125 Wombat Mystery

[Sento]

Hey All,

I recently pulled my Father's 125 wombat out of storage (10 years) and got it running with some fresh fluids and a new spark plug +battery.

It ran consistently for a few days, and now it has stopped & refuses to start.
I don't have much mechanical experience, but I have a parts manual with pictures and a brain between my ears.

I checked the spark plug and piston area, and I have gas + oil, and my plug sparks while I have it out of the case/grounded against it.

I pulled out the ignition coil, as I thought it might be getting a poor connection, allowing it to spark against the case, but not in place (attached a picture of said coil).

-- Not sure what my checklist would be for things to check to diagnose the issues. Any recommended threads to check/ advice for a first time mechanic?

[TheBevman]

Hello Sento, welcome to the board. What year Wombat are you working on?
If you had spark when testing then your coil should be good or at least good enough to run. The coils are pretty simple and robust units, I'd put it back in. If you want to check it there's probably videos on youtube and specs in the manual. (I'm at work now otherwise I'd look.)Also, you're going to want to get a manual, these bikes are easy to work on but it helps.

I'd pull off and clean the carb and make sure all the jets and passages are clean and clear. The carb might have an "O-ring" too, if that's gone you're going to flood the engine or run crazy rich. Try a new spark plug, fresh fuel mixed with a quality two-stroke oil at 32:1.
Feel free to post photos and keep asking questions. This forums full of great and knowledgeable Hodakaphiles.

Bev

[thrownchain]

Get a compression gauge and check the compression, the closer to 150 lbs the better. Also see if you can find a way to do a leak down test. And check that the timing is spot on.

[Stever]

First, congratulations on reviving the Wombat! Now, just my two cents on how to proceed with diagnosing a problem. Start with the most likely and work towards the least likely (especially if you are in a time crunch, like between motos!).

So three things are required to run the engine, namely adequate compression, fuel/air mix in a suitable ratio, and properly timed spark. We are not starting from scratch here, since we know the bike was long in storage and did run recently.

-Not likely that the compression changed dramatically since you had the bike running.
-Not real likely it is electrical that suddenly went wrong, but that is certainly possible.
-Pretty likely that there is varnish and crud in the fuel tank and carburetor of any bike that has sat for a long time.

So, when it cranked and ran a while, it could have loosened a bit of crud that compromised the starting circuit (the choke), or other vital passages. I mention the choke since the bike now doesn't crank at all. There is an EXCELLENT carb article by Ed Chesnut in the Resonator back issues on the club site, Volume 1 Number 3.

Anyway, just speaking for myself, I'd start with the carb, if the bike still doesn't want to run recheck the electrical, and of course I'm making the assumption that the compression is good.

[Bullfrog]

I'm with Stever - I'd recommend a thorough carb cleaning and be SURE that all pilot circuit PASSAGES are clean. The pilot jet and pilot passages are the smallest ones in the carb and are the easiest to plug with grunge (AND they are critical for starting the engine).

Time to install an "in-line" fuel filter too.

Ed

[Al Harpster]

A quick test that MAY help:

Remove spark plug

Squirt half an eye dropper full of pre-mixed fuel into cylinder.

Reinstall spark plug.

Switch ignition be on.

Kick repeatedly.

If you get a brief run, it's going to indicate a fuel problem.

If so, it's likely the carb will require complete disassembly and careful cleaning of all the little holes & passages.

The exploded carb diagram available in the manual or on line at Hodaka_parts.com will be of great help.

If you don't get a brief run from the fuel in the spark plug hole trick:

It just MAY be spark.

Consider buying an in-line spark tester available at auto parts stores. You'll find videos on these on YouTube. These can provide more certainty of ignition performance.

There's a tremendous amount of information on this forum. Don't hesitate to ask and ask again.

Good luck!

[taber hodaka]

make sure plug isn't wet fouled. -------------- Clarence

[Sento]

Alright, Thanks for the advice.

I have the owners manual / illustrated parts list, is that the only manual? I'd love a more repair oriented book, since this illustrated parts guide is useful but doesn't tell me the why or give an explanation; just how things go together.

I'll probably start with cleaning out the carb, since that was the most common suggestion, but I'll post again when I hit a wall, or I get it running again. Wish me luck.

[Al Harpster]

Check Hodaka-parts.com for a manual.

I only have the Ace & iron barell super rat workshop manuals.

I don't believe they will have carb cleaning tips or instructions.

It's likely you'll need a float bowl gasket. The original may tear on disassembly.

I've made my own from gasket material available at auto parts stores. But it's sort of slow going.

[Stever]

Sento, the back issue of Resonator Revisited article that I referred to actually has a second part, in volume 1 number 9 (the Resonators are found through the drop down box on the club site, for members only). That article specifically uses the model 94 Wombat carb. Ed's photos and text are much more understandable than any manual that you are likely to find.

[viclioce]

You can easily confirm spark by removing the plug and connecting the wire back to it. Using something insulated, hold it against the head fins and have the bike kicked over and look for a blue white spark at the plug. Sometimes when restarting old motors which sat a good while can cause the condenser to burn out. If ther is no spark, I would try adding a new condenser to the stator. Victor

[fuji]

Remove the flywheel and Check the woodruff key 🛠

[Bullfrog]

Why?
Ed

[dirty_rat]

Hopefully, from May of 2020 up to now he has gotten this bike running.