Tired Combat Wombat

[dcooke007]

Local vintage racer, Will Gahrmann, dropped off a very road weary Combat Wombat to prep for the up coming race season. We are focusing on getting the bike to run, brake and handle as well as possible in the short time remaining before the first event. Appearance is not an important factor at this point although new plastic fenders and plastic Strictly Hodaka tank will be installed. The engine is partially rebuilt at this time but I think I will start with the fuel tank installation.

The aluminum bar supplied with the tank originally only had two holes on each end and would rest against the lower frame bar with out any mechanical connection. I thought a better way might be possible and after a visit to my local True Value Hardware this is what I came up with. The u clamp is 1 1/4 inch, added some flat and lock washers and a piece of 3/4 auto heater hose. Located and drilled the two additional inner holes for the u clamp.

Installed some 1 inch pipe insulation on the main frame tube. Next put a few wraps of electrical tape on the lower tube and mocked up the heater hose, u clamp and aluminum bar. Trimmed excess length from threaded part of u clamp.

Fuel tank and front fender install completed.

More to come.
Danny

[dcooke007]

I noted the front fork compression was very light and the forks wanted to stick when compressed. There is some pitting on the fork tubes but not in the area the fork seals bear against. Removed forks to rebuild and found the seals in pretty bad shape, rusty springs, plugged up valve passages and bent fork tubes. I went over to my buddies machine shop and we used the hydraulic press to straighten the steel tubes. Cleaned all the parts and glass beaded the fork springs. At first glance it looked like an 03 Wombat front end had been installed but it wasn't. The triple trees are 03 Wombat but the forks appear to be from a 1974 Yamaha MX 250. The internal construction is similar to the late model Hodaka forks but the axle mounting is a little different. Also the fork caps were modified and equipped with air valves that were in very poor condition so these were removed, drilled, tapped and plugged. Assembled forks with new seals and re-installed on bike. I decided to use 6 ounces of 20 weight fork oil in each tube as a starting point. This has worked well in the late Hodaka forks so hopefully will work in these also.The forks now feel a lot stronger with no binding. At the end of this season a new set of forks will be acquired.

Removed the triple trees, inspected and greased bearings also. Sorry but I did not take many pictures due to the dead line I am working against.

Danny

[dcooke007]

Engine is in need of a lot of help also. Although this is a Combat Wombat engine with a GEM reed valve added, the piston is a .040 Wombat with no reed port holes. The cylinder intake port also has not been modified to take advantage of the reed valve.

This is interesting.

Galled countershaft.

Galled first and second gears.

Cracked right engine case. Crack is in the clutch side of the case.

Danny

[dcooke007]

Used a late model clutch cover as a guide to drill cover. Rebuild and safety wire clutch.

Danny

[BrianZ]

I always enjoy your posts Danny. Nicely described and photographed.

Brian

[hodakamax]

Hey Danny--Looks like you have you work cut out for you! Good post and keep them coming!

Max

[dcooke007]

Broken insulation would be one reason there is no spark.

Surprisingly the crank was not to bad. Replaced the thrust washers, bearing and pin. Trued crank. There is some minor pitting on the shafts but not enough to cause a leak or seal failure. An NOS crank has been acquired and will be installed next season.

Welded cracked case.

Replaced the galled gears, countershaft, bearings, seals, etc.. A moly coating has been applied to the gears and shifter components.

Danny

[dcooke007]

The intake tract on the Combat Wombat cylinder is fairly restrictive as well as the GEM reed cage. For the time available a little work here is worth the effort.

To allow the engine to breathe better I matched the intake port to the reed manifold opening. Also as you can see I opened and blended the reed passages. No other port work is going to be performed other than matching case and exhaust ports.

Danny

[Zyx]

Can you explain the moly process and product please? Sounds interesting.

[hodakamax]

All cool Danny, I'm taking all this in. Keep up the good work and posts!

Max

[dcooke007]

GMC, a link to the KG Industries product page is listed below. I use Gear Kote on piston skirts, gears and shifter components. Sometimes use it on non exposed fasteners such as the cylinder head studs on this engine to restore corrosion protection. The parts have to be cleaned / oil free and with some parts pre heated to drive out oil trapped in the metal. Parts made by the powdered metal injection process are especially subject to retain trapped oil and some of these exist on Hodakas. After cleaning parts are blasted at 40 psi with 120 grit aluminum oxide and re cleaned to remove blasting media. I then coat the parts using a detail auto spray gun with a 1.0 tip. I also have a Paasche air brush that I use sometimes in very tight areas. After coating the parts are cured at 325 degrees for one hour. After curing all KG products are impervious to carb cleaner, mek, acetone, etc.. If the metal is porous like the clutch pinion bushing I would expect more moly will be retained in the pores of the metal. If the metal is not so porous it may only serve as a good break in lube. I particularly like using it on close fit piston skirts to provide some protection against scuffing until the engine is run in. This engine will be coming back to me at the end of the season and the coating can be evaluated at that time.
http://www.kgcoatings.com/products/dry- ... -gear-kote

