'72 Wombat (94) Stopped on me twice

[TheBevman]

Hello All,
I recently got myself a second Hodaka (because two is better than one), a '72 Wombat (94). She runs great, has about 800 mi (if the odo's telling the truth) and looks to be original except for the triple trees and bars, even has what I suspect are the original Nitto rubber too. The fella I got her from didn't know any of her maintenance history, but did enough to get her running: New filters, new batt, cleaned carb, changed trans oil, points and said he replaced the condenser as a matter of course (something I haven't verified yet). I knew from my test ride that she was running really rich, bogging down and killing mosquitos near her tail end, but all else seemed to be in working order. Now she's mine and she's a hoot!

Once I got her home, my faithful helper and son and I did a lead down test to see if she's still well sealed, cautiously following the sage advice of those on the board here, and she lost less than a lb of pressure in the 6 min we had her pressurized (the phenolic block gasket was leaking), a sigh of relief followed. After changing out the O-ring in the carb I started re-jetting, again following the adcise found here and the manual, progressing from 170 down to 140 as that was where the bogging stopped (PO had a 170 installed @ 300 ft above sea level ). I'm at 3000- ish ft

Since getting the jetting sorted and actually riding her around I have had her twice take me by surprise by completely cutting out. Both times were with the lights on (IG in night). The first time was after riding for about 10 min, I was going up my street, slight incline, 3rd at about 3/4 throttle and she stopped dead and I had no lights. After investigating the cause and finding nothing obvious I kicked her over and to my surprise she lit off like nothing happened. Second time was yesterday, after about 30 min of trail riding in 90 F temps, with no problems, I went into town and back and she did it again on an slight incline at 3/4 to WOT- again with no lights either and key in night setting. I clutched it, thinking that maybe I has seized her up, but once I got to the side of the road she kicked over easily but wouldn't light off. 5 min later I was tired of pushing and decided to give her a whack and she lit off like nothing happened, lights and all.

So, after thinking about it I'm thinking it could be a fuel vent issue or an electrical issue. The caps vent it clear and the gasket was absent on purchase, currently on order. If its electrical, where would I start investigating? Any and all input would be greatly appreciated. Thanks

[hodakamax]

Hmm, I'm going to guess condenser. If it happens again, quickly check for spark before it begins to cool. That will at least separate electrical problems from fuel problems.

Max

[TheBevman]

Thanks for the reply Max. I suspected the condenser too, just because of what I've read here on the forum, they seem to be the source of much frustration to Hodakafiles and othe vintage bike folk. I was able to break away for a few minutes and pull the shift cover and the flywheel to take a look, mind you I only looked, and found no loose connections and the points and condenser look new. I know it doesn't guarantee its not the problem but I like shiny things.

I won't get a chance to entice her to fail until this weekend, but plan to check for spark if it does.

I do have a question about the lights, why are they going out when the engine dies? Aren't they run off the batt? My brake lights won't even work when it happens and they work without regardless of the key or IG position.

Thanks
Bev

[rlkarren]

On a (94) Wombat, the stop light, speedo light, and horn run off the battery regardless of key position, (other than "Off").

Everything else, (headlight and charging circuit) runs directly off the Magneto. Which means the engine must be running to work. The headlight circuit is activated in key position 2, (Night), and the charging circuit is activated in both 1 and 2. This is also AC current and is variable voltage proportional to engine RPM. I've seen anywhere between 3 - 18 VAC when I was trying to figure out the electrical system on my Ace 90. The Wombat is not much different.

However, if your Emergency switch is set to "DC", then everything is running off the battery in either key position.

If you're losing brake lights or horn when the engine stops, it seems to indicate a different problem than the typical bad condenser. The ignition circuit and the light circuit are isolated so I'm not sure how one would effect the other to cause the problem you are witnessing.

If you wanted to completely isolate the light circuit, disconnect the 4-way connector at the key switch. This will completely disconnect the light circuit and render the key switch useless, but the engine should still run. Hook up a kill switch of some sort and go for a ride and see if it does it again. If it does, then the problem exists in the ignition system and is probably a bad condenser or maybe even a bad solder job on the condenser. If it doesn't then the problem lies in the light circuit and that would require tracing every wire, inspecting each wire and connector for damage and also checking against a wire diagram to make sure it is wired correctly.

$0.02

Roger

[Bullfrog]

Those are gold plated two cents worth.
Ed

[hodakamax]

Roger is darned handy to have around!

