'85 xj700x Carburetor Troubles?

I just bought an '85 Maxim xj700x. It has the Mikuni bs33 carbs... but the internet doesn't have very much info on these.

I am trying to fix a hesitation issue that I think is related to the carburetor being adjusted incorrectly.

What I've done so far...
1) Cleaned carburetors, blowing everything out, and eyeballing every holes/orifice to verify light shines equally through all 4 carbs.
2) New spark plugs.
3) Reset float heights to 17.5 mm.
4) Bench sync'd carburetors.

Since all this, cylinder 1 and 2 are running lean, 3 and 4 are running rich.

I've adjusted the fuel screw on the top of the carburetors, and nothing is really changing, which brings me to this question. Do I have to adjust the screw that is on the air filter side of the carburetors?

I am unable to find if this carburetor has 2 screws, 1 for air, and the other for fuel. Or if the screw on top of the carburetors acts as both.

 

If you actually reset your floats to 17.5mm you may have changed the wetset height.
There is one screw for air/ fuel and there is a screw for synching. You need to know more - here is your lesson:
http://www.xj4ever.com/inside your carbs.pdf
Then this:
http://www.xjbikes.com/forums/threads/the-secret-life-of-carburetors.14751/

This is extra credit and is fun: (there is a video posted by k-more that shows how things work in a CV carb)
http://www.xjbikes.com/forums/threads/stinkin-pod-filters-xj750-maxim.92370/page-2

 

just 1 screw
you have to do a fuel level wet set of the carbs this link tells you how and has the specs


Setting the fuel levels


then you have to do a running sync of the carbs and adjust the mixture screw
there are a few threads on making the sync tool

one is just a long tube the other style is with 2 jars

or you can buy the tool

 

3 sync methods

How To: Make a 2 bottle synch tool

Old School Method of One Vacuum Gauge Carb Sync


$5 Carb sync tool

morgan carb tune andcolor tune

http://www.carbtune.com/

or
https://www.motionpro.com/product/08-0411

you should start by checking the valve clearances. whats the bikes mileage?

also I recommend ohming out your ignition system to make sure it is in spec too.

 

Okay, so the pilot air jet doesn't need to be adjusted? All 4 are completely bottomed out as of now. I can't find anything that says these are supposed to be backed out "so many" turns.

 

I have not been able to wet set the floats, due to the lack of a nipple on the float bowl. BUT, I was just given the fix to that...

Thank you, This will help me a lot. I see that I can purchase nipples to press into the base of the carb bowl, and add the nipple to do a wet set. This is the reason I have not yet done it.

I saw the threads on how to make the homemade manometers. So I made one a few hours before this was created. Problem is that I made it out of Gatorade bottles. Lmao. I feel dumb, But luckily I killed the engine before it got bad. I am going to buy some glass bottles today and rebuild it. On the plus side, I now have a full gallon of Gatorade.

The bike has 17,002 miles on it. And has been sitting for the last few years. Where would I find the info to check the valves? Everything I find ends up being for the Maxim xj700n.

 

I am going to get dressed and go grab some glass bottles for the carb sync, so I 'll let you know when I get that done.

Thank you all for helping.

 

You've got a special engine there. It's a high performance machine with 5 valves per cylinder. Much more work to check valves on an x, but the interval is longer. Make sure you're getting the info for the 750x, and not the "airhead" version.

 

Here's the x valve check info
http://xjbikes.com/forums/index.php?threads/16298
And
http://xjbikes.com/forums/index.php?threads/29661

 

another site you may want to have a look at that may help you
http://www.maxim-x.com/

 

the pilot jet circuit is what gets adjusted when you adjust the mixture screw.

the carbs have 3 circuits in them
1 the enrichment circuit commonly known as the choke. which is used to start and warm up the bike.
2 the pilot jet circuit which consists of the pilot jet, the pilot air jet and the mixture screw which feeds gas for the first 2k rpm (and continues to.) then the main jet kicks in for the fun

3 the main jet . under (above)the main jet is an asperator tube then the slide and needle diaphram assembly and main air jet

 

So I go by the 750x info? Even though I have a 700x?

I've been to that site, and it has helped, but I am at a point where I couldn't find anymore info on there.

I'm confused. Sorry to be a pain in the rear. There's a fuel mixture screw on the top of the carburetor, and then the pilot air jet inside the throat of the carburetor. This being a jet... is it safe to assume it does NOT need to be adjusted? Should it be as far in as it goes? Again, I apologize. My first time messing with a motorcycle, let alone 4 carburetors on 1 vehicle.

 

Also, I just finished the new Manometer. Made out of large mason jars, blue with green liquid. Looks kinda cool.

 

700x is the stroked version of the 750x due to congress.
maxim x site is just another tool in your box.
the 2 air jets and the pilot jet as well as the main jet go it and get tightened no adjustment to be made

 

online manual for 86 700xs
http://www.xjcd.org/node/1104

 

Thank you very much.

This will help me right now. I set the floats to 17.5 mm, and it would not start without carb spray, it would die right away. Just for giggles, I set the floats to 20 mm, and it starts right up. ( The were all around 22 mm. Before I changed them )

I am in the process to doing the Manometer. I'm trying to figure it out.

 

Okay, so I'm trying to sync the carburetors... Damn this is irritating. At first, jar 1 filled up, and 4 was about a quarter full. 2 and 3 were empty. Now jar 1,3, and 4 are empty and 2 is full. I'm ready to just sell this bike. It's really not worth the hassle I've had.

 

I read somewhere, that a different bike needed to have carbs 1 and 2 sync'd, then 3 and 4, then 2 and 3... I'm going to try that. Remove 2 of my jars, and sync them in pairs first.

