xj 600 not firing on all 4...last cry for help

[stevie16v]

As you'll know from my posts. Ive been working on a xj 600s, L reg which had been sitting for a while. Done most things, But it will only fire on cylinders 1 and 2. I've checked everything i can, New plugs, Plug caps, Checked resistances on coil packs, compression seems ok.

3 and 4 do have a spark, But it doesnt seem to be doing much. The coil packs are split into 1 and 4, 2 and 3. So really doesn't appear to be that. I have checked most things that I can, The only common factor i can see between cylinders 3 and 4 is the red and orange wire which comes out of the back. I thought if that was faulty then i wouldn't get a spark at all, Maybe you can tell me otherwise. I'm really just looking for one last pointer before i throw the towl in and scrap it to try and get some of the silly amounts of money i've thrown at it back. Any suggestions?

[Fozzie]

It sounds odd to me that one of each cylinder the coils control isn't working. I would point the finger back at them as something clearly isn't right.

Check all connections and make sure they are on right, as it sounds like somewhere along the line something isnt connected properly. Also you note that cylinder 3 and 4 have a common wire coming out. Why do the other 2 cylinders not have this and what purpose does the wire serve?

Lets get her fixed

[megawatt]

I've pm,d my number mate. Gimme a bell and I'll talk you through both your problems solutions n you can type it up later?

[eastanglianbiker]

have you got the plug leads on correctly one coil does cylinder 1 and 4 the other coil does cylinder 2 and 3

[stevie16v]

Thanks to Megawatt for his help. I've rattle through a few things, Swap coil leads over, Appears pretty much the same, However, I've noticed that with the choke open (about 3k revs, exhaust 4 gets hot and 3 is warmer. I've also taken the airbox off and sprayed carb cleaner into all carb inlets, On 3 and 4, theres a change in engine note, on 3 and 4, there isn't. If i put my hand over 1 or 2 the bike cuts out, It doesnt do this on 3 and 4. Megawatt has suggested taking the rocker cover off and checking the valves, Guess i better get my scrubs on and tell the mrs i may be a while

Plug leads all on correctly aswell

Any more suggestions appreciated

[megawatt]

Nice one Stevie, we'll sort this one way or another

[eastanglianbiker]

has it got all new plugs in it? One or 2 of them could be breaking down under load

[stevie16v]

all new plugs and caps

[stevie16v]

rocker cover off, All valves moving freely (its 8 valve as far as i can tell)

What next?

[megawatt]

You need to check compression next mate. Worth checking clearances as well. If a valve is bent , the clearance should be more. Have a look down plugholes for shiny ring on top of piston???

[stevie16v]

I'll try check the clearances in the morning, Need to wait until i borrow a compression tester to do the rest. Feeling pretty sick with the petrol/oil smell from the bike so need to chuck it tonight.

Wondering if it's worth the hassle, Might sell it for spares/repairs or break it. Bloody thing owes me circa £600 which im never going to get even close to

[megawatt]

Persevere mate, it's worth more running than not

[stevie16v]

It's getting to the point its cost me more than i care to think, and i'm thinking it may be beyond my capabilities. For example, if the compression is down then i'm looking at a new engine? (£200 ish) Just desperate to get a bike on the road and theres one on here advertised not to far away that im very interested in, would need to punt this first tho

[stevie16v]

Hmmm, Maybe i've been a bit silly, Would appear i didn't take out and clean the idle air jets (just reading through the haynes), Could this be causing problems?

[eastanglianbiker]

yes this could well be the cause of the problems as its the idle jets that bike runs on up to around the 3000rpm mark then the main jets take over

[stevie16v]

bugger, i'll maybe nip down and try and take them out, hope they dont shred, The jets on these things are made of cheese

[megawatt]

Didn,t you say the plugs were getting fuel on em???

[stevie16v]

Didn,t you say the plugs were getting fuel on em???

Yeah, They are, It was the idle AIR i was thinking off, Just been down and checked tho, they're as clear as can be. Knew it'd be too good to be true! Squared up a compression tester but wont be able to get it until next week, when im nightshift and 50 miles away from the bike! lol In the mean time tho, after i've checked the clearances. You mentioned about spraying fuel into the intake. Could i do that with the carbs off and just trying to turn the engine over on the start button and listen for it trying to fire?

[megawatt]

Yes mate, if you have a spark and the valves close enough to create a vacuum in the inlet tract, then you will suck the fuel in. If there is compression, spark and fuel, it will burn it and turn the engine over. Good luck mate

[stevie16v]

Thanks for your help folks, Looks like the intake valve on 3 is knackered, There is also a snapped thread on the head so it's going for scrap (see other post)

Cheers again for your help

[Fozzie]

Drill it out and tap it?

It could make a decent bike! And I am yet to see pictures of this thing! So before you contemplate anything else.

[stevie16v]

Sorry fozzie, Already started splitting it, Thrown too much money at it to justify any more to be honest, So on the lookout for another one. The valve was the biggie, Would work out cheaper getting a donor engine which would be £150-£200 and still a risk as i wouldnt know the history of that either. Don't have any great pics of it unfortunately

[Fozzie]

Sorry fozzie, Already started splitting it, Thrown too much money at it to justify any more to be honest, So on the lookout for another one. The valve was the biggie, Would work out cheaper getting a donor engine which would be £150-£200 and still a risk as i wouldnt know the history of that either. Don't have any great pics of it unfortunately

 

Buy this one and take the top end off it and put it on your one?

http://cgi.ebay.co.uk/xj600-motorcyle-e ... 3cb70f7788

Can't argue with £50

[stevie16v]

It would cost me abou £100 on fuel to go get it lol

Too much hassle for my liking anyways to be honest incase it all goes horribly wrong

[redline]

Hmmm, Maybe i've been a bit silly, Would appear i didn't take out and clean the idle air jets (just reading through the haynes), Could this be causing problems?

 

does sound carb related. do you get wet plugs on the the cyls not firing at all?