1975 250 HS Just Wont Start

[lancestrahl]

So I hadn't fired up the Penton in about a year due to getting distracted by Honda I was building (bad I know) but I had winterized it with Sta-bil and have been using non-ethanol gas.

I put in a new spark plug and disassembled and cleaned the carb, and the bike wouldn't fire. I put in all fresh gas as well.

I checked spark on the frame and on the engine fins, and its good. I made sure the float bowl was full and sprayed some starting ether in the air box and cylinder, still won't start.

I added a little gas to the cylinder, as the plug has been fairly dry, still won't start.

I've tried choke on and off, throttle on and off, and all combinations in between, and still won't start.

I'm at my wits end on this one. Compression is good, and kick is firm. Any help would be very appreciated!

Thanks
Lance

[Carl Hill]

Ok first give your can of ether to someone with a diesel truck. Next since you have fuel, compression, and spark you may want to pull the flywheel and make sure the key is not sheared.  The other thing that comes to mind, since it has been sitting is that the exhaust may be blocked. Hope this helps.

[wfopete]

Find a big hill and...

Pete Petrick
175 Jackpiner
Slow but Good

[Jason Rowland]

I'm not surprised...on a full-moon Friday the 13th with a Honda getting all the attention?

Sounds electrical: Spark under compression is quite different from free-air spark, so a plug swap could be the fix. Then I'd get rid of the  corrosion that just happens over the course of the changing of the seasons - all those old magnets need is one more ohm of resistance to overcome in order to throw the whole thing off. Might be worth checking the kill-switch for a partial fault, too.

Then, just for good measure, scold the Honda and put it in the corner...I'll bet your Penton fires right up.

[Dennis DeGonia]

Have you got the needle retainer in the carb on top of the needle?

[ALB]

A few years ago I had a Jackpiner with an Ace pipe that ran like a 250 (power wise). I would fire it up every other month to make sure that it was running OK and it would start 2nd or 3rd kick. One day after it was sitting for about 2 months it would not start.

Checked the pug - it had spark, compression was good. In checking the idle jet in the Bing, it was plugged up with crud that was like concrete. I replace the idle jet it fired right up. Good as new.

Alan Buehner

[lancestrahl]

Thanks Gentlemen,

I'll be trying a few of these suggestions tonight.

@Carl Hill - What would be the best way to get that fly wheel out without pulling the engine out of the frame, rather not have to do that if I can void it. I'll check the exhaust first, that shouldn't take too long.

@wfopete - Better plan than a pull start since I happen to have a big hill handy. I'll give that a go if it wont fire conventionally.

@Jason Rowland - The honda has been dually scolded and is under a cover now in time out. I have swapped between 3 different plugs, 2 NGK and one champion. One for eh NGk's was the one it was running with when I put it away. I did check out the kill switch as well, and id not find a fault, and ruled it out (possibly incorrectly) with free spark occurring. What would be the best way to check that and clean the magnets? Electrical is my weak point

@ALB- I went through the carb and soaked, then sprayed out all the needles and orifices when I cleaned it. The honda had a lot of jet issues, so I made sure they were free and clear on this one.

@ Dennis DeGonia -  I believe it is, but I'll check and reset it tonight. What position do you recommend?

Thanks again guys!

Lance

[chicagojerry]

lance. drop me an email at [email protected]    question though, what kind of carb? bing or mikuni?

[lancestrahl]

Hi Jerry, tried to send you an email at [email protected] but for some reason it bounced back.

Carb is a bing

[454MRW]

Unless Jerry changed it, I have his email address [email protected]

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Penton
1976 MC5 400
1978 KTM 78 GS6 250
L78-79 MX6 175-250 KTM's
1976-78 125-400 RM's
2007 CR125R Honda
1977 MC250 Maico
2017 KTM Freeride 250R

[Jason Rowland]

Hi, Lance - I'd say that the three-plug-swap probably rules out a bad plug.  Since you're getting free-air spark, you may in good shape as far as the ability to make spark.  A bit odd that the ether didn't pop at all. As Carl mentioned, whether or not your spark is happening at the right time could be the issue.

Cleaning the magnets will only make them pretty, it won't increase the flux density that decreases slowly over time, or quickly with sharp blows.  Weak magnets means they can't induce much voltage or current in the coil and you'll have weak spark, especially at kicking rpm.  That big hill is waiting....JR

[chicagojerry]

oops. i gave my email wrong in that earlier post. mike winter had it right...   how's it coming?
chi jer

[Richard Colahan]

You don't get the flywheel "out"...you get it "off"...off the end of the crankshaft using a puller.
If the woodruff key has sheared the flywheel has spun on the crank end.
It can still generate a nice fat spark.
But that spark will be happening at a time when the piston is not in it's desirable position before top-dead-center compressing the atomized fuel/air mixture.
Result? Nada...
Fuel, air, spark, nothing...
Cause it's firing WAY out of time.

Richard Colahan
1969 V1225
Upper Black Eddy PA