Four-stroking Wombat troubleshooting

[Darrell]

Hello Hodaka fans,

Recently the Wombat developed symptoms of condenser failure again. So I put in a new one and had a few good rides on a proper running Wombat after that.

But just now it has started four-stroking so badly, at 1/4 throttle and above, that the bike would not do more than 20 mph.

I decarboned the pipe and even resorted to riding the bike with the air filter element removed just to make sure the thing is breathing. Now I can reach speeds of 30 mph but the four-stroking is constant.

In addition to the condenser the spark plug cap is also new and well-connected.

Anybody have any ideas? Unlike the Wombat my 250SL always runs great, anyplace anytime.

Any and all input is much appreciated.

[Dale]

My first thought is that the o-ring on the nozzle is not sealing completely. When that happens, non-metered fuel is drawn from the bowl. Inspect the bowl cavity carefully for a good smooth surface for the o-ring to seat into. You can also remove the nozzle and test the fit with just the nozzle, o-ring and bowl.

[matt glascock]

I had a similar problem with my 94. Went over the entire carb and induction system with a fine-tooth comb and everything was up to snuff. Turned out there was a small nick in the high-tension wire off the coil that was causing an electrical leak. Replaced the wire and problem solved. There is an excellent description covering coil high-tension wire replacement on the tech tips page here on this site.Try running the bike in absolute darkness and look for a similar problem.

[Bullfrog]

There you go - that is my first thought too. Check O-ring condition, sealing surface condition and tightness of the main nozzle threaded into the body.
Ed

[Darrell]

Thanks guys, I thought you had nailed it by fingering the O-ring on the needle jet nozzle as the problem. I hadn't changed the O-ring since 2010 when I restored the bike.

But after taking apart the carb to investigate I discovered that the entire interface of the parts was just fine.

So, since 90% of all carburetor problems are in the ignition I checked the points (already replaced the condenser last month). Now, these particular set of points has a bit of a history. I bought them as a NOS or reproduction part a few years ago.

They worked fine for a few months until the bike stopped dead in the middle of a major intersection. So happened, that the contact in the pivot arm had come loose and was floating loosely up and down in its mount. To remediate this I soldered the contact into the pivot arm.

All was well for a while until the bike started this serious case of four-stroking. Check the timing and gap on these new but "refurbished" points I saw that when the points were timed properly the gap opens to at least .020 rather than falling into the .012-.015 range. This extra wide point gap baffles me -- the rubbing block is just fine so no clues there.

Anyway, back go went in the original points (glad I hadn't thrown them out) the bike came with in 1973 and that eliminated all the running issues and power loss -- this time.

DANG THEM POINTS AND CONDENSERS! DANG THEM ALL TO HECK!!

That's my best impersonation of Charlton Heston - with a bit of a euphemistic spin on it.

[Dale]

Good find Darrell. I have also had a newer set of points that exhibited that type of gap issue. My symptoms were most obvious when I turned the ignition switch to have the headlamp on. It would immediately run rough and cut out under load. Wishing now I would have saved them for a closer look, but I was frustrated enough with them at the time that they went immediately into the trash can...
I am glad that you have it sorted out.

[Bill2001]

Good observations, Dale &Darrel. A few years ago Bosch started sourcing ign points in China and had problems with the rubbing block bein off-dim and not being ble to set pointgap and timing correctly. I use "old and serviceable" points that will need replacement some day. I guess be on the lookout for NOS.