Hole to nowhere

[thirdstone]

Hi people. There is a small hole on the wombat case cylinder mount. If you split the case's you see each half of the hole and its a dead end. The base gasket has a hole that lines up with it.
What is it for ??

[thirdstone]

This hole

[Bullfrog]

When you find out, let me know.

Ed

[admin]

HT did not have an answer either. I was hoping for a mind blowing answer from the Captain but I guess I will have to wait for the next question.
Everyone I hope all of you have a safe and great Thanksgiving with your families!!
Enjoy the time off.
Thanks
Paul

[JayLael]

The hole is there to trap sealer and prevent air leak at this location. When it's flat right there the sealant is squished out of the area, and over time a leak develops. These voids are common in any case to case contacts that use liquid sealants.

[racerclam]

Jay is a smart guy. I use the hole to fill with epoxy when I put a case port in. Its good to be back on here . I have has technical dificulties getting registered ever since the new format came to be, But Kaity at strictly Hodaka made it work for me. Happy thanks giving 8o)

[michael_perrett]

I would say that it has something to do with the die casting process

[racerclam]

Im currently Porting a 73 Suzuki 125 that has the same hole , BUT it leads to an oil injection port. Maybe Hodaka was considering it as an option someday?

Rich

[Bullfrog]

I had that same thought once Rich - but I really don't think oil injection was on the visible horizon when the ACE 100s were produced. That hole has been a Hodaka feature for a looooonnnnnggg time.

Jay's explanation makes the most sense to me - I'm going with that concept.

Ed

[BrianZ]

Interesting facts about the hole:

1) It is not present on early Ace 100 cases, but is present on later Ace 100 cases.

2) If the hole was drilled deeper it would intersect the threaded hole for the top case screw.

3) The later Ace 100 cases also have a boss located below the carburetor, but close to the hole for the top case screw, such that if the boss was drilled it would also intersect the hole for top case screw. This would provide a passage from the boss, to the threaded case screw hole and then to the hole in question, provided the top case screw is short enough that it does not block the passage.

4) Road Toad cases also have the hole, but in this case there are two more drillings that bring the hole to the outside of the case just below the carburetor. The hole below the carburetor is threaded and blanked off with an M6 bolt.

5) The Road Toad cylinder has a hole that line up with the hole in question, but it is a blind hole and stops before it gets to the intake tract.

Based on this, I would hazard a guess that this hole was a slow evolution toward oil injection that was never implemented in the end.

Brian

[BrianZ]

Excuse my terrible pictures but here are some examples.

Early Ace 100 case:

Late Ace 100 case:

Road Toad case:

Road Toad cylinder:

In my earlier post I'm wrong in my desciption of how the hole could be routed to the boss. The top case screw would block the passage, but the boss was added for some reason, and my only guess would be oil injection.

Regardless, nice discussion for these short winter days.

Brian

[racerclam]

I think it was only there in the wide base cases that started in1972

Rich

[thirdstone]

Wow interesting thoughts out there. I lean towards Jay however if it was to aid sealing I don't think the hole would have been so deep. It does go with the hole in the gasket though.

[rtboone]

I don't have an answer to Thirdstone's original question but I find it interesting to read all of the various theories about the reasons why the hole was put there.

I do, however, have something to add about the RT case passage and corresponding hole in the cylinder that BrianZ mentioned.
I have three RT cylinders, and all of them have a hole bored all the way through to the bottom of the intake manifold. The base gaskets have a hole that matches this hole, and the cases have a passage that exists just below the engine breather. This case hole is blocked with a 6mm bolt that if not sealed correctly, will cause a serious air leak and do damage to your engine. (I found this out the hard way when I "holed" a new piston, and upon doing a pressure test, found that the bolt,even though tight, was the cause of my air leak.)

I had quite a bit of correspondence with Paul and Ed about this( about 1 1/2 years ago) and we never really came up with a definitive explanation as to why this passage was there.

The only thing that makes sense to me, however, is that the factory was planning to oil inject this way, but found that it worked better to inject from the top of the intake rather than from the bottom after the cases and cylinders were already in production. May be the factory did something along these lines in regard to the Wombat.

Perhaps we will never know the answer to Thirdstone's " Hole to nowhere", but it is certainly fun trying to figure it out.

Hope you all had a wonderful Thanksgiving.

Tom

[thirdstone]

Hole in action



Jay is this months Hodaka Guru .