Won't fire

I have a XJ650 maxim. I noticed it would stall at times when the throttle was used shortly after I bought it (I only bought it about a month ago). This happened mostly when it was cold... then it stopped starting, or to be more precise it would turn over but would not fire... so I went ahead with putting the valves in spec and a carb cleaning/rebuild. I followed the church of clean. Used carb dip and cleaned and got air through every passage. Clunk test done. Light test for the tiny hole in the bowl. Fully cleaned with wires and brushes. All o-rings were replaced. Fuel level checked and put into spec. Put the carbs back on. Now it still will not start. It turns over but doesn't fire. I have also tried starting it with jumper cables. Does anyone have an idea of what I should look at next? I just pulled the spark plugs and they look good. Gap seems to be about .686 mm. It would also run a little rough at about 5000-5250 rpm. Not sure if this is related.

I've also replaced the fuse box with a blade type fuse box

 

Have you got the pet cock on PRI, make sure the bowls are full.

 

Yes. Both PRI and on. Also derusted my gas tank, replaced the fuel line and put in a new in line filter

 

It's either not getting fuel, or not getting enough volts to fire the plugs. Try spraying some ether down the carb throats to elimate the gas problem. Other than that - it's the electrical

 

Is there a way to do this without removing the rubber manifolds? Maybe take out the air filter and spray it in that way. Since I don't have ether on hand would it make more sense to check and see if the spark plug is getting a spark. If so, how would I do this?

 

You gotta get the boot off. I suppose it might work to remove one of the rubber caps on the joint and try it?

Have you checked to make sure your choke is working? That adjuster bolt that holds the choke cable in place on the carb can pull out if set too tight.

Good spark on the plugs?

-kaya

 

Choke is working. How do I check the spark on the plugs?

 

Remove 1 plug, put it back in the spark plug boot and rest the metal tip of the plug on the valve cover or head. Try to start it, and watch the tip for a spark.

Repeat for the 3 others.


-Kaya

 

only do 1 plug at atime, and leave the 3 others connected. You can fry your coils if your try to start it with no plugs in and not grounded.

-Kaya

 

Did you clean the screens on the suction tubes on the petcock after your derusting?

Make sure to give it a bit of gas as you crank it with the choke on, maybe your idle is set way low.

 

Definitely sounds electrical to me. Also sounds like it might have been flooding, and had a terrible mixture, but that doesn't seem reasonable after-the-fact. Could be multiple issues in concert. Have you tried pulling the plugs to see if they're wet after you've tried turning it over?

You aren't pulling the throttle back when you press the starter button, are you?

The spark plug is the biggest question right now, did you replace the spark plugs when you got it? Have you checked their condition? Are you getting spark? You know your electrical is probably mostly ok if you hear it turning over, that isolates it quite a bit down the line, which is good, if that's the issue.

You need four things to run:

Compression (did you ever check this? Only thing to be concerned about is--you did put new oil in it when you got it, right? If so, probably not the problem, move on. If you didn't, check compression and change the oil NOW.)

Spark (read above)

Gas (You seem to be getting this, that's what your carb work should have fixed... You sound pretty confident, but are you absolutely sure the petcock is good and everything is move down the system? And you did clean the enrichment circuit, right?

Air (Usually not a problem--problem is usually too much air, making it run hot. Go ahead and check the air filter, though, if it's completely clogged or something is wrong there, that will definitely not let you start).

Idle screw was mentioned above; if it's way low, you'll need to give some gas, but in general *don't*. Adjust the idle screw. If you're constantly at risk of flooding the engine, you'll never diagnose this thing correctly.

 

Not wet

No. But I did try it once

Did not replace these. Was told by the PO that they were recently replaced. Looked fairly new when I pulled them. Checked the spark today and they are getting a spark.

Was told by the PO that the oil was changed recently. It looks very clean. Have not done a compression test. Do you think this is needed, before I go and by the tool for it?

Petcock seems to be good because I used the tank with an extra long tube to check the fuel levels in the carbs. Also could see gas flowing through the new in line fuel filter. Petcock also looked fairly clean when I pulled it. I pulled the air filter. Looks a little dirty but I tried running it a second without the filter and it didn't run. Idle screw was not adjusted. Enrichment circuit was cleaned and I was able to see light through the tiny hole.

Miraculously it started this morning after pulling the plugs and checking for a spark. Full choke and it was at about 1000 rpms. Sounded like it was struggling and only lasted for about a minute.