I also use KG products to coat the engine cases, covers, cylinder, head and other parts. The center cases on this engine have a satin clear Gun Kote finish applied for appearance and protection. As stated it does not come off when carb cleaner or other chemicals are spilled on the surface. Also it is easy to clean since it is not easy for material to stick to. I use silver on the head, cylinder and intake manifold. Brushed stainless is used on the clutch and shifter covers. I sometimes use silver on the engine center cases if they are in particularly poor condition. I have developed a different finish process for aluminum. When aluminum is blasted with 120 grit aluminum oxide, even at low pressure, the surface of the metal has a slightly rough texture that Gun Kote can not fill.....since it is a thin film coating. This in turn leaves a rougher coated surface finish than desired. During my days in the Navy we used an aluminum conversion chemical on bare aluminum aircraft parts before refinishing them. This conversion coating was to provide corrosion protection and provide a surface that was suitable for paint adhesion. PPG makes aluminum metal prep chemicals that provide the same type conversion coatings. So with aluminum I glass bead the parts to clean and get a smooth texture although glass beads are not recommended by KG. The parts are cleaned to remove blasting material and PPG metal prep chemicals are used to condition the aluminum for coating. With this process I have a smoother finished surface and no problems with adhesion.

Danny

[Zyx]

Thanks. Not yet equipped to do all that but I will look into it. Don't have a media cabinet, just an outdoor blaster, but I do have a small toaster oven that will heat small parts. I used our oven once back when I was younger to heat a cylinder for sleeving and I still hear about it 40 years later. I assume the thickness of the coating does not create clearance issues on technical parts.

[dcooke007]

A media blast cabinet is a must....media cost to much to not use it several times. The coating thickness is from .0003 to .0004 inch. The only part that has an interference fit issue is the left countershaft bearing. The fit of the bearing and shaft is close. Masking this area when applying or going particularly light with the coating in that area addresses the issue. For small parts a large convection toaster oven will work.

I am still working on perfecting my process for the ceramic thermal coatings applied to the piston crowns and combustion chambers. The ceramic coating is water based where as the other KG products are solvent based. The water based product sprays kind of funky.

I can coat engine parts for you if desired. There are several members on this forum that have used my services to rebuild, restore or refinish.

Danny

[dcooke007]

A little more work completed on the engine today. Top end installed and pressure tested.

Danny

[rough rider]

Nice, neat and clean work Danny. Those small details add up to a reliable motor. Richard

[Zyx]

Don't make it too nice. I may have to race this guy some day.

[dcooke007]

Thanks, Richard. GMC we are on the east coast so I think you are safe.

Danny

[hodakamax]

Wow Danny, your project is coming together nicely, keep up the cool work! I like your line of thought of doing it right.

Max

[dcooke007]

Received some parts for the bike today and pulled the flywheel to install the lighting coil. The bike will have headlamp and tail lamp and maybe brake lights.

Engine completed and ready to install.

Danny

[dcooke007]

With the engine completed it is time to address the wheels and brakes. Tried wire brush and scotch bright pad but could not remove rust and paint on brake drum surfaces. So decided to use my portable sand blaster. Removed the bearings and blasted the drums with very fine sand from our local Agri Supply store. Wiped brake drum with Evapo- Rust to prevent flash rusting until bike is usable. Front brake drum is pitted but still usable for now. Rear drum actually came out pretty good. Removing the rust and paint keeps these contaminates from getting in the brake shoe pores and reducing brake performance. Replaced the bearings and moving on to the next item.

Front brake backing plate is worn on the axle shaft bore and does not fit the front wheel properly. Replacement backing plate coming.

Thought I was on the down hill run with this bike but new problems keep cropping up. Front wheel and forks are a patch work of parts from who knows where. As mentioned forks appear to be Yamaha, wheel hub appears to be from one of the 250 Hodaka's, brake backing plate????? and matching these up so they will work together is taking a lot of time and effort.

