XJ650 Bogging down then died

I replaced the clutch plates on my 82 XJ650 and took it for a test ride. For the first 5 miles it did pretty well. I stopped and loosened the clutch cable a bit at the half way mark. On the way back it couldn't really rev past 5000 rpm. It was losing power. It just kept getting worse until it died about a mile from my house. It wouldn't start back up though it tried. I put it on the kickstand and checked the oil level. Went to call my brother to come get me and the phone died. After a few minutes I tried again and it started up. Still not any real power. I limped it home.

No, the carbs haven't been rebuilt.
The intake boots are a little cracked.
I'm using PODS, not the original air box.
I don't know the nature of the vacuum system.
The fuel cap is pretty old.
The petcock is original to the bike.

What could the problem be?

 

I changed the fuel filter and it ran for a bit, then did the same behavior again. I limped it home from a couple blocks away.

 

I ordered a new fuel petcock.

 

The petcock can be rebuilt.
To be sure that its at fault set it to prime, make sure the tank has enough fuel, and see if the bog goes away.

 

vacuum hose could be bad 4mm vacuum hose replace it before you replace the petcock.

pop open the gas cap just unlock it to break the seal it has a vent in it

Your Gas Cap and You

was the bike running and riding before you did the clutch?
what kind of fuel filter are you using paper or sintered bronze? paper can cause fuel starvation .
do you see air in the fuel filter fuel line low and not kinked?

 

put the tassles back on

your original post
http://www.xjbikes.com/forums/threads/another-noob.118193/#post-592729

battery post
http://www.xjbikes.com/forums/threads/upgraded-to-325-cca-battery-on-xj650.118205/

now we have your history

check your battery and charging system with that oversized battery your alternator may be dead from trying to charge it up constantly .
check sitting battery voltage. what is it ?
then start bike and see what the voltage drops to when pressing starter button. what did you get?
then bring bike up to 2k rpm what voltage do you get?

 

Yes, it was running fine before the clutch, well the clutch was a little slippy. Now it isn't.

 

look at your spark plugs could be fouled. my soon to be unpoded bike fouls plugs quickly making it harder to start and power loss becomes more evident.
clean the gas cap as shown in the link provided above this would be a good time to rebuild it or at least replace the 2 orings the seal may need to be replaced too if it is all cracked.

as k-moe go for a ride with petcock set to prime if it bogs still unlock the gas cap (good time to have 2 keys) see if it goes away.
if bike started and power did not return after sitting a few minutes it may be due to tight valves. how many miles on bike?
if asperator tubes under main jets are clogged you could be flooding out motor.
there are many things you have to do to get it correct.

I am not a big fan of multi changes at one time because shotgunning will not tell you what was wrong.
keeping battery on a trickle charger may help if it is a charging system issue due to oversized battery.

test the battery as suggested and record voltages low voltage will cause issues to if it is not charged enough to fire tci.

changing vacuum line when you change the petcock is advised do you still have molded original line on there? it runs from a nipple on manifold boots to petcock.

fix the cracked intake boots clean with carb cleaner then coat with black fuel resistant rtv. you will have to remove carbs to do this and may be able to do it with boots on bike

WHAT kind of fuel filter are you using????

if it were my bike i would check valve clearance
Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

clean gas cap
Your Gas Cap and You
replace vacuum line to petcock 4mm id and it must be vacuum line.

test charging system as discribed above
specs
Starting Load Test:

a) Adjust voltmeter to DC volts (20 volt range).
b) Place voltmeter leads to the battery terminals (positive to positive and negative to negative) .
c) Watch the voltmeter as you start your motorcycle, but before the engine is running.
d) If the voltage drops below 9.5 volts, the battery has very low capacity and should be replaced.



