Carbs

and it could be fresh fuel taking the liner out of your tank, and freshly blocking filters and freshly cleaned carbs etc because a few years ago a lot of those tank liners were not ethanol proofed
CLEM
 
Ok. Managed to find all of five minutes to go down and take the jets off the offending carb. Out of the 4, the shorter one, which appears "tilted" in the picture, was completely blocked by some "beige" goo. It has now been submerged in carb cleaning solution, and will be looked at tomorrow.

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All other three and the inside of the carb is sparkling clean.

My question now is; would that blocked jet be causing the no firing situation? What are the 4 jets anyway? I?ll try starting the bike tomorrow morning. I don?t want to wake up half of Madrid right now. :D

By the by, I?ve seen that the o?ring in the longest one seems to be quite mangled (chaffed).I?ll probably replace it.

Cheers.

Carlos
 
Top three items from left to right
  non return valve; choke jet; main jet assembly

Bottom jet is the idle jet

Since this was blocked, you may find that the carb drilling is also blocked.  You need to check this with Stevio's method.  If you can't shift whatever the beige goo is (tank lining??) then try a nylon guitar string to avoid damage to the drilled passageways.

Yes, a blocked pilot jet will prevent the bike from running properly at low revs because no fuel can get through

Might be worth checking the tank lining to see if it has gone soft - either because it wasn't properly cured or it is being attacked by ethanol in petrol
 
Thank you Rob. I just went down again, and I checked the tank lining. Completely hard, no symptoms of going soft.

I actually looked into the (now that I know) idle jet, and the beige goo is now soft (I guess the carb cleaner is doing its job) and was easy to "go through" with the needle of a medical injection (very thin). I?ll take a look at it tomorrow again.

Hopefully this is it! I?ll be glad, although I feel tempted to go through all the jets now (just in case).

Thanks again.

 
"although I feel tempted to go through all the jets now (just in case)."
Yes a good idea, the entire carb bank, as there are lots of passages in those carb bodies.
 
Nope. It didn't work. I still have no firing in that cylinder

There is suction when engine is running, but it just doesn't get hot (exhaust or external cylinder walls).

Did all the suggested cleaning motions, a couple of times, and no improvement was felt.

I'm going to pull the carbs out, and see if I find any other blockages.

Cheers
 
Pull that spark plug, connect to plug cap and earth it to the cam cover. Press starter and see if it is sparking.
Sounds like the crap has sucked deeper into the carb body but eliminate plug fouling first.
 
My Spanish is not good, nut I suspect that means raise the carburettor float.

Probably more to the point is check that float level is correct, and also check that the float valve isn't blocked or stuck.

Before you take the carbs off, remove the rubber connectors between the airbox and the carb intakes, look down the carb throats and check that all slides are lifting when you open the throttle. Sometimes the little internal cables that lift the slides can break or come adrift.
 
Dellortoman, I did that yesterday, to check for suction, and it was what paparracas was asking as well. Yep, the slides move OK.

Before I take them off, I will do a spraying session again today, including float valve. I do have spark in that cylinder, and fuel fills the bowl.
 
When you start the bike does choke have any effect on the left cylinder?
 
No. It will still not fire. It won?t even fire over 3000 rpm, as I tested yesterday, once warmed up.
But I still need to check the float valve, that I could not yesteraday, and will check this afternoon.
 
Sounds like still a carb problem...blockage. I am not sure of the  exact history  on this  bike and the carbs re the order of events in problem determination, but even if the plug is firing out of the engine, worth a new plug to make sure it is firing under pressure.  Any chance to try another carb?
 
Swapping carbs is a definite option once I've been able to check the float level. Another option I was thinking of is to spray some carb starter fluid (ether) into the working engine, just to see if it works even momentarily. I guess it won't explode!

Any thoughts?
 
Squirting a little petrol into the open carb mouth should do the same thing. If the dud cylinder suddenly comes to life for a few revs then you can be pretty confident that you have a fuel starvation problem.
 
just because you see spark on your spark plug when earthed out on the engine does not mean you still have spark when plug is installed in the engine
operating conditions are far different to atmospheric conditions
I'd be checking the HT leads and caps by measuring resistance, to measure the dual coil you need to insert a probe into each spark plug cap at the same time, should get a reading around the 19-22 ohm region on the dual
to measure the middle cap you use one probe into the cap and earth 2nd probe on the engine, it should read 5 ohms less so 14-17 is good

if you cannot get a reading remove each cap and measure across the cap itself, NGK caps have been known to fail, each cap should read 4.5 - 5 ohms resistance

lot of the time you need to trim the HT lead back by 20mm to expose fresh copper inner wire as the copper wire turns green with age at the end and does not conduct itself properly  :D




 
Swap left and right HT leads to right and left spark plugs and see if the problem swaps sides.
I still think it's a carb blockage though.
 
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