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Discussion in 'Thumpers' started by JimRidesThis, Apr 26, 2012.
Way to go, Jim!
Well, I finally managed get the bathroom finished (almost) and that meant I got an evening to play with the XL engine.
This is where I'd got to...
So, next it was on with the piston, rings and barrel, but not before I had removed the crank pinion to fit the new camchain which wouldn't fit in between that and the oil pump :huh
...then, on with the camchain guides, head, tensioner and cam
When I took the engine apart the cam sprocket bolts didn't match each other. One is the OEM M7(!) bolt while the other looks like it's of a bicycle brake system (just a guess) - chromed, domed allen screw.
I guess this might not be a problem, but for the sake of a few pence, I'll get a couple of M7 bolts from the local engineering supplies shop.
More to follow!
Looking Good Jim!!!!
OK, here's where I'm up to at the moment...
...all ready to kick over! The problem is it doesn't want to fire up. Not even a hint of catching. :huh
Which leads me to suspect the Spark or Fuel issues.
There is a spark (though I'm not convinced it's a particularly healthy, fat one so it could be failing under compression). It's got a new ignition coil but it is the original generator in there, and I've read the recent posts on the main XL600 thread regarding the expected output from the ignition side of the generator. I haven't checked that yet, but I will do so when I have some time.
And, for the amount of kicking over on full choke I gave it, I'd have expected the motor to be flooded and the plug to be soaking wet with fuel - which it wasn't. I've cleaned and inspected the carbs, paying special attention to the pilot/idle circuit on the primary carb. All the jets a clean and nothing seems to be blocked.
There seems to be good compression, and though I don't have the tools to hand to measure it, I've no reason to suspect problems in that area.
Any ideas folks? Is there something vital I've missed?
On the plus side, I am developing some excellent muscle tone in my right leg!
I would guess any motor that's not firing when trying to start should eventually have a wet spark plug. Is it wet at all, smell like gas? Maybe you're not getting fuel?
My thoughts exactly.
I gave it a good kicking again this evening and pulled the plug immediately. It was dry. I removed the carbs again and checked the pilot jet which seems clear but I've dunked it in vinegar for half an hour just to make sure. I guess there could be a blockage in the internal fuel ways. What would you recommend? Sonic cleaning?
Check the float height. Is the float valve stuck? If that's is fine then if you break down the carbs you can see through all the fuel ports pretty easily to find a clog.
Now, I'm kicking the bike over on full choke with absolutely no throttle. Am I right in thinking that the secondary carburettor has no part to play in proceedings yet? Can I safely ignore it in terms of the no fuel issue?
Fuel is getting into the primary carb OK, and there's good flow from the tank, so I can eliminate the possibility of issues with the tap or in-tap filter.
On the primary carb:
The float valve isn't stuck and seems to be in good condition. No overflow 'leak' would seem to confirm this?
Generally it's not looking too bad inside. No gunky deposits, blocked jets, etc.
- I haven't checked the float height but I'll do so this evening.
- I've found out that we have an ultrasonic cleaner at work, so I'll separate and strip the carbs tonight and give them a bath tomorrow. Hopefully that should loosen any cr@p in internal air and fuel ways.
As I recall, the secondary carb only kicks in after the throttle is turned a certain distance. I want to say it was about 5 degrees of grip twist?
Sadly, it's been a while since my '85 XL600. I've been enjoying following along as you breathe new life into this one!
Have you undone the carby drain screws on the bottom of each of the carbs? If you do this and fuel flows freely from both the drain tubes you'll know that fuels getting into the carbs and the floats arent stuck closed.
Just a quick thought: are you sure that the idle speed adjustment screw is turned in enough to get the engine to start?
You're right Scott, the second carb only starts to operate when the throttle is opened by a few degrees and as I can't see any reference to a pilot circuit in the secondary carb I think I can eliminate that from the no fuel issue.
I'm pleased you're entertained by the thread BTW - I'm having some fun with this bike, can't wait to ride it!
Thanks for that, yes there's plenty of fuel getting to the carbs.
I'm sure the idle adjustment screw isn't set right. Can anyone give me a starting point, e.g. how many turns after contact with the stop or something? But... would that stop fuel getting into the cylinder?
I ultrasonically cleaned the carb bodies today and I've just checked the float heights (both OK at 20mm) so I'll rebuild them tonight and see what happens next!
Oh yes, while the carbs were off I also checked I hadn't plugged the inlet tracts with rags and forgot to take 'em out.
That will effect things Jim, because if set to low your carb wont be open at all. I don't have my factory manual handy but I believe you should turn the idle knob in until the primary carb is at least open a hair or so. Be careful though because if turn it too far that carb will be open too much and you might get some nasty kick back.
Thanks, that's how I've set it now (and kick back was what I was worried about )
Gentlemen, charge your glass and raise a toast yourselves. With your moral support and sagely advice, a milestone has been reached. It runs!
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"Thar she blows!"
I refitted the ultrasonically cleaned carbs, double checked the top end clearances and set up. It started with zero choke about 3rd kick!
The video sound is pretty rubbish I'm afraid. You'll have to trust me when I say the engine sounds good. And the 'smoke' is just the crappy finish on the exhaust pipes burning off!
Great stuff Jim. No better feeling than when a rebuilt bike starts and runs as it should.
Another XL600R is reborn!!
I love the sound of these engines when the second carby opens up under hard acceleration, don't need no pumpers 'round here
It's been a while since I posted but I've not been idle. It's been a busy time at work but I've managed to find the time to sort the 101 little jobs that needed to be done before I could put the XL on the road. I've been at the 'think I'm finished, oh hang there's that to sort' stage for about a month. Well, the last of the bits needed arrived and tonight I had my first ride up the street. It pulls well, especially when that second carb kicks in! Everything is working and it's now ready for it's MOT test.
The sidepanel RFVC sent still hasn't arrived, but that's only cosmetic so it should be road legal by the end of the week! Pics to follow
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