Honda XL 600 refuses to start despite spark

[crystaljohn]

I have a 1987 Honda XL that is refusing to start. I have checked it has a spark by testing with the plug earthed against the engine whilst I churn the engine over. When I undo the carb' drain plug fuel flows from the drain pipe, this tells me that fuel is getting to the float bowls o.k

Now the beast was starting perfectly up until I had my recent issues with the bike being stuck in 3 rd gear ( see my post about this problem here:https://www.bikechatforums.com/viewtopic.php?p=3752353#3752353)

I have recently removed the r.h. s engine casing to check if anything related to the stuck in gear issue was apparent. I could see nothing untoward in there. The only thing that happened whilst I had the cover off was the oil pump gear was removed from it's spindle to facilitate inspection and then replaced. I am assuming this gear is not related in anyway to the ignition timing? or is it?

Any pointers as to why the beast is refusing to start much appreciated.

[Aff]

Spray some carb cleaner/easy start into the intake and see if it starts.
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[crystaljohn]

Thanks Aff I have already tried that!

It was starting so easily before I started looking for the stuck in 3 rd gear issue!

[Aff]

So you have a good spark and its definitely got fuel.

So unfortunately the only thing left is compression. Do you have a compression checker?
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Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[crystaljohn]

Perfect compression Aff, It's recently been fitted with new piston and rings.

It was starting perfectly, more or less first hit of the button up until I started to investigate the stuck in 3 rd gear problem. I removed the rhs engine cover, removed the oil pump gear and almost definitely have not refitted the gear in exactly the same orientation as I turned the engine over attempting to get it freed from being stuck in gear. I didn't think the removal of this gear would have had any effect on ignition timing, but as the engine is not starting now I wonder!

I have been spraying easy start into the aperture under the seat, but I have just thought that of course the air filter is probably blocking the effect of this so I will remove the side cover and squirt some in there and give it another try.

[davebike]

Have you checked Compression with a tester ??
I would suspect wrong cam timing and bent valves

Dave
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[crystaljohn]

Davebike

I haven't touched the cam timing as far as I am aware ( don't think me removing the oil pump gear has any influence on cam timing?)

As I mentioned the engine was starting and running perfectly up until I removed the rhs engine cover.

The engine has very good compression , I don't need a tester as I can stand on the kickstarter to feel how much compression is there!

[Robby]

It's a 600 single. Even if the compression was low you would be able to stand on the kickstarter and not move.

Check your valve clearances. If they are tight, starting will be tricky.

If you have tried turning up the idle to compensate, turn it back. You don't start a big single with the throttle open.

If it has been standing for a while with a mostly empty fuel tank while you fix other things, you may have water in the carb from condensation in the tank. Drain the carb and look for water.

Charge the battery up. I had one of these years ago with a weak battery, utter bastard to start.

The oil pump gear has no bearing on ignition timing, but you having the cover off to check it intrigues me. If there was a lot of metal floating/flying around in the bottom of the engine, some of it may have stuck to the ignition pickup coil, which will stop it working well. Make sure the pickup coil is clean.

[crystaljohn]

Robby thanks for the tip about the metallic debris around the pick up coil, I think I need to remove the cover again and take a look.

As I previously mentioned the bike was running perfectly up until I removed the cover. I haven't touched the idle,or anything to do with the carb', the bike has only been standing for 1 week, and the fuel when I undid the drain plug didn't have any water in it!

Thanks all for the advice, much appreciated.

[Suntan Sid]

Try a new plug, you never know!
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[Fizzer Thou]

Although there might be a good spark,try another spark plug cap.Having experienced failing internal resistor elements,the symptoms you are having sound familiar to what I had on another bike.
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[crystaljohn]

All good info' coming in here Fizzer Thou.

I have a hunch though, and my experience leads me to believe that my problem of non- starting is directly related to the removal of the rhs cover. I'm wondering what I might have done whilst removing the cover ( removing exhaust pipe and silencer, kickstarter, foootpeg, rear brake lever and switch.... that might have some influence?

I'm busy atm but hope to get on the fault finding again soon!

[unitynotsocri...]

maybe the rear brake switch , or, case/electrical earth problem , any wire connectors etc ?? A new plug and cleaning the internal plug thread may help and on an outside curve ....i'd check the camchain / camchain tensioner has'nt done one ...or two or three teeth .

check the decompresion lever/valve/cable if fitted .

good luck.
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[Robby]

Did you take anything else out or disconnect any connectors when you removed the cover?

I'm not an expert on that engine, the Honda single that I know in gynaecological details is the 250RS engine. On that engine the mechanical ignition advance unit sits on the RHS end of the crank and triggers the pickup coil. It is possible to remove the unit and fit it on 180 degrees out, which will throw the ignition timing out by 180 degrees. The pickup is attached to the inside of the cover and has a cable coming with a connector.

If you didn't reconnect the pickup, it won't work. If you put the cover face down on a dirty garage floor, the pickup may have got some metal crap stuck to it.

If none of this has happened, coincidences happen. I would be looking for corroded earth points preventing a good circuit, particularly if it runs a main earth strap from the engine to the frame, and coil mountings.

If you're not going to get a chance to poke it for a few days, spray lots of WD40 onto anything that looks electrical now and put the battery on a charger. Then try starting it before pulling it apart.

[crystaljohn]

Still not had time to get stuck in faultfinding.

I have a spark when I earth a spare plug to engine and turn the engine over with the starter motor, so I can't see that any electrical problems are preventing starting.

Haven't touched timing chain tensioner, and whilst I had the cover off I observed the relatively new timing chain that my friend and previous owner of the bike had fitted, all looked as it should.

I have to put my hands up and say that I haven't as yet removed the spark plug
I tried to remove the plug when I bought the bike from my friend in August but found it very tight, and not wanting to shear the plug off in the head I thought it would be wise to leave it for the moment and try again after I had used the bike for some time and see if the heat might free it up somewhat. readers of my previous posts will know that the bike had been standing for 2 years in a builder yard unloved and neglected until I bought it and lavished it with lots of care and necessary new parts. I have had another try recently to remove the plug but I still feel that the plug is too tight and I don't want to shear it off in the head and then have to remove the head to deal with it.
I will of course have to deal with this at some point, and it looks like my hand has now been forced as the heating/cooling cycles haven't done the trick!

I will try some easy start tomorrow , this time on the carb' side of the air filter, unlike my last attempt spraying it though the underseat apperture.

Many thanks for all your contributions, they are much appreciated.

Pic of the bike being used by me at Brands this year when my Ducati 749s started playing up so I used the XL instead.

[Mev]

Did you ever find the cause? I have the same problem and could do with some advice. Any help gratefully received.

[Suntan Sid]

Remove plug, squirt some petrol directly into bore, replace plug and try to start it.
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[jaffa90]

[bikenut]

if the op was to post an exploded view of the oil pump and clutch cover aqrea, maybe the diagram will show an electronic ign pick up and its wire??

sparks and fuel and compression and breathing, so should run, that is if all is happening at the the correct time.

Sparks in open atmosphere don't necessarily mean sparks under pressure, those darn red neon plug caps again......
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