Maxie

[TheBevman]

Well over due for an update here. It's been a bit since I've been able to get much time to tinker with the Wombat, until today. After rereading the thread it was clear I didn't have my facts straight. As Roger pointed out, lighting and ignition are two separate systems and the lighting circuit wasn't part of my problem. Thanks Roger for setting me straight.

Today I took the wombat out and after a thorough warm up and a few laps of the neighborhood, 20 min or so of running from idle to 3/4 throttle, without a hiccup, I went out to check her top end jetting. Unfortunately, she still dies on me after a min or so of 1/2 to WOT, road (flat or incline) doesn't seem to matter. When it starts to happen, I can feel her start to get sluggish and lose power and within 5 seconds she starts to chug, at which point I clutch it and she dies.

When I pull over to a stop, 5-10 seconds, she'll start after 2 kicks like nothing happened. When she starts I have to coax her with a bit of throttle but then she idles great. Thinking it was a venting problem, I even rode her without the fuel cap on and the vent tubes pulled, she still died on me. She's great putting around the neighborhood but she doesn't seem to like the open road.

Since I last posted I have replaced the condenser, checked the wiring and timing, added a kill switch, cleaned the carb (twice) and checked the float height, cleaned the points, replaced the clutch bushing (unrelated, but still did it) and a new plug. I also went from a 160 main jet down to a 145, in increments of 5, because I was thinking she was just running too rich.

Jetting is currently at 150/ stock needle, 3rd groove/ 2.5 slide/ 25 idle jet. The 150 responded better than the 160 main jet did. I'm using 91 ethanol pump gas and Maxima castorol 927 at 32:1, the gas 3 weeks old but has stabil in it. Stabil says it'll last 2 months.

So, any ideas?

Bev

[rlkarren]

That's starting to sound like a plugged pipe. Pull the spark arrestor out so that you have an open pipe and take it for another spin. If you notice an improvement, "cookin'' the pipe" might be in order.

Roger

[TheBevman]

Thanks Roger, do you mean the pipe itself or the spark arrester? I did pull the baffle/ spark arrester and burn it out shortly after buying it (70 miles ago), I also bought and installed the "spark arrester inner" (the bit that mounts at the back of the pipe with the screw) that the PO didn't have when I bought it, forgot to mention that. I haven't cleaned the pipe at all but did have a look and it looks dry and sooty in there.

[TheBevman]

Oops looks like I shouldn't read and watch the game at the same time. I'll pull the baffle, give her a go and get back to you.

[matt glascock]

And SKIP the ethanol in your gas or you will live forever in jetting purgatory not to mention ruining seals, internal motor corrosion, and the million other reasons to avoid ethanol in 45 year-old 2-stroke motors. Heck, the problem might solve itself by switching to branded 91 octane pure gas. Also SKIP the Sta-bil for similar reasons. Fresh 91 octane pure gas + Yamalube 2R 2-stroke premix oil at a 32:1 ratio = happy motor. Doing this just might solve all your problems.

[BrianZ]

It's hard to diagnose over the internet, but it could be a fuel flow issue. If the fuel flow is poor the bike will run at partial throttle settings but when the throttle is opened there is not enough flow to the carb to support the increased demand. Have you checked the fuel flow through the petcocks? They have screens built into them that can become clogged. Another thing to check is fuel line spiggot on the carb. I have seen grunge build up in here that prevents fuel getting to the float bowl. Another possibility is the float bowl vent, make sure it is not blocked or it could prevent fuel flow into the carb.

Brian

[MTrat]

Don't forget to check that the fuel cap is properly vented...

[TheBevman]

Well, after the game I pulled the baffle and took her out and... she ran like crap! Wouldn't take throttle, i had to feather the clutch to keep her going but she just wanted to bog down to an idle. Roger, would I need to make any jetting changes to compensate for the freer flowing exhaust?

Matt, I may just break down and go with the ethanol free 91 but at near 5$ a gallon I don't think this wombat is gonna be my daily driver like I hope.

Brian, I'd thought that this was a flow or vent issue too, I pulled the fuel line from the carb and drained the tank to check the petcocks and the filter flow. There wasn't a problem. I was thinking of the carb venting too so I went through it twice over a white rag to see if anything came out and all was well, not even a bit of grit. I even suspected float height and it was even with the carb flange when inverted.

MTrat, I took the fuel cap off and ran her up the road and she still did it.

The only other thing I can think of is grounding, my old Triumph suffered from a similar issue so I might make a grounding strap and give it a go too.

