Main Jet setting at 4000 ft Please Help

[MTRob]

I have a 125 Wombat 94A and can't get it to quit fouling plugs. The motor has been bored oer 40, Points and condenser new, set at 13 gap.
Why am I fouling plugs and it runs for a while then starts bogging down and backfires then stops. I change the plug do a little adjusting to the carb
but still does same thing. What the main jet settting at 4000 ft and what else can I do. It has the Carb Model M24 SH-83B
MTRob

[Dale]

MTRob, When it runs, does it run well? Excessive smoke prior to bog? If it seems fine and suddenly has these symptoms, then the condenser is suspect even though it is new. If there is excessive smoke, then the clutch side crank seal might be at fault.

I would recommend a leak down test and a new condenser. Carefully check all wiring between the points and condenser too.

As for main jet size, stock was either 140 or 160 and your banjo bolt will be stamped with one or the other. I run 160 at 2700 feet on two different 94 Wombats. 4000 ft would probably bring you down one size.
Dale

[Pep]

+1 on everything Dale said - especially that condenser.
Typical bad condenser: runs, as it gets hot it starts running rough - bog, surge, backfire, die. In the time it takes to swap plugs, things cool down enough to start, run, repeat.
If not that, then definitely do a leak down.
If you're convinced it's the carb, see if you can find a spot on the throttle where it acts worse - that can help you identify what to do on which jets.
-Laurie

[rlkarren]

What jets are you using?

I'm at 4400 ft. and I have:

25 pilot, 1 turn out on the air screw.
standard needle and needle jet, center notch
130 Main jet

Same carb as yours, and my cylinder is .010. I was able to switch to a 135 main jet in Athena, with no problems, (possibly slightly rich though). Theoretically you should be using the same... but not all motors are the same. For example, where Dale uses a 160 on his Wombats, I would probably use a 135 on mine at 2700 ft. I have no doubt Dale has his machines jetted correctly too and I'm certain I'm correct on mine, if not very slightly rich.

But your symptoms seem to point more towards an ignition problem. Make sure your timing is correct. the point gap method is not very accurate, in my opinion, and .013" will get you into the "ballpark" but it won't be exact. Try using one of the other methods in order to set your timing more exact, for example try using a timing light. You'll have to stop and start your engine repeatedly while you adjust and check, but it's very accurate. I think you might find your timing to be much different than .013", (but that is another discussion on this forum).

Failing all that, the only way to test a condenser is to put in a new one or make sure you don't have a cold solder joint.

Just a couple thoughts I thought I'd share, (which will probably be edited once my brain has rested)

Roger

[kc57]

Have you checked your float height ?

[taber hodaka]

MtRob there can always be a possibility of mixed carb parts. The 94A pilot jet was 25, throttle valve "slide" 2.5, needle 4E1, main jet 130-150.
The 94 pilot 15 to #17011, 25 >1701 slide 1.5, needle4J13, main jet 160-180
The 03 pilot 45-50 slide 2.0, needle 4f6, main jet 160-190

An Altitude Jetting Guide sent out July 10 1974 FROM A Hodaka distributor follows as a guide.
Early 125 cc Wombat
Settings will vary with humidity and temperature changes.
Sea level --- to 1000 feet
main jet #190 --- Needle 4F6 --- Needle setting fourth notch down.
1000 --- to 3000feet
#190 4f6 third notch down.
3000 --- to 5000feet
#180 4f6 third notch down.
5000 --- to 7000feet
#180 4f6 second notch down.
7000 --- to 9000feet
#170 4f6 second notch down.
9000 --- to 11000feet
#160 4f6 first notch or top.

Clarence

[MTRob]

Thanks Guys, Taber tried 180 did not work at all, went back to 140. I am going to put in new condenser and jet it at 135, since I have it apart I'll change the points to. Plus check float setting. Will let you know We are at 4000 ft. Hope this works 2 years in rebuild.
Thanks
MTRob

[Zyx]

I guess I would have to ask if it is oil fouling or fuel fouling. Jetting would lead to fuel fouling perhaps, but the engine is very tolerant of fuel richness now that we don't use leaded gas anymore. If it is oil fouling and your blend is right, could be a crank seal. Also possible is bad gas. Seems like gasoline does not last long these days, so if your gas is old, it could be causing plug issues. 30 years ago, gas would last all year in a can. These days it seems to turn into paint thinner in a month or two.

[MTRob]

Thanks, At first since it was a new honed 40 with new pistons and rings, I made the gas fuel mixture at about 30 to one. And the plugs looked oiled fouled, then I drained the tank and put in 20 to one. Now they look fuel fouled. I will try other things Condenser, points, float, jetting. I would pull my hair out but I don't have any left.
Thanks
MTROB

[Zyx]

Curious. 30 gas to 1 oil is leaner than 20 to one, far as oil goes. You might expect the fouling to be the other way around. Sounds like something else

[rlkarren]

Thanks Guys, Taber tried 180 did not work at all, went back to 140. I am going to put in new condenser and jet it at 135, since I have it apart I'll change the points to. Plus check float setting. Will let you know We are at 4000 ft. Hope this works 2 years in rebuild.
Thanks
MTRob

in light of my other discussion, I think it would be wise for you to use standard jetting. I am at 4400 ft and I'm now using a 140 Main which is slightly rich I could probably go to a 135 and make further fine tuning adjustments with the clip position and be just fine. That 400 foot difference is not going to make that much difference in your mixture.

