Maxim 750 wont start suddenly

To start off, i'm new to motorcycles. I like them a lot, but i only know minimal repair knowledge. like, replacing spark plugs and stuff. I just bought a used Yamaha Maxim xj750 and it was running very nice. When i bought the bike about two months ago almost, it had a dirty carburetor, and and front piece with blinkers, a headlight, and a radio. I took the front piece off and put a headlight from ebay on there, no front blinkers, and i also replaced the megaphone muffler with a waaaay quieter muffler which seemed to add good back pressure to make it run smoother. that or it was my imagination, again, im new to this.

The guy i bought it from swore up and down that he had done a full oil change with 10w40 motorcycle oil. Stupidly enough, i believed him. I was riding the motorcycle and had switched into third gear and began to accelerate. then it started making a louder high pitched noise while coming to a squealing halt. I held in the clutch and then it started to roll to a stop and then it shut off. Won't start now. I checked oil, put more oil in because it was incredibly low, check the spark plugs which all worked seemingly fine. I did have to replace one fuse to make the odometer and speedometer work. When i try to start the motorcycle it makes a fast high pitched noise like it almost wants to start but wont. If i try to much, i have to recharge the battery. I dont know whats wrong and i was hoping to maybe find a solution i could do myself without spending a fortune to fix the bike.

 

what year is it

did your oil light come on? sometimes when the oil light comes on if you have a defective diode block the starter will spin

if it is an 82 you do not have a diode block

 

Did you check the oil level prior to riding?
Is there any visible signs of an oil leak?

 

Its a 1982 maxim 750. and i dont see any signs of an oil leak. the only odd smell i'm pretty sure is the carburetor seeing as one of them is very dirty. i just havent gotten around to cleaning it yet.

 

I think you need this:
http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/
And this:
http://xjbikes.com/forums/threads/in-the-church-of-clean.14692/

It IS a lot to digest, but truly required for a fundamental snapshot of what path you are about to take.
Ask questions as required, there are very helpful people here.

So, no leaks but did you check the level before you rode?
"... put more oil in it because it was incredibly low..."
That is disconcerting.

 

i didnt check before i rode the bike, but when i checked the small window, it was like a puddle just sitting at the bottom

 

While on the center stand or side stand?

 

side stand

 

i don't know why it stopped but

the starter spins fast and could make a noise like that, listen to that.

don't run down the battery down that low, it don't like that. 3 or 4 five second tries should tell you if it's going to go or not.
keep a battery tender on it while you're investigating

 

oil needs to be checked on centerstand and/or put a level across the frame to level it and look at oil it takes a few min to fill the sightglass

 

thankyou everyone for trying to help but i took the bike to a mechanic and within two minutes of hearing the bike try to start diagnosed it with a bad motor. Im gonna go cry myself to sleep for the next week. If anyone has any suggestions to a new bike thats below $1000 then that would be great, but im just gonna go sell this one for parts.... R.I.P

 

http://www.ebay.com/itm/COMPLETE-EN...ash=item41c5295112:g:wZ4AAOSwa-dWs4~v&vxp=mtr

 

i can look into it, my friends were saying the same thing, they want to help me try and figure it out. i can think about it. thanks for the link

 

I have never had to tear a whole engine down for 'having a bad motor', and would be inclined to take the mechanics diagnosis with a grain of salt. You are new to motorcycles and you need to become better versed at becoming your own XJ mechanic. Where in the states are you? There may be another member who could stop by and give it a listen in your area. Or at least see if there is any opportunities for a second opinion.

Here's the thing with motorcycle mechanics, some actually know a thing or two, some go to the Tech school and learn very rote subjects/ troubleshooting skills often times for very specific newer bikes, some mechanics are younger than your bike. My personal experience is that I found out really quick (thankfully through integrity) that no one in my area would touch a motorcycle of my vintage, not to mention it was a Yamaha and not an HD. I did find a place that specialized in vintage Japanese bikes and they did do me right the one time I took the bike there, but $$$ and I am cheap. I joined here and read, read, read and listen to advice given. This site has made me a rather decent motorcycle mechanic for my 81 XJ650 Maxim, there is a learning curve, but asking questions until you get an answer that you understand is the key. (Read: no such thing as a dumb question).