[Dale]

I too believe that you must eliminate the ethanol fuel. Another thing to consider is the possibility of a leaking head gasket. I have experienced the very symptoms that you describe and it only occurred under full load and full heat saturation. This is also a 94 Wombat. It acts like a plug fouled, but after a minute cool down, it is good to go again. My leak down test was good with the engine cool but, over time, I could see the blow by past the head gasket working its way down the cylinder bolt threads.

When I pulled the top end, I discovered very fine scratches that looked to be a poor lapping job by the previous owner. I have since re-lapped both surfaces, installed a new gasket and am currently waiting for warmer weather to test the result.

[rlkarren]

I am at a loss. I thought sure it would be a plugged pipe as the symptoms you describe sounded just like mine when I had a plugged pipe and didn't know a pipe could get plugged. On the other hand, I've also seen what Dale describes too.

If it were me, I would start the process of elimination; eliminating what it is not, starting with the ignition. Take the time to make sure the timing is absolutely correct and all components and connections are good so that that can be eliminated, then the carburetor, and then finally the top end itself, in that order. That probably sounds like overkill, but that's just me.

$0.02

Roger

[taber hodaka]

I have seen exhaust ports that were plugged almost completely. -------------Clarence

[Bill2001]

I agree with Dale, Roger, Matt and Brian on this. Make sure the ignition is up to spec, even replacing points and cond. Carb is immaculate, and not just a Gumout spray. Check and _Verify_ that the jetting is correct-- this includes the slide valve, the needle and the neefle jet. Run only alcohol-free Premium, and a quality Premix oil. Leak test and leak-free. After warmup.and adjustments, new sparkplug and do plug cuts at 1/4, 1/2, 3/4 and 1/1 throttle to verify jetting/mixture. You may have done some of this already, but this is my bucket list.

[Bullfrog]

. . . and don't forget to check that the pilot air passages and pilot jet fuel delivery passages are clear (not to mention the pilot jet). Pilot jet and pilot circuit passages are the smallest features in the carb - and the easiest to clog - and are often overlooked.
Ed

[RichardMott]

I know it was mentioned before, but the pilot jet can drive you crazy if it is not absolutely clean. Very small hole.
Ethanol free 91 fuel. YES.
Use a timing light.

[TheBevman]

Well... there have been some developments, to say the least.

First and foremost, I think I got to the bottom of the sudden stop issue. Upon cleaning the carb yet again and finding all passages clean, I noticed this just before putting the float bowl on.

The last time I started the wombat I thought she was smoking a bit more than normal, but it was cold too. So, for piece of mind and because I already had the carb off, i decided to do a pressure test. Good news, she passed and less that 1 psi in 5 min, when pressurized to 6psi (as she'd done before.) then on a whim I tried a vacuum test after reading up on how it's done, which to my surprise I was already set up for. So, off with the pressure apparatus and on with the vacuum brake bleeder. What I'd found said the same requirements as the pressure test, that seals should hold 5-6 psi and drop less than 1psi. Well, there is found my problem, I couldn't get the vac above 4 in/Hg and then it would drop to below 3! Upon pulling the shift cover and the dipstick I unfortunately heard some rather concerning sucking noises. Bummer! To be continued.

[TheBevman]

Here's a better shot

[TheBevman]

Well, the surprises didn't stop there. Knowing I needed replace both crank seals i figured on just getting down to the matter at hand and opening her up, in case anything else was needed. Upon pulling the head and barrel I was greeted with this sight.

Not too bad.

Then I got to this.

Ouch 1

Ouch 2

Ouch 3

Ouch 4

Ouch 5

Not good and I think My jetting adventure a few weeks ago might have added to that mess too, when I progressed down to a 145 main jet for a run. From what I read it looks like it ran lean and it suffered a four point seizure from not being warmed up properly. Any input would be appreciated.

Good news is that the bore looks like a good hone will return its serviceability. Also, the pistons top ring was pinched on the exh side but I was able to get it out and the ring valleys show blow by in the same area.

Continuing on with the tear down all was progressing well until I split the cases and found this.

It may look bad but the scaring is rather light

The crank isn't as bad either. When I cleaned it up most of the marks were just oil and grease. There is a bit of a ring from the bearing rubbing it but it's actually very light.

So you may have gathered that there should be a shim between the crank and the bearing, to stop them from becoming acquainted in such a way. Well, I did find it... a few weeks ago behind the clutch thrust washer when I tore into that, I didn't mention it in the post I did on that evolution. When I found the shim I just assumed some one put it there by mistake not that they assembled it without.

So, parts are clean and those that are needed are on order.

[michael_perrett]

Interesting welding on the cylinder fin.

Mike Perrett

[ossa95d]

Mike it looks like it was arc welded with a nickel silver rod.