Yes thanks Ill experiment a little with the fuel cap and draining of carb.

I read some more online about this. That its not only fuel getting "old", but a combination of that (evaporation/breakdown of some chemicals) and the fact that air has water and other polluting stuff in it that mess with the properties of the fuel. Makes sense in a way, even though it seems crazy it would happen in a week and be the only reason to my challenges. I also think the "vent hole" the tank of my bike is a little too open. Ill get some tubing there to still let pressure out but not leave it so "open" for gas to go in and out.

Got my Iridium spark today btw. Will be interesting to see if there is any difference at all.

You should really find a way to check the condition of the spark so you can clearly see what it does. Do this before you put the new one in and the engine will spin over easier, bring the wire and plug over to the kicker side. If you have to find a piece of heavy wire and wrap it around the threads on the plug and ground the other end good on the engine, turn the lights off so the spark sticks out more. I'm more and more thinking it has to do with spark , or lack of it, than fueling unless you get some really,really bad gas that has a lot of garbage in it.



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Yes I agree, probably not (only) fuel. On my journey the bike ran on black market fuel that was so bad it had a darker tone than normal gasoline (yes I checked carb for dirt after).

I tried to check the spark the other day but didnt see, so I was doing it wrong (bike worked). However, in the middle of all this time with fouling spark plugs/difficult to start I did do a test in daylight. We did see spark then and the bike does run. I guess it could be an existing but weak spark... which I think would be hard for me to judge.

Again, new spark plugs and the bike works fine. I might have to kick it 10 times but that is ok for me. The problem is fouling spark plugs and kicking for 30 mins. A bad spark could of course foul the plugs over time...

I will ask someone to help me check the spark, or try the wire approach you suggested. Its a relatively easy test and if the spark seems strong it leans even more towards original diagnosis, which was pointing at oil leaking in from valves an/or piston ring.

It can be hard to see the spark in daylight sometimes - and even then what do you judge it against. It is harder for a spark to jump a cold plug but you'd be unlucky to have an ignition system just good enough to run hot but failing when cold. A new plug, iridium or not, should help if things are marginal but it'll soon carbon up again.

Having said that I thought the main advantage of iridium plugs was that they're used as fit and (almost) forget items in cars as the tips don't erode like normal copper ones. I wouldn't have thought you'd see much cold starting advantage over a new ordinary plug - not until you'd done 50k on it anyway.

Back in the stone age there were a number of things we'd do if the ignition system was marginal - firstly close the plug gap down (to somewhere around 20 thou / 0.5mm (or even less if things were desperate)). That saved a few thousand volts and would often fire up a fouled plug two stroke. I've never needed to do it on a CDI system though.

Second, take the plug out and (after cleaning it) wipe some pencil lead on the electrodes. If you have a weak spark the graphite improves it (probably by burning but I'm not certain - this is folk wisdom, not science ) for a spark or two and may be enough to get things going. This has worked for me many times.

To check whether it's carb or spark take the plug out and tip a spoonful of neat fuel down the plug hole. Put the plug back in and try to start as normal - if it fires for a few seconds and dies it's probably a carb problem. If nothing happens it's probably ignition (or compression).

You could try using Easy Start (or the far better named Aussie version if you can get hold of it ) but a spoonful of petrol is cheaper.

Some say iridium make for easier starting. I have my doubts but for $20 and simple procedure Im happy to try.

Regarding cleaning... its of course good to have that option, but I try to keep a few extra spark plugs. I would prefer to fix what is causing the fouling rather than just cleaning them. But again, you never know when you get a spark plug and have no extras

I spent a long time trying to sort out a poor cold kick starter (43F). A bunch of stuff I did made little difference.

Two things made a big difference though.
1. I finally gave up on my stubborn insistence that the glued up carb rubbers were OK and bought new ones. They were definitely not OK, they were leaking.
2. Shutting off the fuel just before getting home.

Number 2 actually sorted it, but I got so fed up with it that I very happily bought my mates 600E when it came up for sale.

Thanks.

How did you come to the conclusion that you actually needed to change the carb rubbers?

I will try to shut the gas. But again, my problem is somewhere around spark plug fouling. A new spark plug and the bike works more or less as wanted (maybe still a little hard to start sometimes, until it fouls again...

Did you figure out the problem?

Thanks for asking. Not really. But I went on a ~3500km trip and brought 5 spark plugs. I actually didn't have to change a single one...

However during my 20k+ km trip I changed 4 (I think) and during the recent 3500km trip the bike used 0,5l oil and smoked a lot during cold starts so something is definitely not right.

One strange detail I noticed was that one cold morning (almost 0 degrees C) I couldn't see any smoke at all when I started. Usually it comes instantaneously or after a few seconds. I later started other cold mornings with smoke. I thought it might be related to oil levels (too much oil leads to "overflow" or something), but I got smoke other mornings after that (and no oil refill). The only "unique" thing about the morning without smoke was that I had first ridden all day, then left it cold, then started it again during the afternoon (with smoke) and just riding it shortly (2km?) before it rested for the night (and the subsequent morning was the one without smoke). This indicated that maybe the engine needs to get really hot and then cool down in order to cause subsequent smoke.

Another reflection is that since the smoke comes only after the bike has rested, maybe leaking from the valves is more likely than anything wrong in the cylinder. Leaking seals in the cylinder shouldn't build up oil during rest (I think?). Not sure though. I have been trying to get in touch with a mechanic who can help me. One mechanics instant reaction to one of my spark plug photos in this thread was "too rich fuel mix".

Neither of these is easy to do on a TTR600.

There is no battery (kick/bump start only and I never managed to do the latter with mine if only because of the high seat). Hence, the spark is directly generated from the kick - a weak kick gives a weak spark.
Yep, judging the spark while thrusting on the kick start is not easy.
A darkened room is helpful (for seeing the spark or lying down for a while after all that kicker effort).

The spark plug is very inaccessible; it is "buried" inside the horseshoe shape of the rocker cover and it needs a specialist spark plug spanner to shift it.
Maybe I had to remove the fuel tank; memory fades!

Also, the TTR600 doesn't have a cush drive; I think this changed with the TT600RE model "for softies" which introduced the electric button to the handle bars.

__________________
Dave