As anyone who rides a penton with the Sachs motors knows it has a specific and high rpm power band. Having said that, typically when the rpm drops way down and just before you have down shifted, the engine sound gives the typical bogged down performance and sound as with any bike. On my penton 125, not only does it show the bogged down feel, it gives the appearance as if the spark also begins to cut out and so longer time to clear it out before getting going again. The ignition with the old motoplat performed this way as well as with the new MZB ignition system. Keep in mind, that when the rpm is up, both systems are per formant. This situation is a problem when you get in a mud hole....?
I have not yet installed special spark plugs with the fine tip used with the MZB system yet. I had to order them special for the new MZB ignition system.
I have the 2.73 jet needle and the needle is new along with the float and float adjustment. Ignition timing problem is ruled out since it
was checked and cross check by using 2 different ignition systems.
Any adjustment comments would be grateful.
peter klinck
Another thing to clarify, when it is "loaded up" as I mentioned above, that could mean a momentarily wet plug for as giving too much throttle when it is bogged down in attempts to get the rpm back up. Is there are carb. or plug adjustment recommendation?
peter klinck
You might check the choke plunger and see it it still has the wax / rubber bottom on it. Another idea is the slow jet size. Might also check the needle jet for wear. Drop your new needle into the carb from thew top and hold up to bright light. Try and see around the needle from the bottom. If this is worn it usually wears oblong. Ted
Ted,
Thanks for the comments. Yes, I bought an NOS choke plunger (for 2 125s)and noticed today that in one bike that wax seal was and is not there anymore. I'll check the race bike plunger and maybe order more new plungers from Bing Int'l because both my 1973 pentons 125s have the same problem.
Secondly, could you give me an example of a "slower jet size"? My pilot jet is a 45, the needle jet is a 2.73 purchased with a relatively new needle in 2011.
peter klinck
Peter,
Those little Sachs engines have a lot of usable power below the "hit", and in my opinion finding and using that power is one of the joys, and challenges, of riding a small bore machine. That is also why I chose a 125cc KTM EXC over the 200cc version as my "modern ride".
That being said, if I were in your shoes and were able to lower the needle, I would drop it a notch, or even two, and see if you notice a difference. If you notice a difference and the engine is running cleaner, you know you are looking in the right area and can start to fine tune the carb.
I also want to mention that when looking for that low end power, I have always felt that it is important to coordinate the slide opening with the engine RPM with the use of the throttle. If you are pulling up a grade and the engine is pulling hard, and you know you can't pick up much speed or RPM, try to have the slide positioned just a little more open than needed, not wide open, and work the throttle just a tad. To often a lower gear is engaged to soon and while engine RPM is gained, often all you get is wheel spin.
Hope this helps.
Paul
Peter,
I agree it's best to buy the new choke plungers directly from Bing Intl. as I recently did. I learned a hard lesson by buying a NOS plunger from a seller on eBay thinking it would save me a few $$. As it turned out, the eBay plunger was no good and fell apart as soon as the fuel got to it. I notified the eBay seller and they sent me a couple more at no cost but they were badly degraded due to age and were unuseable. In the end, the cost of buying a new plunger from Bing was $14.83 shipped which was approx the same as what I paid the eBay seller for one that turned out to be no good. From now on I'll only get them from Bing. The Bing part number is 22-935-05 and they describe it as a "start piston". Good luck !!
Dave McCullough
Paul, Greetings.
Yeh, a same bore motor like the sachs engine is what I have also like about them is that specific power band, how to stay in in and work around it. It takes more skill and this challenge is always what drives me.
POINT: So you suggest to "lower the mail needle one notch" to be leaner to confirm. Secondly, because of so many adjustments in rebuilding a bike, I have not fine tuned the carb., etc. I arrive in Mass. on the 21st. via 51 tk and two 125s. I hope to see you there.
Dave, Yes, you are correct, Tom G. sells the NOS choke kits and I just blew one out this week. It is age (wax) and the ethanol issue. However, I am using non-ethanol 91 octane gas now. I ordered this morning 2 plungers and they arrive this Friday. Thanks.
peter klinck
Paul, yes a small bore not a "same bore"
and lower the main needle not the "mail needle"..sorry for the errors. I should be in bed it's 11pm. cheers.
peter klinck
Peter,
Yes, if you find that the choke is working properly, I would suggest that you lower the needle one notch, that would be leaner.
Paul
Paul,
Thanks for the advise.
peter klinck
There is something called silicone that I think can replace that old wax from the sixty 's and seventy's , someone told me the stuff is cheap too [:0]
I have been working on transforming the Berkshire MX for use at the Dalton RR. First to come off was the Circle F pipe to be replaced by the OEM quieter exhaust. Once only that change was made the performance changed considerably to the worse. What was once a very quick bike had no top end. Mine has a Mikuni and and the symptoms sound similar to what you are describing with your bike and the Bing. I tried everything possible to get the Mikuni dialed in with no luck. Having one advantage over yours with the easily adjustable PVL I made a slight change to the timing and the bike came back to life. Now it's zippy and quiet :D Photos for the what did you do to your bike coming soon.
