I have a 78 Honda CX500, and it is just beyond difficult to get running the first time on chilly mornings. I've drained the battery to the point of needing jumper cables from endless cranking before, and it takes the 6-8 tries on average in 45-50 degrees after sitting for 10-12 hours before itll sustain combustion. Usually it runs for a moment after cranking it and the moment gets a little longer after each try until it can finally support itself, so im not just sitting there mindlessly abusing the thing when there's some other problem that won't allow it to run, like no ignition spark.

A few places I read online claim that the main cause of these difficulties is the lowered temperature of the gasoline and the carb components... stuff that dictates how well the gas can evaporate. If this is the case, could I help the situation by somehow pre-heating the gasoline after it leaves the tank and before it reaches the carbs?
I was thinking I could build a small chamber (1" diameter by 3" long ish) with fittings on each end to attach it to the fuel line, a built in heating element+thermostat that runs off the bike's electrical system, and a switch to turn it off after the engine is running fine. I don't have a concrete idea right now of the parts/materials for such a thing, but suppose it was effective enough to quickly bring that small volume of gas up to 85 F right before going into the carb... Would this actually help or would it just be a waste of time? Would I also need a way to pre-heat the carbs themselves? I found a few sites selling block/oil pan heaters, but these plug into 120v power and they seem to be more for preserving your engine by getting the oil ready to do its job before it actually has to.

Any other ideas that might work better than mine are welcome. I'm just looking for concepts right now, and hopefully DIY will have some helpful input on how best to built it.

thanks
-Jon

Choke + push start?

Is your bike jetted right?
Mixing fuel and a heater is just asking for trouble.

Try new spark plugs, and make sure the air filter/s is/are clean.

Grab a can of carb cleaner and just use that with choke to get it going.

That will work great I had an old rickman 125 and that was the only way to get it running in cold weather.

That will work great I had an old rickman 125 and that was the only way to get it running in cold weather.

I got two bottles in my jetski, one in the front, one in the back. Why? Because the last thing I want is it to stall out on me two miles from shore.

thanks for the replies guys,

It has a choke and yes I have it all the way on when starting in the cold. I've also tried it in all different positions between off and on to see if it has a sweet spot, but full on seems to be the best.

i'm not sure if the jetting is all correct. It's an old fuckin bike, and during my ownership I've only had the carbs off it once, which was with a retired motorcycle mechanic who works on ppls bikes more as a hobby from his home. He cleaned em lightly but said they looked to be the correct sizes and didn't think any parts needed replacement, so I havn't messed with em since. My exhaust system has some holes rusted through it, could this be causing a lack of back pressure that might be a problem? I've heard if you replace your mufflers with straight pipes that you sometimes need to rejet. Anything there maybe?

I put new spark plugs in it less than 1000 miles ago, so I doubt that's the problem. And the air cleaner is clean and in good shape.

I'll try the starter fluid though. Should I just shoot it down the air intake? Do i need to spray it while cranking the starter, or just do a short burst before cranking, and the vapors coming off the air filter and stuff will be enough?

I'll try the starter fluid though. Should I just shoot it down the air intake? Do i need to spray it while cranking the starter, or just do a short burst before cranking, and the vapors coming off the air filter and stuff will be enough?

Both work. Right down the carb throat is best, though.

I got actual starter fluid instead of carb cleaner and it seems to be doing the trick... is there any advantage to either one? The starter fluid I got says it has an upper cylinder lubricant mixed in, I assume to keep the engine from destroying itself in the time its running when all laws of thermodynamics say it shouldn't be, and I doubt carb cleaner has that. So why use carb cleaner instead? I'm mostly just curious, cause I've used the stuff on small engines before for cleaning carbs, and upon starting it definately has the same type of effect, and this isn't the first place I've seen people mention using it.

anywho, thanks for the tip
-Jon

It works flawlessly on marine engines, which take a long time to warm up and get lubrication going. And it's been working fine for me for three years, so I guess it's personal preference. And carb cleaner is like 89c for a big can.

Starter fluid spray. Ether

Decompression lever if you dare.