Home Forums Hunting & Shooting Hunter's Campfire Cold-Blooded Motorcycle Question

Picked up a small 125 for myself and the oldest to ride and use.
Nice bike. Runs real well except that it is fairly cold-blooded.

What is it exactly that causes this and what can I do to try and resolve it?

As it stands now, my daughter would most likely not be able to get this bike started and keep it going on her own.

Lots of variables.

First thing to do would be to make SURE it is running ethanol-free gasoline!

Once you run a tank or two of real gas through it we can address other issues, if any still exist.

Check to see if the spark plug is the proper heat range. A hotter plug might be a simple fix.

Hard to say, without knowing what it is. Most times, they are set really lean to please the epa. I would do an idle drop adjustment (low speed mixture adjustment) and fatten it up a bit on the idle circuit.

That no good p husking ethanol gas ruins more stuff.

What year is it? Did it sit for a long time. Is the tank rusty?

run some sea foam through it, change the plug, check the air cleaner filter. thats the usual stuff. if it needs a lot of choke to run then it is probably a gummed up carb.

2 or 4 stroke? Do you mix the gas or is it oil injected?

When an engine is cold the fuel will tend to stick to the metal of the intake tract. Not as much/ not enough gets to the combustion chamber so it doesn't run right. It's too lean. That's why a choke is needed. As the metal heats up not much fuel sticks so the problem goes away.

As previously mentioned it sounds like you're carburetor is too lean at idle.

You could try solvent to clear junk away in the idle circuit. The very tiny passages get gunked up easily, especially with ethanol in fuel. You could try adjustment to richen it up, you could change the idle jet if all is clear already.

It won't get better on it's own. If you park it for a while it will likely get worse.

Buy one with EFI.

Mostly good advice here, but the first thing I would do is take the carb apart and give it a good cleaning. Make sure the float level is correct. This will get you back to stock and then you can decide if there is an inherent problem or it just needed maintenance.

A lot of small engines are set really lean for emissions. Usually not to hard to improve if you do your homework.

Jerry

It's too lean . My wife's Yamaha 125 is the same way but manageable. My KLR is the worst bike I have ever had in this regard but my XR 400 ran a close second until I replaced the carburetor (if you own an XR400 and have not installed the XR's only kit, you are suffering needlessly).
I don't know what carburetor your bike has but, whatever it is, it probably needs to go up a size on the idle jet.
EFI is a goodsystem in many ways but I'm still not convinced. Poor throttle response, surging, and the feeling that the throttle is connected to a rubber band are all reasons to prefer a well carbureted bike. I like my 650 V-Strom in many ways and the EFI is pretty decent but with all of the problems I mentioned. Rode a friend's Yamaha 250 dual purpose bike and found it's injection system to be very good with few response issues. Hard to argue with it.

My last bike was a Honda V65 Sabre. It was very cold blooded . Would not start below 50 degrees
Come to find out I do not like riding below 60 degrees. Never had an issue!

Appreciate it guys. I am no mechanic, as if you didn't already know that. I will ask my mechanic about upsizing the idle jet and I will run some seafoam through as well.

Doesn't necessarily mean it has to be cold out. Just sitting for a while and it takes some patience to get it going.

Seafoam is good stuff but the main thing it does is counteract SOME of the damage ethanol causes. Keep that stuff (ethanol gas) away from your small engines!