85 XJ700 Super Noob Questions

Hello All,

Just recently purchased my first motorcycle and it's an '85 Maxim XJ700 (Air Cooled) and I am absolutely in love with it. I must say, I am happy it was my first purchase. I have some technical and mechanical questions based on how the bike is running right now though, as I am sure it has seen plenty of neglect and I want to restore this beauty to it's full potential.

So for starters let me say that I have no mechanical background and very minimal knowledge, but none for a motorcycle. I am looking to purchase the manual I have read and seen talked about around these forums (the online one) but I am highly mechanically inclined and a very fast learner so I would like to be the one doing all the work on my bike.

I just got her tuned up (Spark Plugs, Carbs cleaned, Oil/Filter, Lines greased and fluids) the guy said he changed the brakes, but front and back take forever to stop and I nearly have to mash them down, so assuming he didn't touch those.

These are some of the issues I am having right now with the bike (it runs pretty good):
1.) My choke seems to be my biggest issues right now, I put it full left to start and warm up, then I ease it to the right as it warms up. Thing is, I seem to Idle up to 4,000 until I slide it further right and the biggest problem is there seems to only be a very very small sweet spot with the choke, as in if I don't slowly place it right where it wants to go I idle up to 4.000 or the bike kills out. Also I seem to have to adjust it occasionally while riding and when gearing down and stopping while the clutch is in. My idle also shoots up to 4-5,000 when i put my handlebars left (read somewhere on here that might be due to my throttle cable getting tugged?)

2.) I don't know the name but my gas lever that has positions for primary, on and reserve. I turn it to on and the bike runs fine, engine actually sounds better when it's on "on", but when I get super low on gas and my light cuts on the bike starts bogging down a little and then when I pull the throttle back it starts to choke up and clack, as if the carbs are closing or something? It does this on the throttle until the bike dies out, won't even start back up until I throw that lever back onto primary.

3.) My gas tank looks to be what seems as super dirty. There are splotches of black all throught out the inside of it and it looks almost sludgy or seaweed in appearance. Is this normal or is there a way and chemical I can clean it out? Someone mentioned that might get into my carbs and clog them. Lastly when I got the bike back from the shop my oil was clear and half way up the viewfinder on the side, now it completely fills the window and it's not completely black but I have only put 400 miles on the bike and it's pretty dark, and never drops to halfway in the window. And I am only getting about 30 miles to the gallon TOPS, I know I read up on the bike and it said the bike should be getting 70 MPG, but now throught about five full tanks and I am getting no more than 30.

I appologize in advance for the massive long post and mylack of knowledge, thank you for any help in advance!

 

First of all welcome to the forum.

I cant help much with questions 1 and 3 but I can at least give ya some insight to #2.

The three positions on your Petcock are Prime, On, and Reserve. You are correct to be running in the On position normally, however when you start to get to the low fuel and the bike starts sputtering you would want to switch to reserve.

The Petcock on the XJ's is a vacuum system and thus there is no off setting. The Prime setting will, for lack of getting technical, bypass the vacuum system and allow fuel to flow to the carb bowls freely. Usually you should only need this if you completely run out of gas or in the spring for startup. If you are switching from on to Prime when you are out of gas you may still not be getting fuel to the carbs properly and that may be causing your problems.

 

So I'm sorry, just read through your post again and my scattered brain missed out on a few more points that I may be able to start some insight into for you.

The Manual, a good service manual is a great thing to have. Most of the guys on here would probably not be able to stress that enough. I have mine on order and I can't wait till it shows up.

Brakes on these bikes are a common subject in the forums. If you think they are going bad check the wear marker for the rear and the pad thickness in the front. The Rear you can adjust some and I had to do that on my bike when I first got it. One thing you forgot to mention was how many miles are on the bike. If the bike has low mileage, brakes are probably originals. Might want to take the rear apart especially and take a look at the pads.

