TTR 600 hard to start but runs well
 

A year ago I bought a TTR 600 2001. I hadnt touched a bike before so Im no expert. It had done 27 000 km. I had issues starting it from the start and sometimes I had to kick it for maybe 30 min before it started. While running it was fine. Never a problem to start it when hot/recently used.

I went on a 20 000 km trip :scooter: and the same characteristics continued, but since I rode the bike every day it usually started "ok". Sometimes I started the day sweaty from kicking and if it stopped before getting hot I needed to let it rest or get someone to push-start (yes, a PITA but I managed). After about 10 000 km it wouldnt start, the plug was fouled and a new plug fixed it. At that time I was on 3k+ altitude and soon I had to change plug again. Then once more. So 3 changes in a short time. After that I was on lower altitude and it lasted the remaining maybe 5000 km.

After getting home it rested for a few months. Then it was hard to start but again.. after 30 min it did. After a bit more it wouldnt start. Another spark plug change and it started well. I hardly drove it and after a week I tried again and it was hard to start again... (i.e. I had bike on for maybe 10 min with new spark plug, left it for a week then hard to start. So potential oil leaks should not have had time to foul plug?).

Spark plugs have always looked the same when fouled. Sooty, like pictures shown for "too rich mixture". I attach a photo of it.

I dont think that the carb is dirty. It was cleaned (it didnt look dirty) once during all this and nothing changed. During that cleaning I also got help to "lean" the mix by a half or one turn (cant remember for sure). I didnt notice any change.

Easy answer would be "too rich" and maybe it is. But shouldnt a "too rich" mix be easy to start with a spark plug that ran for ~10 min? Although the fouling looks like rich mix, it doesnt make sense to me that an almost new plug is hard to start cold due to rich mix (because then it wants richer mix?).

Attaching photo of latest fouled spark plug.

Also, I got help checking valves by some mechanic who seemed a bit sloppy. He did change 1 or 2 of the valves which were out of spec, but the bike didnt behave any different after that.


Any ideas? :(

Does the motor use oil ? It looks more like oil fouled than fuel fouled. You are fully correct, if it was over rich in gas, it would actually be opposite in hard starting issue, easier to start cold, but hard to start once hot. I had one messed up carb that made the bike miss and run real bad, any hard throttle and black smoke blew out the exhaust, still the plug never fouled, it takes a lot of gas to do that, enough to be very bad running at all times that you would have noticed.

You need to check the spark condition, is it a sharp, big blue spark or tiny weak orange. Then a compression check and leak down test to see where any comp loss is from. Valve clearance should also be verified correct if any concerns about previous work.

I suspect weak spark topped with some oil burning. Ignition coil may be weak or a poor grounding of the motor. Can you get an Iradium plug to try? I use Denso IX24B , splug fouling issues and weak spark is where iradium plugs are a big help , otherwise not a real benifit for the cost.


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It does use some oil. It has since purchase (used). Maybe 2-3dl on an 800km trip. Fuel consumption seems unchanged for 20 000km+ but I havent done any serious testing.

If its not black from gas I guess it has to be oil (the fouling doesnt seem "oily" though). However I dont look forward to all the job and money (in relation to the total value of the bike) that I probably have to put in to test compression, find problem and then fix cylinder if its broken. Feeling a little disheartened to be honest jeiger Leaving it at a shop for fixing would probably cost as much as I could sell it for.

I will check the spark again, but Im pretty sure its ok.

Thanks a lot for your help!

EDIT:
btw since I got home it started puffing out white smoke when I start it. It goes away after maybe 15 seconds of enginge running. I heard it could be ok and climate has been cold, but ofc it could be related to this (oil seeping into cylinder while bike rests?)

That would be a sign of a bad valve seal, oil leaks down into cylinder when cooling down. The smoke should be blueish, white smoke is water and unless your dumping gas in the pipe it shouldn't be that. Excess burning fuel is black smoke. I'd say it is from that seal, just enough oil is fouling the plug, but I wouldn't doubt if the sparks a bit weak also to foul that easily plus the hard starting, I've seen a plug that was a ball of sludge yet still the motor ran (smoked like hell though).

An Iradium should cure it as it is for now to get by.