The rear wheel looked like a standard run of the mill Combat Wombat.....but not. Installed the rear wheel and noticed the new rear fender I installed did not line up with the center of the wheel. I was thinking I know I carefully measured and drilled the holes for the fender. Did a little checking and found the rear wheel was off center quite a bit towards the sprocket side. With the axle tightened the wheel rotates properly. I did replace the sprocket side spacer and seal and looks correct. I have a 03 Wombat and pulled it along side to compare. Compared the right and left rear axle spacers and they are the same length. Both models use the same 949290 left and 929289 right spacers. Checked the parts diagrams and noticed the Combat Wombat used a combination of mdl 94 and 92 sprocket flange, drum and brake backing plate. The 03 Wombat uses mdl 99 and 98 sprocket flange, drum and backing plate. The rear rim is aluminum and may be some one used some 03 parts. Rather than try to figure out what parts are on the rear wheel assembly I can simply shorten the right side spacer and space out the left one to center the wheel. I spent a good deal of time trying to figure out what was going on so no pictures at the moment.

Danny

[dcooke007]

One of those days today but did manage to make some progress. Working on the rear wheel alignment and what a mess. Contrary to what I had stated I began to thoroughly check the bike over looking for the root cause of the misalignment. Removed the swing arm and checked for any bends but proved to be reasonably straight. Checked swing arm bushings and they also were good and flush with frame. Since the wheel needed to move to the right I considered driving out the right spacer and trimming the swing arm tube but after thinking it through I decided not to. A lot of time was spent checking parts and I am back to my original thought of moving the wheel right by working on the spacers. Will has never rode this bike and the modifications are not his doing.

The first picture shows the wheel assembly that was on the bike and how far to the left the alignment is off. It could be at least one reason there is no chain guard on this bike. I pulled off my 03 Wombat wheel and in the second picture you can see I have the same results. No real surprises there just wanted to make sure I had not missed something on the original wheel.

Installed the engine, original wheel and chain to check alignment. As you can see the engine sprocket and rear sprocket appear to be in alignment even though the wheel is so far off to the left. This complicates things because if I move the wheel right now the two sprockets are out of alignment. Time to take a short break and search my attic.

I found another 03 Wombat rear wheel assembly and compared the sprocket carriers. The first picture is the sprocket carrier from the original wheel and the second one is from the 03 Wombat. It might be hard to see from these pictures but the sprocket location on the 03 carrier is further left than the one on this bike. All other dimensions appear to be the same except the bearing spacer that goes between the carrier and wheel. I decided to use the 03 carrier and bearing spacer and see what that would do for me.

Scratched my head for a little while and went looking for my plumb bob. I could not find it but did find my chalk line.... and now you are thinking this bike has finally got the best of Danny. I needed a way to check the wheel alignment and string was what was called for. The rear wheel needs to be reasonably aligned with the front wheel for good handling. I loosened the center triple tree bolt sufficiently to allow the string to freely pivot and center on the bolt. This should give a good reference point for alignment. Fished through my tool box and found an assortment of washers and spacers. I tensioned the string and centered it along the main frame bar for a reference point. After some juggling the spacers around I think I finally got it.

Installed the chain and lightly tensioned it. Looks like that is good too.

[dcooke007]

You can see the assortment of spacers required to center the wheel. Monday I will measure the washers / spacers and make a proper spacer for both sides. Four washers approximately .120 inch each were added to the left side and the same amount removed from the right. I am still not sure what was changed on this bike to require such modifications. I do not have any other Combat Wombat parts to compare. In the end using the 03 Wombat carrier and spacing out the wheel allowed the sprocket and wheel to align properly. Might be able to add a chain guard now.

Danny

[BrianZ]

Danny, I measure the right side spacer on my Combat Wombat and it is about 1.1". Is there any chance someone has played with the spoke adjustment on your Combat Wombat to bring the wheel out of center?

Brian

[Zyx]

In the photo, the chain looks slightly canted. Is chain alignment correct? If everything else is right but the sprocket needs to shift out by a quarter inch, you can make a spacer for the sprocket. I have used old used up sprockets and just cut the center out, placed between drive flange and sprocket. Some earlier models actually came with a spacer under the sprocket. Just a thought.

[dcooke007]

Brian, thanks for the info on your Combat Wombat spacer. That is the same as I have on this bike. The nice thing about Hodaka's is some of the same parts are used on several different models. The rear wheel spacers on the Combat Wombat and the 03 Wombat are the same. So that base has been covered. The brake backing plate "looks" correct and I "think" the sprocket carrier is correct. At some point in the history of this bike much has been changed. Will does not need it correct just reasonably competitive in a short time frame. I did check to see if the rim is centered on the hub and it is. Unless the rim is supposed to be off set? Thanks for your input.

GMC, the sprockets appear to be properly aligned but the input about shimming out the sprocket is a good idea. In this case it is just easier to swap out the sprocket carrier. I do have some sheets of shim stock and had considered making a shim if required for small adjustments. Thanks.

Danny