What engine do I need to buy?

[TurboLagging]

Here's the skinny:
I bought a 1982 XS400 from a guy who had it seize up (supposedly) during a road trip, and he needed the money to get back home. Some kind of hippy. I have no idea what was going on there.
He described it as a "J Maxim R," which I find odd for several reasons. First, the VIN on the title is a 9-digit, and doesn't show up in any database. I am thinking it might actually be the Engine IN, that's my best guess; after all the number is stamped on the engine, not the bike itself. Sholdn't there be some place on the frame? Second, I have found no such bike anywhere on the net. It has Maxim wheels -> Maxim? I don't know if it's a DOHC or SOHC so I don't know what engine to buy. Seca? Heritage? Should I just get it rebuilt?
I am, however, very blessed, because once I boosted the battery and put it back in, (after stupidly trying to move the bike while in gear AND trying to start it by twisting the key when there is a neat little button marked "START") I could hear the starter kicking. All is not lost!
Thanks for reading and I appreciate any and all advice.

 

[Scorpio1963]

If you can post a pic of the bike that would help identify your bike.By the wording you use to describe the bike its maxium or seca which uses the dohc engine.If the bike has a full frame its probaly a hertage special with sohc engine.
If theres no down tube on the front of the frame its probaly a maxium

 

[crashcourse]

You might be able to unstick the engine. Plenty of info available with the search function here. Welcome to the forum!

 

[Maxim-umm]

VIN should be stamped on the head tude (neck) of the frame where the forks are. My bike is a 1982 Maxim DOHC. Check out my picture and compare the engine with yours (my carbs and airbox are removed, that's where the blue towels are sticking out). If they look identical, then you have a DOHC. If they look different, then most likely a SOHC.

 

[TurboLagging]

Howdy all! Thank you for replying! I am totally stumped here. I tried a couple different things:
1) changed oil. Was 10w40, is now 20w50. The oil called for in the manual is 20w40, but no place around here seems to carry it, and all the motorcycle shops are closed for labor day weekend. I'm just trying to get it to crank and get the bad oil out. Btw, old oil had a few very small but visible metal bits.
2) pulled plugs. I sprayed WD40 down into the cylinder and let it soak, air out. It was bone-dry when I looked in there with a mag light.
3) put her in gear and tried to push it, turn the engine over, see if it was really stuck. It turned, I think. Uncertain, here's why:
4) me and my idiot friends put a fresh, charged battery in it ( from an older suzuki someone had), put the plugs back in, tried the lights, they work, tried the horn, that doesn't work-just hear the solenoid click, tried to crank, starter just clicked. Too little juice? Then we dropped it into gear going downhill in a mental attempt to turn it over and crank. Back wheel locked up. Now it always locks up in any gear, so I'm not sure what happened, really.

No clue what next. Best guess is to pull the engine and transmission, pull the head, see what the damage is. I could see the edge of one of the exhaust valves in the head. It never moved even when the pistons did.

Advice?

 

[willem]

yea that might not have been the smartest thing, with the hill

Guess you'll have to take the engine out yea. But my guess is that if it was fixable, it probably isn't anymore..

oh and that's a maxim! no doubt

 

[Maxim-umm]

xs400J maxim DOHC. Definitely sounds like you'll have to pull the engine and dig in there. If you don't already have a manual, go here (http://www.xs400.com/forum/showthread.php?t=4503) and download all of post #3. It's technically for the Seca model, but you can use it for the Maxims as well.

 

[Scorpio1963]

If you found small metal pieces in the oil you are better off replacing the engine if you plan on keeping the bike.This or part out and buy something that runs.Theres deals out there you just have to look.

 

[TurboLagging]

Well, shoot...I mean I tried everything I could think of to crank it. It didn't start in the beginning, and it didn't start at the end. I know now that the engine is kaput, haha. Not much different I could have tried. It was fun trying to drop it, I'll say that...and I know it'll be fun to ride when she's ready. Name is Sally-May, as in Sally-May start or Sally-May not.
Going to rebuild the engine, or try to find a crate engine, not sure which. I'll know once I tear it down and see what's what. Thanks all!

 

[Scorpio1963]

Just to let you know if you want to rebuild your engine pistons,rings and rod and main bearings are extremely difficult to find.You may be able to find the parts on ebay but buyer beware make sure you buy oem or better and not junk.
If you can find the parts you have a totaly remanufactured engine and then you know what you have.
Its probaly easier and cheaper to find a replacement engine.

 

[TurboLagging]

This is probably a dumb question, but will a Seca engine fit? Seeing as the service manuals are the same...any other engines? It would be much easier to find a good condition engine if that were the case.

 

[Scorpio1963]

Yes both seca and maxum engines are the same.

 

[willem]

they're not exactly the same, the seca has 6 gears and the maxim has 5. But I think the mounts are likely the same. I can measure stuff if you like

 

[Scorpio1963]

Either way they are inter changeable.Just one less gear.The case and gear box are the same size.Im almost certain the top mounts are the same also since both bikes use the same style frame.