Working lights with a PVL? (Mini 12V battery)
Dale Fisher
Penton Owners Group - Memberships
Facebook - Cheney Twinshock Racing Group - Administrator
'70 Six-Day 125 - V2017
'71 Six-Day 125 (Dave Fisher's) - V5553
'72 Mudlark - W257
'73 Jackpiner - 175 21159727
'74 Berkshire 100 - 40171056
And some silly other bikes...
One thing to check that gets overlooked on these old bikes, even when rebuilding them sometimes,(I've forgotten it myself sometimes) is a clogged exhaust system. Pull it apart as much as you can and burn out all the carbon and spooge, and get it as free flowing as you can.
Another trick I learened from the great Speedy Clasen is to file a notch at the bottom of the slide, 1mm deep and 2mm wide. This lets in a bit more air as the slide starts to come up and helps low end and mid range. I think Speedy said they did it to the 27mm Bings they used on Zundapps, but I tried it on the 36mm Bing on my '77 250 Hercules GS/7 and it helped out a lot on that bike. Someone else mentioned timing and after checking all the before mentioned areas, maybe just a careful tuning session with the air mixture screw to finish it all off. I'll bet you are closer to what you want than you think. My third bike back in the day, was a '72 125 SixDays, and I liked to ride it in the enduro bike class at observed trials meets. I replaced the Bing with a Mikuni, changed the ignition it to a point system with a heavier flywheel from a sand cast 100 Berkshire that I had at the time also (mainly because I burned up the motoplat and couldn't afford a new motoplat yet) and it performed quite well in trials, and would still hold it's own against most 175s on the top end. Wish I were the same size and weight I was back then!
Type at you later,
Dan McEntee
Dale, Daniel,
Interesting info about how to modify or adjust something so the bike performs better, especially at the low rpm end (the slide, etc.). I will also check more carefully how dirty the pipe is too. And yes, the bike is getting closer to what it should be, especially with the MZB and the uridium spark plug. I will also test the low end rpm on my land tomorrow with the new choke plunger.
Gooddirt,
Yes, the Bing Int'l Co. choke plunger cost me 19.76 dollars, arrived today. The idea of trying a silicone can work too if it firms up similar to the original choke plunger gasket.
Another point, according to technician Jerry at Penton Racing Products, the modern MZB and the older motoplat ignitions operate better with a platinum, uridium or similar spark plug with the fine tips. That should also contribute at the low rpm when being bogged down too as a plug could begin to get wet.
Thanks,
peter klinck
Blue or black RTV type (using it from 1996 on 10 bing cups ); one is 33% softer than the Wax the other is 5% harder than the Wax, but then it all depends on the base line of the OEM factory hardness and if it was stored at sea level; was the storage baggie air tight? and for how many years.... [^]
Paul and others,
In addition to replacing the choke plungers with new ones from Bing Int'l, I lowered the needles one notch on both 125s, so made it leaner. I raced both of these 125 pentons and there was a big improvement in the overall running. However, when the rpm is very low, I have trouble if the plug is really wet, in neutral, to work the throttle and get the rpms back up for the clean out. The top rpm and power is good, even though dropping the needle down one notch. It boils right down to just avoiding giving too much gas when it is bogged down and to be sure to drop it down into the next gear in time and thirdly, another small adjustment while we are getting closer.
The bikes in general are now reliable for racing. I will talk to some of you at the ISDTRR next week. I race enduro again tomorrow with the KTM guys.
peter klinck
[?][?]Are you running the stock pipe with the spark and muffler insert? Drill some more or bigger holes on the insert larger end dome. did you cut the slide ? I cut a 2mm deep and 3mm wide notch and use the replacement automizer; what needle #4 or #5 ? How about to much oil on the air filter , oil mix to gas ratio, oil type, grade of gas old or fresh, spark plug heat range; a new plug?[:0]
Quotequote:Originally posted by pklinck
Paul and others,
In addition to replacing the choke plungers with new ones from Bing Int'l, I lowered the needles one notch on both 125s, so made it leaner. I raced both of these 125 pentons and there was a big improvement in the overall running. However, when the rpm is very low, I have trouble if the plug is really wet, in neutral, to work the throttle and get the rpms back up for the clean out. The top rpm and power is good, even though dropping the needle down one notch. It boils right down to just avoiding giving too much gas when it is bogged down and to be sure to drop it down into the next gear in time and thirdly, another small adjustment while we are getting closer.