Charging System Tests:

a) Adjust voltmeter to DC volts (20 volt range).
b) Place voltmeter leads to the battery terminals (positive to positive and negative to negative).
c) Start the engine.
d) Bring engine up to approximately 2,500 rpm's.
e) Compare the voltage reading to the specification given below:

For all XJ-series models, the maximum available charging output VOLTAGE should be as follows (all values are approximate):

* approximately 500-2000 rpms: 1.8 volts gradually increasing to 14.2 volts
* 2000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all models except XJ700-X and XJ750-X)

Ohm out ignition system
XJ650 models:

Pick-up coils:
1980-81 XJ650 Maxim and Midnight Maxim: 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982 XJ650RJ Seca (non-yics engines): 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982-84 XJ650 Maxim: 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982 XJ650RJC Seca (yics engine): 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982-83 XJ650 Turbo: 120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

if the above does not fix your problem it is time to clean/rebuild carbs pull those main jets and the tubes under them see if the tubes are clogged.
it is time anyways to clean them.

 

The problem is fixed. You were close. The answer we were looking for is "out of gas." I didn't think it was because the trip was on 75 miles. When I stopped and put it on the side stand it moved more gas to the petcock side. In the end I decided to replace the petcock because the gas was only trickling into the clear filter. I drained the tank and it only had about 1/3rd of a gallon of gas in it. So... out of gas.

I do think the petcock needs replacing because it gets starved of fuel after about 15 minutes of riding at high RPM. Then has trouble keeping up on fuel delivery. The existing petcock doesn't perfectly shut off. It had a tinsy extermely slow ooze of gasoline. When mean on startup the entire fuel system is full of gas. After a while the excess gets used and it starts to starve a little bit on high RPM's. I did crack the cap to check for a venting issue causing this, no change.

If I'm riding and do high rpm for a bit I can feel it struggling. If I hold down the clutch let it go to idle rpm while still riding down the road, count to 5 and then try the high RPM riding again it's goes like a bat out of hell... until it starts starving again. I put a new fuel filter on it. But I can see that the fuel delivery issue is FILLING the filter, not delivering it out the other side. So it's either petcock issue or a venting issue. But I don't think it's a venting issue.

I told my Harley 1%er 68 year old biker brother the bike bogged out on me and he said... "did you check the gas? Get a stick off the side of the road and stick the tank! If you're out then find a bottle and wave down another bike. They can pull the fuel line and fill up the bottle for you...." Bikers!

Anyway thanks for the help. I'm an idiot. Gas!

 

out of gas on a 75 mile trip? was tank full to start with?

low gas mileage you need to do some work on your bike

 

If you run out of gas after 75 miles...You have
Some serious carb work to do..

 

If the petcock is decent, it can be rebuilt. Your problem could be collapsing fuel line or the filter you're using. Paper filters don't allow enough flow and the bowls run dry, which has the same symptoms as running out of gas.

 

Is this a Maxim, or a Seca?

 

Maxim

View attachment 29343

 

OP, please put that info in your signature.

The reason that this is relevant is to give you an accurate idea of how far you should be riding before needing to flip to reserve. You really should be getting at least 45 MPG, and you're not getting much more than half of that if the tank was full when you rode those 75 miles.

The other relevant bit is that the Maxim 750 tank holds a gallon more fuel, and drops right onto your 650.

 

Thanks for the help. I don't think it ran out of gas in 75 miles. The trip was saying 75 which made me think I had fuel. Changed the fuel lines and a new copper fuel filter, new petcock and new fuel cap. No difference. High rpm running under load it starts to bog down after a while. If it dies and I look in the clear fuel filter it is completely empty of gas. I have run the bike from fuel in the filter and bowls and watched it flow based on vacuum. But I noticed rust in the fuel filter - that has less than 20 miles on it. So I have rust in the tank.

Ps. I'll add a signature with the 82 Maxim 650 on it. Thanks.

 

Complete the repair today. The final answer was, some rust in the gas tank It looked fine from the top, but it had some rust in the bottom. I shook it with water and BB's, then etched it with Mariatic Acid from Walmart. Then neutralized, rinsed with water then rinsed with fuel. I will seal it next week. Don't have the sealer this week. Now it runs like a top. Will peg out the speedometer in 3rd gear without redlining the rpms. Runs great any speed all day.

Not much LOOSE rust when I bought it, the more gas I put through it and ran it the dirtier it got. The rust would stick to the petcock screen on high fuel use runs, then when given a break would settle off, then do it again. Didn't really need the new air intake boots. or the new gas cap but they look nice and it's nice not to worry about them.

