1979 390 OR...a little help please!

Hello to all! I'm new to the forum and hoping to get a little help from you guys please. I'm in the process of buying a 390 OR and I had a couple questions before I do the deal. It is currently a rolling chassie with all parts but the motor is out of the frame.

My question is the reason the motor is said to be out is the main center gasket between the cases has dried out and failed mainly right at the top of the motor just below the intake manifold. Owner says it is pulling air from there which makes it hard to start.....does this make sense? 2nd question when looking at the top of the head I see 4 head bolts/studs plus 2 other places that look like they could/should have bolts but don't. Is this correct? How many head bolts are there 4 or 6? I'm sorry I have no pics at this time.

I assume to split the cases to replace the center case gasket is a bit of a job that takes special tools? Are there any other percautions or advice that might be offered up that I may want to be aware of?

Thank you in advance for any help that is provided. Looking forward to enjoying this great forum.

Mike

Yes, to split the case does require some special tools. You can't just go pounding and prying, because the magnesium cases are too weak and the crank will be knocked out of true and/or ruined. It's a VERY tight assembly (good for engine longevity, bad for an otherwise quick/easy gasket change!).

You need a case splitter to get them apart, and a crank installer to get them back together. I had them custom made and now that I have the tools it's a snap. The actual gasket part is easy. It's getting together and apart that takes some tools and know-how. I would not personally let that deter me from picking up a good builder bike, but I don't have to pay someone to do it.

Be wary of "I know a guy who can do that for you" advice... lots of people think they can, and many of them have NEVER done it! Verify!

As for the the center gasket story,don't believe it.Probably needs top end rebuild.The head has 4 cylinder studs and 2 head bolts.If the bolts are missing that might cause low compression and hard starting

Thank you for the input and advice. I think the bike is worth buying I'm just trying to hedge my bet because of all the unknowns that go with the hobby. It does seem odd that the 2 bolts are missing. I better take a closer look and see if they are broke off in the cylinder by chance.

Thanks again

Mike

Panarai,
I think your missing bolts are 8mm, 40mm length & 1.25 pitch. Welcome to the site.
Rick

Good advice from auto. Yes, always assume the worst. If those bolts are missing it's either because they're broken off, or because somebody's incorrectly installed the head, or had the head off looking around (and maybe found problems and just threw it back on).

I appreicate that!

Thanks again to everyone for their help and insight.

Mike