Bigger tire = higher top speed?

[Mrs.Spaceman]

Just a random idea...

Has anyone put on a bigger rear tire to increase their top speed? Theoretically, if you had a 12" wheel and increased it by one inch, if your top speed is 50 mph with a 12" rear tire, it would be 54 mph with a 13" rear tire, assuming the motor can produce enough torque to handle it. Of course the acceleration would be lower, but that seems to be an easier thing to control with inexpensive parts than top speed.

[MPA]

The rear wheel on a rattler is only 10".

With a 130/90/10 you are probably limited as far as how much bigger tire you can get/will fit/is available. An easy way would be to get a higher aspect ratio (the 90 in the #s) but with it already at 90 it's likely not an option, so you would have to look for 140/90 or 150/90 if they are even available.

There is one guy on the rattler group who talked about swapping out the actual gearset. I saw this done on a youtube video and it didn't seem too hard to swap the gears, but you will lose acceleration while possibly not gaining a higher top speed due to the power of the stock engine.

Myself - I'm not sure. The big bore would be cool but once you add in the price of a carb and the kit and the gears you would be looking at a few hundred dollars. Also with a big bore people are saying they would not be reliable enough to use as a commuter so I think I might be forced to look at something else. We'll see how the variator swap works out first.

[Mrs.Spaceman]

I was guessing on the tire height, I didn't actually look it up. From across the garage it looked like a foot tall I just thought of it while sitting in my cubicle this morning and thought I'd find out if anyone actually tried it.

I'm thinking about doing the 70cc kit this winter (I have a Roughhouse). I've already had a new exhaust, clutch springs, rollers, and the usual minor upgrades installed. Things like roller weights and jets are cheap and easy to swap out. Part of the reason I've been doing the upgrades is that it's FUN. I've been having the mechanic at the dealer's do everything because then they still honor the warranty, but I sit there and watch everything. I've learned so much in the process. I even researched how CVTs actually work during a lunch break because I didn't know. Yeah, I'm a dork

As far as acceleration goes, I don't really have much of an issue right now other than my wierd lag problem. I might also be swapping out my variator in the near future. The mechanic said he has one on the way and will let me try it out before I buy it.

[Hugo]

I was guessing on the tire height, I didn't actually look it up. From across the garage it looked like a foot tall I just thought of it while sitting in my cubicle this morning and thought I'd find out if anyone actually tried it.

I'm thinking about doing the 70cc kit this winter (I have a Roughhouse). I've already had a new exhaust, clutch springs, rollers, and the usual minor upgrades installed. Things like roller weights and jets are cheap and easy to swap out. Part of the reason I've been doing the upgrades is that it's FUN. I've been having the mechanic at the dealer's do everything because then they still honor the warranty, but I sit there and watch everything. I've learned so much in the process. I even researched how CVTs actually work during a lunch break because I didn't know. Yeah, I'm a dork

As far as acceleration goes, I don't really have much of an issue right now other than my wierd lag problem. I might also be swapping out my variator in the near future. The mechanic said he has one on the way and will let me try it out before I buy it.

You won't be able to install a larger wheel on the rear. There is just barely enough clearance for the stock set up.

[robert]

sounds cool this past weekend i did a bore kit on my rattler. it was not very hard although i did not replace my reed valves. does anyone know what the setting is on that??? i am doing my variators now and the carb jets its going well. I ran it with just the boor kit and increase in power was incredible. again , any suggestions out there on the reed valve setting and is it very hard to do???

[BGK]

sounds cool this past weekend i did a bore kit on my rattler. it was not very hard although i did not replace my reed valves. does anyone know what the setting is on that??? i am doing my variators now and the carb jets its going well. I ran it with just the boor kit and increase in power was incredible. again , any suggestions out there on the reed valve setting and is it very hard to do???

You don't set it. you just take the old ones out and put the new ones in. Don't lose the screws and don't drop anything into the crank case. Use some loctite on the screws but make sure you don't get any on the reeds themselves. Save your old reeds in case the new ones break. Reuse the metal reeds stops.

[Mrs.Spaceman]

Yeah, not a lot of room there. I hadn't really done any research before presenting the idea, but it would be the cheapest way to get some higher top speed if there was room to do it. I suppose the rear fender could be taken off, but the mess it would make is NOT worth it.