :22:

As far as plugs, KO and HKO's run the same (NKG C7HSA), correct?

So, I grabbed a new plug, gap'd it, stuck it in and it fired right up! :4::4: After a few cups of coffee this morning, I'm pretty sure I discovered my issue - mostly human error. I noticed that because the previous plug/case is stripped, I wasn't seating the plug fully. It would get really tight and I would stop, not realizing it was only half way seated. I realized this as I inserted the new plug in better light. :22:


FYI - Those who may search this thread, a good Honda plug, gap, float valve reference: Data Tables

That's the right plug. Nothing wrong with human error...it's not the mistakes, it's how you handle them and what is learned in the process. Show me someone who makes great omelets and I'll show you someone who's broken a of eggs learning how.

I'd be really hesitant to part-out this engine. The number of H-motor keeps dwindling and the subset in decent running condition is smaller still. If you're talking about a stripped plug hole, it's worth pulling the head and having a pro repair the threads with a Helicoil or timsert...$35 + a new head gasket gets you down the road and the job done right.