DS wheel swap

[matt glascock]

Toaster tank DS on the rack. Basically stock with a few performance enhancements to the motor. Looks like ports polished and exhaust port raised a mm or so, high compression head/Dykes ring piston, VM 24 carburetor. I want to morph it into a hare scrambles bike and possibly a sleeper some day with reed conversion and all the fixins. The stock 19" front wheel ain't cuttin' it. I scooped up a decent 21" wheel assembly off a Wombat. This will add an inch of height to the front of the bike. Ultimately rear suspension upgrades will be required if I go any farther with it than a fun woods bike which I could use to return the bike to stock geometry, but in the meantime with this minimal one-inch height increase between the axle and ground, are there any steering geometry influences I need to be concerned with? (My best run-on sentence EVER.) Could the very slight change in rake be adjusted out simply by dropping the triples down the fork tubes an inch or so? I'd really like to avoid that if possible. It is a wheelie-freak machine in current trim and I'm sure that condition won't be helped with the 21"er until I get the swinging arm extended a couple inches.

[BrianZ]

I did pretty much the same thing as you have planned, a DS with Wombat wheels, Wombat swing arm, Super Rat top end, and a reed valve set up. It made a great little woods bike.

I would think that dropping the front end a little should help, but it will be a much better bike with the longer Wombat swing arm and larger rear wheel. Too bad we're not closer. I have put my DS back to stock and would be willing to swap rear wheels and swing arms.

Are you running the stock DS pipe?

Brian

[matt glascock]

Sweet!!! Yep on the pipe, for now. If I go any farther with it beyond the mods original to the bike, in the day, when I got it, I have a Torque Engineering pipe I can mod to fit. That would be cool to swap wheels/arms. I don't really like cutting a perfectly good swing arm (although the three I race have had said surgery). I look at as a legit, period-correct mod.

[Bullfrog]

Matt,

The mod you have undertaken (swap in a 21" front wheel for the stock 19" unit), has done a couple/three things to the machine (never forget - everything you change is connected to everything else on the machine, and there may be unintended consequences):
1. You now have a front wheel which will roll over bumpies more easily - but it will have slightly less powerful brakes (larger rolling radius with all other brake factors unchanged).
2. Since the new wheel raises the front end, you have increased the "rake" specification. Kind of the first step toward a desert sled (or chopper )
3. The height change and the rake change have also increased the "trail" specification. Yet another step toward desert sled or chopper steering geometry.

As it is right now, your Squirt will not turn as well as it did before. Also, since Squirts (and Wombats and Combat Wombats) were supposed to have the forks extending up through the top triple clamp by 1" in stock trim - that isn't really an option for reducing height/rake/trail.

Y'all know I'm kind of "old school" - but you may not know that the toaster tank squirt is my all-time favorite Hodaka model (well, as long as I'm not sitting on a Combat Wombat or a Wombat 03 when you ask!! ). Sooooo . . . I tend toward the concept of . . . if you truly want a Wombat or Combat Wombat chassis . . . why would you start with a Dirt Squirt to get there? Why not optimize the Dirt Squirt to be what it is? "The Fun Hundred"! (the grumpy old codger opined . . .). It's lighter, lower, shorter, will turn under any bike on the track and is absolutely grand out on the trails with virtually any rider.

Finally, (and this is probably the most useful part of this message) - I advise searching through the Resonator Revisited articles. There are a couple of 'em on "rake" and "trail" - they could be helpful in your quest.
Ed

[BrianZ]

I had my modified DS on a tight twisty hare scrambles course and rode it against my brother on a '78 Suzuki PE250. The DS was faster. We switched riders, this time with me on the PE250. The DS was still faster. It's hard to beat a light, low maneuverable bike on tight single track, especially if it's wet. As Ed has already stated, the DS will turn really well with those smaller wheels, but for me the biggest advantage to the larger wheels was tire choice; There isn't much available in the 17" and 19" sizes.

Brian

[matt glascock]

Captain, thanks for bringing me back down to earth. After some serious DS love this past spring, I have personally declared the Dirt Squirt the best all-round dirt bike ever (see "Dirt Squirt Throwdown"). Both of the Squirts I was thrashing last spring were already converted to 19"/21". This one is stock with the exception of a few performance mods. Fun story: My modern bike is a KTM 450 SX-F. It defines the adage "taking the bull by the horns". It is a monster. After finishing 4 motos on it, I took the same DS we are discussing out for the "pit bike" race (100cc and under) and absolutely MURDERED the field. Stuff it into the corners, flick it around, do whatever. And that was on an SX-style track that has mellowed out lines around the doubles and triples for the kid's safety (less intense jump faces and all tabletops). Great bike and a riot to ride. Maybe I will leave this one as is. Especially in light of the fact that I have a pair of CWs for serious woods and VMX work. Also, good point about the front brake function, Captain. I had not really considered that fact.

Brian, I have an '80 PE175. Man, did they over-do the mellowing out of the engine mapping. I got my a$$ absolutely crushed by one of my pals on an '80 YZ100. They have nice, plush suspension but the motor is a bit mellow for a race bike.

Bottom line - DS = best dirt bike ever. I'll leave this one alone.

[viclioce]

I have a Wombat 94 frame I’m building up now to be a Wombat Combat so to speak! Wombat frame with a Combat Wombat motor which has been ported & reeded!

So I’m going to put a 21” front wheel on it. It’s a conical hub front wheel. Not sure which model it’s from. I’ll have to shoot a pic & post so someone might tell me from where it came!

Probably will put an 18” rear wheel since I have 3-4 rear wheels from which to choose! Pics soon! Victor