The bikes in general are now reliable for racing. I will talk to some of you at the ISDTRR next week. I race enduro again tomorrow with the KTM guys.
peter klinck
Hi Peter;
Moving the needle doesn't affect the top end operation, the the mid range off of idle through about 3/4 throttle. Top end is affected by the main jet size. Make a high speed run at full throttle, then clutch it in while hitting your kill button, and coast to a stop. Then check your plug. That will be the best reading for checking top end. If you get a good plug reading after several of those, then you can work on mid range and try leaning out the mid range. If it blubbers on acceleration, it's too rich. If hit hesitates or falls flat, it's too lean. You can also have some kind of air flow restriction that causes it,such as an oil filter oiled too heavily, and also the clogged silencer and spark arrester. Make sure you have good air flow through the passages for the air/fuel mixture screw. All the little things add up. And double check the info about notching the slide also. Have fun at the ISDTRR. I was fortunate enough to attend in 2003 in Dalton, but can't make it this year. Have fun and ride safe.
Dan McEntee
Hi Peter,
which BING Carb are you running onyour bike? 1/27/19?
Best regards
Guenther Vogt,
Hercules Club, Germany
******************************
Hercules-Interessengemeinschaft e.V.
URL: http://www.herculesig.de
******************************
Paul,
Thanks for your trouble shooting and addressing the carb problem mentioned above at the ISDT reunion ride in North Adams last weekend.
Sure enough, your bringing a bag of carb jets to help solve this carb's problem and I'm sure, other trouble shooting issues with other riders was much appreciated.
So as you suggested, you and I took out the 140 main jet and installed a smaller 135 main for this 73' Sachs powered penton 125 and it made a great improvement when I was caught a few times with the rpm down on a stony hill. That cured the problem. I would agree, it is best to try to work out the jetting first rather than for example, cut the bottom of the slide initially as was suggested above.
In addition, I noticed the bike didn't hold an idle and I had to play with the adjustment during the race moving the slide up or down with the idle screw. Well, the exhaust system was never cleaned as I thought after returning home. I used the recent POG suggestion and burned the pipe red hot section by section until done using a oxy acetylene torch. Wow, did I get a lot carbon out of that pipe. Using an electrician's "snake", I ran the wire up and down with a flared end. Especially noticed the center tube inside where a lot of material was removed. I'll run it tomorrow for a test. Thanks again Paul.
Guenther68, My Bing carb is a 1/27/20
peter klinck
"Penton Carburetion Secrets" 1974 July article " you'll be pleased to know that even the 2mmx 3mm notch on the front of the slide , comes stock"
The Atomizer Number is # 40-404 ; this also is a PENTON FACTORY Tech update.
Need I say more[?]
Peter,
It was a pleasure to meet you and visit with you at your own private Pentonville on the Hollerich Farm, as well as to get to look over your own version of the Cycleliner. Your Penton transporter brought back some great memories to Jack as he told us of learning to drive on the Penton Farm in pretty much the same truck in his younger days. If you could post a picture of your truck I am sure others would enjoy seeing it.
I am glad the jet change we did helped, as you continue to sort out your machine I would suggest that you make only ONE change at a time, as you probably already do, or possibly put a carb on your bike from a perfectly running machine, with a cylinder of the same vintage, to see if the carb is the entire issue. Often times these issues are a combination of a number of factors and can be tricky to properly resolve.
Here is a story about the carb on John's bike that he rode in the Legends Dual Sport ride that weekend, and the issue we had...
I had brought along a complete carb, including the needle & slide, spring, cap, ect.. for use on the machine that John rode, as the one from that machine wasn't back to Jack from getting some replacement parts installed. The carb I brought was borrowed from a machine that had last seen use about 10 years ago at an ISDTRR and had a cylinder of similar vintage to the one it would be used on. I pulled the carb apart to clean it and saw that it had a 130 main jet, figuring that the dual sport would have a decent amount of road involved I changed the main to a 140, and did a very careful cleaning of the entire carb body, passage ways and jets.
On Friday after unloading at the farm, I installed the carb, the machine started on the 3rd. kick and ran flawlessly on numerous test rides that day. I had brought along enough extra carbs, jets, and assorted items to be able to set up a Bing service center if needed, but everything was working fine...for now.
Saturday morning I wanted to warm up the machine before we left, it started on the first kick, but it just didn't want to come off of idle and into the mid range properly, even after several runs and surely being properly warmed up. About that time John came over and wanted to try out the bike, I explained the situation to him, he sat on the machine and carefully worked the throttle, all the while using the clutch to put various loads on the engine, you could almost see the wheels spinning in his mind as he did this...all I could think of is how did such a perfectly running machine turn to crap overnight.
