45 engine start up

[Streetbobber74]

hello , got a WL having trouble keeping it running, need some help. it will fire up fine for about 3-5 seconds then idle goes very high and then engine cuts right out. wondering if this sounds familiar to anyone, just seems like it doesn't get a consistent flow of gas or something. hoping its just something I'm doing wrong. any thoughts
thanks

[Lloyd]

ST Make sure it is getting fuel first, if it is may be the float is stuck, What carb? Fuel filter? Bad petcock???? Lloyd

[Ohio-Rider]

If the fuel seems to be ok, check for a leaking manifold.

[rdillon]

Ran into this very thing one time on a newly rebuilt engine. The rubber sleeve fuel line seal had gotten out of place on assembly and was partially blocking the flow into the fuel strainer on the Linkert carb. It would get just enough fuel to hit. Would rest for a few minutes and kick again, problem would repeat. Just took some looking......

[diesel55]

hello make sure the gas cap is vented. the best

[Rod K]

If your motor is starving for gas, sometimes it will speed up just as it dies. Another thing to check is the gas shut off rod on the tank. Try setting it on reserve by pulling it up. If it is a repro unit they can cause problems because of alignment of the rod and the seat...Rod

[Sargehere]

Recheck that it's timed on the front piston on compression; with the small lobe of the cam breaking the points. Takes only a couple of minutes. Harley Flatheads will run 180º out-of-time, but really weird, rear cylinder every time, front cylinder every other time, when you do get um to run. Makes you pull your hair out 'til you find it.

[sirhrmechanic]

The 'speeds up' just before it dies is classic sign of fuel starvation. It's leaning out as the fuel runs out. The advice above about checking flow, fuel cap, float (and float needle), etc. I think is right on.

If there is an obstruction, fuel will trickle down into the float bowl when the bike isn't running, giving the appearance that all is good. Then when run, the engine drains the float bowl faster than fuel can flow in. As the float bowl gets dry, the engine gets artificially lean, thus runs faster as it dies.

Other things to look for are crimped lines, solder that has gotten into lines at joints, sealer at joints, etc. The 'flow' from the tank to the carb inlet (or out of the carb with the bowl off) should be a gush, not a weak trickle. That's the first thing I would check.

Sargehere... I never knew that it would run 180 out... I'll file that away in the memory banks because that's a great tip!

Cheers,

Sirhr

[JohnR]

Fuel filters. Especially inline style. (in the fuel line)

[len dowe]

Recheck that it's timed on the front piston on compression; with the small lobe of the cam breaking the points. Takes only a couple of minutes. Harley Flatheads will run 180º out-of-time, but really weird, rear cylinder every time, front cylinder every other time, when you do get um to run. Makes you pull your hair out 'til you find it.

Sargehere is right on. Learned this the hard way.

[Streetbobber74]

thanks everyone for all the info and advise, so thankful to have you guys and this site as a resource. I've got a lot of learning to do. thanks again