1989 Honda BF40A Scraping noise from fly wheel area

[chopperguy]

I've had this engine for over a year and take it out atleast once a week. It runs like a champ. Recently I noticed a scraping noise coming from the vicinity of the flywheel. There was a similar post to this one from 2004, but the guy never said whether he resolved the problem.
Anyway, while the engine is in neutral the noise occurs and gets louder with RPM increase. So far I have checked the idler pulley bearing for the timing belt. There's a little play but no roughness or noise. The belt looks like new. I inspected the underside of the flywheel and there is no evidence of scraping of the magnets on the flywheel. I could take a video of the noise if necessary, but I am hoping someone here will know the problem because I am stumped.

Here is a video of the noise -

BTW, made a mistake on the year. Its a 1998.

 

[chopperguy]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

I've had this engine for over a year and take it out atleast once a week. It runs like a champ. Recently I noticed a scraping noise coming from the vicinity of the flywheel. There was a similar post to this one from 2004, but the guy never said whether he resolved the problem.
Anyway, while the engine is in neutral the noise occurs and gets louder with RPM increase. So far I have checked the idler pulley bearing for the timing belt. There's a little play but no roughness or noise. The belt looks like new. I inspected the underside of the flywheel and there is no evidence of scraping of the magnets on the flywheel. I could take a video of the noise if necessary, but I am hoping someone here will know the problem because I am stumped.

Here is a video of the noise -

BTW, made a mistake on the year. Its a 1998.

WOW Come on guys, thought I could get some help here. Any ideas?

 

[MattFL]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

My 1999 developed a knock that turned out to be the magnets on the flywheel hitting something. A new flywheel resolved it. Apparently this was a known problem with thethe flywheel magnets and Honda paid for the flywheel even though it was out of warranty . Mine only made noise when it was hot. Can you hear the noise if you remove the spark plugs and turn it over by hand? If yes, remove the flywheel and repeat to see if it goes away or if you hear it better.

 

[chopperguy]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

Thanks I did not know that I will take a look.

 

[TOHATSU GURU]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

The windings on the coils under the flywheel may be loose due to age. Take the flywheel off and see if they copper windings move on their mounts.

 

[chopperguy]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

Thanks for the input. Yesterday I pulled the flywheel. Coils were tight as was the exciter for the spark plugs. The magnets on the flywheel are tight and don't really have any marks on them from rubbing. Any chance it could be the timing belt making the noise?

 

[MattFL]

Re: 1989 Honda BF40A Scraping noise from fly wheel area

It's hard to tell from the video, but the noise sounded metallic to me. Does it make the noise if you spin it over by hand (remove the spark plugs to make it easier)? If yes, use a big wrench on the flywheel nut to turn it over both with and without the flywheel and see if the noise is gone without the flywheel. If the noise is gone, then it's likely the flywheel hitting something. If the noise is still there, then you can rule out the flywheel and look further.