If I can get it started tonight, should I immediately try and sync the carbs then try to do a colortune and hope that this is currently just a tuning issue and maybe was just a flooding issue before? Should I first buy the compression tool and test the compression? Thanks for the help guys

 

I cant say for sure, but it sounds like theres something going on other than a tune. I would go to Autozone and rent the compression tester. That way you dont have an extra tool that you dont use all that much laying around.

If your getting spark, then its probably not the plugs that are bad. It is cheap to replace them though. Since your gonna be in Autozone anyways......

Its not something simple like the kickstand kill switch or something? Mine went to hell and I had to splice and cross the wires to fire the bike. I would just go cut it assuming its bad though. Check the wiring. See it everything looks okay.

What do the tips of the plugs look like? Black? Tan? White? New?

Sounds like the carbs struggling. Did you do a bench sync?


Well get this figured out.

-Kaya

 

Here's a picture of a spark plug. I was trying to get a picture of the spark but was unsuccessful, which is why it isn't the best angle for seeing the head. I can take another better picture tonight.

 

Spark plug looks good.

On your trip to whichever autoparts store, get a spray can of starter fluid, a.k.a. ether. Spray it into the airbox - you can even leave the filter in. If it starts and runs on the ether for a minute, then you know fuel flow is a problem.

The auto parts stores also often have an in-line spark tester as does Harbor Freight, I believe. That are pretty cheap.

Also, just for sh*ts and giggles, take each spark plug out and light a barbeque lighter in each cylinder. If you get any sort of ignition then you know you have too much fuel in the cylinder.

 

Maybe start with a new set of plugs. Even tho the one in the pic looks good you cant always tell if its fouled by sight alone. & once a plug is fouled, its done. Even if this dosent help, its always nice to have an extra set laying around. Best of luck to ya.

 

If you do the above test, be careful for rubber, and do it soon after trying to crank, because gas evaporates fast--wait even a minute and you might lose the fuel anyways.

I give a +1 to renting the compression tester; if compression is bad, it would give you these symptoms. Hope this isn't it, and it usually isn't, and I don't know what would have caused it to steadily get worse and then kill the bike except for bad or no oil... Unless you had seals that had previously been badly worn just getting worse by being used or something, or had bad compression to start with, started burning oil (blowby) without you realizing, and slowly ran out, then causing the issues here.

Your oil level is still good, right? And this guy wouldn't lie to you and not have changed the oil, he's an honest friend, right?

The fact that it started after pulling plugs makes me go back to wondering about possible flooding--when you flood it, and pull the plugs, it dries it out really quick and will usually then start right up. If the plugs aren't wet, though, I don't know what to tell you at this point.

Your air filter sounded fine. Your spark plugs look fine, I think.

This one time it got started is interesting. It says we're close. Would be great if you got a recording of it if it does run again, some people here would be able to tell you a lot by the sounds, I imagine.

Have you tried starting it in different throttle positions? Did you try revving it when it was idling? What's the position on your idle screw?

You sound like you're doing a lot of the right stuff, I'm sure it'll be cleared up soon. Cross your fingers that it's not compression, that's a PITA.

 

Here's a video of it before i read the compression. It only started a couple of times and only for a second. It pains me to even listen to this. All four cylinders read at 150-155 psi and this is without warming it up... for obvious reasons. Would not start after compression reading. Starting fluid would not start it. I bought 4 new spark plugs and am thinking of throwing those in after a gap them in a few minutes

http://www.youtube.com/watch?v=8mczeb4L ... el&list=UL

 

Just retried with starter fluid and she started right up and revved around 5000 for idle.

 

Two questions:

1. Did you do a bench sync?

2. What are you using to jump the battery in the video?

 

I did bench sync. I'm jumping it with my car. It's a smaller car battery. I'm going to see if I can get it running again. Maybe turn down the idle and try to sync the carbs with a manometer

 

I hope the car isn't running when you do this, it could fry the TCI pretty easily.

What kind of manometer are you using? Homemade, 2-hose, 4-hose, vac gauges?

 

home made 2 hose "baby bottle" type

 

Hook up the hoses and do a sync.

You can do this without the bike running by hitting the starter and letting it roll over 2-3 times and watch the levels.

Do 3-4, then 1-2, then 2-3.

You aren't looking for a perfect sync, just closer to perfect than what you have now.

 

Also, reset you plug gap.

