IMHO, MaximX XJ750 running too rich!

Hi Everyone,

I think the engine on this bike is running too rich because I can smell gas when the bike is running and it seems to bog a bit when I "crack" the throttle. No signs of fuel leak. Also I seem to be getting less than the specified mileage on this bike, about 130Km when the fuel light comes on to switch to reserve.

Does this sound right? Or am I concerned for nothing?

Any help with this would be greatly appreciated.

Chuck

 

Air filter clean, Did this situation just start? Year of bike, do you live at an elevation of sorts, In the mountains? More information please.

 

Sorry, The bike is a 1986 Yamaha MaximX 750 I just purchased it a few weeks ago. Seemed to have somewhat of a gas smell from the first day I received it. I am awaiting the XJCD package so I don't know how to change the filter, no owners manual came with the bike either.

 

Air filter is under the seat. Should be in a black box looking thing. The lid on the box should be held down with I believe three screws. Take a look at it. If it is dirty then clean or replace it. Some one here will probably chyme in and give you lot more information about you bike.
Welcome to the site. Always like to give as much info as I can to a new guy on the site. Fill out your signature and that will help a bunch.
The reason I mentioned altitude is because. My house sits at 6000 feet inelevation here in Colorado Springs. I had to a couple little things to get my xj700 running correctly.
Again, welsome.

 

My XJCD package is on it's way but I would like to check the air filter, anyone be so kind as to post pics?

Thanks,
Chuck

 

You can find all the parts diagrams and part numbers at Yamaha's web site....... http://www.yamaha-motor.com/sport/parts/home.aspx

I think you may have a 700cc if it is a 1986 model.

 

Congrats on your "-X" - it´s a great, fun-to-ride bike.

The bogging and fuel smell and possibly rich condition can be caused by a lot of things - the X-perts will have numerous possibilities to chime in with .-)

´bout the air-filter, I do the following:

Remove the seat by unlocking it in the right-side keyhole (it can be a bit tricky and you may have to fiddle a bit with the double side snap locks).

You can now see the top of the airfilter box forward of the battery...

Unbolt the the tank by removing the rear bolt now exposed.

Elevate the rear end of the tank as far as the fuel and vacuum-hose will let you (should be around 3") and secure with a small woodblock or similar (you may or may not have to disconnect the fuel-level wire connector - also exposed when the seat is removed) .

- Or remove the tank completely by disconnecting the 2 mentioned hoses (make sure the petcock is set to "ON" or "Res", not "PRI", which will allow the fuel to flow even when the engine is shut off) and the connector. Check the hoses condition and check that no fuel is dripping from the petcock with the fuelhose removed.

Remove the rubber "air-guide" above the filterbox (no part# but is shown on top of #15 (airbox cap)- and it secured to the rubber tank mount with 2 small rubber tips.

- the air-intake is fitted with a removable plast/rubber duct (#20), which has to be removed to get the airbox cover off and the filter installed again.

Loosen the 3 screws holding the airbox cap - the forward one has limited space due to the frame-hole above it - and remove the cap.

Filter out - notice direction and that it is held in place by an elevated edge in the bottom of the filter box - and check/clean and/or replace.

Easy - right ?

If you want to replace, you might want to go for a reusable foam filter: UNI NU-2283 (around 20$) - no rejetting required. There´s also a K&N airbox filter replacement but it may need rejetting..



More info and tips for X´ers: http://www.skylinc.net/users/hap/maxim-x/

 

Thank you so much for the quick response FinnogAngela. Hopefully I will have time to check it tonight, I start the motorcycle course tonight.

Chuck

 

You´re welcome - good luck 8)

 

Set the Pilot Mixture Screws to the Factory Preset + 1/8 Turn Out.

Not quite 2-1/4 Turns Out from the bottom.
See what that does?

 

Sorry Rick but I won't know the location or even what they are until my XJCD package gets here next week. I will definately try that when I can look at the manuals.

Thanks,
Chuck

 

Don't wait for the CD's.

GET YOURSELF A FACTORY WORKSHOP MANUAL!

The moment you open that book ... It pays for itself!

 

I thought that the XJCD has such manuals?

 

It does!
Manual is nice to have in front of you while at the bike!

 

The Factory Manual is comprised of the Owners Manual and Workshop Manual.

Two of the most valuable resources for an Owner and a Do-It-Yourself maintenance and repairs.

Its completely portable and you can read from the book while you are learning and doing for yourself.

 

Hi Everyone,

I have changed the plugs and the air filter, I am now getting somewhat better gas mileage but I still smell gas. Also, when I removed/replaced the plugs all four were exactly the same, black and sooty and not wet. That could've been from the extremely dirty air filter I suspect.
Is it possible for a novice but very mechanical person to check the needle/seats and float levels? It was suggested by a local bike shop that it might be leaky needles/seats. Could it be something else?

Thanks.
Chuck

 

How's the bike run?
Do you get "Out-of-the-hole" good?
Have you got good deceleration ... or, does it seem to Coast on you?
Any bogging-out going through the gears?

 

Hi Rick,

After the air filter/plug change the bike runs great, better than before, seems to have more power. Deceleration is good and no "coasting". By coasting I am assuming you mean the rpms take their time coming down? No bogging at all through the gears.

Thanks,
Chuck

 

There's a small window of Tweakiness where you can "Select" Rich or Lean according to how you like to ride.

If you run it a shade RICH ... you got Cruiser Mode. Smoothness. With a little less Engine Braking. The Bike will "Coast" on the Pilot Mixture.

If you come in a Degree or two on the Mixture ... there's a "Crispness" in the Throttle ... far less "Coasting" and High-Performance Engine Braking.

The former has your Plugs looking a nice deep brown. The "Nothing to worry about" Brown that's really good for Cruising all-day long without having to worry about the engine getting too hot.

The latter is for Zoomer's who play Race Driver and are always overtaking the leader. The Throttle response is immediate. The Engine Braking is HUGE ... the Plugs are light brown to almost clean.

To deliberately run like that requires paying attention to the Plugs because the 2 and 3 hole can get hot and you might start "Using" some oil.

But, If you run Racing Oil and are equipped with a big Oil Cooler, you can get away with it.

I was on that edge for my run into Vermont. I wanted to be able to play on the back-roads and make the Climb to the Mountain Top; "Quick!"

But, I didn't backtrack my route and took Highway back home from Upstate New York. This had me parking the bike on the Center Stand at Rest Areas for a visual of the Oil Level Window.

The cooler saved the day. I didn't use any oil ... and now that Summer is over ... I can quit playing "Beagle flying Doghouse" and just enjoy the scenery that will burst into color in a week or so.