I know that not all motors are the same, but I'm pretty sure standard jetting should get you running. My earlier comment about finding a known working ignition and carb is probably your best and easiest method to pinpointing the problem. Also, choose a fuel/oil mix and stick with it until you resolve the issue. The reason for this is that after discussing fuel/oil ratios and it's effect, (and in the simplest way I can explain what I understand), mixing more oil into the gas is OK as long as you do not alter the fuel to air ratio. The ratio of gas to air must remain constant, so if you mix in more oil, you are displacing fuel with oil, creating a lean situation. Change to a larger jet, or jet needle adjustment, to restore the fuel/air ratio.

In other words, in a very broad sense, changing your fuel/oil mix, is the same as changing jets to rich or lean your fuel/air ratio; but certainly not the recommended method.

Eliminate the variables and make constant what you can: Fuel/oil mix, standard jetting, timing. Then, concentrate on your ignition. This is where finding a known working ignition would help. If there is no change then the likely culprit is carburation, which implies possible air leaks and seal failures.

my $0.02

Roger

[MTRob]

Thanks again guys. I pulled it all apart and put in new points and went to put in the new condenser and noticed on the top where you solder the top of the condenser it moved back and forth inside the casing. This must be a bad condenser Right? I just got the condenser now wait week for new one. Put an OHM meter on the points and the sound will not shut off with the points opened or closed. Condenser must be bad? Ideas? Spent 2 years rebuilding this 94A Wombat ground up and the ignition is driving me crazy
Thanks
MTRob

[Zyx]

Take the condenser out and check continuity again. If it now breaks circuit when points open, sounds like the condenser may be short to ground. I don't know about the solder thing. Are you referring to the mounting strap?

When I resistance check a new condenser, there is an initial period showing continuity between the condenser case and the contact tab, around 10 to 30 megohm, but then it goes away until the condenser is discharged. I don't fully understand how these critters work, but if you are using a buzzer to check continuity, I suppose it is possible that you would find continuity across open points. I don't remember ever testing or setting magneto points with a buzzer. I just set the gap with a feeler and let it go at that. If you are getting a nice fat spark, the system is working no matter what you find at the points as far as continuity.

Here's another thought: If I remember correctly, the function of the condenser in the ignition loop is to keep the points from arcing, not to provide spark. The coil does that. So potentially, your system will fire even without a condenser. If the condenser is shorted inside, that would divert the electrical impulse from the magneto straight to ground, and the bike would not fire at all. If you have a spark, the condenser is not shorted, and finding continuity across open points with a buzzer is simply the way things are. I don't have a magneto system to check at this point. If you have a multi-tester, check the resistance of the condenser by itself. There should be a shown resistance which falls to zero, but which comes back after time, or if you touch the tab to the condenser case to discharge the condenser. Your multi-tester is not putting a large electrical current through the condenser, so you are not building a charge that will spark or shock, and your condenser will not hold such a small charge for long, but perhaps long enough to give you the open-point buzz that you got.

[Dale]

The condensor is required in the circuit in order to generate spark. No condensor = no spark.

The best way to check the condensor is with it out of the circuit. Put a meter across it and you should have low resistance one direction and infinity the other. It is a go, no-go test only. When in doubt, replace it. In addition, with it in the circuit, you are always going to have some continuity. If you connect a buzz box, you will hear it all the time as you rotate the magneto, but you will hear the pitch change when the points open as the resistance changes.
Dale

[Zyx]

Having checked two new condensers just today, to see how they acted, I find they have the ability to build a charge in either polarity (direction). The function of allowing electricity to pass one way but not the other is a diode. Using an ammeter on a condenser, I get a building resistance over the space of about three seconds from zero to 32 - 36 megohm, then it drops back to zero. It does this regardless of polarity.

I admit I have never tried to run the magneto system in a Hodaka without a condenser. But I have done so in Jeeps for short periods of necessity, and the system worked just fine, just not for so very long because it tends to burn the points. Of course, automotive ignition systems work a bit differently because they are battery and alternator fed, rather than magneto fed. But the two systems are more alike than different from each other.

The spinning magneto builds an electrical charge in the ignition coil with the points closed, much the same as would an automotive battery/alternator system. When the points open, the built up charge in the coil fires a spark in the plug, but there is also a tendency for the current to jump the point gap, more or less like it would jump the plug gap, with the difference that the electricity on the points side of the coil is low voltage (8 to 15 volts) originating from the spinning magneto, and on the plug side of the coil is very high voltage (45K volts or so?) generated by the ignition coil. The condenser in circuit offers an alternative low voltage path to ground versus the open points, and diverts the electrical pulse through the condenser to ground so that the points don't arc. I don't know if the magneto/coil would spark a plug if there were no condenser in circuit, having never tried it. But as far as I know, the condenser does not create spark, the coil does that. The condenser more or less absorbs spark in the point circuit minimizing but not eliminating arc. Points do eventually burn out, as we know. Without a condenser it happens today or tomorrow instead of next year or the year after. Any ignition system with a condenser that is electrically perforated allowing perpetual short to ground will ground the ignition and it won't fire. That is not the same as having an open circuit at the condenser lead (i.e., no condenser).