You are at .686mm

You should be between .700mm and .800mm

 

That running engine sounds like its starving for gas. If it revved up on starter fluid and ran at a high rpm untiil the fluid was used up, I think you've got a "not enough gas" condition

 

So it revved up to 5000-6000 and stayed there, even after the starter fluid was gone. After that point it would start right up and but idle way too high. I tried adjusting the idle screw and could not get it to go down. Throttle would make it go higher. At least it is running now. Not really sure why it worked after the fluid was gone. Man is this a process...

While it was running like this I did try and sync the carbs with a manometer. I think I got it close but I didn't want the bike running too long at this rpm. Started to colortune and the first one looked good. I have a slight gas leak so I am going to take the carbs back off this weekend and tighten up some screws. I think I didn't tighten up the carb bowl screws all the way after I adjusted the float heights. I'm also going to check to make sure the cold start plungers aren't being pulled up at all at rest and make sure the butterfly valves close all the way to see if that is causing the idle issue.

 

A step in the right direction, awesome!

Just keep at it and go through everything methodically and you'll have her running right in no time.

 

My guess would be somewhere in the idle screw, throttle cable, or butterflies, or a hell of an air leak.

 

Where should I put the idle adjust screw back to? I think I almost fully unscrewed it to get the rpms down with no success, then screwed it back in until it had an effect in the opposite direction. I'm thinking I should unscrew it until the butterflys are completely closed (I think it was like this anyways after bench syncing) then use the choke when I put them back on, and adjust the idle up until it is in range. That's if I can get the RPMs down. Thanks for the help. I'm sure I am going to have a 100 more questions the way this is going.

Both throttle cable and choke cable have a very slight slack so I know the high revs aren't coming from there. Not sure about air leaks but I didn't notice anything

 

When you take the carbs off, ensure the butterflies are installed correctly, not backwards.

After checking everything, re-bench-sync the carbs.

Before syncing any of the carbs, use your sync gauge, i.e. business card, paperclip, etc. in the #3 carb, and adjust the idle screw to hold the butterfly open enough for your gauge.

Then sync all your carbs to #3.

It should idle high (slightly) after this, then you should be able to back the screw off to get it to idle down.

 

PS tskaz, make sure you have enough thread left on the idle screw.

 

Ah, yes, especially if you have fitted the idle spring washers from chacal.

 

Took the carbs off. Checked everything and almost everything looked good. Bench synced the carbs more accurately first using a small strip of a card then using the holes at the top to get it closer. It will only run with starter fluid now and the RPMs are at 4000-6000 at idle and I can't decrease it and dies when it seems the fluid is gone. Immediate throttle response. I originally put the mixture screws at 2 1/2 turns out before but changed them to 3 this time (I didn't check all of them before tearing the carbs apart but one or two of them were at 3 1/2 to 4 turns out before the rebuild). Sounds like it is starving for gas but all the jets look clean with the small holes clear. Air traveled through all passages from the bottom of the carb. The enrichment was also clean and open. I carb dipped, carb cleaner, aired, brushed, wired, carb cleaner, aired, wired, and brushed the passages the first time. Would rather not have to repeat the whole process. Any ideas on what to check?

 

Id bet your floats are off.

I gotta admit, I havent caught up on this thread since i last posted, so im unsure if you have tried this but this is what it sounds like. Or mixed up jets. Your fuel jets are:

110 main
40 fuel pilot

Have you adjusted the floats? You and me seem like were in the same boat although I need to adjust my valves before I get my carbs squared away. I troubleshooted for a while, and upon research I found my cleaning job was sub-par. Carbs, while simple, require a great deal of accuracy and anal retentiveness in order to get them running right.

And we havent even tuned the carbs yet......


-Kaya

 

Diaphragm piston clunk test?


-Kaya

 

Clunk test passed before I polished the pistons but still polished with 600-2000 paper. Passed afterwards too. I'm going to check the floats again

 

Pistons are slow to return after rebuilding everything, but I assume they work on vacuum and open with vacuum from the engine allowing gas to flow into the carb throat

 

With your carbs right side up. (piston pushing down) there should be a good drop in how it drops. It makes a vacuum and a clunking sound when it reaches the bottom of its stroke. You can feel the air go in and out of the kidney shaped diaphragm breather.

Upside down, and the pistons hang a little bit, but with them in their normal configuration. There should absolutely be a good amount of force pusing the piston down.

A vacuum is created when you push the slide up, and the spring and vacuum push it back down.


