Doesnt Start anymore

Need Help, I cleaned The carbs on a 750 and got bike running but it only ran for about 30 seconds, At 4000 Rpm. I heard a pop And saw a puff of smoke. Not sure where the smoke came from. And now it wont start and doesnt turn over like it was before. Please Help

 

do a compression test

 

I might have burnt up the starter It was really hot. Would that make a pop noise and smoke?

 

No it wouldn't. You need fuel, spark and compression for the engine to run. Depending on how big of a pop the engine made and how big of a cloud of smoke came out of it you might have some major damage. Do a compression check, then check for spark, then check for fuel. If you're starter no longer turns over, then the aforegoing isn't possible at this stage in time, therefore - start with getting the starter fixed. You might also want to put your location in your profile. There might be someone on this forum who lives just down the street from you.

 

STOP! SLOW DOWN!!!

Take off the left engine cap and carefully and slowly turn the engine over manually. It should turn over nice and easy.

Now....if the bike was running, the starter obviously worked fine before the pop/smoke whammy. So, you are either neglecting to tell us a step of what happened, or it's not your starter.

And if it's not turning over like it was before, then how is it turning over now? Slower, lumpier, not at all, just a click and then no turn over and a really hot starter?

 

I Was cranking alot trying to get the bike to start With a jumper.It would start and run for just a few seconds. I think it was getting to much air. I then cupped the carbs with my hands to block some air intake and it fired right up. Ran for about 30 seconds and then shut off. When i tried to start it again is when it popped. It turns over very sluggish as if the battery is dying. But its not i have direct power to it with a 200A jumper. I will take the engine cap off and see if the engine turns over. I really hope it does. Im fixing up this bike on a low budget.

 

Get a new battery. Jumping with a bad battery isn't the same. Not 100% sure why, but I know from personal experience that it won't work. Drained battery yes, dead no.

 

Also, Does anyone know An easier way to sync the carbs without getting the tool made for it.

 

Yes. It's not an easier way to sync the carbs, but you can make the tool to block the YICS passages by taking a 1" wide strip of t-shirt like fabric, tying knots in it, and soaking it in an oil like marvel mystery oil or something similar that won't evaporate very quickly . Pull it through the passage, cap it off, and you will have sufficiently blocked the YICS passages without the drawbacks of buying an expensive tool that's been known to break anyway.

The process of syncing is still just as difficult. If it's the first time you've done it, I recommend a bench sync first.

 

Yes, This will be my first time doing it. How do I bench Sync? Im new to alot of this stuff Especially for these XJ's. This Forum I see To be a big Help In my Bike Build. Awesome!!

 

Do a search for more pics and info but basically you look at the butterflies with the carbs off to get them all the same to start out with.

 

I Cant Figure Out How to Sync the Carbs. I still cant get the bike to run. Would the bike still run if the carbs are out of sync?

 

How far have you gotten? Did you bench sync? It should run with a bench sync, just not all that well.

To bench sync, you take the carbs off and look at the front through the butterflies. Unscrew the idle screw so that they are closed as much as possible. Look at carb 3(?or 2, can't remember, but it's the one that can change with the sync screws). Turn the other screws so that they all are the same amount of open. Then open them all back up using the idle screw to the height of a paperclip or something of similar size. Done. Not perfect, but it should at least start.

Did you get a new battery? If not, it will NOT run, ever, no matter how often you charge or jump it. You can't bring a battery back from the dead.

Did you turn over the engine manually? It sounded like you had a crankcase explosion, which is a result of fuel in the oil. Take off your oil cap and smell. Tell me what you smell. Turn your engine over gently by hand....if it's not easy or it stops....well, try it without spark plugs in, but if it's still not easy, it's toast. Ded engine.

 

Here is a pretty good write up on bench syncing, worked for me and many others. I used the business card strips personally. Then once on the bike had to back the idle adjustment screw back a few turns to lower the rpms and then tweak with warm up.

bench sync

 

Slow way down....

Cupping hands over carbs? That means no air box to carb boots. Planning pods or just didn't put the boots on? They make a big difference on these bikes.

I will bet good money your floats are low. Were they checked with the clear tube method using fuel? covering the carbs with your hand makes more vacuum in the carb and will pull fuel from a lower level in the bowl.

How clean are the carbs? Half way or close doesn't get it done.

If you really can't get it and we can get a break in the weather I'm close enough to come by and lend a hand. Not this weekend though, I'm out of town and it's raining, again.

 

I Just put pods on. I will try this bench sync method and Do the clear tube to check fuel. I Bought a new battery and checked to make sure the engine is turning over.It turns over just fine. I will check my float levels next. And try this bench sync method. Iwingameover I will try this weekend to get it running. I Appreciate you offering to come up and help me. I will let you know if I need it. Thanks Everyone else

 

Before you waste a lot of time playing around with your carbs, how about making sure the engine is still operable. The possible explosion in the oil sump sounds pretty serious to me. You should at least try and check the compression to make sure you haven't done serious damage to it. If, however you've had the engine running with your hands over the air intakes, then I guess that means you've probably already checked for major damage.

