M94 Transmission issues

[Bullfrog]

I thought I might be pushing it to use the b_ _ ch word in my previous post, so I went with "grumbling". But now you know what I really meant.

Just out of curiousity, where in the heck on the RPM band is your shift point??

Ed

[matt glascock]

You're a much classier person than me, Captain. In this case, I thought it was the only worthy verb option to describe a guy "fussing" about a 10K+ bike he bought as a "play bike", and for about a nickel per RPM. Shifting at 7200 - 7400K. BTW, I did check the motor mounts. All A-OK.

[ossa95d]

Glad to hear that the problem has been rectified. I guess we can assume that one or all of the changes that you made collectively addressed the issue, but in summary it seems that the problem was either fuel delivery (addressed by the mods that you made) or point float (addressed by the racing points). Doesn't matter at this point as long as it's running great!

[matt glascock]

Thanks Pop. You are correct in that I didn't adhere to any scientific process in the set-up. A 60 degree day in December means seat time and more seat time. I would not be surprised if all maneuvers played at least a bit part role in sorting out the fade issue. Its one of those situation where I'm happy to accept success without question to the method . Thanks for your input.

[Hydraulic Jack]

10,200 rpm from an iron bore Wombat isnt science, its amazing. As far as lacking low end, I am not surprised given the top end. But you might be able to have both worlds. I would contact Rich Gagnon at Rich's Taylor'd Porting and discuss a Venturi vaned 28mm Mikuni. He posts here as Racerclam. Might very well get some of your low end grunt back as well as a solid high end. The Venturi vanes do work when using a larger carb on a ported cylinder. We didn't know this stuff back in the Hodaka days, but we do now. Might also ask about torque grooves on the cylinder head. (Edited. Not the piston. Pop is right, and I wasn't thinking. Must have been late.)

[ossa95d]

Jack, I have seen torque grooves on a head but never on a piston. Is that really a thing or did your typing fingers get ahead of your thoughts?

[matt glascock]

Jack, I do have a VM 28 (no vanes). Maybe Rich could fabricate and install the vanes. I'm a bit concerned about running lean right now although if that was the case I would likely have blown the motor by now. I also considered a VM32 but it runs well with a stock carb. The 28 is probably the way to go. I'll look into it.

[Hydraulic Jack]

Rich can modify your carb, and I think he usually works with your equipment rather than starting with an off the shelf carburetor. He has a website showing his many services. Note, carb vanes look simple, but they aren't. It is easy to do wrong, and not easy to do right. It would be nice if this were an inexpensive modification, but it takes literally hours (all day or more) to do carb vanes. On the other hand, they work. Largest benefit would be getting back bottom and mid range torque while not affecting top end.

If you are worrying about running lean, you could consider an Intelajet, which allows adjustment of main jet mixture while running. Find out if they can be mounted on the VM28 but I think they can.

[racerclam]

thanks jack for the vote of confidence. I do mods to existing carbs as well as new. Most will go to bigger carbs since the dividers make a big carb behave small. Intelajet can be used on any carb. AS for venture dividers there has even been gain in top end , verified on dyno , one of my road race customers with RD400 had noticeable improvement in out of the corner acceleration and when he ran on dyno had a one hp gain all the way up

Rich

[Hydraulic Jack]

Perhaps I should have said the dividers will not sacrifice anything on the top end (I don't doubt the gain but don't have a dyno).

What I do know is that the dividers on a stock 32mm Mikuni on a stock Super Combat took an MX bike with no guts in the mid range, unrideable in the woods, and made it a terrific woods bike that will also pull third gear berm shots in MX without fanning the clutch, with no other modifications to the engine. I can't say that the low to mid range is more than your average woods bike would have, but it is now totally usable, pulls hills without screaming, and does what it needs to do. Wish I had this set up back in the early 70's when I was racing Hare and Hound. The Bad Rock trail ride at Hodaka Days was no problem at all with no changes to gearing or jetting, even though I was set up for the MX event.

[matt glascock]

Hey Rich and Jack, This carb mod really interests me. The big question now would be if the VM28 or VM32 would be the best candidate. Mind you, it is currently running a stock carb with a 240 MJ. This bike performed well in a hare scrambles this fall but looking back, I made all my hay on the MX track integrated into the course and the woods riding was relatively open including about a half mile of sand along a river bank where the bike was right at home and just flew. I can predict that the current set-up would totally suck, right up until the motor explodes, on a tight/hilly single track course which is pretty standard around these parts. Thoughts? Thanks fellas!

[Hydraulic Jack]

Rich will have a better idea of which carb will best fit your needs. My thoughts are that the 28 might do everything you want. If I was faced with constant tight stuff, hills and sand, I would probably drop back to an 03 cylinder mildly ported with the 28 Mikuni to try to get more midrange and low end power, even if I gave up some on top. Since you have the 28, I would start with that.

If you get to the point of pulling the cylinder, map out your porting. Use a rolled up sheet of paper and trace your port openings with your finger. This will leave impressions in the paper. Then firm up the impressions on the paper with a pencil or pen. Beats trying to measure things down inside.

[Hydraulic Jack]

Something else that will help with mid range power would be reed valves.

[racerclam]

Agreed Reeds are always a good thing as long as your allowed them in your class. I do have Reed to fit the Iron wombat cylinder. And yes an o3 cylinder would be better , but I can do much to help the Iron cylinder. I would Like to know if anything is done to your currant cylinder and what you are using for a pipe?