Rust in the gas tank. I switched back to the original petcock.

 

Runs great I'm sure the gas mileage was a tripometer error. No problem with the carbs. They are doing a great job. If I have a carb problem I'll get into the carbs.

 

That's really good to know! Thanks.

 

A tripmeter error is unlikely. The bike can seem like it's running great, but still be wrong enough that fuel mileage suffers greatly.

 

It's been about 500 miles no issues. Regarding gas mileage. 82 xj650's get between 33 and 47 MPG. With a 3.2 gal tank at 37 MPG I would (and did) hit the reserve at 75 miles. It doesn't mean I have to "fix" anything. Plus I'm running pods which can affect gas mileage. My car is a Prius. It gets 45 MPG, I don't mind if my bike gets 37. I can afford the extra $2.25 per tank.

http://www.fuelly.com/motorcycle/yamaha/xj650_maxim

 

http://www.fuelly.com/motorcycle/yamaha/xj650_maxim

After 500 miles it's running great. The issue was rust in the gas tank.

 

When I look this up it says they both hold 13 liters. Do you mean a 750 Seca tanks holds a gallon more? Because the specs say it holds 18 liters. I
f so, then you need to know the difference, please. Someone might take your information seriously.

 

2000 miles in and still running great. Still unholy pods and unholy carbs.

 

xj 750 Maxim spec on fuel tank


XJ650 Maxim spec on fuel tank



fuel info from factory service manuals. a 750 maxim tank will fit onto a 650 maxim frame giving you more fuel longer distance between fill ups as the 750 Maxim tank holds a gallon more than a 650 Maxim

 

To the MPG problem - I had a similar one with my 80 XJ650 Maxim - Bike ran great - but I was hitting reserve at 80 - 85 miles or about 35 MPG. Also , all spark plugs had a strange look - the insulators were blotchy, not uniform in color. I would call em "zebralators". A mix of black and white areas all over the insulators. Many chapters and dollars later into this diagnosis I replaced the needle jet and jet needle assemblies in the carbs. Then sync'ed, colortuned, and synced. Bike ran just as before, but the plugs now have that lovely brown/tan uniform color, and i'm getting 45 - 48 MPG. The only thing I did notice after this change was cold starts required just a little more choke time. Good luck!

 

Please re-read. I was comparing the 750 Maxim tank to the 650 Maxim tank.

 

You're right. I'm wrong. Sorry I was an ass. I got a newish 750 tank in today. Very Clean, Black, Sweet. and a gallon bigger than the 650. My apologies. I'm often a jerk, but I know when I'm wrong.
Tony

 

Thanks. When the riding season is over I'm going to churchify the carbs. Thanks for the info!

 

I am still having high speed, high demand fuel delivery issue. If I prime the copper filter full of fuel it'll run like a scalded ape but after running high RPM's (over 7000) or running high speed (over 75 mph, particularly up hill) for more than 30-40 seconds it still bogs a bit. I'm 100% sure it's fuel delivery from the petcock, not a carb issue. I can watch the clear copper filter run dry. I'm still running the original petcock. Will rebuild it. I have another one but it's not a stock petcock. The connections are backwards. I can make it work, but I really need to find a way to get a petcock to deliver high demand fuel. The intake boots are all new. The vacuum line is new as well.

 

my 750 had that issue with fuel filter filling with air. I moved the filter back past the carb past the bracket on the first carb used it to secure fuel line in a down hill angle ran the fuel line from filter past the PODS then under them to the fuel tee . i get good fuel flow bike runs smoother.
At 70 miles per hour up hill it starts to bog down near the top of the hill. its the pods that cause this.
same fuel line setup on my other 750 it has the air box no issues on the same up hill and I can keep going faster.
I have an air box I am going to install in the podded bike to see if this issue goes away . I fully expect it to go away.

the further away from petcock the filter is the better. it gets the whole filter below the feed from the petcock. just a little air shows up now.
I use a cone shaped fuel filter and when mounted I try to make the angle of the cone horizontal .that way air can not be trapped in filter body.

side note better MPG = less fuel demand

I am going to try a cylindrical fuel filter next

 

Could also be the FUEL CAP is partially clogged and not venting properly, thus causing a "vacuum lock" to form inside the tank. Next time this happens pop the fuel cap and see if the issue disappears........

