Hi Carl, you are the first person to modify a Razor RSF650 for offroad use that we have run across so far. How well did the MX650 front forks fit onto the RSF650 frame?
We know a lot of electric scooter and bike tire suppliers and could try to find the knobby tires that you need. However, we have not received our first shipment of RSF650 tires yet so we do not know what size they are. If you could read the tire size off of the original tires and let us know, then we could begin searching for a knobby version of them.
Thanks for replying. The front fork from the MX650 has the same basic geometry/dimensions/application with the exception of the front brake mount...a great fit. I'm expecting to relocate the top mounting hole back towards the fork by about 1/8 inch in the existing mounting plate that's welded on, shaving any excess off by grinding and shaping to fit the caliper...OR....buying a larger disc to accommodate the gap/difference in positioning. It also might fit as-is but I haven't yet tried since I wanted to mount the new tires on the rims before putting things back together. The RSF650 stock-tires, front and back, are 100/80-10. I won't be replacing the front plastic fender so a taller tire will fit, the width is the problem obviously....it's limited by the space between the posts. I did dry fit and test this suspension without the front brake caliper and it drives much nicer and provides a softer ride. I think a 110/90-10 tire would work but I won't be able to measure for sure until I put it all back together to check the clearance of the rear tire and motor mounting area. I have the bike completely apart to paint the upper trellis framework and the front forks, leaving the swing-arm original. I'm going camo-green (plasti-dip) with camo-pattern wrap on certain areas of the plastic cowlings and "tank". Knobby tires would complete the look nicely. I also replaced the rear sprocket to a 89-tooth (80-tooth is stock) for more torque (off-road terrain) and don't know how many links to add to the #25 chain. Do you have a chain already mocked up for that configuration? The motor and wheel distance did not change, just the added teeth on the rear sprocket. I'm completely new to this entire hobby (obsession now) and it's been a lot of fun and a lot of learning about electric mobility....the ideas for future projects are flowing...but keeping them at this scale. I'm limited by time and space only....
Thanks for sharing that information about switching RSF650 to have MX650 forks. That is great to know.
Also thanks for letting us know that the RSF650 tire size is 100/50-10. We checked with all of our tire suppliers and could not find a knobby or turf tread 110/90-10 tire. We did find 120/90-10 and 130/90-10 knobby and turf tread tires, however, I am sure that you were able to also. How about a 4.00-10 tire? They are available with knobby treads and are supposed to be equivalent to 100/100-10 and 110/90-10 tires although 4" is 101mm so it should be closest to a 100/100-10 metric size.
We have an online calculator that can be used to determine the new chain size when installing a larger sprocket. It is available at this link: https://electricscooterparts.com/chainlengthcalculator.html
Here is a quick guide showing how to use this calculator to determine the new chain size when installing a different size sprocket.
Please let us know if you have any questions.
Great suggestion, I might use that setup in the end. Are the brake discs larger than on the RSF630 stock tires? I like the RSF650 rims and want to keep that look consistent with the rear.