With your choke, I don't know that it is the way that it is supposed to be, but I know mine is the same way. Might be a carb issue, some of the Wizards around here would have more insight.

And the thing I know about gas tanks is that if there is gunk in them, it will find it's way to the carbs which on these bikes is a very popular topic. Even if they were just cleaned, if there is gunk in the tank, they may be blocked again.

Your MPG question, my 650 gets around 50mpg. unless I am out having fun then it quickly drops... I dont know if 70 would be expected from the machine, but depending on how you drive it, you might be seeing signs of gunked up carbs, or whoever cleaned the carbs may not have synched and tuned them properly. Unfortunately as most of the Wizards on here have said many times, there is no-one that will take care of your carbs like you will.

Hope some of that helps some.

Enjoy

 

I have the same bike and I can almost guarantee that you didn't get the carbs correctly cleaned and/or the float levels are not set correctly. Let's just say that it took me "several" times to get it right. If you didn't follow RickCoMatic's carb cleaning instructions to the letter you probably didn't get them completely clean.

Now the the MPG--I initially got 30 mpg also. I checked all the normal stuff and re-cleaned the carbs, did the wet check on the floats and basically eliminated (with the help of Len, RickCoMatic, BigFitz) everything but the float levels. I even measured all the jets and needle valves to insure they were stock. Finally I decided to reset the float levels with a float gauge (.63 in +/- .039 in) and found that they were all too high--even though the wet check had been in specs. I set them all to .63 in. and the wet check was still in spec and the mpg went to 40. I have since re-checked them and set them to .66 in and haven't checked the mpg yet. My pilot screws are at 1 3/8 open.

By the way, if you do not have a float gauge you can make one out of a piece of metal--I used a piece of aluminum sheeting. Check this link for a picture on the one I made. Note that I made this one to sit on the top of the carb body so I adjusted the height since the .63 in spec is from the inside lip of the carb body.
http://www.xjbikes.com/Forums/viewtopic/t=37364.html

the "choke" issues should not be an issue if the carb is completely clean. I never have to use mine to start or ride the bike. However, just to check it I did use it one time and as the bike warmed up the idle went up to probably 2500 and I cut it off. Don't plan to use it except in the winter and just to start it. If you have to use it while riding then something is wrong.

One final comment, when you do the wet check be sure there is no air bubble in the tube or you will get a bad reading.

 

Thanks Osprey, it's nice to be apart of the community now.

Ah sorry I forgot, the bike has 36.4XX miles on it. Seems that everything is original from what I can tell, including the pipes, which have brownish discoloration right out front of the engine.

Typically right before my Fuel light comes on is when the bike starts acting as if it is literally about to run out of gas, so it is at that time that I should switch the Petcock over to Reserve? So if I absolutely need to switch to Prime and On/Reserve won't work when my fuel light comes on, then I have a problem with fuel flowing to my carbs? Yeah there is definitely a good bit of gunk in the gas tank, so I am assuming that if I am having the carb flow problems like it sounds like, then that would probably be my culprit. The Choke basically has to stay on, when I have it positioned at about half way is when the bike seems to respond best and stable the idle at 1,500. I can't throw the choke completely off or the bike will die out. I don't ride it hard at all, always shift at 4,500-5,000 RPM and I cruise on it. Also when I fire the bike up with the choke on, sometimes as it's warmed up the rpm's won't shoot up at all on there own, but if I roll the throttle back they do and stick at 4,000

I had the Carbs cleaned by a shop, but the bike sat at the shop for about two months while I was Deployed before I picked it up. I definitely want to and need to readjust and clean them myself. Where did you purchase your manual at, do you have a link? Also, what oil is preferred to run in the motor (Live right outside Atlanta, GA) and what tools should I purchase to be able to do all the maintenance I'm going to be able to do on the bike.