Rich

[matt glascock]

Hi Guys, That's what I was thinking, Jack. The 28 would be my guess as it runs well with the 26. I think adding a reed cage would give me more usable power. Most likely, the bike will be used for enduro/hare scrambles unless I completely redo the suspension although a couple MX tracks I run basically use a supercross style track bypassing the do-or-die doubles/triples, rhythm section, etc. I have a piston port CW for classic class, but since there are no AHRMA events around here, I mostly race in open class vintage events around here where year and displacement are the only qualifying features. Rich, the jug was modified. The owner of the bike had it set up for desert racing - H&H and some hare scrambles according to his son. He PO can no longer talk because of a stroke. His son who sold me the bike told me it was ported, but the PO did his own work the build/spec sheets are long gone. Just looking with an untrained eye, The exhaust posts were raised and the transfer ports have had work as well. The cylinder looks like it has maybe one overbore left as the piston crown is stamped +6. The pipe is manufactured by "JR Powerpipes" which is a long defunct SoCal power house that I can not find any information on. It looks like your typical vintage aftermarket performance pipe. It has a nearly worthless glass pack silencer. I can easily map out the dimensions if you'd like. Thanks for all the help/input guys!!

[Bullfrog]

Interesting description of the engine. A couple of notes - 24mm carb was stock on the iron barrel Wombats, so the 26mm unit you are running is already an "upgrade" . . . and you can't simply bolt on a reed manifold (with reed cage and reeds) to run a reed valve. Some additional cylinder porting is required to incorporate a reed induction system.
Ed

[matt glascock]

Thanks for clarifying that carb detail, Captain. I forgot the M94 was fitted with a VM 24 in stock trim. I'm kicking around the thought of converting to reed induction for more usable power and that brings up the possibility of changing to an 03 top end. With probably one overbore left on this jug, I'm not too sure how involved to get with it in terms of porting anticipating a limited life expectancy (of the cylinder ). I had Charley Brown at Superior Sleeve sleeve my 78.5 RM250 C2 which works well, but was a bit spendy. Here's a reasonable question. If it is even possible, how much is involved in retrofitting an 03 top end to M94 cases. That might be the way to proceed.

[Bullfrog]

03 cylinder is a "bolt on" to the model 94 cases . . . so you need a torque wrench. OK. OK. There are other details - fitting up a carb and air cleaner, fitting up the pipe, proper head and compression, etc. But cylinder is a "no sweat bolt on".
Ed
PS: Just please, please don't get an oh-3 cylinder then have it ported into being a Super Combat cylinder. An oh-3 cylinder is a terrible thing to waste.

[matt glascock]

Ha Ha. Torque wrench, eh? Hmm...where did I leave that?... No...that's a Dremel...Hmmm...No...that's also a Dremel. I like the sounds of the 03 head. Most of what you describe is pretty basic fab work so no problem there. I have a line on an 03 "parts bike" so I may be in good shape for the conversion.

PS - 03 heads are getting rare as hen's teeth. I might snuggle with it, but I wouldn't cut it.

[Bullfrog]

. . . a little TIG work, a little lathe work . . . and any cylinder head from any alloy cylinder Hodie 125 can magically become the cylinder head for any other alloy cylinder Hodie 125.

But an 03 cylinder with 30mm exhaust port height can never be as sweet again after the exhaust port has been raised to 26mm like a Super Combat.

Ed

[matt glascock]

Word Brother. I'm making a play for the 03 tomorrow. Fingers crossed it is not thrashed. The owner says the motor is "stuck". Who cares. The cylinder is getting bored anyway. Sad face/head shaking rehearsals underway.

PS- Captain, could you give me a quick rundown on your main race bike. I'm most interested in engine, exhaust, ignition, and suspension mods and anything else you've changed/upgraded. If you have the time. Thanks.

[Bullfrog]

It has been suggested that I do a Resonator Revisited article about my "race" scooter. Among the neatest things about it are:
1. I rode this rolling chassis in the mid-1970's in a few ISDT Qualifier events (frame/wheels)
2. The machine was sold off when PABATCO closed the doors.
3. Somehow it spent a few decades in the possession of our own Hodaka Days Race Track Marshall, Thal Anderson.
4. Thal noticed some semi-odd things on the machine and called me to see if I knew anything about the oddities. As the conversation continued, the evidence mounted that he was talking about the first machine I assembled out of parts after hiring on at PABATCO.
. . . AND THEN . . .
Thal gave the rolling chassis to me! As we used to say in the last century, he is a gentleman and a scholar!!! At the time we agreed that I'd "owe him one", . . . and I still do.

So, a quick glance over - Model 03 forks matched up with 14.5" Progressive shocks. More-or-less stock piston port cylinder (OK, OK, not quite stock), standard cylinder head/compression,stock 28mm flange mount carb with one flow straightening vane at half-throttle position, stock ignition, custom expansion chamber. CW primary gears, Model 94 transmission. AND Model 94 luggage rack (allows me to have a nice fresh drink of water on the MX start line on hot days - you won't believe how well a garden variety bottled water tucks between the bars on the luggage rack! Usually, the water bottle will stay in place thru a whole moto - and I can also have a drink right after exiting the track! )

Ed

[matt glascock]

Thanks for the rundown, Captain. A RR write-up, with pictures, would be great. Its effectiveness as a race bike is only equaled by the coolness of the back story. Did you start with a 94 motor or is it a 95 motor with 94 transmission? Also, do you have the build sheet/dimensions on the chamber? Just looking at a couple Go Pro vids you've posted, it seems to get on and stay on the pipe over a greater rev range that my piston port CW. Great bike. Thanks Captain.

PS - The 03 deal was a bust. One fork was destroyed, the bike was obviously in a flood, the head was missing a half dozen fins and was cracked to boot. The motor wasn't "stuck", it was consumed by rust AND he wouldn't budge from $750. Someone has been watching American Pickers again.

[Steve Arnold]

Matt, what piston does the hot Wombat have, is it original heavy two ring stock, or something else ?

[matt glascock]

Hi Steve. No, its a single Dykes ring piston.