And it starts - '81 650 Maxim

As I mentioned awhile back, my wife bought me a 1981 XJ650 Maxim with 23k on the dial for Christmas. I am just now getting around to doing something with it.

Today I pulled the carbs and tore them completely apart. I just sent Len an email about parts. I _think_ I can do this (my first) carb rebuild for about $150 + Chemtool.

I did break the pilot airjet on #1. If anyone has one they do not need, please let me know. I am also looking for some intake boots.

Where are the actual mixture screws? I know where the sync screws are, but I have yet to see a photo that points them out.

Here are photos taken as I worked:
http://picasaweb.google.com/danieltturn ... directlink

And here are some when I went to pick her up:
http://picasaweb.google.com/danieltturn ... 650HMaxim#

 

Hey! I don't have any 650 badges on my chrome airbox covers!

 

It seems only the 81 650's had badges on the chrome covers -- mine has them too.

Nice colour on the bike eh? Silver Mist I think Yamaha calls it - they only used it in 81. That was the colour of my bike, 'till I had to change the tank.

As for the mixture screws -- when you're looking at the tops of the carbs, there's a small recessed screw right beside the choke/enrichment plunger - that's the one. Your picture DSCF0486.JPG shows it.

 

KD5UZZ... What size are the pilots in the 650? I might have a spare or two.

 

stereomind, they wee 165, but after some more reading I think I may have misread them. I will check tonight. I was in downtown Tulsa a few days ago for a concert and saw a nice 750 maxim. I thought for sure it was yours, then I realized you have a seca.

Can I do a compression test with the carbs removed? You are supposed to hold WOT during the test, right?

 

Right... compression check without carbs is just fine.

I have a set of 650 bodies that should still have all of the air jets in them. If you'll be in the neighborhood again any time soon, let me know.. I'll get the jets out this evening.

 

No rush. Turns out they are 195. I still have to find the funds for the rest of the parts. I am now north of you a bit, in Bartlesville.

 

You are also supposed to the the compression test when the engine is hot ... hard to do if the carbs are off ...

 

Don't have anything constructive to add, but I just thought I'd say: That right there is what you call a "Keeper". :wink:

 

Drat. The ones in my parts set are 205's... I could've swore they're from a 650. Well, if you need them or anything else, let me know. Bartlesville is about 45 minutes from here... (Owasso)

 

Thanks for the info on the mixture screws. I have posted a few more pictures. If anyone wants to use them for documentation, feel free.

I have decided to pull the carbs from my '82 to see if I can get the '81 running. Wish me luck. It will not happen until I change the oil in the '81... right now I think..

And I have finished taking the carbs apart. #1 body is soaking in some carb cleaner. right now. Any suggestions on how long I should let it sit?

As of right now, when I blow compressed air into the pilot airjet hole I do not get the kind of pressure I would expect from the 'tube' that sticks down into the bowl. Is it because there are other places the air is going? or is it more likely that it is blocked?

 

Any thoughts on the long term implications of having fuel in the oil?

I just finished draining the oil and found more fuel than oil.

The bike has been sitting for about 8 years, and I suspect that for most of that time it has had a mix of the two.

Over night soaking of the bowls seems to have opened up the enrichment jet/well thing.

 

Swaped carbs from the '82 to the '81. Setup a 'tuning' tank (qt of oil, cleaned out, rubber hose through the oil container cap). Set the choke, hit the button..._instant_ VROOOOM! Nice idle (as I guess it should be, idle is rather close for all bikes, right?) I didn't have the airbox hooked up, so I shut her down after about a min of running.

Tomorrow I am going to hook up the airbox, swap the front tire ('81 has a flat), and take her for a (slow) test ride.

Then, swap front brakes, and figure out how to pick the gascap lock.

 

Congrats on getting it running! If you can't get the gas cap lock open it would probably be best to take it to a locksmith. He can cut the keys for you too.

Probably will want to get the tank fixed. A quart at a time won't get you too far. Wait a minute. The stock 650 tank doesn't get you too far either

 

Don't I know it! When I got mine I had read specs that listed it as having a 5 gal tank. Imagine my confusion when I am driving down the freeway @ 70 mph and my bike suddenly quits after only 90 miles ... I reached down while I was coasting to make certain the fuel line came off and switched it over to reserve just to see ... low and behold, it starts up again. I thought, "How can I already be down that low? Do I have a gas leak?????" Then after some discussion with folks here, I find that most 650's have a 3 gal tank and only a few the 5 ... what kind of moron made that design decision??? That gives the bike an effective range of less than 150 miles, assuming everything is perfectly tuned and you ride for optimum mileage ... There are places where you can't even go in this country because you simply can't tank enough gas ... That's a big part of why I want to figure out a gas gauge that will work with the 750 tank I have picked up.

 

I am also very aware of the limited range. On a trip last year I skipped a fuel stop. Got to ride on the back of my brother-in-law's shadow for about 20miles.

My solution?

http://picasaweb.google.com/lh/photo/-O ... directlink

I can even share my 1gal reserve!

 

And now for the problems...

She seems to be running on cyl #1 and #2.

Pipes for #3 and #4 are cold.

If #4 plug is pulled I notice no difference in running. If I pull #1 she will not start.

The airbox is not connected. I get about the same vacuum when I put my hand behind the intake on all cylinders. I also get fuel spray on my hand if I partially block airflow.

I did a compression test and got the same readings on all cyl.

I am getting spark on all plugs.

The right pipes do not seem to pulse like the left.
*** UPDATE ***

I went back out and checked to see if gas flowed when I open the bowl drain plugs. I got fuel on all bowls.

I started it back up and let it idle for awhile. This time, pipes #3 and #4 got hot, but maybe not as hot as #s 1 and 2.

