1982 xj650 Cranks but wont start 2 days after buying.

Hello, I bought a 1982 xj650 maxim 2 days ago. It ran beautifully and started right up when I was testing it before buying. Rode it home 25 miles and had no issues, seemed to run just fine.

Its now 2 days later and it cranks but doesn't start. I tested spark on all 4 plugs and they looked nice and blue.
I can smell gasoline when cranking it, also sprayed starting fluid in the spark plug holes but didnt hear a sound.

I don't get how it would start right up before but now nothing. I tried half choke, full choke, no choke. Idk what to do. Is it possible I have the petcock on the wrong setting??

If you need more info or would like videos id be happy to post. Please help me I feel like I just got ripped off...

Thanks. -Anthony

 

first do not use throttle it should start with out it just the choke.
second is there gas in the tank?

put bike on centerstand and check oil level in the sight glass.

could be your battery is weak and needs charging or replacment.
hook a meter to battery and record voltage then press starter button does it drop below 10 volts if it does tci will not fire.
if you leave the key on for about a minute do you get a back fire?

petcock has 3 positions run/on, reserve and prime if tank is full it should run in all 3 positions


still have glass fuses? could be bad connections at ignition fuse

 

Okay, tank is full. I was trying to use the gas to start it. Maybe I flooded it.

I hooked my multimeter up and pressed the starter and all of a sudden it started up. I have no idea why as I've been trying to start it for the last hour. Even had the choke off.
I am uploading a video of it running to Google drive. Will reply once it's done

Also, what do you mean backfire if I leave the key on for a minute?? Will it just ignite?

Thank you

 

first thing is keep a notebook
when you have it running test your charging system

in this thread you will find the specs
The Ultimate Relay, Switch, Sensor, and Diodes Guide

make sure your battery cables are clean and tight (hooked meter to it and it started)

 

Wow thanks so much. I'll have to test it tomorrow as it's too late and I don't want to piss the neighborhood off.


What confuses me is when I could not get it to start I still had good spark. Plugs are very new and spark was blue.

The seller said he rebuilt and tuned the carbs. I'm guessing he did a slop job at it.

It won't let me post a link so I will message through video to you.

 

Okay first unless you know or trust the PO , you should check it over . One item check the petcock if it is factory ,then there is a vacuum line going to it, make sure it is in the ON position. If it is in the PRI, RES fuel will flow constantly , if needle is not fully seating , you can leak a whole tank of gas into the crank case. If it is an aftermarket petcock probably has ON ,OFF,RES you have to put it to off when not in use. This can also foul the plugs verified by pulling plugs if one or more are wet. Highly suggest you go to top of page click on xj4ever read the information overload hour , purchase a service manual . Do your research on the site and don't be afraid to ask questions , if your afraid to ask a member on the public forum, start an IM message , I've helped a few in the manner . Good luck

 

Emphasis mine.

 

Thanks for all this info. The Petcock seems stock, and I left it in on position the past 2 days.

But, the vacume line is missing. I see where the port for it is but it's uncapped. I'll attach a picture.

 

The vacuum line must attach to a port or manifold of lines on thee intake.
Engine vacuum opens the petcock, safety so if the bike dumps n stalls it shuts off fuel.
For now try the PRI setting, this bypasses the vaccuum diaphram alliwing fuel to the carbs.
Hope this helps

 

To note: when cranking the ON setting barely allows gas in till the engine starts.
Hence PRI setting, or prime, to fill carbs if they hsve been serviced or the bike has been sitting and they are empty, so you dont have to crank the bike for an hour to fill the carbs.
Contrary to Jetfixer, my bike appears to still shut off fuel in the RES or reserve setting when not running try prime.

 

I'll try that tomorrow and will report back.


I really really appreciate all your guys help. Its amazing how many good post I got on here so quickly. Makes me happy.


You guys have a good evening.

 

cap off the port on the carb intake manifolds it can make it hard to start if not capped

 

his video
New
https://drive.google.com/file/d/1UzB2_gUtAuj88qp8fe3iuYx_DO8hU6qv/view?usp=drivesdk

 

Is this the port you are talking about?? It looks already capped.

 

Also am I going crazy or does it seem like there is no oil in this bike???? I can't tell if the sightglass is foggy or if I nee
d oil.

The bike starts fine now, only need a touch of choke. However, I need to obisobio change oil and oil filter and do that valve thing people talk about. I will not start it til I get fresh oil in her.

 

Well in the pic, the oil is low,BUT--are you on the center stand or side stand?if it's center stand you're waay low. If it's on the side stand, you will see the oil leve go up just standing the bike upright. Put it on the center stand on a leve surface. THEN check the glass

As far as the petcock....the vac line operates the RUN and RES part of the petcock. The PRI is a free-flowing setting. If all for vacuum ports are capped, you have no line goin to the petcock. So the petcock should be set to PRI in order to ride, but you need to make sure to set it back to RUN or RES when you stop. Otherwise, you could load up the crankcase if you have any leak petcock or floats......best thing to do---get the vac line hooked back up and verify the petcock is in good working order.

Next thing.....check the voltage of the batter WHILE you're cranking. Let us know what it is. What you describe is ALSO symptoms of a bad battery.

 

It's on the centerstand. I'll do an oil change asap.

 

I have not noticed any leaks if I park it on ON. Bike runs good on the PRI setting. Is it a bad idea to leave it how it is for now? I have other more important things to fix first so I figure if PRI works fine I'll use that.

The one time I measured the battery while cranking it didn't go below 11 volts but it started.