 

When I check the floats (clear Tube Method) do i do it on the bike first and if there off take the carbs off and adjust the float needle? Then do i Put back on bike and repeat until there all at the top of float bowl? Or can i do all this With the carbs Off the Bike?

 

You can do it with the carbs off the bike. You need to find a way to hold them level front to back and side to side while having access to the drain screws and the drains and a way to feed them fuel.

 

Ok Thanks

 

Did compression test. #1 reads 130, #2 reads 120, #3 reads 120, #4 reads 140. That sounds good to me. Time to try bench sync and do clear tube method.

 

those are not bad numbers. Have you checked the valve clearances yet?

 

No not yet . Not sure how to do that.

 

bigFitz has a write up in the FAQ Suggestion section called "Air head valve adjustment w/pics" Explains the whole thing. Do that before your vacuum synch and tune or you'll just need to do the sync and tune again later after you do the valves.

 

I did the sync and checked the level of fuel in the float bowls with the clear tube. I didn't get your message about checking valve clearance until I had already did all this. Carb 3 was empty . But carb 4 was good. I'm confused. Had the petcock on pri so it would fill them up.

 

If one carb didn't get gas, the float and or needle valve is stuck closed. Either it isn't adjusted correctly or it wasn't cleaned thoroughly. You can't take short cuts. There are several threads about cleaning and adjusting carbs. Do it thoroughly, step by step and you only have to do it once. Miss any step and you will keep redoing it over and over again.

 

you did a bench sync right? I was reffering to the running vacuum synch after the valves.

The float could be stuck up or the fuel inlet to that carb is plugged. Did you take the needle seats out when you cleaned? They have small screens on the top (sometimes) that can clog.

Take the rack off the bike and remove bowl 3. see if the float moves freely. If not remove the float pin and clean it good. Then check again.

What about 1 & 2?

With the carbs upside down you can measure with a ruler the height of float 4 from the base of the carb and set #3 to that. It'll be in the ball park, still make sure it's moving then check it wet.

Floats are a PITA but in this case where you have one not getting any fuel it can and will certainly make a huge difference.

 

I have about 30 hrs into the carb cleaning. If I have to do it again I will. This time it should be a breeze. Yes I did Bench sync. When I did the clear tube #1 Carb was right on, #2 Carb was about 1/8" Lower , #3 Carb was Nothing And #4 Carb was the same as # 2. Looks like I know what im getting into this evening. Tearing carbs apart again.

 

I had to clean my carbs 3 times before I got them spotless and shiny. It takes some work and attention to detail but when you are done there is definitely a sense of accomplishment.

Welcome to the club of owning an XJ with pods... you will become very familiar with your carbs as it will most likely need different jets and many much tuning! I know mine have. I wish I had started with a stock box just to know the difference in performance but it wasn't an option.

As far as the pop/bang and smoke you heard, I would guess it was a backfire in the intake tract due to unsynced carbs. Did the smoke come out of the pods? I had this happen to me when I was first starting up mine with unclean and unsynced carbs. Scared the dickens out of me but didn't do any damage. Keep at it you'll get there and you'll love riding it!

 

Ok guys, fuel levels are good in the carbs. Bench synced and still won't start. #3 #4 plugs are dry. #1 #2 plugs wet.

 

open the drains on #3 and #4 verify that they got fuel into the bowl.

How well did you clean the enrichment jet in the float bowl? That can make it nearly impossible to start a cold XJ if it's dirty.

 

#3 #4 have plenty of fuel. I was talking about the spark plugs. The enrichment jet is the long one connected to the carb that goes into the bowl?

 

Are the slides in the #3/4 carb sliding freely... do they clunk when you drop them? Do you have spark on all 4 cylinders?

 

yes it is the long one in the bowl. There's a brass tube that comes from teh carb body and there's a small jet in the bottom of the bowl.

I think you've got either an enrichment and/or pilot circuit that's not clear on those two and two plugs are not getting wet with fuel if you're cranking it and getting no fire.

TMHack... the slides shouldn't matter for starting and idle. Doesn't hurt to check them though.

 

Wet with oil or wet with fuel?

 

1/2 is wet. means no spark. 3/4 is dry. may not be enough fuel or they are firing. but it's tough to get a motor to fire up on 2 cylinders.

try new plugs.

you can also check for spark. put a screwdriver into the plug caps. and hold the screwdriver up to 1/2 inch away from motor. you should get spark with any distance of less then 1/2 inch.

 

Yea, I understand that, just throwing it out there.

Also like snowwy66 said and I mentioned earlier, check for spark. If your plugs are wet, usually means no ignition of fuel...