Can co-authoring a paper as a new grad harm my reputation/career? To be specific, I just graduated with a Bachelor's degree, and my final project supervisor has asked me to co-author a paper with him about the subject of the project I did with his supervision.

I'd love to join the research community, and I guess this would a be good starting point, but there are two issues I'm concerned about:


The first is related to the subject itself: (a) I'm not convinced of the quality of the suggested solution. (b) The project tries to solve two different problems.
The second issue is that I'm not interested in the field of the project. My interest is in a different field. Though, both are related to computer science.


So, would participating in this paper do any harm to my reputation or my chances of getting into a good graduate program in the field I'm interested in?

Update:

Thank you so much for the kind answers. Almost all of you agree that the second issue is harmless, but there are different opinions regarding the first one.

So I said that my supervisor knows better, and I decided to go on and started planning the outline of the paper with his help. When I got to the writing part, I noticed that the main body doesn't relate to or even mention the main problem that we've specified. This is when I decided to decline the offer. It just doesn't feel right.
I somewhat disagree with the previous answers. I think it is largely improbable that publishing a paper would harm your career, but it could if, for example, it is really poor and someone happens to read it. 

Eykanal in a comment to Dave Clarke said that "no one would consider holding you accountable for the content of the paper"; I recall that there is a important trend to insist that all authors of a paper should be accountable for its content.

The fact that you do not want to pursue in the direction of the paper is completely harmless, though. There is really no problem working in different areas, the only thing to be careful about is not to spread oneself efforts too much, but this does not apply here.

So the main issue is (a); here I would say that it can be difficult to judge the quality of a result, especially for an undergraduate, and I would advise to trust your advisor. So it is really, really unlikely that co-authoring this paper could do any kind of harm to your career; in fact it could do more harm to decline this opportunity, since your advisor would probably not understand and you will probably need his or her recommendation.

At the end, I do not disagree that much with other answerers; but I would be less general in my statements.