Pull the plug and spin it over to have a quick look at the spark.

I will def check the plug spark and try iridium plug. Im planning on buying some other spare parts so I might throw in a valve seal or two just in case.

I have not noticed any blue smoke but I havent specifically looked for it either.

Thanks again!

Update. Today I went for the year's first longer ride. Total about 2-3hours.

Bike started after ~10 kicks with the "new" plug that had only been run twice shortly.

As usual nowadays white smoke. I was outside and it was a little windy, but I could only see white (i.e. not blue) smoke.

After running the bike for a while I stopped for ~20 min. After that started first kick.

Rode some more. Stopped for ~2h. It started after ~3-4 kicks.

Rode home and checked spark plug again (first time I check without having problems).

See spark plug in attached photo (slightly white on tip. Some black soot near threads.

The smoking only occured right after first start of the day, after resting a week.

Amateur diagnosis:

Hard to start + a little white spark plug = Slightly lean mix (I did lean it out a little a while ago).

Last 4 spark plugs were fouled pretty quick and they were very black (see prev photo). Also white (not really blue) smoke when I start after ~1week rest). I guess this could be oil burning. But the black is really more like soot than oily. Not especially wet, although I could quite easily get it off with my thumb.

Would anyone make a different diagnosis? Maybe the plug doesnt look so bad..? It could ofc just be bad valve clearances or leaking valves/piston ring. Or even weak spark. I checked spark on plug but didnt see. Its a little tricky to do alone though, so probably just me doing a bad test.

I ordered iridium spark plug Monday this week but it didnt arrive yet... I also bought shims to test valves. Have not invested in a compression tester... Might do that if other things wont solve.

Have you checked if the bike is overfilled with oil? That and worn valve stem seals cause white-ish/light blue smoke on startup.

Kicking a bike over is pure technique, I have a frined that can start just about every bike in 2 kicks or less. He has always been riding kickers, so he has it down to an artform.

Thanks for you reply!

When cold the oil is below inspection window. When warm it just just at the top (i.e. moving a lot, maybe a little much but only very slightly). Before I have had too little oil also. Same smoke from what I can remember.

About kicking... yes its a technique. But since sometimes I try for 30 minutes until my leg/ankle hurts (cold/bad spark/whatever) and sometimes it starts on first try (hot), doesnt it seem reasonable that its more related to the bike than me? :scooter:

I needed to give my bike a few kicks with no ignition on, then turn key, turn on choke, and give it a good kick or two. Just trying to start it would result in same frustrations as you. Also it helped a lot to run the carb dry-ish, so i closed the petcock a few hundred meters before i came home.

So for me it was:

Turn gas on
Give it a few kicks
Ignition on
Choke on
Kick
Usually rev the bike slightly when it catches on, just like a 2-stroke

Each bike seems a little different, this worked for me and my xt350 when cold. Warm seamed just about normal, just kicking it.

Ive got a TT600R too. When i first got it, it would take 5-10 kicks to start. I had a 10.000 km service done at a Yamaha dealer, and the valve adjustment made all the difference. Now it starts in 2 kicks cold and 1 kick hot. Cold for my bike is when the oil temp drops to about 40-50 degrees.

I had it winter-stored for 3 months and it started in the 5th or 6th kick. Remember, that current is stored in the CDI capacitator and provided to the spark plug, so if its stored for a while, then the first couple of kicks is to "fill" the capacitator with current.

Note that mine also has some very light white smoke at start-up, but only when its very cold. Its probably condensation while the exhaust heats up. The smoke is so light its only visible at night in the glow of the tail light.

Do you remember to turn off your lights when starting it? With no battery, the lights take too much of the current away from the spark plug. It makes alot of difference in starting it. Even holding down the front brake (brake taillight), can cause it to be hard to start.

Also, do you remember to turn your fuel petcock off when parking it? The TT600R doesnt like a open fuel petcock when parked, even for a short while. Mine also refuses to start, if i turn the gas grip to rev it at start up. It totally drowns out.

So the procedure for me is as follows:

Lights off, and hands away from the gas and brakes
Find top dead center
choke on
fuel on
kick

My most important advice though, is to get the valves serviced by someone who knows what theyre doing, eventually spending some cash at the Yamaha dealer to make sure.