I just can't believe that after listening to a bike crank for two minutes that someone can say "yep, that motor is shot".

 

Do you remember how much oil you put in it?

Did you ever check the level on the center stand? Too much oil can cause bad things too.

Perhaps post a short video / sound clip of it cranking so we can evaluate.

 

I would say investigate further before saying it needs a new engine. And a couple of questions that have already been asked that will help with the diagnosis. If you don't know the answer, just say I don't know, no big deal. To reply to a particular question simply click the left control button on the mouse and drag the mouse pointer across that text to highlight it and click reply when prompted.

So once again, do you know how much you added? This would help tremendously so there is no speculation as to whether the engine was run without sufficient oil to do damage.

This is a great clue also, you have a Computer Systems Monitor. If low on oil the "OIL" indicator should have displayed on the LCD screen and the Red Warning Light would have flashed to alert you.

It does sound terrible. My first thought is the reduction gear assembly gear bushings in the starter are toast, or the starter clutch.

How did you check them, did you actually check for spark?

Is this related to after the incident or something you just did earlier before having the issue?

 

Check your carb bowls - ultimately out should check your fuel levels. But for a quick check get a small container, crack open the drain screw (probably add a small hose to the drain port) empty the bowl into said small container, then empty container and repeat for all 4. All 4 carbs should fill to the same level in the small container.

You mentioned a dirty carburetor in your OP. Dirty on the outside? Dirty inside? Did you do anything to clean it?
It is almost Sunday, you may be looking at going to Church.

 

Did you read these links? ^^^^

This can (should) seems overwhelming to you. But with help from many here you can make this work! Methodically approach your bike, the first link above is a good over view. Don't be in a hurry, patience and proficiency will pay off.

 

Based on the sound:

she's making compression

the starter clutch has some slippage/kickback and I agree that the starter may be the major contributor to the noise.

the fuel mixture is close, but not close enough (she's trying to fire)

I don't hear any really bad noises that would indicate that the engine needs to be replaced.

 

when i checked the oil levels, it looked dry to me. i bought a quart of 10w40 motorcycle oil and put the whole bottle in which got the oil level to about 3/4 up the window.

I did actually check for spark and all four spark plugs sparked.

the fuse issue was about two weeks before this happened.

The carburetor is gunked up on the inside, i havent done anything to clean it yet because i'm afraid i might screw something up. i did attempt to remove the carburetor unit, which is four carburetors synced together, but i didnt make much progress.

 

Im going to read through the forums when i get a minute, i have a lot of work and this is my last year of high school. finally, so i'm gonna read the crap out of the forum when i get an hour or two to myself.

 

Did the "expert" check compression? The quote engine "shot" is rather BS unless you have a hole in a piston or a rod hanging out of the case it can be fixed. I would check compression first, if you don't have a gauge go to Autozone and they rent them . With all 4 plugs out put gauge in one of the cylinders crank with throttle wide open crank it over about 4 pulses see what it reads. 155 to 125 is good .. 120 to 115 not so good you just don't want it reading 0... ideally all 4 cylinder should read about the same. You can also put a cap of oil in each cylinder and see if reading raises if your dry crank is low. One other thing make sure battery is charged doing this. Don't give up and with help from the forum you should be able to get it running again. Cheers

 

Most modern motorcycle places don't want to touch these older bikes, it is just not cost effective for them. To clean the carbs you are looking at $300+ and that is low ball. These bikes are really a labor of love. The hours that go into trouble shooting and then getting all the little things working just for safety of riding will take some time. As many above have stated, it is really hard to tell if a motor is shot in that short of time, unless there is something very obvious. major oil or hole in the block. Keep at it and work the process slow and sure, you will get her running I think you are really close.

The church of clean will need to be done to make the bike run even close to it's potential. So once you get it running and know it is worth keeping and riding, take those carbs off and get them clean.

 

no, the expert didnt even touch the bike. he looked at it and said it looked nice, whats wrong with it? and when i tried to start he told me to just put it right back on my trailer, its shot.