 

Okay, So I did 1 and 2 together, 3 and 4 together, and then 2 and 3. Looks good. I couldn't find the EXACT middle, but, I let it sit for a minute or so before I went onto the next. And there wasn't a dramatic difference in the fluid levels.

It is honestly sounding a crap ton better already.

 

The carburetor sync did wonders. All I have left to do now is to adjust the hell screw. Or as others says, the mixture screw. Oh, and to order the carburetor nipples to wet-set the floats. I just went on a 20 mile ride, at one point got it up to 75 and then backed off... Speed limit was 60. Before today, I couldn't get it above 60.

Another question... I've looked for info on this, and found 1 post about it... The shifting speeds. I know most people go by the "sound of the engine" , not the speed. But at about what speed should I be shifting from 1st, to 2nd, and so forth...

The only thing I've found was a guy saying he was doing 80 in 2nd... and 105 in 3rd... ridiculous numbers. I am assuming he was testing his bike to it's limits. If I go by the sound of the engine, I'll be maxed out by time I get to 60 mph. I did test the clutch, 30 mph, shift all the way up, and see what happens. Giving it gas, it will gradually build up speed. Full throttle will speed up the process.

Any help?

 

In that .pdf, it mentions I can purchase the nipple that wedges into the base of the carburetor... Where do I purchase it?

 

Colortune helps for the mixture screw.
Shift after you get into the powerband range ~6k.

 

Look at my FZ600 thread in tech chat. For wet setting all you need is some spare battery vent hose and some red electrical fittings, there are pictures showing what I did

 

Start a conversation with Chacal.

 

It's a sportsbike engine, not a V-Twin. Rev the crap out of it and it will respond with pure, unbridled joy.
The indicted redline is a bit on the conservative side (but don't exceed it. it's there to provide a factor of reliability).

 

I've never even heard of Colortune until now. I will be buying one when I get my next paycheck. I've already spent a little more than I was supposed to.

I will try this, I seem to try shifting around 4-5k.

I will check it out as soon as this reply is posted. ( I thought of trying to wedge some clear tubing into the hole, and try it that way... =-/. This would probably be a bit better.)

 

Okay, so everything I can do at this current time is done until payday. It's running a whole lot better. Why I didn't mention this I don't know... After I posted this, I took it for a spin on the highway. It topped out at 60... no power at all. The carburetor sync fixed a lot of the minor problems I was having. After the sync, I took it back out, and got to 85 before I slowed down ( speed limit is 60 ). It also starts a lot easier. Rpms, are at around 1,050, and the bike is loving life. I heard what sounded like arcing earlier, and I just checked. Plug wire 2, and 4 are arcing to the valve cover, and 4 also to the frame. I will pull them apart tomorrow and clean them. I did find an article on someone having that problem, took everything apart, cleaned, and put them back on and all was well. I think they are around 10k ohms, I will look it up. Unless someone knows off the top of their head.

 

You really should just plan on splicing in new plug wires, replacing the wires (Plug wire digging into coil method), or covering the existing wires with self-amalgamating tape. Cleaning won't do crap if the wires are arcing. Anothr option is to get new coils that have easily replaceable wires (Honda CB750 coils, or contact Chacal for Dynacoils).

 

I'll end up buying new wires, just can't right now. The link for "Plug wire digging into coil method" is dead. The amalgamating tape is a possible temp fix. The one thread I found, the guy took the innards of the plug boot apart, and cleaned everything with sand paper, then put it all back together and the arcing quit. I'll have to just look into this stuff when I get the cash to spend. I'm going to try to clean them, hoping the path of least resistance is through the plug when I'm done.

 

Not dead. I just messed up and posted my private bookmark for it.
Here's the public link Spark plug wires
The wires are moulded into the coil housings. Another method Ive used sucessfully is to cut the wires as short as I can get away with and use NGK splicing fittings to add new wires.

 

from 750 owners manual and as you can see yamaha does not recomend down shifting all that much
mostly you want to be able to move out on the bike if the need arises so correct gear for the rpms

 

So basically, I'd cut open the coil, shove a new piece of spark plug wire onto the metal contact, then fill in the void with the 5 Minute Epoxy. I assume the spark plug end will not matter as long as it fits into the recess between the valve covers.

Those speeds sound more like how I shift. Can't be much different for my bike.

Thank you both.

 

from 700xn and 700xnc owners manual

 

Yeah... That seems a little too quick to me. I'll take the bike for a spin in the morning, and take note on my shift pattern.

 

As if! Shifting 4 times before you hit 40kph?! That is too short! When would you hit top gear, 60? That would mean that you are in top gear for over a 100kph range! I've never seen such close shift points. I'm not an expert, but I think that's being overly cautious.

 

thats yamahas shift points, myself I like the 5.3 sec trip to 60mph

 

I've owned a MaximX750 and I can tell you these engines like to rev a lot, prepare to a good kick in the butt when you hit the power band (6 K rpms and up). But for a more relax ride, shifting around 5000 or 5500 would be ok.

 

The spark plug caps unscrew from the wire. If they are in good condition they can be swapped over easily. The caps contain resistors, so if you get new caps you will need to match the resistance, or use resistor plugs.
I can't remember if they are 5k Ohm, or 10K Ohm on the 550. Guys?

 

Those are the recommend shift points for achieving the best fuel economy. Keep in mind what was going on in the world when the manual was being written.

 

Around town I do my best to keep the engine in the "quiet zone;" between 2500 and 3500 RPM. This requires the I use every ounce of maturity that I own.

 

chacal of www.xj4ever.com sells new plug caps if you need them

 

Looking in the catalog that XJ550H wa snice enough to link, it says 10k +/- 20% for the XJ700X.