Here is my TT: https://youtu.be/C_LfJv6WrW8

Amen to that.

I learnt all of that with my TTR600 via the "difficult route" of trial and error including a broken automatic decompression cable.
Kicking on TDC is highly important; so is all the other advice above.

I've had similar issues with an XR600 Honda - sometimes hard to start cold but almost never when hot. Years of err ... analysis taught me two things :

1. If the bike is left for more than a few days the fuel in the carburettor deteriorates - the most volatile part evaporates and whats left won't atomise in the airflow. It can then take hours to start on the kickstart. Undo the float chamber drain screw, let 30-50ml or so of fuel drain through and try again.

2. Cold starting technique. I don't know the specifics for a TTR but with the XR it was - turn fuel on, choke on and "dry kick" (pull the decompressor in) 3-4 times. Then find compression stroke and(using decompressor) just ease piston past top dead centre. Then full power long swinging kick (not some wimpy two stroke thing) keeping the throttle shut. If it doesn't start go back to the finding compression stroke bit and try again. Most important - don't touch the throttle until it fires.

If it doesn't start the second time, turn the fuel / choke off, open the throttle fully, pull in the decompressor and kick the engine over 4-5 times (easy with decompressor in) to clear out unburnt fuel. Then back the start and try again.
I very rarely had to go round that circle more than twice if I followed all the stages exactly . You must put some effort and weight behind the kick to get the engine turning over quickly. Get that wrong or don't follow the procedure exactly and it'll never go. I once had a friend ask me to try the XR. I told him if he could start it he could have the bike. Ten mins later he gave up. I followed the above instructions and it started first time.

All of that presupposes there's nothing wrong with the bike - valve clearances, plug, ignition and all the other stuff but if it starts /runs fine hot it sounds like there isn't much wrong.

Thanks a lot for all the advise guys!

I have read a lot about starting procedures and I started my bike several times every day during my 3 months journey :) Sometimes even with a more or less fouled spark plug.

That doesnt mean my technique is perfect of course, but I dont think its my kicking. Just the other day, for example, I couldnt start it. Checked spark plug, which was black (first post). Changed spark plug and it started first or second kick.

Ive had friends try to kick start my bike and its obvious they dont have the force needed (just like I probably did before having kicked this f*cking bike a million times :D). Again, Im no expert but I know how to kick that lever down :)

The only thing Im not doing from what you all said is turning off the fuel. It makes no sense to me that gasoline would be "old" after a week in the carburator. But I will try both turning the gas off and emptying the carb.

Im often worried I will break the kicker, but I will start experimenting with really giving the kick full force. Its not that I dont push hard already, but I think I can give it a little more and if it breaks I guess at least I know Im kicking hard enough..!

The valve clearance part was good to hear. As said I did have them checked (by so-so mechanic) and it didnt change anything. But I will try to find time to do the valve clearance check, now that I recently bought the tools as well.

I will also try the closing of fuel and let it run dry. Of course also the iridium plug, when it arrives.

Technique and old fuel might play a part, but there must be something more considering the spark plug fouling. Maybe the valve clearances. Lets hope so! :)

Thanks again for all advise! Always helpful to get others' perspective.

For this aspect, in my view, it is all about the "length" of the kick and not solely the amount of force applied.
I mean that when you are tired it is quite easy to not fully follow the action of your kick right to the end of the stroke of the kickstart - it is the latter which turns over the piston of course through the firing sequence of the 4 stroke cycle (hence TDC is essential).
Happy days, not.

When stopping at the end of a days' riding my technique was to turn off the tap and let the bike idle until it died thereby clearing the carb completely of fuel; I still do this for my XT225 because of the issues about modern fuels.

For stopping "momentarily" I tended to run off a bit of fuel from the carb after closing the tap and then kill the engine - this was a kind of superstition I suppose, based on the above and a feeling that the heat of the air cooled engine could evaporate fuel from the carb very quickly, .....................perhaps, maybe?

I do the same , as I'm pulling into my driveway or parking lot, I reach down and shut the valve off to get rid of most fuel in the carb.



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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 :smartass:) 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 :rofl:) 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.