94 Wombat tuning help needed

[Tether]

Earlier this year I picked up 3 model 94 Wombats. The first one is done, runs and looks good. I’m now working on the second one and I just can’t get it to run right.
Starts good, idles fine and runs good in the low end then flattens off in the middle to top. Smoking a fair amount in that range.
Here is what I know:
It is what appears to me to be a enduro/cross top end with reed valve.
Compression 150
Timing spot on
Spark crisp
Plug new b8hs
Exhaust system clean
Air filter clean and lightly oiled
Fuel non ethanol premium, Yamalube 2R at 32:1

Carburetor:
28 Mikuni
Main. 210
Pilot. 45
Needle jet N8
Jet needle 5F3 on 3rd slot from top
Slide. 2.5

I believe the carburetor is clean as I have been through it a few times.

I don’t have a great place nearby to really run the bike but I did the best I could to get a full throttle plug reading, pictures below.
Any ideas/advice on where to go from here is appreciated.

[Bullfrog]

I need a bit more information prior to attempting long distance diagnosis.

The enduro/cross kit had a Combat Wombat alloy cylinder modified for reed valve induction, is that what you have? (Yes, I know you said you think that is what you have . . . there is no information to confirm it.) Do you know the measurement from the top of the exhaust port to the head gasket surface? Did you happen to take any photos of the porting?

What exhaust system and what air cleaner are you running?

Ed

[Tether]

Exhaust and air cleaner are stock wombat, except that there is no snorkel on the air cleaner.
It is the alloy cylinder with a reed valve. I did pull the cylinder but I did not take any photos or measurements. It does have the reed valve piston (.30 over) I will pull it again and take the measurements and photos. I was aware that different porting was required so I probably checked but can’t say for sure.
thanks

[Tether]

As best I can measure the top of the exhaust port to the top of the cylinder is 24-25mm.
Pictures of porting and piston.

[Bullfrog]

The stock Wombat pipe is probably the limitation on how it runs at the upper end of the rev range. I ran a Wombat pipe on my scooter for a time, but switched to a custom expansion chamber with full spark arrestor/silencer some years ago . . . and I'm not going back.

What I can see suggests that the porting is pretty much "factory" for the enduro/cross cylinder. If that is correct then the exhaust port to head gasket surface should be 28mm. The Super Combat cylinder measures 26mm at that spot - so I hope your measurement is in error. More advanced exhaust port timing than the Super Combat would be hard to live with.

A decent expansion chamber will probably "wake it up" in the higher revs. The Wombat air cleaner as you report running it (no snorkel) is probably not causing the problem. You might try a jetting run with the outer cover off to double check that - if it goes leaner and/or "wakes up", then the air cleaner snorkel hole just isn't delivering enough air. (I run a modified Wombat air cleaner on my CW engined bike. It works well.)
Ed

[Tether]

Thanks Ed,
I think we might of had a conversation at Hodaka days about my bike. I was hanging out down by the pool with my wife and to Wombats, one that took first place in the show and this one I’m trying to get right. The conversation we had was about the 200+ pounds of compression that is an “engine killer” turns out the head had been milled, too much. I had a stock combat head that I put on that took the compression down to 150.

I checked my measurements on the exhaust port, and yes my first measurements were off. I measured it this time using a depth gauge to a small straight edge in the port and got 25.7mm. Looking closer It appears that this port has been worked on, its much smoother than the others.

Thank you for your help. I need to think about how far I am willing to go with fixing this bike that has been kinda hacked up. Although it is a challenge.

Bob

[Bullfrog]

I remember the 200psi conversation!

I'm going to round your measurement to 26mm - so essentially, you have a Super Combat cylinder, running with a street legal exhaust system. I think you see the problem.

What plans do you have for the bike? An un-modified exhaust on an "EnduroCross Kit" leaves the cylinder as an all around sweetheart for dual purpose trail and play racing use. Your existing cylinder might be very good trading stock. It is no longer a dual purpose cylinder, so, for someone searching for a good cylinder for extensive porting and racing use, you have some trading stock.
Ed

[Tether]

Got it!
Thank you Ed for pointing me in the right direction. It was the pipe. I had this pipe that is on the bike now. I had to weld on a new header and clean it out. The pipe came with the 3 Hodakas I bought. Looks very similar to the regular Wombat pipes but with a small straight through silencer.
It runs extremely strong now with that pipe, with just a little hesitation at the bottom.
Thanks again Ed.

[Bullfrog]

Bob, does that pipe look like it was . . . perhaps, maybe (cross your fingers and hope) . . . a Combat Wombat pipe at one time? That would be a good thing for sure! I had many discussions with Harry Taylor about making a Combat Wombat engine be all it could be (without turning it into something else -- you know, without raising the exhaust port and getting into clutch fanning and road race power bands). And every one of those discussions included talks about this expansion chamber or that one . . . and every single time, Harry said something like, "You know, kid, the Combat Wombat pipe is a pretty good pipe."
Ed

[Tether]

I don’t know enough to tell what the pipe is from, I’m fairly new to the Hodaka world. What I do know is that pipe made a huge difference.
I am figuring out some stuff though. When I bought the 3 bikes one was mostly together, another was about 75% together and the 3rd was in boxes. it becoming apparent that some of the parts went on the wrong bikes, I’ll get it sorted out eventually.
I am going to sell this one because I am mot into racing and like the tamer street/trail stuff.
Thanks again..
Bob

[mark heckman]

I like the Honda Elsinore shocks on the Hodaka in your picture. I have a set on mine with the top mount in the forward location as well.I modified mine with shock shafts from the 250 Elsinore which are 1/2" in diameter verses 7/16" on the first year 125 Elsinore.

[Tether]

I was wondering what those shock were, the came with the bike. They seem to work well.