mechanic

[danwarren77]

Anybody know a good mechanic in the southeast. I'm located in Charleston SC...Thanks

[Modracer70]

What do u need to have done?

Dave

[admin]

Danny Cooke on this forum. No brainer he is one of the best !
Paul

[Yamadaka]

Where is Danny located?

[admin]

Hopewell Virginia

[dcooke007]

Dan dropped his recently acquired Combat Wombat off last Friday for some work. Engine runs and actually shifts through the gears. Most of the bikes I get don't run so this is a first for me. We are starting with a complete engine tear down and restore.

The exhaust pipe is sound but unfortunately the DPO has modified it.

Olds school .060 over Wiseco piston assy.

Cylinder studs installed up side down.

Ignition and flywheel look brand new from a mdl 94 Wombat. They look so good I am not going to replace the points or condenser. Removed the lighting coils, installed blank cores for 95 model Combat Wombat and ready to go.
Danny

[dcooke007]

Cleaned up the center cases, inspected and found the not so unusual broken shifter cover lug. At least it is not broken completely and still there.

Have not seen this before. Spiral pin for the clutch lever has been replaced with a screw and done in such a way that the case is cracked.

Self locking nuts and heavy duty screws installed...which is a good thing. The bad thing is the steel plates were not relieved where the screws go thru causing binding.

This steel plate is actually broken and may have been caused by the lack of clearance between the fastener.
Danny

[dcooke007]

This is 5th gear and you can see the groove worn where the control shaft ball rides. This gear will have to be replaced and I looked for a flattened control shaft ball but found none. I suspect the gear was reused in a prior rebuild and the balls replaced. I am going to replace this with a 19 tooth model 94 rather than the 20 tooth combat wombat gear.

This is the interior of the clutch pinion gear. The pinion gear bushing did not have the same wear pattern, was in good condition and obviously replaced. At this point new replacement straight cut pinion gears for the combat wombat and super combat are not available. The moderate scoring to this gear can corrected and reused. My machinist buddy will use a Sunnen precision hone to remove the raised / galled metal and not enlarge the gear appreciably. Any minor remaining pits will hold oil and have no detrimental effects. I will post a pic when completed.

Most folks tend to look at the shifter ratchet teeth and fail to notice wear in these areas of the ratchet and shifter guide arm. This much wear I consider excessive...particularly the shifter ratchet. Any excess wear in the shifter components adds clearance and lost motion when the shifter is operated.

[dcooke007]

The fractured shifter mount stud on the left engine case broke off completely with a small amount of pressure applied with my finger. I am sure there are several ways to make this repair but this is how I did this one. Other breaks may require a different approach. I drilled the case all the way through and tapped 6 x 1.0 mm. Fabricated a screw in insert from 1/4 inch aluminum stock also threaded 6 x 1.0 mm. I filed a small amount of material from the broken stub to apply the weld filler.

The 1/4 inch threaded aluminum insert was a good fit through the screw hole of the shift cover. I was very close with the location of the drilled hole but not quit perfect. A light tap with a small hammer aligned the broken stub properly. I left the broken stub a little high so it can be machined flat with the mounting surface. At this point the broken stub is ready to tack weld, remove the shifter cover and complete weld. This will have to wait till later and I will follow up with pictures. Also I plan to install a heli-coil to restore the threaded hole.

Danny

[viclioce]

Way to go Danny! This is one lucky guy for sure! His ride is gonna blow folks away when you're done with it! Great pics too! Keep us posted as you go! ; D Victor

[hodakamax]

Thanks for your posts Danny, I always like your projects and innovations.

Max

[DGardner]

I fixed my case along the same lines as Danny is doing and now have about 7000 miles on it. Thanks Danny for posting the photos of your build. DG

[Zyx]

are you folks using TIG or MIG to weld the case?

[dcooke007]

Tig

[Zyx]

Must be nice.

[dcooke007]

Other projects have been keeping me busy but did get some time to accomplish a few things. It only took a couple of strokes on the Sunnen Rod Hone to remove the raised metal inside the pinion gear. You can see some of the remaining pits that will hold oil and have no effect on the pinion bushing.

Welded the clutch cover and drilled the hole for the spiral pin. Doesn't look to "pretty" but will do the job.

Welded the broken shift cover mount, removed excess weld and installed heli coil.

Danny

[danwarren77]

Looking good

[DGardner]

Danny your work is just amazing! Thanks for sharing with the group. DG

[dcooke007]

A little more accomplished today.

This engine was already at .060 bore and I do not like larger cylinder bores. My concern with large cylinder bore is how thin the spigot / cylinder extensions get. I have seen some of these crack and brake with extensive damage. So with that in mind I spoke with Dan and we are going to use the existing piston and rings. Piston is in good condition with .003 piston to bore clearance that should be appropriate for this old school Wiseco piston. The piston shows little wear and I do not think it has much run time on it. Piston rings end gap is .008 inch and both rings are in good condition. With all that in mind and that this piston has been run in this cylinder I am comfortable using it. The alternative would have been to find a replacement cylinder or plating the cylinder bore and a new piston and ring kit. At a later date, if required, removal of the top end can be done and other options performed.

The air filter has some issues and the piston had some minor dirt scratches. A little polishing with 600 grit and then moly coated the piston skirt. You can see there is no horizontal port for the victory porting and it is a two ring piston. Although the piston would work as is some performance loss would occur with out the horizontal piston port. With that in mind I located the bottom of the horizontal port and verified location with a used super combat piston. My thoughts were to create two small ports the width of each vertical leg of the victory port and regain some level of victory port function. The area underneath the bottom ring is very thick and I angled the port opening down to prevent removing excess material from below the bottom ring. Also by using windows instead of a slot more material remains to support the lower ring. Any way we will see how this works.

And this concludes the days work.
Danny

[Zyx]

The piston pin and bearing will thank you. The windows appear conservative.

[dcooke007]

GMC,

The port windows are on the conservative side. The combat wombat is a piston port engine with a blind boost port cast in the cylinder above the intake port. The location of the horizontal port on the factory combat wombat piston is in the same location as the factory super combat that was used to verify my measurements. The bottom of the horizontal / window ports on both pistons pictured matches up with the bottom of the victory port with the piston at bdc. The height of the window ports on the modified Wiseco piston is shorter than factory spec due to the two ring piston. So no need to go lower on the ports and the bottom ring prevented going any higher. I probably could have gotten away with a single slot all the way across but erred towards caution. Dan is not a full blown racer and this should work well for him.

Danny

[bchappy]

In the late 60s (before I started playing with reeds) I was grinding slots starting beside the intake port on each side and curving over the intake port (similar to the Victory port on the Combat Wombat.) I was drilling holes in the piston to match the ports when it was at the bottom of the stroke. It was called a 5 ported Hodaka. It was a noticeable performance increase. Yamaha had it and when I saw their cylinder I decided this could be done to the Hodaka. I am sure a lot of old timers were doing that back then, but I have not heard it talked about in a long time,

[dcooke007]

Bill,
Sounds like a good idea to me. Do you have any pics you can post?

Danny

[bchappy]

Sorry Danny, I don't have a single picture of my work as all we had back then was a Brownie Hawkeye camera and I think the reason we didn't take many pictures was it just cost too much to buy the film and have them developed, and maybe we didn't realize we would ever want them. Plus it was all secret stuff that we didn't want to show anyone else. Maybe I can draw it sometime today.

[viclioce]

So how will this ported piston work compared to the one next to it in the pictures with the additional lower ports? Just curious. ; D Victor