 

^^That just proved my point, most shops don't want to spend any time on our older bikes. A labor of love begins...

 

IMPORANT NOTE: If done this way (all four spakplugs removed) it is vital that the TCI be unplugged or it will be damaged. The sparkplugs must have a reliable path to ground when the TCI has power.

 

Reading the forum a ton, gonna order an owners manual on tuesday, and im also going to start cleaning the carburetor tomorrow. Any tips? things i should use?

 

Go to a parts store and get a gallon can of carb dip that has the parts bucket in it, and I figure about 2 cans of the aerosol carb cleaner per carb as well......plan on the minimum of replacing the throttle shaft seals, the idle mixture o rings and their washers, and all the fuel piping o rings. I believe you have Hitachi carbs, so the butterfly screws you might get by without, but should order them anyway while you are placing the order. Take TONS of pictures while disassembling, and do one carb at a time.

 

Read the church of clean and take your time. Order the shaft seals from xj4ever right top corner of the page...PLEASE note you will NOT fing these on eBay. To replace you have to "break the rack" this means you remove from the rails and sepearate from each other. You can do this it is not really difficult.

 

^^^ all of that.

Ask questions if you aren't sure.

 

That is fairly significant, and I don't know exactly how low you would have to be to starve the motor of oil. Still not sure if your OIL warning displayed and the warning flashed, but since you did not mention it that could be a good thing.

I would go with Jetfixer's suggestion first as the compression test will be a good indicator of the motor condition. Just be sure to follow the directions for doing it as suggested and ask about anything you are not sure about.

 

He mentioned in an earlier post that he checked the oil level while bike was on side stand. I fear he has over-filled that crank.

 

I think that has been addressed, and he is checking it correctly; on the centerstand. Plus in the video he has a shot of the sight glass that shows the level just over half full. That was after some cranking, so I am not sure how active the oil pump is during that interval and how much it might lower the level - if any.

 

not sure how to go about a compression test, but i've emptied and removed the gas tank, probably gonna sand and repaint that, and i managed to get the carburetor off with only two pinched fingers and three scratches. im about to head to work right now. i dont know where to get the replacement rings however. i checked the store forum thingy but had no luck.

 

You remove all 4 spark plugs start with #1 cylinder (right side) thread compression tester into spark plug hole. Crank engine over with starter engages about 4 revolutions and see what gauge reads. Write down readings see what they read. All you need to do is IM message Chacal (xj4ever) with whay you need he will send you back Part Numbers and prices .

 

Do a compression check before you go any further.
The XJ engine can run for a surprisingly long time with no oil in it without doing any significant damage, but it's better to know what shape the engine is in BEFORE you spend time and money on anything. Even with a running bike, a compression check is the first thing to do.
It will tell you a lot about what's actually going on inside, and is a good reference for comparison if something comes up later.

 

trying to find a compression check tool. cant find one that isnt gonna cost a ton of money. i just wanted to let you all know whats up

 

Where are you located? You can get one on amazon for about $20

 

Autozone will rent them out.

 

did the compression test, the tool just came in from amazon today, its reading 100

 

All 4 cylinders? Or just the one? Sometimes, the meter is out of whack, so the actual number isn't that important, more so that all are pretty close to each other.

 

Try a dry test of all 4 cylinders please note all 4 plugs need to be out and a fully charged battery. Write down all readings and then put a little oil in cylinder and then try to see if comression goes up .

 

add a little atf and acetone 2:1 mix to cylinders to free up the rings the rings may be stuck.

 

from left to right, the first cylinder read 100psi, the second read 90 psi, the third read 100psi and the fourth read 115 psi

 

Oh boy those are low numbers but was this dry or wet readings? This also could mean your valves are out of adjustment .. I would suggest pulling valve cover get some metric feeler gauges (NAPA) there are links on the site on how to check and adjust valves. Most dealers will have shims , my local dealer had them for 9.00$ each I had to replace 3 of mine. The only tool you need beside feeler gauges , is a large zip tie and an adjustable wrench . Check and adjust valve clearance and see if readings go up.