tracking down an air leak

[mcolburn]

Hello,  I am new to this list , although I have been reading your posts for sometime now.  I have wanted a Penton for a long time and reading all your posts just made it worse.  My father used to have a green (sachs)125 that he rode in the Flint Hills and Chadwick enduros back in the early 70's. He rode for fun, and said you were lucky to finish, let alone place.   Even though I remember him coming home looking all banged up,  the bike looked great.  He eventually sold it and quit riding , but I knew eventually I would buy one  as he said it was one of the best bikes he ever had .  Finally, I  bought a 73 Jackpiner recently  from the original owner and it is close to stock.  Since then, I have rebuilt the forks , replaced tires, cleaned and rebuilt carb and air filter , and changed fluids and plug.  This bike has nice compression and starts on first or second kick, but it will run a bit and eventually rev to the moon as I have seen some others on this list describe.  I replaced the mag side seal, even though it wasn't seeping .  I am going to retorque the head once I warm the bike back up.  There is an oil seep behind the sprocket, is there a seal there that could suck air?  The only other oil seep is where the clutch fork is attached to the mag side case.  Someone has even gone as far as putting clear RTV around it.  I don't know if these are of any significance, but  I don't know where else to check.  My slide on the carb is a little worn, but I don't think that would be my problem.  It doesn't stick or anything and everything in my carb is in correct order.  I am worried there may be a seal or seals on the primary side that need tending to , but  that area looks like a nightmare to get into.  Any ideas where to look?  Thanks, Matt

[Larry Perkins]

Take some water with a little dish soap in it and put it in a sprayer.  Spray liberally around the cylinder base and the carb and intake boots.  Your leak is probably there and it will bubble and show you the spot.

Larry

[mcolburn]

I appreciate the advice Larry.  I will try the soap trick as soon as I can.   Matt

[tmc3c]

Hey Matt, I also had that problem and my bike would rev to thr moon and then die.I am not sure if it was just the slide or a problem with my gas cap not venting right. I changed both and it runs fine now . This might not be anywhere close to your problem but until another fellow rider headed me off who knows I could still be hunting.Just another thought,hope you don't mind.

Thomas Carmichael

[mcolburn]

No Thomas, I don't mind at all.  Thanks for the insight.   I  read your  post awhile back and wondered what finally fixed yours from the problem.  I didn't know yours would rev up and then die.  Mine just revs up and keeps going, and I think it would go till the tank is empty if it had the chance.  It has only done it twice .  The first time I pushed the kill switch and it didn't even act like it was going to stop, so I panicked fearing engine damage and just grabbed the plug wire.  I  can assure you that my magneto works real well,  Ouch!  Now I have a small string attached just in case it acts up.  I am going to replace the slide as it does look worn.  My air screw and idle adjustment screw on this bing 84 do not respond much if  at all.  It takes large adjustments to make a difference.  The only way I can get it to idle / run is with the choke approx. half way open.

[tmc3c]

Matt, I also hit the kill switch but other times it would just die which I belive the gas cap was the problem.I removed my choke altogether and put a small bolt and nut in the top of the carb with silicone around the bolt.My large air screw doesn't do much good either.Stay with Matt and it will come together and it will be worth it all !!

Thomas Carmichael

[Rain Man]

Hi matt and welcome to the Penton Owners group:)  
   revving to the moon is caused by a lot of different problems!  The throttle cable may have a kink in it.  The carburetor slide may be freezing in the bore. You could have a crank shaft seal air leak.  
    To correct this over revving problem, you need to eliminate the potential for  problems:    IE:    the frayed throttle cable, the high float level in the carb, the leaking seals and loose bolts on the carburetor intakes. to high an idle adjustment screw on the slide  Good luck and, most of all have fun!!

Raymond
Limington Me.

[ehletra]

Hi Matt I have a 125 that would do the same thing. I did everything people told me to do and it still did it. well it turned out I used senthedic 2 cyle oil in sted of the cheap stuff so it did what your bike  does. so I draned out the gas and put new mixed with the cheep oil and it started and ran like uasule I hope this helps!!
Travis

[mcolburn]

I suppose I could try a different oil than I am currently using.  Right now,  I have been using Opti 2.  I will have to check, but I don't think it is a synthetic.  What brand of oil and ratio are you using Travis?

[ehletra]

I run 20 to 1 in it. Im not sure if its right but the guy who had it befour me had it set to that. make sure when you get the gas it isent the ethonal because it doesent help any thing. I use citgo  2 cyle oil its called it works good and its cheep! I hope you get your bike going.
Travis