I should do this test again. Would it be a bad idea to do the crank test with my oil that low? I think I should at least fill it first.


Thank you guys so much for all this help.

 

Add oil. It could be your is low enough to trigger a no-start.

Leave it on prime while running. DO NOT leave it on prime when you shut it off

 

Okay cool. I gotta find a place that sells motorcycle oil today. Any recommendations for oil?? I should probably use the search function for that.


I really appreciate your help guys. I've got some stuff to do this morning but when I get free time I will try the things you've told me.

 

I use Yamaha yamalube 10w-40 In Everything. The only other thing I use, if I don't have llama lube… Is the brand maxima 10w-40.

Use traditional Dino juice.... not synthetic, and also-don't get anything with friction modifiers.

 

Any JASO MA, JASO MA-1, or even JASO MA-2 oil will do.
Oil thread ink in my signature.

 

I use Valvoline 10w40 motorcycle oil , I get it at Autozone . Agree with hogfiddles DO NOT use synthetic oil.

 

What's wrong with synthetic oil?

 

Nothing is wrong with synthetic oil.

Nothing is wrong with conventional oil.

Nothing is wrong with new bikes.

Nothing is wrong with old bikes.

It's just that Our clutches were not made for synthetic oils, or oils with friction modifiers, etc...... In them. Use those, and you're pretty well guaranteeing yourself that you will have slippage issues.

 

I have a question.
you rode your bike for 25 miles and the petcock is still set in the position where you rode it home?

sounds like the petcock has been modified and the output nipple has become clogged. it unscrews.
no open vac port .

 

That would depend on what position it's in........

 

Not just the clutch ,but stater clutch slippage also .

 

All of that depends on which synthetic you use. There are now (and have been for about 5 years) synthetics that are wet-clutch compatable.

Specifications > word-of-mouth > marketing.

 

I rode the bike home on the PRI setting then when I parked it I set it to ON.
The bike starts perfectly when set to PRI.

 

I live in a cold climate and I think synthetic would help reduce cold start wear alot. I'll make sure it's wet clutch compatible.

 

That would be because the fuel can readily flow. If you have it set to ON or RES, the diaphragm is not opening to allow the fuel to flow properly.chave you tried getting a replacement vacuum hose to connect from a vacuum port to the petcock so that you can see if the petcock operates properly?

 

Not yet. I can't tell where it is supposed to connect to the carbs.

 

it connects to any of the 4 vacuum ports on the intake boots. vac line is 4 mm

typicaly #2 or #3

 

I use Shell rotella T4 15W40 oil you can get it at wall mart about 14$ a gallon

 

The ones right on top roght? All 4 of them are capped off. I'll have to try and connect it

 

yes the black caps come off they should also have clamps ( spring or wire ) on them.

 

Ok, so I can connect to any one of then correct?? I'll let you know when I do, I'm redoing my floors at the moment.

 

yes any port in a storm will do.
I would go with #2 as it is the easyiest to get at . I would stay away from 1 and 4 ! because of the angle and 4 because of the added length and obstructions

 

okay cool. I'll go pick up some vaccume lines.

After I connect it I would set the petcock to ON and try to start it??

 

first set to prime to fill carbs for about 10 seconds, then turn to on and start it .
you only need to set to prime if bike has sat for several days after that or if you run it out of gas.
depending how much fuel you have in the tank you may need to set to reserve.
Your fuel tank has 3.4 gallons and the last .8 gallon is reserve.
if you want to increase your fuel capacity you can put a xj750 maxim tank on the 650. it is a direct swap. XJ750 maxim tank is 4.49 gallon total using .9 gallon as reserve

 

I am going to the store to pick up oil and vaccume lines. I will report what happens

 

Is this what you mean? ( see attachment)

I ran a line from the empty port on the petcock (hard to see in pic) to #2 vac port on top of the intake manifold.

The bike starts pretty good on ON. I rode it up and down the street a couple times and it dies if I hit the front brake hard. (clutch pulled in) (did not do this on the ride home).
The fuel tank is almost full. Switched to RES and had the same thing happen. ran it on PRI and the same thing happened. Its late so I can't do much more testing. (loud). Is it cause the line is too long??? or is there some sort of switch? maybe the kickstand switch is getting triggered or something.
It seems to die almost immediately. like I turned it off. I will have to test it again someday when the weather gets better. its hard to find a time to test it.


Thanks for your help.

 

picture

 

You have a pretty sharp kink right at the top of the port. I don't think that is the cause though.... the symptoms you describe now are indicative of incorrect float height. The engine can bog under hard breaking like that ...
Too much fuel can cause temporary flooding.
Too little fuel can cause temporary starvation

Whatever the case me be-- don't allow yourself to get discouraged. You have an old bike that some things have gotten out of sorts. Once we get things back in order, you'll have a stone cold reliable bike again. No doubt.

 

I see. The low oil light would flash really quick when it died and it died suddenly. I will do a full oil change when I have time and try again. I will also shorten the line.

But it's most likely what you said. Thank you for the help

 

That indicates a sticky oil sensor float, too, unless you hadn't put oil in yet....

 

I topped it off but I think I put a tiny bit too much in. On the centerstand it's all the way up but if I tilt the bike a tiny bit I see the air.

I'll just do it right and full oil change. In my rush to fill it I put lil too much on.

Sorry about that, I was trying to work too fast.

 

Is it possible being slightly overfilled would cause that?
Nonetheless, I will further investigate the problem.

I appreciate your pointers. Hope you have a good evening.

 

A LITTLE too much wouldn't cause that.