The left side of the block was warmer than the right, but the right is warmer than it was.

I cleaned the plugs and they do not seem to be wet. I have swapped plugs from #1 to #4 and do not notice a difference.

Now the right pipe seems to pulse more like the left.



****************

It seems that whatever the problem, it has gotten a bit better.

To recap: I seem to have fuel, spark, and compression. WTF?!

Maybe if I hook the airbox up it will do better...

I'm off to give it a shop.

 

When you swap plug one with plug 4, the right side got hotter than the left you said? Sounds like one or more plugs isn't firing quite right maybe. Perhaps earlier when you tested, and got cold on the right, there was something funky with the coil connection? That would explain both cylanders on that side not working right. Later, when you played with pulling the wires off the spark plugs, somehow the connection was partially or totally restored?

It could be that the coil is acting flaky, there is something wrong with the wires coming from the coil, or you just didn't have those wires fully engaged with the plug ...

That's where I'd be looking anyways ...

 

Is it possible that the aquarium airhose that I am using as fuel line between my 'fuel tank' and the carbs is unable to flow enough fuel to provide fuel to #3 and #4 to allow them to fire correctly at high RPM?

I have been 'blipping' the throttle quite a bit, for no reason really, maybe that is causing #3 and #4 to starve? (fuel intake is between #1 and #2). The 2nd time I ran her last night, I let her idle more.

 

That is a possibility - most air hose is pretty small..

 

tumble,
Swapping plugs made no change what so ever. The left has always been warmer. #1 and #2 seem to fire fine no matter what plugs I use.

Thanks bill, I'll see how it acts when I just idle.

I do not see wet plugs in #3 and #4, and I get fuel on my hand when I block the carb intake, so I am pretty sure I am getting fuel into the cyl. I see spark on #3 and #4. I think it is firing, just very lean due to a small fuel line.

 

The clutch seems to be sticking. Not too surprising after having sat for so long. It may be that it just needs adjusting.... I hope'

 

An inadequate fuel line would starve all 4 cylinders equally, methinks.

I would suspect idle circuit blockage or an air leak that's leaning the mixture out too much on the affected cylinders.

Have you checked the float levels?

How do you know the clutch is sticking? can you not roll the bike in gear with clutch pulled in at all?

 

the bike has a flat...can't roll.

If I put it in gear, hold in the clutch and hit the brakes the engine dies.

 

I don't know Stereo, if fuel is trickling in I could see this happening. It goes in between 1 and 2. I could see most of it getting into 1 and 2's bowls under load and starving 3 and 4 some what. Picture a pipe with 4 holes in the bottom. With enough fluid all 4 holes flow - with a trickle that would not necessarily be so.

Checking float levels is a good place to start though.

Of course I have been wrong before and will be again

 

Bill -

Agreed, but the fuel line or petcock would have to be almost completely blocked. If you look at the flow rate at idle or even when goosing the throttle in neutral, it really doesn't take much to keep the bowls full... Once you put some load on it, that's a different story... I've been wrong plenty of times as well, though :mrgreen:

One way to find out for sure is to check fuel level in 3 and 4 while the bike is running, and then kill the engine and let it prime for a minute... then check the level again.

 

If the air line hose fits the connectors then it must be the correct size, right?

Perhaps the flow tube past carb # 2 is partially blocked?

 

I actually have the airhose jammed into the real fuel line. The ID of the airhose and the ID of the fuel line differ by the wall thickness of the airhose X 2. Without actually looking I would guess this is close to 1/2 the overall ID of the fuel line.

Fuel consumption is mentioned in the main carb cleaning post. IIRC the quoted figure was basicly a gallon an hour @ 5k RPM. Seems to me that airhose should be able to do that. Who knows.

Because of the cluch issue I may have to put this on the back burner, I can't afford to rebuild the clutch right now. Which means I am stuck driving the gas hog of a truck, further cutting into the $$ supply.

 

Also,
These carbs worked fine on my '82..

 

I hooked the airbox up and #3 and #4 are hot. It doesn't idle as well, maybe an indication of rich idle?

Pops a little at high RPM.

I'll drop the tank off at the locksmith tomorrow morning.

The clutch cable was loose in the bracket. Seems someone has been fiddling with it.

I get a fair amount of 'clank' when I shift. I am not going to worry too much about that until I do another oil change. I spilled some fuel, so I am going to wait a bit before I work on it more.

Thanks for all the comments and suggestions. It is great to have a sounding board, especially one that talks back.

Although I think I have a tendency to over-think a problem.

 

Conclusion?

Hooking up the air box seems to have cleared up the problem of cool pipes in 3 & 4? So not having the air box connected will throw off the bike's performance significantly.

If the carbs are synced on one bike, should they be resynced if moved to another?

It looks like the Rotella T from shell would be a very good choice for these bikes. It seems to be very good for wet clutches and older machines.

 

Definetly resynch those carbs.
You are synching to the weakest cylinder so a different bike will have a different synch.

 

That is what I thought. So that will still need to be done.
Would that cause the "pop"? Or would that be something else?

 

A pop is generally a cylinder running lean.
After you synch you will colortune or plug chop so this should work itself out.

 

Took her for a ride tonight, after the dang locksmith took two days (three trips to his shop) to get a key made for the tank.

Very sluggish at low RPM, get it about 3k-4k and she pulls like no other.

Handles very different from the '82. It seems to be a little lower to the ground (a few inches, maybe), and the handlebars are 2 - 4" wider. I still have a little work to do on the front brakes.

And a lot of work to do on the carbs. Tomorrow I'll start that...

It is hard to get into neutral when the engine is running, quite easy otherwise. Need to do another oil change.

EDIT:
Just went by mommayamma.. they didn't have either the airfilter OR the oil filter...WTF?? Oh Len...