The Hodaka Club Forum

I hope you all are doing well. I have questions about next year's vintage racing.

This year my stock 95 (upgraded suspension) and I got smoked all season in the vintage MX 125 class (non ARMA, just for fun). I enjoy the group I race with and would like to stay in the Vintage 125 class, so I'm pondering next year's options to be a bit more competitive. I don't need to crush the other dudes but it would be nice to be more in the mix. I'm usually racing against 1974 YZ, Elsinore, Husky, and a crazy fast Super Rat.

I know these options don't have anything to do with my ability or size. I'm mostly asking how would you go about being more competitive on a Hodaka.

These are the options in my head and would like to get any input you may have.

Option 1:
Keep my 95 and send it's engine out to get ported and reeded. Would this be a big change? Maybe purchase one of those super expensive HT pipes??

Option 2:
I have the option to purchase a Super Combat engine. Can this be put in my 95. I don't know if this is possible or a good idea.

Option 3:
I have an option to purchase a Super Combat, but it's in boxes and kind of pricey. I have no problem working these bikes but not sure it's worth the risk putting big money into a project that once completed won't be that much different than what I have already.

Option 4:
I find out that Super Combats are much better than Combats and I spend my time until next season looking for someone with a Super Combat willing to sell, or trade for a "Super Ace" and/or Combat.

Option 5:
Sell the race Hodaka's and look for a different 1974 bike to race. This one makes me a bit sad, one of the highlights about racing my Hodakas is all the Hodaka story's I get to hear.


So in summary, how would you go about being more competitive on a 125? Go Super Combat, upgrade Combat, ditch them both and go with something else.

Looking forward to your thoughts
Jay

Option 2. (Engine is a "bolt in" swap.) You'll have some details to work out with larger carb and air cleaner connection. Exhaust system you choose will also have a MAJOR effect.
Ed

PS: Running reeds in AHRMA 125 Class will put you with the fast guys.

Thanks Ed - I race in the PNWVMX where it's very relaxed. I like to stay away from the AHRMA fast guys.

. . . just so you know my true colors - option 5 borders on being blasphemous to me.
Ed

I have found the Hodakas to be very competitive against the other brands. My MX model is top shelf but has all the mods, but even my slightly modified Road Toad has won against all brands at the highest level.

Ed - I hear you.

Pop - Can you share the Mods you have on your bikes? I currently only have upgraded the suspension on my 95.

I can only offer up teensy bits of info right now, since I'm off to the wilds of Idaho with my smartphone and I'm borrowing a Starlink connection to the world. The easy to type stuff is suspension - Progressives (14.5") at the rear, forks/triple clamps from Wombat 03 (stock, I've ridden 03 forks with emulators and didn't perceive any significant difference). Engine stuff in a few days . . . tho I will note that I'm still piston port to stay in AHRMA Classic class.
Ed

Re cutting the combustion chamber to a more modern design yields great results at modest cost.

dcooke007 wrote: ↑Mon Sep 09, 2024 2:17 pm Re cutting the combustion chamber to a more modern design yields great results at modest cost.

Super Combat 2.jpg

That looks like the Singh Groove modification upped to the Nth degree. Singh Grooving would typically be four kerfs placed like compass points (centered bowl chamber) and their function would be to increase flow of compressed gases into the squish band for more complete combustion,

With an offset combustion chamber grooving would likely only be effective on the exhaust port side of the combustion chamber,

In the example shown in the photo I suspect that the total surface grooving would soon be rendered ineffective by carbon buildup. Post modification compression ratio would be a tad lower too. Also the grooving within the combustion chamber bowl doesn't appear to have a purpose if it's expected to direct flow to the squish band at any rate, although it might have a function that I'm not realizing.

Better picture attached. Not Singh groove or anything related. Much more going on here.

100cc Road Toad head. Combustion chamber re-designed and machined for 125cc Combat / Super Combat engine. Late model 100cc heads share the same bolt pattern and casting as the Combat / Super Combat Wombat. The 100cc combustion chamber is much smaller and leaves more material for machining and remaining mass. Super Combat heads can be modified this way but less mass will remain. Modern squish with .8mm piston to head clearance. Total combustion chamber volume more centrally concentrated. Combustion chamber volume a few cc's less than Super Combat head. Chamber designed for premium pump gas. Chamber design less detonation potential and more efficient combustion.

I have two of these heads and the machining is impressive. Chamber volumes are exactly the same. You can barely feel the "groves" when running your finger over the chamber. Not sure what purpose they serve .. it is a secret. One installed on a reeded Combat Wombat. Engine runs cleaner / crisper. More torque and able to run in higher gear where before would have to down shift more. Operates better all the way around. Running a little less timing as combustion process is more efficient. RK Tek performed these modifications and well worth the expense....$150ish. Even Harry Taylor's instructions included cylinder head modifications.

Unless you have a ton of excess energy while racing the close ratio transmission in the 97 motor will wear you out. I could never tell if I was in the wrong gear, spinning the rear wheel or slipping the clutch. All 5 gears are very close together. I would put the SC cylinder, piston, reed cage and 32mm carb on the 95 as a package. The jetting should be close right from the get go. Its a straight up bolt on. An H3 pipe and some down home engineering to figure out an air cleaner setup and you have a wide ratio Super Combat that will curl your toes. The CW exhaust is very good, but it puts the carb very close to the pipe and interference issues are many, as the reed cage and bigger carb are a bit longer. You can do all these mods without even taking the engine out.

I don't know about the SC transmission ratios "wearing you out" -- but from an old endurance racer viewpoint, I kind of find the first, second, third, third, third ratio spread to be kind of frustrating. (But I guess true MX racers like that.)

Ed

As a senior rider, not only did I find the close ratio physically tiring, I found it mentally tiring. Trying to remember which gear I was in coming out of a sand corner or landing from a table top took away from my concentrating on the track.. These were 30 minute motos. and the looser the track the harder it was. The more power the bike made compounded the issue. With Rich Gagnon boost porting, an HT3 pipe,, a 34mm carb with 3 vanes and a modified single petal reed cage, these 125s can be screamers, but first, second and third gear felt and sounded the same. I bet I shifted 3 or 4 times as often with the SC transmission. In our area we raced mainly sand tracks. If we raced grass tracks or loamy tracks, I probably have leaned toward the close ratio.

I would find a Super Combat and build it. The main purpose of a Close Ratio Trans is to keep the engine revving with minimum RPM drop while shifting through the gears. The bigger the Engine, the less of a need for a Close Ratio Trans. Watch NHRA Pro Stock Cars run. They have Close Ratio Transmissions so they can keep the Engine revving at 10,000 RPMS with virtually no bogging between shifts. Get two Super Combats built identical BUT one has a Close Ratio Trans and one has a Wide Ratio Trans. Race them side by side for 600 feet and the one with the Close Ratio Trans will get there first. Joe