Thanks Tabaka, I'm saving the link now, and will use that as a float gauge

 

Here are the best carb cleaning instructions you will find:

http://xjbikes.com/Forums/viewtopic/t=2 ... n+own.html

Remove the gas tank and at least wash it out. Remove the petcock and be sure the internal filter is in place and clean. ( Mine was actually not attached to the petcock--just laying on the bottom of the tank!) Absolutely put an in-line fuel filter between the petcock and the carbs. While you have the petcock off you might want to clean it if you have any doubt about it working correctly. Plenty of info on that on this site.

Read the instructions carefully, proceed slowly, don't assume anything, don't hesitate to ask questions, and don't be in a hurry.

 

If you think that you have more oil in the case than before, stop riding immediately and take the oil cap off and take a good sniff. With your fuel problems it sounds like you may have a stuck float(s) or a malfunctioning petcock which will allow raw fuel to get past the carbs and fill up your case. This will dilute your oil and could lead to a catastrophic engine failure.

 

Okay just took the cap off and smelled, it definitely smells like gasoline in my oil case. Also the bike smells strongly of gasoline when I crank it up. So what is my option here, replace or rebuild the Petcock and flush the oil with new oil? Sad to say this but my bike is my only transportation to and from work. Not my ideal situation but its the card life has dealt me and I know with my issues this is bad. Need to get it fixed pronto. Thanks for the help

 

OK, as a temporary fix, put an inline shut off in your fuel line. These can be picked up at most small engine repair shops. Once it is installed put in some new oil and a filter. I know you need it as transport, but when I had gas in the oil I drained it and let it sit empty overnight with the filter off. My logic was that the contaminated oil would drain completely and the gas would evaporate. Reinstall the new filter and oil and run it for a while to see if that gets rid of the gas smell.
Now the only thing that is a P.I.T.A. is that when you stop riding, even for a short while, turn off the inline fuel valve and run it til it starts to idle rough, sorta like when you go from main tank to reserve. By doing that you will make sure that your bowls are empty and that fuel will not run down through the head and contaminate your oil again.
Once riding season is over then you can look at sorting out the petcock and clean the carbs.
My 2 cents.

Good luck and let us know how it works.

 

You definitely want to stop the gas from getting into your engine. Like Maxim said, could lead to catastrophic engine failure or you could hydrolock the engine like I did. There was about half a quart of gas that leaked by and that was all it took... The things mentioned above shouldn't take you more than an hour to do.

 

First two images are of the right side of my Petcock, and the bottom picture of the left side. Forgot to take pictures during the day and this was a quick picture take since it's night time, I'll update with daytime photographs tomorrow. (Also forgot to rotate the pictures so they're all turned around)



Right side of the Petcock (It looks pretty tore up) and under that black hose on the bottom right of the petcock there is gasoline sitting. It also appears if that part of the petcock is the most worn and possibly the seal broken allowing fuel to leak.



Different picture of the right side of the Petcock



Left side of the Petcock, there appears to be a lot of buildup, dirt and possibly oil?


I purchased a brand new OEM Petcock earlier today and the gasket that connects it to the gas tank. Found one for $98 and it's in process now. Just planning on installing a brand new one as the current one looks extremely worn out. I may buy a rebuild kit for this one and restore it depending upon how it looks when removed. I am also picking up new oil and oil filter tomorrow on my lunch hour along with looking to purchase the inline shut off valve. Will a manual explaining how to install the inline shut off valve come with the valve itself telling me how to install it? Looking to get tank cleaner, the petcock and further new oil all at once and do the installs for next weekend or the following. I am going to take your Advice Maxim and drain the oil and let it air out before installing the inline shut off and new oil. I just need the engine to hold out all of tomorrow and saturday morning. It's been okay so far. Thank you guys tremendously for the information and help. I would not have even ever begun to know where to start looking for these repairs. I'll update ASAP.

 

I don't know how much fuel has gone into the Engine (It does smell strongly though) but I am hoping I don't have to go through that terrible process as you did.

 

Take a look here:


here's the link
http://www.xjbikes.com/Forums/viewtopic ... +shut.html