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Hi, first post on here. I've been a 2 stroke rider since I was little kid and now that I'm almost 43 I figured it was time to catch up a little with the newer bikes.

I still have my 03' KX250 but just purchased a 2009 CRF450r and I'm having the time of my life trying to get this thing to cold start properly, and by cold start I just mean when it's been sitting. This bike runs perfect when running and starts like nothing when warm... but, only way to get it started is to 1) put a little gas in the cylinder, or 2) dampen a shop rag with gas and toss it by the filter.
Any insight into this issue is highly appreciated, thanks.

Things I have done so far:

-Adjusted valves, they were barely out of spec,
-Leak down test, not leaking 1psi at 100lbs
-compression test just because, perfect with manual @78psi with auto decomoressor still intact
-fuel pump has 50psi and holds over 40psi even after 30mins, although I don't have a hookup to check while still attached to the injector.
-cleaned the injector and checked while hooked up it is spraying fuel
-checked the TPS with power supply, it's perfect with manual
- changed the ETS cause was out of spec
-changed IAT sensor, just because
-cleaned all plug-ins and added Dielectric grease
-checked coil and stator
-changed the plug cap cause was spotty on resistance
- new spark Plug
-new air filer
-changed oil and filter and gear oil
-cleaned the MAP sensor
-New fuel filter

I'm sure there's more I'm forgetting but I'm at a loss here. I know (think) it's a fuel problem, but what after all I did and checked. Can this be the a ECU MAP issue, not being rich enough when cold? Don't want to spend $150 to send to Tokyo Mods for nothing, or buy a new injector for nothing either. Maybe I just suck at starting it.. idk. But if that was the case I hate to see what this will do when it's 20 degrees outside. I can't start it when it's been between 75 and 90 degrees out.. I just wanna ride it already more than a few mins after tearing the bike down to get it started.

Thanks all!! Hopefully I posted in correct place here since I'm new on the forums.

Welcome to the site !!

You did not mention this , so follow this procedure on starting and then report back if it starts cold , even if it is 80 degrees use this procedure for first start of the day or after sitting for several hours .... if not then you should look into the valves .... usually if the valves are bad enough for it to be hard to start it will pop , pop , pop , pop , at higher RPM when you let off (backfire thru the muffler)

Okay so.. I did that starting procedure per manual, and many others I have read.

Here is what I have figured out now that I been racking my brain on this thing. It's just plain old not getting enough fuel to start and that's it I think even tho the fuel pump and injector is fine.

If I turn the idle screw down (to right) four clicks then pull the fast idle it fires right up. Then I have to turn the idle back up before I turn the fast idle off or it will stall out. This I'm pretty sure is enriching the fuel / air mixture which goes along with why it will start right up if I put a little gas in the cylinder or put a gas soaked shop rag by the air filter.

Once running even for a few seconds it will run perfect and start right up unassisted.

Is it possible that someone screwed with the programmed mapping and now when it's cold it don't get enough fuel in the 0-2000 rpm range, then hot it runs perfect, strong as hell actually.

I would imagine if the MAP sensor was bad it would still start and would throw a MIL code? I can't check the voltage per my altitude on the MAP sensor cause I don't have a handheld diagnostic tool to do so per manual.

I have an appt at the dealer on Nov 2 to get it plugged in and stuff (for $110) but unless they find something faulty, I not sure they can load only stock MAP back on the ECU. In that case it won't be adjusted for the pro circuit exhaust system.. or can they adjust for that?

So damn frustrating.

You should not have to re-map for the pipe , I went from stock to full Titanium Yosh system on my 20 and just bolted on the pipe and rode ... no issues , no lean condition ... Hopefully Leardriver will chime in , or you could try PMing him and see if he has a fuel related answer , as I would think the system would detect altitude/air density and adjust the mapping or fuel mixture to compensate

Here is Leardriver's contact , just go to PM: Send Private Message , as he is the resident intake/fuel system guy

https://www.crfsonly.com/forum/memberli ... le&u=14707

I am thinking maybe a weak injector , it will still work , but at lower RPM' it won't have the pressure , same might be for the fuel pump ... the fact that you are adding fuel and it works fine , is saying it is most likely a fuel system issue rather than a electrical issue ...

Yes I agree, it's most definetly a fuel issue. It's just so strange though, if I screw with the idle and the fast idle four clicks up or down, idle knob in/out it will start. Just plain old pull knob and kick... nothing. Just flooded it seems, which makes no sense at all since if I put a teaspoon of gas in the cylinder it started right up.

So I took the injector out again, put over 50 psi to it and no leak. If I hook it to the power supply at 12V and at 1/2 Amp. It opens and closes fine. I sprayed cleaner thru both ways, I just don't get what the issue is. I just rode it today for 4 hours, ran perfect like a freaking powerhouse, thing has some power, I love it. Just need it to cold start easy lol.

I will PM the LeadDriver, hopefully someone will say yes I seen this before without paying a garage $100's to diagnose it. I have about 20 hours into this thing tearing it down and putting it back together again, checking resistance, replacing sensors, ETC. I wonder if the MAP sensor is bad cause when I got it, it did have some filter goo on the back side of the butterfly. Maybe it has . in it idk. It's not coding on the MIL plus don't know if that would even cause it to not start at all. I figure that would just be like a wrong jet size, would just be bit lean or rich.

Thank you, I appreciate the reply JimDirt.

No problem for what little help I gave , but yea , contact Leardriver , as he is the resident intake expert here , and if anyone has a answer or a direction for you to investigate , it is him ... , keep us posted on your progress , that way if someone else has the same issue there is a reference to go by ... I just have not messed with EFI enough to point you clearly in the right direction , and don't want to waste your time trying this and that , but Leardriver has , so he should be able to guide you into resolution of this problem

Okay I sent him a PM, I will keep this updated for sure, I see allot of posts that aren't and that helps absolutely nothing.

I think I need to figure out how to energize the system with a 12V ans try starting it with full fuel pressure to say its a pump problem but I can't seen to find anywhere on where to hook in a battery without using the hookup from Honda which is not cheap I'm guessing. I seen somewhere to unplug the condensor and hook it in there but I don't want to fry the ECU if that's not correct. If anyone knows where to find that info while I'm waiting on a reply from leardriver that would be great.