This is another eBay acquisition that I was originally going to fix up and sell. However, once I got going on it I started thinking, "you know, this one would be perfect to make that 'Ultimate Trail 70' I've been wanting to do"...so I did!
I have always thought that the 3-speed CT70's were geared poorly for adult use (of course, they originally weren't MADE for adults, but...). They're especially not so good for actual trail use. As I think I've mentioned elsewhere, my friends and I ride these on real trails, they'd don't get babied. They need to WORK for a living! Anyway, the 3 speeds have first gear as a low creeper gear, which is good. Second gear, though, is a pretty big jump from first. I frequently found myself either winding first gear high or shifting to second and feeling like I was lugging the engine a little bit. And third, well, that's just for cruising gravel roads, pavement, or other very simple, flat surfaces.
However, the 4-speed trannies have a VERY nice, even gear split between all four gears. However, 4-speeds also used manual clutches. I prefer the auto clutch. Could I make the autoclutch work with a 4-speed trans? Turns out it does work out, no problem at all. Very cool!
So, this bike was fully rebuilt from the ground up with the intention of becoming my Ultimate Trail 70, with a big emphasis on TRAIL. I was building this one for real dirt use, not for scooting up and down the subdivision or putting around a campground. She needed to work well with the weight of an adult in a real woods environment. That meant good power, good gear distribution, and good suspension.
We've already discussed the trans and clutch situation, and that worked out great. One of the other things that CT70s don't do terribly well is handle tough trail conditions with a 200 pounder like me on 'em. I've located some rear shocks that have springs about 1.5 times as stiff as stock CT70s, and they work great. But on previous bikes I used the shocks on, the front end didn't "match"...it was too soft to balance with the springs on the back. After some searching I ended up finding some front fork springs for the mid-style CT70 forks that were about 30% stiffer than stock. Perfect! Now the front suspension can "keep up" with the rear, even in tough trails. (Actually, the suspension is a little stiff for non-trail conditions, but again, the point of this bike is real trailwork. She's PERFECT there.)
To go along with the 4-speed transmission, the original CT70HK models had a much larger rear sprocket, a 45 tooth compared to most standard 3-speeds which had a 35 tooth. I changed the sprockets on this bike to match the original 4-speed configurations, with a 14T front and a 45T rear. After the first ride on the trails, I decided to gear her down even further...I replaced the 14T front with a 13T. Perfect! Now first gear is a true creeper gear used only for big hills and super slow work picking through the woods when you have to go off-trail because a downed tree or something blocks the main trail. She runs in second and third in normal trail conditions all day long. 4th is used pretty much just for very open spots and/or getting back and forth to the trails. She tops out at about 30mph (without winding the living crap out of her), but that's plenty fast for trail work. Even on a fullsize bike 25-30 is FLYING on close trails, so she's just fine.
So, in these pictures I hadn't yet installed the lower exhaust heatshield, and I also have put on an aftermarket rear luggage rack for strapping on a windbreaker or etc. for trailriding. I also have installed a correct 79 seat in place of this K0 repro seat, and have removed the Euro-only assist handle (never use it). Otherwise she looks pretty much like she does here. I have my "Ultimate Trail 70", and she IS! You can see a couple photos of her out on the trail in the Riding Photos section (in those photos she has the luggage rack and a lower exhaust shield, but the shield is chrome. I've since put the correct flat black lower shield on. Still has the wrong seat in those photos, though).
SOLD MAY 2009