Popping/backfiring?

milestones54 · Post by **milestones54** » Sat Apr 07, 2012 8:19 pm

Hi all

Picked up my first bike this week, little CB72 in pretty good nick.
A whole lot of a fun and gets a lot of attention

A problem is bothering me however. The bike is backfiring after about 10-20 minutes of riding. It will pop/backfire even when the clutch is in or is in neutral (rather than deceleration) and I'm not quite sure of the cause.

I'm sure this is simple but I'd love to get a few opinions before I start attacking the problem

milestones54 · Post by **milestones54** » Sun Apr 08, 2012 9:35 pm

I'll also add that the bike idles slowely higher as it heats up (I had it idling at maybe 3700 today)

Kirk · Post by **Kirk** » Mon Apr 09, 2012 8:23 pm

Welcome to the site. I will throw in my two cents, had the same issue with a cb350. Turned out to be a timing issue and rusty gas tank fouling the carbs. Also had a loose muffler.

Try the search function there are a lot of posts such as this one.

http://www.honda305.com/forums/right-si ... t=backfire

You might also add your location to your profile , someone close to you may be able to help you out or give you more guidance.

Also try Ed Moore's tuning recipe located here.

http://www.honda305.com/cb77_700/cb77-716.htm

Thanks,
Kirk

Jlovvorn · Post by **Jlovvorn** » Tue Apr 10, 2012 11:17 am

Check the play in your points cam now, before you spend three months chasing your own tail like I did.

See "Superhawk from Hell" etc, etc.

rzgkane · Post by **rzgkane** » Tue Apr 10, 2012 11:37 am

Have you confirmed excessive play in the advancer?

Jlovvorn wrote:Check the play in your points cam now, before you spend three months chasing your own tail like I did.

See "Superhawk from Hell" etc, etc.

Jlovvorn · Post by **Jlovvorn** » Tue Apr 10, 2012 11:59 am

I have confirmed too much play at the cam.

Parts are still coming in. Pulling engine this weekend.

I wanted to have cam bearings, chain, tensioner gasket, new tensioner, and some other stuff all at the ready before pulling the engine.

Having studied the operation of the spare head I ordered off EBay - which has the exact same can play and visibly loose springs - I feel confident mine needs fixing.

rzgkane · Post by **rzgkane** » Tue Apr 10, 2012 12:02 pm

Please take many pics and post them for all of us to learn from. Good luck.

Where did you get the new bearings, chain and tensioner?

Jlovvorn wrote:I have confirmed too much play at the cam.

Parts are still coming in. Pulling engine this weekend.

I wanted to have cam bearings, chain, tensioner gasket, new tensioner, and some other stuff all at the ready before pulling the engine.

Having studied the operation of the spare head I ordered off EBay - which has the exact same can play and visibly loose springs - I feel confident mine needs fixing.