250-500cc WXC360 Hard Cold Starting

So I mentioned in my build thread that I had fouled a plug on day 2 of my big bend trip. I wasn't shocked after going to a higher elevation (but without the cooler temps I anticipated) and spending much more time at lower revs. Before that plug, this bike has never had a plug problem. I've owned it 4+ years, and I changed the plug once simply because I figured it was time. Since I've been back, I've had a hell of a time starting the bike when it is cold. Once it has run for a couple minutes, I can start it on the first kick just like always. Bike seems to run fine once it is started, and I don't notice it being down on power.

Compression is 135, which is not as high as I've heard for this bike, but I would not imagine that is the hard starting problem. I didn't notice the spec in the manual, but I may have missed it. Not sure how many hours are on the top end, but I need to pull the jug to fix a small coolant seep at left front of base gasket so I'll get to see how things look anyway. I was not planning to replace anything, but who knows what I'll find. It does have the original TM carb, and it needs to be replaced simply from wear and bad previous owners -- someone rounded the end of the idle screw so that the slide will stick if you tried to up the idle rpm. Both screws on the top cover have been replaced with random hardware too. I've lived with it simply because the bike was always so easy to start and worked just fine everywhere else. PWK is eventually going on the bike, but I've been spendy lately, and I'm thinking I should wait on that.

Thoughts?

start at the most basic, assume the plug could be the problem, replace it
2nd, test cold start, when idling warm pull it on, this should cause bad idle or quit running

Def not the plug. That was my first thought, and it has been changed with same symptoms. Will test cold start next time I'm out there and see what happens. What is your thought on the compression? As I said, don't think that is the prob, but I'm curious what the ballpark is on the earlier 360. I'd expect the later bikes that end up with a decompression head are going to be higher.

135 seems on the low side to me.

it will run with lower compression just won't be "crisp" as in lack of high performance
the later compression seemed to be the port timing
exactly how do you start yours cold?

I'm running WR250 with a Lectron. My compression is right around 200 psi with a new piston. Before I fresheners up the top end I had about 185. Not sure what a 360 should have. Are you holding the throttle wide open when taking the taking the reading? It will read low if you don't

Yes, holding throttle open for reading. I did still have the air filter fitted, and I'm due to clean that after 14 or so hours of riding. I'll check compression again without the filter before I pull the jug.

The starting routine that has always worked is cold start on and crack throttle while kicking. Since I've had it that is the one-two kick routine. Starting hot is same except no cold start.

I agree about 135 seeming low. I want to say I was 240psi+ on my 250 KTM.

Btw, I found the receipt from a previous owner spending $600 with halls for a recon jug and new piston in '09. I've owned the bike for a while, but it was my spare for several years. No idea what kind of life it led before me. I'm thinking it is due for rings at the very least.

funny how you do your cold start, opening or cracking the throttle defeats the enticer circuit
best method, turn on fuel, put on gear, turn on enricher, kick SLOW 2-3 cycles, then kick, first time on pretty much anything including my 500's
dont confuse compression, at least what you have, with hard starting
all that said my 99 360 had a bad ignition, but the opposite of your problem, first kick cold, 50 kicks hot, ran hard but would stall right out of the blue when riding
will be interesting to see what really is causing this

Yeah, I know the cold start process I stumbled upon is completely odd, but I stumbled upon it while getting used to the kickstart on this bike. I was inadvertently cracking the throttle, and it just worked. I very much think I have a carb issue.

The only reason I mentioned the compression is that I was surprised how low it was. I would not have checked it if I wasn't planning to pull the jug.

I'm still running through the fuel from my trip. Maybe it will go back to normal with different fuel and the cleaned filter. If the rain holds off, I'm riding again Saturday morning, and I doubt I'll be able to do more than that before then.

my 360 with a fresh piston and running/starting strong had 165 psi. down 30 psi means you need to think about the topend..
250 bikes are higher is compression usually..

I concur if 165 is what I started with. I'll do another check when I clean the filter (hopefully tomorrow).

I have an update of sorts! I think I need to clean the carb. I went out to try 2premo's method, and nothing. I kicked and kicked. Then I remembered to check the plug wire...Still disconnected from checking compression. Once back on, it started on second kick. If I can kick it 20+ times and not have it flooded, fuel isn't getting in the cylinder when I'm first kicking.

Cold start when warm does make the idle rough so that seems to be richening the mix.

THIS GUY!

I had to give this method a go, and since I flubbed it last night, I did it this morning. Doing it exactly like you said, first kick. Thanks.

Aside from the screwed up idle screw, the funky screws in the top, and the reputation the carb has, I find it hard to convince myself that I should put the pwk on there. I know I want to, but I wonder if I should just find another TM and rejet it to match. I'd probably be happy keeping this carb with just a non-modified idle screw.

the TM got a bad rap, the older ones seem to work just fine, don't quote me on this as it's just my guess but it probably has to do with emissions in some odd country that has the carb used on a bike for daily transportation
that being said my 93 TM works flawlessly, when I had my 92 I was most pleased with it too
my 98 TM works well, not perfect but can be tuned, my 99 is a paper weight, I tried to tune it but gave up and replaced it with a Lectron
this is just personal experience,
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the tm started excellent on my 95...ran pretty well too. was an upgrade to switch to the lectron i felt, but the bike started 1-2 reliably with the tm set to factory jetting.