bike wont start getting spark and fuel

Hello, appreciate any help i can get. About a month ago on the first sunny day of spring got my 82 xj750 out started her up and rode fine. 2 weeks later tried to start her again nothing but a click. Turned out to be a bad starter. Replaced starter. Engine turns but wont start. Ive changed oil, tested battery, cleaned my carbs, got new plugs, checked and am getting spark. Did a valve job on it 2 years ago so i dont think thats the problem. But theres got to be something im missing here. Tried starting fluid but only produced a couple hiccups and loud backfires. Is it possible the timing is off? Would a new starter cause any kind of problems? Any suggestions would be greatly appreciated

 

If you have fuel coming to your carbs and sparks...what color is your spark? is the same spark in all four cyl? Did you try to push start it?

 

Spark is more white, ive been reading threads and everyone says big blue spark. Mine is more whit than blue or maybe just bright outside today...havent tried to push start since starter went. But ill gove it a try

 

Oh and spark is uniform through 1 and 2

 

Are the plug wires connected to the correct cylinders?

 

Yes theyre numbered, even i couldnt mess that up

 

No luck on the push start

 

Check your compression on cylinders if the timing jumped your pressures should be off

 

My guess is fuel delivery issue thoe

 

Unscrew the plug caps and cut a bit from each plug wire to eliminate corrosion and see if you don't get a better spark.
Are the plugs at all wet when you pull them?

When you cleaned the carbs did you go to church?
The Church of Clean

Is the petccok working properly?
Have you tried setting the petcick to prime and giving the float bowls a rap with a screwdriver handle to rule out stuck floats?

 

Tapped float bowls, and cut plug wires, did notice a change but still not blue. white at each end and yellow orange in middle. Set petcock to prime, did notice some fuel gathering at screw at bottom of float bowl at 1st carb. Dont have the tool to check compression....yet. hoping this is a simple fix i have overlooked, if i cant find an answer by next weekend ill probably get the tool. Oddly enough petcock still works flawlessly in all 3 modes and im pretty sure its the original. Never went to church, but was shown how to clean the carbs by a guy i would consider the pope. Clean them every other year, but will read the full article and get back to you if there is anything i missed. After cutting plug wires i did notice more hiccuping than b4. When i used starting fluid there were more backfires. Maybe the coils? Idk...if there are any more ideas please let me know. Appreciate everyones help!

 

Oh and yes plus are wet

 

How many miles since the valve clearances were checked? I doub't the problem lies there, but it's worth doing if you've had 5,000 miles since the last check.

 

if you changed the starter and now it doesn't start, that's a clue !
did you try to start it on prime? is the vacuum line on the petcock? are the plugs wet after it doesn't start?

 

what do you mean by this? fuel leaking out of screw?
if you have fuel flowing and gathering under bowls you nay have a bad needle valve or seal for needle valve which means fuel is freely flowing into cylinder flooding it out making it hard to start.
have you done a wet fuel level check?
Setting the fuel levels

 

Wet plugs are a problem. Pull them and let everything dry out. The post which plugs you are using , they should be the non resistor ones. Seen this too many times when people change plugs and use resistor plugs and leave the resistors in their plug caps.

 

Just for kicks try draining a little fuel from the float bowls.
If the screws are not froze up I don't think it would be that big of a task.
Sometimes water will get in the bottom of the bowl and stay there because it is heavier than fuel

 

Well, I'm gonna go with a bad battery. You may THINK it's testing good, but the reality is it can still be bad.

Dave Fox

 

Agree with Hogfiddles ...have you tried starting with battery charger ...mine has a start switch boosts voltage up spins engine over much quicker. A battery that is low on voltage will not turn over engine as fast as it should.

 

It may be time to go to church... Do you have any idea if the carbs have ever been split and thoroughly cleaned/rebuilt? I tried to do a "good enough" job last year (top and bottom, but no split). It did get me back on the road, but it left me wrestling with a plethora of problems from no/hard start to schitzo idle, backfires because I was constantly diddling with the fuel enrichment, etc...

I finally went to church 2 weeks ago. Not only did I find and repair a crack in #2 intake manifold (hello vacuum leak!) but did a full split, dismantle & clean & replacement of ALL seals. Most of my throttle shaft seals were petrified.

It's like a new engine. I'm floored at how she starts and runs now... and that's just with a bench sync. Can't wait to really tune her.

 

I think

 

I think its the float bowl gasket leaks little when the petcock is set to prime and gathers at the screw. But doing a wet fuel level check is a good idea.

