XJ750 Midnight Grabby Clutch

Hey Everyone, I'm new here but have monitored the forums from time to time. I picked up a 1983(ish) XJ750 Midnight Maxim a few years back. It has ran pretty good so far but this riding season I started it up and had 2 good rides around town. I took it out again and when I let the clutch out all the way it reminded me of when I learned how to drive a stick shift for the first time......jumping and jerking down the road. I had to hold the lever in about an 1/8 of the throw all the way home from work.

I started looking into it and thought it might be gummy/dirty gas and fouled out carbs. Since I forgot to install inline fuel filters the last time I had the carbs out I thought that might be it. So, I pulled off the carbs, blew them out, put them back, installed inline filters (wasn't going to forget them this time) and then thought about the gas tank. Since I only had about a 1/4 gallon of gas I drained it out to see what it looked like. Well can we say red? Yep, it was all rusted gas so I thought for sure I had found my problem. I cleaned out the tank, de-rustified it, resealed it and put it all back together.

All excited I started it up, let it warm up for a little and took it for a test drive. Got out on the road and sure enough the 15 year old teen boy learning to drive daddy's truck came out again. So I got it back to the house and thought......hmmm, wonder if there's enough oil to lube the clutch? I took a look in the view window and it looked dry.

Got the manual out (never changed the oil in a bike before) and it said it should take about 4.6 quarts of oil. Well, I had 4 quarts so in they went. Started Anna up (yeah my wife named her Anna) and took her out again. I noticed the clutch being "a little" better but still jumpy. Got about 1/4 mile from home and all of a sudden she threw a cloud of blue smoke. Limped her back to the driveway, turned her off and got off to see massive amounts of oil flowing from the air filter housing (the plastic housing between the motor and the air filter).

I'm guessing I overfilled the crankcase and the oil simply found the path of least resistance..........but I'm a newbie so that's why I am here asking for some help.

Any idea on how bad I messed up? Any ideas on the clutch?

Regards,
Mike

 

certainly sounds like you over filled it. when they are overfilled they pump oil up the crank breather into the airbox.

put the bike on center stand.
open the oil drain then watch the oil sight glass to make sure you can see a difference when the oil drains.
change the filter.
add motorcycle specific oil (other oils often have friction modifiers that can make your clutch plates slip giving you a jerky ride as you describe).
add enough oil to leave a small bubble of air at the top of the sight glass.
probably have to change the air filter it it got much oil on it at all.

you may want to have a look at your clutch plates while you are working on it to see if they are toasted.

 

Thanks Maverick........I figured I over filled the crankcase and wasn't to worried about that problem. Th clutch is the one I was more worried about. I'll check the clutch plates as soon as I can figure out how to pull it apart.

Cheers

 

First things first. Oil capacity is WAY LESS than 4 quarts; so yes, you overfilled.

It didn't hurt the clutch, but you may have oil-fouled your air filter.

Things that you need to keep in mind regarding oil level:

-There is a small number (something like "2500CM3") cast into the clutch cover very near the oil filler hole. CM3 means cubic centimeters, that is your oil capacity. If it's 2500, it means two and a half liters.

-You will not see any oil in the sight window with the bike running or with it on the sidestand. It needs to be off for 10 minutes or so and be on the centerstand to see the oil in the window.

-The ideal level is above the upper marks on the window, with a slight bubble showing at the top. (This bubble is your insurance against a float issue suddenly filling your crankcase with fuel-- if one day the bubble has disappeared, you know you need to investigate.) The slight overfill is to keep your oil level light from coming on during hard acceleration. You will end up putting MAYBE 200CC~300CC "extra" in it.

Clutch: How many miles on the bike? That will give us a lot of clues; unfortunately pretty much any answer will lead to the same conclusion though--- you need to pull it apart and have a look.

Clutch basics: http://xjbikes.com/Forums/viewtopic/t=29541.html Although this is based on (and contains specific info for) the XJ550 and its brethren, your clutch is virtually the same, but slightly less complicated. Yours will have no tabs on the plain plates nor "clutch boss spring" to worry about.

 

Thanks Fitz,

As soon as the weather stops raining (I'm in Seattle) I will get out there and pull the clutch out to have a peek. The bike has 28,881 miles on her at the moment. Not sure if that's a lot of miles for a bike of her age but I suspect not.

Sounds like I have a fun project ahead of me!!

Mike