John then took off on the machine and it was obvious it wasn't running properly in the low to mid range. When John returned he was all smiles, he said that all of a sudden the machine cleaned out and was now running perfectly.....he stated that he figured that a bit of water had accumulated in the float bowl and had caused the issue. The bike then ran flawlessly the rest of the weekend and always started with ease :)
Paul
Paul,
Thanks for your trouble shooting and addressing the carb problem mentioned above at the ISDT reunion ride in North Adams last weekend.
Sure enough, your bringing a bag of carb jets to help solve this carb's problem and I'm sure, other trouble shooting issues with other riders was much appreciated.
So as you suggested, you and I took out the 140 main jet and installed a smaller 135 main for this 73' Sachs powered penton 125 and it made a great improvement when I was caught a few times with the rpm down on a stony hill. That cured the problem. I would agree, it is best to try to work out the jetting first rather than for example, cut the bottom of the slide initially as was suggested above.
In addition, I noticed the bike didn't hold an idle and I had to play with the adjustment during the race moving the slide up or down with the idle screw. Well, the exhaust system was never cleaned as I thought after returning home. I used the recent POG suggestion and burned the pipe red hot section by section until done using a oxy acetylene torch. Wow, did I get a lot carbon out of that pipe. Using an electrician's "snake", I ran the wire up and down with a flared end. Especially noticed the center tube inside where a lot of material was removed. I'll run it tomorrow for a test. Thanks again Paul.
Guenther68, My Bing carb is a 1/27/20
peter klinck
"Penton Carburetion Secrets" 1974 July article " you'll be pleased to know that even the 2mmx 3mm notch on the front of the slide , comes stock"
The Atomizer Number is # 40-404 ; this also is a PENTON FACTORY Tech update.
Need I say more[?]
Peter,
It was a pleasure to meet you and visit with you at your own private Pentonville on the Hollerich Farm, as well as to get to look over your own version of the Cycleliner. Your Penton transporter brought back some great memories to Jack as he told us of learning to drive on the Penton Farm in pretty much the same truck in his younger days. If you could post a picture of your truck I am sure others would enjoy seeing it.
I am glad the jet change we did helped, as you continue to sort out your machine I would suggest that you make only ONE change at a time, as you probably already do, or possibly put a carb on your bike from a perfectly running machine, with a cylinder of the same vintage, to see if the carb is the entire issue. Often times these issues are a combination of a number of factors and can be tricky to properly resolve.
Here is a story about the carb on John's bike that he rode in the Legends Dual Sport ride that weekend, and the issue we had...
I had brought along a complete carb, including the needle & slide, spring, cap, ect.. for use on the machine that John rode, as the one from that machine wasn't back to Jack from getting some replacement parts installed. The carb I brought was borrowed from a machine that had last seen use about 10 years ago at an ISDTRR and had a cylinder of similar vintage to the one it would be used on. I pulled the carb apart to clean it and saw that it had a 130 main jet, figuring that the dual sport would have a decent amount of road involved I changed the main to a 140, and did a very careful cleaning of the entire carb body, passage ways and jets.
On Friday after unloading at the farm, I installed the carb, the machine started on the 3rd. kick and ran flawlessly on numerous test rides that day. I had brought along enough extra carbs, jets, and assorted items to be able to set up a Bing service center if needed, but everything was working fine...for now.
Saturday morning I wanted to warm up the machine before we left, it started on the first kick, but it just didn't want to come off of idle and into the mid range properly, even after several runs and surely being properly warmed up. About that time John came over and wanted to try out the bike, I explained the situation to him, he sat on the machine and carefully worked the throttle, all the while using the clutch to put various loads on the engine, you could almost see the wheels spinning in his mind as he did this...all I could think of is how did such a perfectly running machine turn to crap overnight.
John then took off on the machine and it was obvious it wasn't running properly in the low to mid range. When John returned he was all smiles, he said that all of a sudden the machine cleaned out and was now running perfectly.....he stated that he figured that a bit of water had accumulated in the float bowl and had caused the issue. The bike then ran flawlessly the rest of the weekend and always started with ease :)
Paul
Paul and others,
Thanks once again for your (suggestions) and support in carb adjustments here and at the ISDTRR.
Yes, we (Paul and I)solved the low and mid range problems at the race with a good improvement in the woods for this 1973 penton 125.
After returning to Vermont, I did a test run and noticed the high end range power was a bit flat and not clean sounding. I remembered Paul your first suggestion; "lower the needle not one (after testing) but 2 notches" if necessary. I will back up a bit and try the 140 main jet again AND drop the needle again one more notch.
I'll try to operate photo bucket to see if I can load a photo of my "1951 camper or trailer", so to speak.
peter klinck
Hi Peter,
referring to Sachs and Bing the setting should be
Main jet 140
Needle jet 2,70
Needle #4
needle position 2
Idle speed jet 45
Best regards
Guenther Vogt,
Hercules Club, Germany
******************************
Hercules-Interessengemeinschaft e.V.
URL: http://www.herculesig.de
******************************