 

cap is the first part of fuel system that I clean

 

You're definitely not a jerk. Jerks never apologize

 

It could also be a float height issue. It's easy to run the bowls dry at high speed if the floats shut off too soon. I am, however, thinking the gas cap vent, or petcock is more likely.
Vacuum line collapse is another suspect.

 

Thanks. Great info. I have an oversized battery so I'm committed to the pods. (Why do you have an oversized battery? Because it won't crank fast enough with a regular one. Why don't you fix that? I did fix it with an oversized battery. But you need to rewind your starter. I'm not going to do that, the oversized battery works great. But it can cause other issues. Hasn't so far, if it does then I'll address it at that time. Why don't you just "fix it?" Because I don't work on bikes. I ride them. That's a shitty attitude. Thanks. Every time I've ever taken anything mechanical apart it has never worked again. I have the reverse Midas touch. I know my abilities.)

I'll look at moving the filter. I'll also probably go with a higher capacity petcock from Pingel. I don't care about gas mileage and I'm not switching away from the pods. So I'll find an alternate solution.

Thanks for the info.

Tony

 

I bought a new cap when I initially had the issue. There was junk in the tank that I flushed, acid etched and flushed again, no liner added. I thought there might be a residual issue so I kept an eye out for a 750 tank that was squeaky clean to replace mine. Now I've done that as well. It's not the tank or the cap. I will agree that it very well could be the pods plus the jetting. I get 37 mpg, which means the bike is pulling 20% more fuel than it's supposed to. These old bikes weren't made to cruise at 75 mph non-stop for an hour. They were built in a 55 mph world. That's not saying they can't. But it puts them under additional stress. Add hills or passing and it just can't deliver the fuel fast enough without the stock airbox and jets. My next step is to increase the fuel delivery and see what happens.

 

I have literally watched the filter run dry. Not just some air, completely dry, under high rev, high draw. So I'm 95% sure it's a delivery issue from the petcock. new vacuum line, new intake boots. I even tried a new petcock. No difference. That being said the bike runs like a sewing machine under normal riding conditions. 70 mph or less without hot dogging it. Or even 75 mph on moderate roads. 75 on long steep hills, not so much. Hot dogging it runs it dry of fuel and it has to work to catch up.

Good info, thanks. In the next few weeks I'm going to upgrade the petcock and triple the flow capacity out of the tank, still using a vacuum petcock, and see what that does.

 

I wonder if there might be some crud hiding in the tank that's blocking the standpipe screen.
I'll be interesting to see what you find when you pull the petcock out.

 

And yes I did score the 750 tank on ebay. I watched 3-4 times a week until a good one showed up. Got it for $130 plus $35 shipping.

 

Two tanks, two caps, two petcocks, two filters, same issue. Originally when the bike was really bogging down (to the point of dying) it was crud in the tank. I cleaned, etched and flushed the original tank and it cleared it up to the point where I am now. Then I replaced the tank. I did go back to the original petcock because the aftermarket one had the ports on the wrong sides (vac facing back, fuel facing forward). So technically if the screen itself is deteriorated then it's possible. But it looks fine to me. Next time the tank is almost dry I might look at replacing the original screen with the screen off the replacement petcock. I don't think it will fix it but it can't hurt. (Time to go drive my tank dry.)

 

Hmm... that sounds to me like the problem isn't with the petcock or the gas cap vent then, unless both of them need to be rebuilt (possible, and quite likely).

 

My best guess at this point is the combination of pods and jets are pulling 20% more fuel than "normal" so the petcock can't keep up when i ride like a maniac. So I'm going to put on a maniac petcock and see what that does.

 

Eliminate the guess, and save some money. Ride with the petcock set to prime. See what happens then.

 

what kind of filter are you using? metal element or paper. paper has been known to cause issues

i would think the fuel flow of a 750 petcock would compensate for a podded 650 demand