Another girl enters the garage - Maxim 400

Well, OK, she's not there yet, but I'll be picking her up tomorrow. I was looking for a Seca 400 or Maxim 400 for a girlfriend new to riding. I finally bought a Maxim yesterday with 15K on the engine.



It was being sold by a small, bottom-rung car dealership. They had advertised it for a long time on Craigslist. Once the price hit $500, I went and saw it. It started OK, but the chain was so loose and the chain adjuster to corroded that I wasn't going to drive it. They already admitted that the clutch was slipping, and I'm OK with that repair. The bike will need to be completely gone through like all these bikes, but we are looking at getting it safe and reliable, not a complete restoration like I did with my 550 Seca.

I had two quick questions for the group. Take a look at the fine fuel line on this thing:



Ignore the fine gorilla glue (?!) applied to the carb boot for the moment. So, am I right in assuming that the previous owner put that on/off valve on that line because the petcock doesn't work properly? That's my guess.

The second question is what's the best manual to get for this bike? I only see the Haynes one for sale ( http://www.ebay.com/itm/Haynes-Repair-M ... 0e&vxp=mtr ); I have not seen the factory manual for sale anywhere, and that's what I've usually bought in the past.

 

"Ignore the fine gorilla glue (?!) applied to the carb boot for the moment. So, am I right in assuming that the previous owner put that on/off valve on that line because the petcock doesn't work properly? That's my guess."

Yep, and of course a problem with the floats not seating

 

Ah, so you are saying that the floats aren't working properly, don't shut the fuel flow off, and if left on when the bike is off, gas will probably overflow into the engine via that overlflow tube?

 

Looks like it. Complete carb clean needed. I like having a shutoff valve (less fuel line tho) but that looks like it was an emergency fix. Missing hose clamp too.

As always, you'll need to strip to the valves and start with measurements then move forward.

 

So they bought a foot of fuel line from the parts store and used it without cutting it? No doubt they put the shut-off valve in because of a leaky petcock.

I would be looking that bike over very carefully to see what else the PO rigged up or neglected.

 

You did do a compression test, right?

The lawn mower fuel valve is for the same reason you see them on XJs, the petcock isn't shutting off completely AND the float valves in the carbs aren't either.

As for a service manual: I have a 'pdf' of the "World Market" FSM for the XS400. It's based on the "Seca" version of course, and it's in five languages so it can be a bit goofy to wade through. It's also too big to email but if you PM me with your email address we can trade info and I'll drop a CD in the mail for you.

 

You're assuming he doesn't speak those 5 languages, he might find it easier than just the one!

I only speak a few, but I'm fluent in Sarcasm, Cursing, and Bastard.

 

Actually, I can read fluent French too, but give me English.

In the end Fritz was right about checking the compression. I did bring my compression gauge with me when I went and saw it, but because the chain was too lose to drive it and it did start, and I did have the price down to $300, I didn't care anymore. Worse case scenario to me was that it would be the parts bike for another one. I did hope for the best though with 15,000 miles on it.

Once I got it home and ran through it, I found a few entertaining details, like the owner had bypassed 2 of the (busted fuses). Nice. When I warmed it up for a couple of minutes, a fair amount of gas leaked on the floor; this had to happened when I tried it at the shop. Still not sure where it was coming from, but I already suspected a stuck float. The readings I got were 120 and 122 - not so good when the range should be 140-170, at least according to the online Seca 400 manual I located, and I assume this is the same engine. I didn't do a wet test... yet.

So where I am now is that I've removed all the cam cover bolts and will check the valve clearances this morning now that the engine has cooled. I might get lucky and this could be part of my problem. Anyone feel like placing their bets?

 

With only 15K on the motor you could be lucky.

The book I have says compression should be 113 psi minimum, 142 psi "standard" and 156 psi maximum.

What's more important is the difference between the two, which is negligible. You're in the range I might expect for a motor with tight valves, those numbers should come up a bit with the valves in spec. I'd be much more concerned if one was pushing 156 and the other only 120.

I also have two gauges, because it never hurts to get a "second opinion."

 

So.. this is embarrassing, but I'm unclear how to undo the screw cap on the generator cover of this bike. I mean, that's gotta be where I can rotate the generator rotor to moves my cams, right? The whole cap will come off, but then some wires from generator are attached to the cap and stop me from fully removing it.

 

Oh, and no, that's not a picture of my bike, obviously. Just one I stole online. And I thought it was a screw-off cap, but once I bent a quarter held by pliers in that slot, I figured I'd best consult with folks who know better!

 

lots more info here: XS400 forum.

 

Thanks zap. I had checked that site's archives but couldn't find anything.

Anyways, left to my own devices, I was successful in using one of those round spark plug gap gauges as a screwdriver and got the thing off. It was tight! And, the good news, is that the valves were indeed tight, so hopefully once I replace the shims, I'll get some improved compression readings. I just wish I could do a cold compression test, as must stuck carb float could be some work to fix only to find out my engine's not worth salvaging.

 

More info on here than the XS400 froums, they cate more to the SOHC 400's

Cosmetically it's in much better shape than my old girl, and she was reliable as hell..
A little TLC will get yours there..
Get the carbs off and gone over, only have as much work as the XJ
Otherwise, most of the basics are the same as your 550

Seca/Maxim 400's were prety much the same, the Seca had different wheel sizes, headlight/ cluster/bodywork and a 6 speed tranny. The rest was the same, wait, carb jetting was slighly different...