New to the community...

Thought I would introduce myself and ask some questions all at the same time...

Just bought an '81 maxim 650 from a guy on craigslist. He had the add up for over a week that said make an offer. No pictures, just a brief and vague description. So I shot him an offer and he took it. I drove an hour and a half one way to finally see what this thing looked like...expecting to find a hunk of crap. Especially for what I offered him. This is what I found and brought home for $300...



I know it needs a new fuse box. I did get it to start today, though it was spraying fuel into the air box. It sounded good till I discovered the fuel issue and turned it off. I've never torn into carburetors, is this fuel issue an "easy" fix or....?

Any help would be much appreciated.

Shane

 

Not sure why it didn't include my signature...maybe I have it fixed now...

 

Hey man, that trunk is huge!!!

Nice catch, by the way!

And welcome!

 

That's so my old lady can have lots of junk in her trunk...LoL! So glad she hasn't figured out where this forum is yet. Hahaha

The luggage is going to have to go...once it's running well I will begin to chop on it. I'm thinking bobber of some sort. Either way at least I have something to ride again.

 

I second that, nice find, especially for the money. Interestingly enough it looks like a previous owner swaped the headlight for the Box style headlight of the '82 750's. Just an interesting thing to do.

As for your fuel issue. There are a number of things that could be causeing that problem. More than likely I would say you may have a float that is stuck and you could be flooding the motor. Open the oil fill cap and sniff, if ya smell gas do an oil change before trying to start the motor again, and by all means dont try and start it again till you tear down the carbs.

Most likely you are looking at a carb cleaning/rebuild anyway if the bike has been sitting for a while. While you are at it, you will want to check your valves as well. There are write-up's on here for that if you need help.

One last thing, many on here will harp about it and for good reason, the braking system on that bike looks original. If it is, replace it.

Other than that Welcome to the forums, there is a wealth of knowledge here, by all means ask questions. Someone on here will usually know the answer.

 

Funny you mention the headlight, '82, 750...that is what he advertised this bike as. However the title is for an...

Year: 1981
Make: Yamaha
Model: XJ650HS
Date first sold: 05/05/1982

 

Just checked the VIN on the title against number on the frame and the motor. It is indeed a 4H7 Maxim 650.

 

Since it's a pre-YICS motor, it's not an '82. It's an '80 or an '81.

Good strike; it looks like it's pretty much all there and in quite decent shape. Good starting point.

 

YICS...??? :?: What does that mean?

 

So I checked out the tank and it has some rust in it...I know that if that isn't the current culprit of the carb problems it will be soon. So do I replace the tank or do I attempt to clean it and re-line it?

 

Welcome aboard! You're gonna have fun here!!!!

Dave

 

Many of our bikes are "YICS" motors. It was an XJ thing. Yamaha Induction Control System. (I think) Basically, as I understand it, it's a system of holes going through the engine to help equalize the fuel/air mixture going to each cylinder.

The idea is so that carbs don't have to be as in synch as on other bikes, the YICS takes up some of the imbalance. You have to block off the YICS passage to do a (really anal) synch of the carbs. Though some folks don't bother.

 

Welcome to the site, and that's a great find for the $. The YICS was designed to increase performance and mileage, and did it all without any moving parts. XJ YICS bikes have four small chambers cast into the back side of the head that act as secondary intake chambers which use the engine vacuum to draw in a small amount of the intake charge when the valve closes then that mix gets sucked back into the cylinder at an angle on the next intake stroke. This swirls into the cylinder and improves combustion and atomization of fuel! Those Yamaha boys were come crazy high inventive engineers for the 80's!

The tank diagnosis is dependent on how bad the rust is. If it's almost through to the other side it's time for a new tank, if not you can probably repair it. POR-15 is the best product I've found for this. It is important to exactly follow their directions so it will last. You should also pick up a nice in-line filter to protect your carbs after you get them TC&TS.

 

how bad is the rust? I'm going to try evaporust on mine, keep checking my resto thread and when i do it, i'll post the results in there.

Chris

 

Welcome btw!!

 

TC&TS ?

I'm not up on all the abbreviations. Thanks for the welcome and the info.

The rust doesn't look anything more than surface. How hard is the clean up and relining?

 

Shane_Wood,

Welcome to the club.

Gary

 

If your tank isn't super rusty, I would recommend a phosphoric acid flush and hold off on the "lining" until you're sure it's necessary.

You could also use electrolysis or try Evap-O-Rust. I'm only suggesting phosphoric acid because I've used it twice now with great success (on mild to moderately rusty tanks.)

 

Is there a thread on here about how to do a flush?