1982 Yamaha xj650j issues

Stalls after going 1 mile or so. Will start back up after a couple minutes but will only go a couple of miles. Just purchased new plugs because pulled out old ones and are wet with oil but didn't look burnt. Also choke cord need to be adjusted. I think I need to take tank off to get to adjustment area.


1. Air filter saturated with gas. ( going to reuse because clean just wet, so going to hang in garage to let dry).

2. No gas coming out of overflow so float ok? Do I need to use premium gas? I plan on adding premium with amzoil fuel cleaner after adusting choke.

3. May need carbs cleaned and also vavles adjusted.

Any suggestions would be appreciated

 

Plugs wet with oil? Have you checked compression?

Most running issues resolve to carbs needing cleaning/adjusting. Please add your bike year, model, mileage and any mods to your signature. Makes it easier to get help.

Most of the XJs will run well on regular gas (87). Floats bad/stuck sends gas into cylinder since they are tilted that way - what are you calling overflow?

Do you have gas in your oil?- I'm not sure how gas gets to the air filter without going into the oil and up through the crank exhaust tube.

Check your petcock is working properly. It is vacuum controlled and should not leak in the On position with the engine off.

 

Bill is correct - no overflow. It runs straight into the engine. Sounds like you need float work (and an oil change). Also probably the petcock.

Sounds to me like your petcock is messed up. Running fuel slowly all the time. Runs out (into engine and air filter) when parked, but not enough to keep the bowls full when riding.

Choke cable is adjusted from the right side where the cable clamps above the carburetors. No need to remove the tank. Although you will be removing the tank and carbs to resolve all the other issues.

 

Check the vacuum hose that goes to the petcock. The diaphram may be ruptured and gas is going into your engine throught #3 intake carb holder. Your crankcase may be too full and gas and oil is going into your air box.

 

A good many of our Members have had issues with the Stock Petcock.
Either leaking-by or set in the wrong position (PRI) instead of Fuel or On.

You can very easily check for your Petcock leaking-by ... by detaching the line running to the Carbs and putting-on a line that will drain into a collection container.

If you find that your Petcock is leaking-by you have the option of trying a Repair Kit or buying a New Petcock.

If it were me ... instead of rebuilding the leaking Petcock; Id just get a New one.
Considering that the Original Petcock lasted for 25-years or so before it needed work ... I'd like to start a second 25-years with the New Petcock rather than risking the possibility that the Kit didn't fit just right and having to try modifying the Kit pieces to make it work.

 

I agree with this completely, however I will say the rebuild "kit" i got from Chacal worked perfectly on my bike. I made sure everything was super clean, replaced the vacuum diaphragm, bolted everything back up, no issues since! Well ... except for that one time I had switched to RES to get to the gas station then forgot to put it back .... heh.

 

i also am having petcock issues. are there any aftermarket options for petcocks?

 

i am looking at http://www.z1enterprises.com/reference/petcock.aspx

does anybody know what adapter plate you need to use a non stock petcock?

 

Talk to Chacal on this site ... he's got tons of options available, from parts to rebuild your current one (which worked out perfectly for me) to complete aftermarket petcocks, at honestly what seemed to be very fair prices to me.

 

There's a drawback to installing an aftermarket Petcock!
Most don't have Vacuum Operated Shut-off's.

If you forget, out of decades of habit, to shut-off the Fuel flow; you might find a Crankcase full of gas for a moments forgetfulness.

Given that the OEM Petcock worked so well for nearly 30-years; it might be a wise choice to just replace the old with new and be done with it.

 

I have an 81 750 the petcock worked perfectly on mine and almost always leave mine on except long sits mine did a simalir thing in that when i shut my bike off gas would leak from the air box over flow due to a carb getting dirt stuck in to hold it open(i belive). i traced it to my #2 carb and fixed it with stp. if the air filter is getting soaked in gas a carb float would be my guess since a carb shouldn't leak gas even if a petcock is open

 

my bike also had some starting issues from the carb tho. I would start with no power from the stop(due to rich running on one cylinder) and i would have to turn on my choke(fuel modifer) and roll on the gas just to get all four carbs to about thte same opening to start,

 

I'm confident the Design Engineers thought that having the Fuel Supply shut-off, when the Engine was not running, that they employed the Vacuum Operated Petcock as a safe-guard against flooding the Engine, Airbox and Crankcase with gasoline as being absolutely necessary.

Modifying their design by using a Petcock which does not shut-off after the Engine is stopped places the Power Plant at risk of being flooded.

I realize some people are inclined to make compromises when they have an option to save a few bucks and deviate from the stock configuration.

But, replacing a Stock Vacuum Operated Petcock with one that does not shut itself off when the Engine stops running because it can be done for less money than procuring a new Vacuum Petcock is not a wise course of action and is something I would not ever recommend.