Bound to happen

[moparkid]

Well after 60,000 miles my sweet baby has decided to leave me stranded by the side of the road. Today I did a full blown maintenance of the bike...oil and filter, tranny fluid, air filter replacement and valve adjustment. Got out on the road and it was performing better than ever....that should have been a red flag right there!

An hour into the ride she started cutting out and then she died. Would not restart immediately but after sitting for about 20 minutes started right up but would die after a minute or so. Managed to get it back home and this morning it started right up but died after 3 minutes and wouldnt start again. But an hour later started right up, but then again died after a minute or so. Sounds like a fuel problem to me but have no idea where to begin.

I know you'll read this Karl and I await your expertise!

Thank you!

[Stig / Major Tom]

I'm not Karl, but I DO owe him some $~!
So, anyway - I remember reading two issues related to your symptoms:
Karl's famous vent the gas cap thing to prevent vacuum forming in the tank and fuel no longer passing to the engine.

And....something about an electrical part was failing - evidenced by the part over-heating and the needing to cool before the scoot would run again.

Fingers crossed it's just the tank forming a vacuum. Easy fix.

Stig

[Neil955i]

I'm not Karl, but I DO owe him some $~!
So, anyway - I remember reading two issues related to your symptoms:
Karl's famous vent the gas cap thing to prevent vacuum forming in the tank and fuel no longer passing to the engine.

And....something about an electrical part was failing - evidenced by the part over-heating and the needing to cool before the scoot would run again.

Fingers crossed it's just the tank forming a vacuum. Easy fix.

Stig

Sorry Stig, but I think it may be the latter.  Be strange for the tank vent issue only to start after 60,000 miles?  I experienced it virtually from new!

[Stig / Major Tom]

Sorry Stig, but I think it may be the latter.  Be strange for the tank vent issue only to start after 60,000 miles?  I experienced it virtually from new!

I agree - maybe something changed with the gas cap (gasket, or?)....seems unlikely true enough.

Stig

[CROSSBOLT]

Stig was right! First thought that popped in my pea brain! Like he said, quick and easy to verify or rule out: have your second key in the gas cap and when she starts to stumble, stall or quit, quickly open the gas cap. It will pick right back up if it is vacuum vent. Sumptin' else if it does not.

I can see it happening from brand new to 60000 miles or anything in between.

[moparkid]

Well it's not a gas cap issue, I used second key, started bike and opened gas cap and bike still died....is there a fuel filter somewhere I do not know about? Plug gap is good, although the plug cable is loose, it has never been a problem before but will order new spark plug cap as a precautionary.

[CROSSBOLT]

Well it's not a gas cap issue, I used second key, started bike and opened gas cap and bike still died....is there a fuel filter somewhere I do not know about? Plug gap is good, although the plug cable is loose, it has never been a problem before but will order new spark plug cap as a precautionary.

Have you checked the spark? Cycled the run/stop switch? Cycled the side stand?


Done all that? Then you may have some snot in the injector. It may not be the easiest thing to eliminate but is do-able. The first phase is easy: just pull the injector out while leaving it connected to fuel and wiring. Prop it so you can see what sprays out when you try starting (it won't start, just crank it over a couple of turns). The spray should be a fine mist each tome it squirts.

Back flush it on the bike or take it to a shop that specializes in cleaning Bosch or Honda injectors. Back flush on bike is simply remove from fuel hose and stick the spray head in the fuel hose and tighten the clamp. Catch the dribbles in a small cup you can see through. Have your charger handy 'cause you gonna do several start sequences to get much out.

I suggest this only because it worked for me when I just KNEW it was not a vent issue: I had vented the cap! And opened it! And I had no codes.

[moparkid]

Not sure what you mean by "cycled run/stop, side stand but will go thru my DT repair manual and find out about those things and will do it. Thank you Karl.

[CROSSBOLT]

Not sure what you mean by "cycled run/stop, side stand but will go thru my DT repair manual and find out about those things and will do it. Thank you Karl.

Cycled: on-off-on-off check with ohmeter for good or funky contact. Same, same with side stand switch. There IS an unused plug down by that side stand switch that lets you bypass the switch entirely.

There is another question about HOW the engine quits: does it stop all of a sudden? Does it just kinda fade in power til it quits? Or does it on again, off again..?

[moparkid]

It just quits...its almost like it runs out of gas. I am going to check the injector in the morning and then maybe empty the tank and see if maybe I got bad gas...I usually always buy my gas at the usual place for sake of continuity but last fill up was done at a different place...a mom and pop joint and it was still a full tank when it started acting up.

[boksaman]

My guess is that something is wrong with valve clearance job. Maybe tolerances are bad, and get worse when engine heats up.

[Neil955i]

My guess is that something is wrong with valve clearance job. Maybe tolerances are bad, and get worse when engine heats up.

Ordinarily I’d agree, but OP states valve adjustment done.

[moparkid]

I am actually going to readjust the valves as that was the first time I ever did that. And its my belief that just because it says .04 (.10mm) doesnt necessarily mean its carved in stone, and maybe like all older hot rods you adjust more by "feel and ear" than by the book.

[CROSSBOLT]

I am actually going to readjust the valves as that was the first time I ever did that. And its my belief that just because it says .04 (.10mm) doesnt necessarily mean its carved in stone, and maybe like all older hot rods you adjust more by "feel and ear" than by the book.

.004"/.1 mm just to be certain! 60k miles, couldn't hoit!

[boksaman]

Hope this helps, it's step by step manual for valve clearance Kymco downtown 300i

https://imgur.com/a/4YtWVZV