My magneto fired engine is off the bike and stored, so I can't pull the condenser and try it without one. If someone wants to experiment by pulling the condenser to see if it will fire, go ahead.

[Zyx]

And anyway, a condenser should be checked for capacitance, not resistance. The capacitance is or should be the same regardless of polarity since the function of the capacitor (condenser) is not polarity specific and will build an electrical charge in either direction.

[Dale]

I guess capacitance and resistance testing must have changed since I was in the biz. I will bow out of this discussion...

[Darrell]

A condenser may pass a bench test, but under continuous load and in the presence of engine heat it might go south on you.

[Bullfrog]

The wiggly "innards" on your existing condenser are a clear cut indication that it is BAD.

I think (perhaps, maybe) that it is my understanding that you put in the new (now completely shot) condenser recently.(?) If so, then I would suspect that the condenser was overheated by the soldering operation. (Don't feel like you are being singled out. There are three kinds of people in the world - the one's who have never tried/never will try to solder in a new condenser, the one's who have tried and failed and the one's who WILL try and fail.)

The sheer thermal mass of the multiple relatively large wires and the solder pad on the condenser require a LOT of heat to achieve the temp required to "flow" the solder. HOWEVER, the heat MUST be of short duration to keep from frying the condenser itself. Probably the best way to pull off the job is with a genuine, old fashioned soldering "iron" -- a pretty massive chunk of copper/brass on the end of a steel shaft and with a wood handle (looks sort of like some kind of clunky screw driver). If you don't have that . . . I can suggest two options

1) Find someone with experience at installing condensers on old bikes and pay them to do it.
or, (if unwilling/unable to do #1)
2) Dig out the old Weller solder gun and put the largest tip on it you can find. Prep the solder joint for soldering - wires in place and "strapped down" by the strap on the condenser. PRE_HEAT the solder gun tip and get a glob of melted solder on it. Use the thermal mass of the PRE-HEATED tip (and solder glob) to bring the wires and solder pad up to temp as rapidly as possible . . . as soon as the solder "flows" into the joint and wets out the wires and solder pad . . . get the heat off the joint AND start dabbing the joint with a cold damp/wet towel. You MUST limit heat flow into the innards of the condenser. Um, did I mention to PRE-HEAT the LARGE soldering gun tip . . . I mean HOT! (because that helps to make the operation go faster)

Ed
PS: I'm purposefully not going into concepts of testing condensers, since it is clear the existing one is bad (and there are not enough keystrokes in my fingers to address the issue this evening).

[michael_perrett]

Has anyone ever mounted their condenser remotely for easier removal? Or better yet, a condenser from brand X which does not need soldering?
Mike

[Bullfrog]

PSS: MTRob, amongst those three kinds of people . . . I'm one of the middle kind. Since I used to work for PABATCO/Hodaka, I think that means you are in good company.

Ed

[RHall1972]

I'm curious to know the answers to Mike's questions as well. I remember a post on the "old" chat board where someone had indeed relocated the condenser for easy access.

[taber hodaka]

Yes. Clarence In the total loss for the flat tracker the condenser is large and remote. Coils will spark without a condenser, that is how I check them. Ed gave the very best of advice on soldering, the condenser is very fragile inside aluminum foil and wax paper almost. If your points are not lasting a very good indicator of a failing condenser. I believe the majority of Hodaka's ridden in the day never had a new condenser, unless a shop did it as a routine but I will say very few ever needed one.. Clarence

[Zyx]

Mine is still working since purchase new in 1971. Probably it was made in the USA. Today, they could be made anywhere in China.

[Zyx]

I guess capacitance and resistance testing must have changed since I was in the biz. I will bow out of this discussion...

Capacitance is measured in Farads, resistance in Ohms. They are not interchangeable measures, nor are they looking at or for the same things. The resistance seen in a capacitor changes as the state of charge in the capacitor rises and falls. Checking a capacitor for resistance only lets you know if the internals are fried to the point of short to ground, because you will see a zero resistance all the time, and no rise and fall. Otherwise, it can't tell you if the capacitor is working "correctly." Capacitors store electricity and releases it on demand. In an ignition system in particular, the capacitor/condenser smooths out the power surges from the magneto to the coil when points open. When a capacitor reaches full measure, it stops storing, and internal resistance falls, but that is an curious observation rather than an explanation or test of function. Most multi-meters will check for both resistance and capacitance, so I would think checking capacitance is a better move than checking resistance if you want to know your condenser is working. This stuff hasn't changed lately, perhaps we are just talking at crossed purposes, or describing the same thing from different directions.

Not to mention that I think I hijacked this thread. Sorry about that.