-Kaya

 

Now it starts and runs without starter fluid. Runs for awhile, sometimes dies after 5 or so minutes. Still idles high at 4000 RPMs and the choke has no effect on the RPM (I can see it pulling up the cold start plunger) but there is immediate throttle response. I'm guessing this tells me something but I am not sure what. Either something is clogged within the cold start or that is where I have an air leak causing the high RPMs. Any advice on this front? My next steps are to take it back apart and check the float levels again after I take a short break. Thanks for the help.

 

I wouldnt call it help yet.


Its just ideas. If it makes you feel any better, Ive had my carbs off and cleaned 4 times. It sucks, but its all a learning process for people like you and I. When my boots were leaking, I found I had low to no idle, and it didnt effect choke. That was the only way I was able to get it running. Full choke. You can always shoot some carb cleaner at the boots or use unlit propane from a torch. That would rule that out.

What I found happens is it allows too much air in 1 or more cylinders, and make it run lean. Not so rich your RPMs are shooting.

Hopefully someone comes in here with a better idea. Im just tossing thoughts at you to give you some place to start.


-Kaya

 

Recap for anyone that can help and hasn't been following:

I have a XJ650 maxim. I noticed it would stall at times when the throttle was used shortly after I bought it (I only bought it about a month ago). This happened mostly when it was cold... then it stopped starting, or to be more precise it would turn over but would not fire (this was right after I threw some gas additive carb cleaner)... so I went ahead with putting the valves in spec and a carb cleaning/rebuild. I followed the church of clean. Used carb dip and cleaned and got air through every passage. Each part cleaned multiple times with wires, brushes, carb cleaner, air, and dip. Clunk test done and passed and still polished the piston. Light test for the tiny hole in the bowl and I have checked the enrichment hole several times after taking the carbs off my bike. All o-rings and hardware were replaced. Float level checked multiple times and put into spec. Compression on all 4 cylinders at 150-155 psi. Gas tank derusted, new fuel lines, new in line filter, petcock looks good and I know the tank is sending gas to the carbs. It usually will only start with starter fluid when cold then starts alright after that. Idles at 4000-6000 RPMs and I can't get these down. Idle screw will not bring this down. I have checked the butterfly valves multiple times. There is a slight slack with the throttle cable and choke cable so these are not being held open. Throttle gives an immediate response with an increase in RPMs. Choke gives no response on RPMs (I'm guessing this is a clue on what is going on and I can see the plunger being pulled). Jets within the bowl have been checked multiple times and their holes are clean. Mixture screws set at 2 1/2 turns out. When I try to start it cold it sounds like it is starving for gas. So I have two problems:

1. It doesn't start when cold and sometimes dies after a few minutes of running. Will start with starter fluid. Sometimes it continues to run, sometimes not.

2. Idles way too high. Most of the time it idles at 4-6000 RPMs. Rarely but sometimes it starts at 2000 RPMs but then shoots up to 4-6000 after a minute.

I believe this is a video of when it started with lower RPMs then went higher. There is a noticeable clicking sound. Also shows the response from the throttle.

http://www.youtube.com/watch?v=1TbuDl3p ... e=youtu.be



I'm guessing this has something to do with the cold start plunger area. Any help would be appreciated

Most likely unrelated but I want to mention in case it is related, there was a dripping as shown in the picture after one of the times it stalled after running for a few minutes. I couldn't trace the leak any further back than what the picture shows at the linking with a cap. Couldn't smell anything from the liquid making me think it was water. Probably about 10-15 drips came from there

 

RPM problem possibly solved:

For anyone that encounters the same problem, I think I solved the RPMs. Butterfly valve 4 was seated a half millimeter off causing the other three butterfly valves to be open a half millimeter at idle. I noticed this when I took a screwdriver and pushed down on the spring between carbs 2 and 3 where the throttle attaches. The RPMs went down and when I took the carbs off I noticed when I did the same thing valves 1-3 would close by half a hair leaving valve 4 as the cause of the problem

 

That-a-guy!!

I sure hope something like that pops up with my carb troubles. My fingers are crossed for ya.

Let us know how it goes,

-Kaya

 

That's a sync screw. All you did was "correct" your bench sync.

You still need to do a running vacuum sync.

Valves in spec?

 

Valves in spec. It was the butterfly valve itself or the disc. I don't know how to better describe it. I had to undo the two screws on the plate and reseat it to get the other three to close completely (or the almost unnoticeable amount if I wasn't looking for it). The sync screw was irrelevant.

Vacuum sync is next on the list then colortune.