Losing power/backfiring

[Disliked23]

So I'm riding to work today and about halfway through the ride on some twisty hills she starts losing power. Intermittent bogging down, then surging, then bogging down. I limp her to a place I can pull over and she's backfiring off and on on the right side. So I rode her a couple of miles the rest of the way and she never dies, but does the bogging down thing every once in a while (more often in higher gears at higher speeds).

The only thing that's different from the last time I rode it was that I accidentally left the petcock on and it sat that way for a couple of days. Normally, my fuel filters are about halway full of fuel and there's air in the top half. Now, the filter that is visible (right side) is completely full of gas. No air in there at all.

Did I somehow get too much gas in there, causing it to run super rich on that side, fouling a plug or something?
Got 9 hours to figure it out or she stays here overnight.....

 

[Flugtechnik]

If your float valves are working properly, leaving the petcock open shouldn't be a problem. And I think that would present itself at startup or at least at the beginning of the ride.

How much gas do you have in it? I've noticed that on a full tank, my fuel filters will not have any air in them. Maybe something to do with the pressure from all of that fuel. Ideally, you shouldn't have any air in the fuel lines / filters, but I don't think it hurts it.

When it is idling, does it rev up before it begins to bog down? I think that means that the carb isn't getting enough gas, it leans out, revs up, then runs out of gas and that cylinder stops firing.

If the cylinder just dies, it is probably because the plug is not firing, fouled, bad coil, or bad plug wire. If you change the plug and the problem goes away, most likely the plug was fouled and you are running rich for some reason.

However, it is hard to tell the difference when you are cruising. You just feel the one cylinder dieing. Several times, I have mistaken running out of gas (need to switch to reserve) with a fouled plug. But this usually happens on the left cylinder because it is farther away from the petcock.

I now keep a spare plug and a little plug wrench in the toolbox.

 

[Disliked23]

So if I don't have a plug in my pocket and I pull it can I just clean it off to get it home? I had a shop go through the carbs and they said they didn't need a rebuild and she's been running just fine for quite a while now....

 

[adamrjordan]

I would check your points to make sure they're okay. Your symptoms can happen if they aren't adjusted properly.

 

[anarki650]

+1 on the points. Pull your cover off and take a business card and rub it between the points. That'll clean em up pretty good and knock off any residue that may have built up. Unless they're completely shot that should get you by until you can put a new set in.

 

[Flugtechnik]

So if I don't have a plug in my pocket and I pull it can I just clean it off to get it home? I had a shop go through the carbs and they said they didn't need a rebuild and she's been running just fine for quite a while now....

It's worth a try.

 

[Disliked23]

Left plug is good, right plug is black and has a little buildup. Nothing horrible though, and nothing blocking it from sparking. Think I could do any major engine damage by trying to limp it home?

 

[Flugtechnik]

Did you make it home?

 

[Disliked23]

haha. No ride home for me. Threw it in the truck and got it home and it did it again when I started. Checked everything I could and then remembered that it was backfiring on the right side when I first got it and someone had mentioned it could be the float getting stuck in the carb on that side. Don't have time to take them apart so dropped it off at the shop. Luckily, they have one of my backup engines there with carbs on it and the guy said he would pull the float out of the other carb and see if that helped it. I hope that's what it was. When I started it at the shop it didn't show any of the symptoms it had been for the last two days so I was happy/bummed all at the same time. Will update when I find out for sure what it was. I'm super glad I found the shop that I did. Two full time parents and a new baby doesn't make for a lot of time to actually work on the thing. Casey at motofactory here in portland has been super helpful and I recommend them to anyone in the area. Their shop is literally full of about 10-20 70s hondas at any given time. He showed me a recitifier he installed from oregon motorcycle parts and it looks like pretty high quality stuff. I'd rather spend the 20 bucks on a new rectifier with a lifetime guarantee that pick one up from radio shack that I have to mod to install.

Gonna put the hondamatic on craigslist hopefully by this weekend and once it sells the spending spree is on! Can't wait til I can finally start my build thread.

Are intermittent issues like this just gonna be par for the course with a 40 year old bike?

 

[anarki650]

Are intermittent issues like this just gonna be par for the course with a 40 year old bike?

Not once you get them all worked out. I went through a period of about a year and half debugging my kz650. I'd have something small but serious enough to keep it off the road pop up every couple of months it seemed like. Once I got all the bugs worked out (fixed correctly) she's been issue free for about 2 years.

 

[ericngsta]

I actually got that a lot when I was working out the kinks on a bike. turns out that the filter was preventing good gas flow. trying runnning the bike without an inline filter, fixed it right up. Try that before trying anythign else with the points etc.