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Author Topic: Transmission ratios for 250R-based hybrid project  (Read 729 times)

Offline 69HemiGTX

Transmission ratios for 250R-based hybrid project
« on: May 28, 2022, 02:11:28 PM »
Howdy again, y'all! I haven't posted here in forever, but I figured I could pick the brains of some of y'all for advice. My question concerns using a dirt bike engine in a 250R-based ATV. Specifically, what transmission ratios would work best given the following combinations in the attached table? What would be a good starting point for final drive ratios? The primary riding will be in the dunes and trails, with some trips into the woods every once in a while. I'm not interested in drag racing at all. Any reply would be greatly appreciated.
Laeger\'s narrow chassis, Roll Design +3 a-arms, CR500 link swingarm, Custom Axis LTs, Curtis Sparks 265 National engine, LRD pipe and silencer.

Online croat1

Re: Transmission ratios for 250R-based hybrid project
« Reply #1 on: May 30, 2022, 07:19:38 AM »
What engines are they?  By chance is option 1 a YZ400/426?

Joe

Offline 69HemiGTX

Re: Transmission ratios for 250R-based hybrid project
« Reply #2 on: May 30, 2022, 08:25:29 AM »
KTM SX, XC, and XC-w in that order.  All 250-300cc two-strokes.
Laeger\'s narrow chassis, Roll Design +3 a-arms, CR500 link swingarm, Custom Axis LTs, Curtis Sparks 265 National engine, LRD pipe and silencer.

Online croat1

Re: Transmission ratios for 250R-based hybrid project
« Reply #3 on: May 30, 2022, 05:57:04 PM »
I was curious as what guys were using for the KTM 2 stoke conversions.  After about 30 minutes online I found this.  I did reach out to a old R guy that’s into Hybrids big time now.  I’ll post what he responds with.

Joe





Offline 69HemiGTX

Re: Transmission ratios for 250R-based hybrid project
« Reply #4 on: May 30, 2022, 09:21:28 PM »
That's kind of what I was thinking because first and second are lower geared, but some riders complain about the gap between second and third.  Compared to the KTM, the 250R has lower ratios for each gear and had a 13:38/39 final drive depending on model year.  I wonder if something like a 13 paired with a 40 or 41 would drop the KTM's ratios closer to the 250R.
Laeger\'s narrow chassis, Roll Design +3 a-arms, CR500 link swingarm, Custom Axis LTs, Curtis Sparks 265 National engine, LRD pipe and silencer.

Online Jerry Hall

Re: Transmission ratios for 250R-based hybrid project
« Reply #5 on: May 31, 2022, 12:57:39 AM »
I was curious as what guys were using for the KTM 2 stoke conversions.  After about 30 minutes online I found this.  I did reach out to a old R guy that’s into Hybrids big time now.  I’ll post what he responds with.

Joe






How do the primary ratio (crank to clutch} ratio compare to the Honda 250 ratios?

 Remember the overall ratio is the: 
                                                         1 / [(primary ratio) x (transmission ratio) x (the sprocket ratio)] x (the circumference of the tire) = (the distance traveled per engine rotation)

Online croat1

Re: Transmission ratios for 250R-based hybrid project
« Reply #6 on: June 18, 2022, 02:33:32 PM »
KTM SX, XC, and XC-w in that order.  All 250-300cc two-strokes.

He said to use the XC or XC-w

 

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