(From the "forum Idea post"): I just noticed through observation that they're geared really low. Lots of low end grunt. My son (almost 3 yrs old) almost rolled off the back of the seat when he goosed it. And my daughter (almost 5yrs old) complained that it wasn't as fast as her dirtbike. So, with higher gearing, it should take off a little slower and have more top speed. I'll get into the cylinder next year. I got 45mph out of her Suzuki JR50 dirtbike with some porting, so I can see a lot of potential in this little sled. I might fab up an articulating rear suspension over the summer too.
Ok, so Harry suggested 12-36. What's stock? If the stock clutch is 13 then wouldn't I save some loot by staying 13 and going 13-39 or if it's 14, then 14-42?
11-42 is a 3.82 gear ratio (stock).
12-36 is a 3.00 gear ratio (per Harry's suggestion).
Hmm, I'm thinking that I'll keep the clutch outer and just change the driven sprocket to a 33. Is that right? 11-33 is 3.00 gear ratio. Will this work with the chassis and chain tensioner?
Don't forget the gear reduction box which has a 1.952 gear reduction also...word of caution.....the lower rod is not designed to sustain any high rpms over any length of time. This motor was designed not to rev over 6000 rpm. There is no slot cut into the lower rod to get any lub into the lower crank bearing.....Suzuki does make a slotted rod for that motor.....if you want I can get you the part # and you can go to your local suzuki dealer and order the part.....last time I bought them they were around $47 dollars also if you get the rod it is alil tight on the bearing a will have to honed out about .0003 to .0005 thousands for a proper fit
Hah! I guess if I ever have the crank assembly out I'll have to address that design defect! On the 50cc dirt bike motor there's a small hole drilled, but not a slot. Maybe I'll drill a hole or machine a slot if I get that far into it. Might as well if I'm going to true and balance the crank...
Doh! Your prolly right. But I'm a cheap bastard. I'm actually wondering if your replacement rod is from the JR50.... I've got one of them and it's not even blued... The con rod I have is suzuki motorcycle P/N: 12161-04001. What is your P/N?
We automatically use this replacement rod in every Kitty Cat engine we rebuild or mod. The connecting rod/crank pin point is a major weak point in the Kitty Cat engine.
The correct part number is 12161-04710 and retails for around $58. We carry these rods in stock and sell them for $49.95.
Hey Jonn did you see my kid crash last weekend during the improved kitty race. It was the one where my wife went running across the track and so did I because I could not see over the snow bank. That is what happens when you run a different gear. The funny thing is that he rolled it the same way he was leaning. I guess my carbides were sharp. It was good to meet you this weekend, sorry I had to bail on ya. It makes a guy very busy when you have two boys racing, and are letting another family use your other sled. Thanks for all your help this past season. As you saw I still have work to do on that 120. Oh ya GO TO BED
I missed the crash. I think I was working on someone's sled in their trailer when Improved KC ran. It got kinda hectic in the afternoon for both of us and I finally had to leave. I'm hoping to attend your clubs banquet in a few weeks and figured we could talk then.
I'll keep in touch this summer as we dial in the AC120 issues.
PS. Don't forget to let me know when the ice breaker is scheduled to come through.
Jonn, the breakers are coming in sometime this week. One has problems already and it hasn't left the pier yet. Maybe they should try a different gear instead of the stock one I will let you know more as I find out. I am finding things I need to do to my F120 by comparing it to the one we just bought from Birds. I turned my pilot jet out 1 1/4 turns and adjusted the dial jet before the last race with the F120 and the thing kept up with the pack. We still came in last.
And my daughter (almost 5yrs old) complained that it wasn't as fast as her dirtbike. 
So, with higher gearing, it should take off a little slower and have more top speed. I'll get into the cylinder next year. I got 45mph out of her Suzuki JR50 dirtbike with some porting, so I can see a lot of potential in this little sled. I might fab up an articulating rear suspension over the summer too. 
Oh ya GO TO BED