honda305 Home honda305 Auctions honda305 Gallery honda305 Forum


honda305.com Forum

Login
□ Search
□ FAQ 
□ 
Vintage Honda Owners,
Restorers, Riders and
Admirers

Knocked my bike over, why's it running poorly?

Jlovvorn
honda305.com Member
Posts: 477
Joined: Tue Dec 27, 2011 11:10 am
Location: Washington DC

Post by Jlovvorn » Mon Dec 03, 2012 11:35 pm

Could be unrelated to fall.

Pull lines off the tap and see if you have two good flows. That will rule out tank gunk theory.

You might redo the carb settings and tuning, just to rule them out.

If it isn't carb setting or fuel delivery, that leaves spark and timing.

All Honda twins will drop one side with low battery. Might check it.

Have you looked at the points? Could have a short or came loose.

Very nice mystery.

akpasta
honda305.com Member
Posts: 342
Joined: Wed Oct 26, 2011 6:31 pm
Location: San Francisco

Post by akpasta » Tue Dec 04, 2012 12:58 am

I appreciate the interest in my post. Thanks guys. My left cylinder has been rich for some time, it always has had a slight amount of smoke, but after 3000+ miles I always figured it was no big deal, and really this change is extreme, it's never done anything like this ever and it happens just shortly after the fall, I figure it's attributed to that.

Anyways.

I can't see how it would be lack of fuel because the plug gets dark so fast and choke does nothing. I'll check some of the stuff you guys mention but it really doesn't seem like any of that.

Davo, who posts on this forum a lot built my bike and I bought it from him almost a year ago. So it's well-restored, but it also means I didn't restore it myself so I haven't been through the carbs. The only carbs I've ever messed with have been aftermarket custom stuff on small mopeds and what not, never something engineered by a company like Honda. What could go wrong in one? What would I even look at?

I checked timing, fuel flow. Did NOT check air flow to the left carb, will check that tomorrow for sure... it's a good point.

What would make one cylinder rich and the other not?

CliffC
honda305.com Member
Posts: 256
Joined: Sat Jan 13, 2007 3:52 pm
Location: Roseburg, Oregon

Post by CliffC » Tue Dec 04, 2012 1:27 am

AK,
This is just an outside chance and the more I think about it, from what you are saying it sounds like carburation but before I did anything else, I would put in a new set of plugs. I cracked the insulation on one once and couldn't see it until I happened to fire the engine at night and saw a blue line on the outside of the plug. Cliff

akpasta
honda305.com Member
Posts: 342
Joined: Wed Oct 26, 2011 6:31 pm
Location: San Francisco

Post by akpasta » Tue Dec 04, 2012 2:10 am

Not a cracked plug. I've swapped the plugs from each side and the left side still seems to be the problem. No plugs were damaged in this mishap either. They're good.

I usually start with the most simple explanation and work from there. Plugs were first thing I looked at once I had a wrench in front of me.

User avatar
davomoto
honda305.com Member
Posts: 2508
Joined: Sat Nov 18, 2006 7:36 pm
Location: Marin County CA

Post by davomoto » Tue Dec 04, 2012 10:16 am

Have you tried new plugs? The air filters were new when you purchased the bike, so I don't think that is the issue.

Davo

akpasta
honda305.com Member
Posts: 342
Joined: Wed Oct 26, 2011 6:31 pm
Location: San Francisco

Post by akpasta » Tue Dec 04, 2012 11:29 am

I have not tried new plugs. If the shops were open last night it would've been the first thing I tried. I did swap the plugs and the left side plug was working fine in the right cylinder. Also the right side plug looked really good, and it produced the same symptoms in the left cylinder. I'll try new plugs as a stop-gap, but unless they both went bad somehow, I don't think it's that.

akpasta
honda305.com Member
Posts: 342
Joined: Wed Oct 26, 2011 6:31 pm
Location: San Francisco

Post by akpasta » Tue Dec 04, 2012 9:06 pm

Just tried new plugs. No change. It's definitely in the left side. Right side runs well and warms up normally, left side doesn't warm up as fast and is really rich.

When I check for spark by putting the plug next to the engine block and kicking the starter, the left side makes big, fat strong blue spark. It's too dark to check for broken wires right now, but in my past experience it would seem that if a wire or connection was weakened/severed by dropping it, there would be not be such strong spark, right?

The fall could not have shook a jet loose. But I suppose it could have messed up the float level somehow, though running rich would lead me to believe it's too high, but then wouldn't gas be coming out of the float bowl through the overflow?

What else in the carb could it be? Has anyone else encountered a rich condition from something in the carb being plugged? I would think this would lead to a lean condition, not rich.

thanks guys.

Post Reply
cron




 

CB-77 | CYP-77 | Road Test | Riding Log | Literature | Zen | Marketplace | VJ Survey | Links | Home