 

you should fix that or you may suck air into the bowl when running or go up in flames. if it leaks on prime it will leak when motor is running

 

Going up in flames is never a good thing. Stop riding it and fix any fuel leaks before you go any further.

 

I tried starting with jumper cables to my car so i dont think its a battery issue. Ive tried starting on prime, yes vacuum line is attached. Im not sure what resistors are on plugs but im thinking the round things at the top of each plug? If thats the case yes i took them off. Its been about 2 years since valve clearances i would guess 3-4000 miles since then. Read the church article on carbs. I have just been doing the tops and bottoms of my carbs. This is quite a bit more extensive and little intimidating to be honest but plan on giving it a shot this weekend. Ill keep u posted

 

Resistor plugs are a part of the plug design; the bits you removed are the adaptors for automotive plug wires. If your plugs have an R in the identifier code then you have resistor plugs and should replace them with non-resistor plugs.

 

the term is plug caps ( which contain resistors that fail) they are the spark plug boots that screw onto the wires and go on the spark plug not the nuts on top of the spark plug

when you check the caps you may want to trim back the plug wires a little incase the wire inside is corroded

 

I think i got the wrong plugs ngk bpr8es. But the top says ngk with a big R underneath. Can you tell me what i shoulp ask for at the shop?

 

NGK Bp7es.

Gary H.

 

I believe the plugs should be 7 not 8 at least that's what I use in my bike I think the plug is bp7es but that's without looking at them (my motor is being overhauled at a small shop)

 

Jinks lol

 

make sure the caps are resistor caps it is not uncommon for someone to put plain caps on and go resistor plugs

 

.

Gary H.

 

Mechanical minds think alike, I started by using 8 in my bike and I learned that it changed how it ran and it ran like carp

 

8 is just a cooler heat range than a 7. At least in NGK terms. I would be pretty surprised if going from a 7 to an 8 made a noticeable difference. Two steps, maybe, but one would be hard to detect in a four stroke. In cold weather, I often bump up to a hotter heat range plug to keep motors running warmer. If your mixture is set properly, going to a slightly cooler plug should just help your motor run cooler with no adverse effects.

 

I put in 8 and got a lot of backfiring put 7 back in no backfiring, could have been bad gas that just happened to run out right before I switched them, I guess odder things have happened

 

It could also mean that you were right on the edge of a rich mixture, and the cooler plugs just weren't burning it completely.

 

If your plug wires and caps are the originals. You need to run non resistor plugs of the proper heat range. You can run resistor plugs if you remove the original caps and run standard non resistor caps. If you are running resistor plugs of the cooler heat range and have resistor caps you will have weak spark and your bike will not run very well at all!

 

YICS engines seem to be a bit less tolerant of running plugs that are outside of the specified heat range.

 

Writing this post with literally tears in my eyes. Compression check 0 on all 4 cylinders. Hand turned and peered into spark hole to see the head of a broken valve come up and dissappear. Theres no telling how much damage i have done to the engine cranking it over and over again. Fml. Dont know if the engine is even worth trying to save now.

 

Pull the head and take a look. Might be junk, might be salvageable.

 

I agree with k-moe. Let's not jump to conclusions. Pull the head.

Gary H.

 

Wow that's a shock. Don't believe I have heard someone dropping a valve before. Obviously that can happen but it seems rare.
Don't know where you are at but I have a sweet 750 Maxim engine with 21,000 on it. Took it out of a running bike. Let me know if you need it.
MN

 

I guess 0 in all 4 cylinders because of YICS? Or is there a broken valve on each cylinder? If its a 650, I have a head off an '82 Seca.

 

Dang dude I feel for you, I had this happen to a car once timing slipped and klickity click kchunk pull heads and have a look around hopefully pistons are ok

 

The YICS system has no effect on compression. The ports are located behind the intake valves.

 

Zero compression/broken valves on ALL seems weird. How is this possible? Especially when there were no odd noises (grinding, clanking, etc.) leading up to the current apparent symptoms...

 

Wrong shim size mabey?

 

Too little valve clearance would certainly cause low compression, but the valve would have to be pretty far open to register 0 compression, and I just don't think an incorrect shim would be nearly enough. Maybe if a shim wasn't seated in a bucket properly, but on all 4 cylinders?

Maybe the cam chain skipped- could explain the broken valve, plus other valves being held open inappropriately causing 0 compression across the board.

 

Are these motors interference motors? I would think if they were he shouldent be able to turn the motor over at all