bikepilot

I run either race gas or non-ethonal in all my bikes. No swelling issues, they run better and it is more tolerant of sitting which happens sometimes during ski season.... If you are going to run ethenol then I guess Beta's alumni frame tank would be a real advantage.

My 9yr old currently has an Oset 20, Beta 80 Sr, and Cobra 50 (motocross bike). The Oset 20 is a little small for him. Osets are a great way to start. The 24 model Oset should fit a typical 10yr old well. The beta 80 is also really user friendly if you want to go straight to gas and clutch, but I'd suggest the Oset for starters. My son started on his first Oset for his 2nd birthday and has learned a ton riding them.

Our '23 Sr has 1 1/8" bars (aka fat bars). It's easy enough to tell just by looking. If the bar has a taper in the bend they are 1 1/8", if the same diameter everywhere they are 7/8ths. 7/8ths will usually have a cross bar and fat bars usually will not.

Most trials bikes seem to come on around 140 F. I don't know if the 50 is the same. For fuel mix if he is riding it like a trials bike I would mix at 75:1. Beta calls for 1.5% oil. If he's using it for a trail bike and flogging it I'd mix 50:1. The 50 is based on the 80 Jr in case that is any help. Have fun!

I find a 125 has plenty of power for anything I have the skill for (I ride intermediate class) but it's concentrated at the upper rpms. Don't be afraid to rev the snot out of it. You won't hurt the bike. Expect to be in lower gears vs the 250s and 300s. I own and also race small bore two stroke MX bikes and got comfortable with ringing their necks at an early age! For sudden bursts of power it's more about stored energy in the flywheel than instant torque when snapping the throttle open. Again rev higher as that will store more energy. As for the bike don't overlook jetting. 125s like big jets. Keep going richer till performance tapers off. You may find that it'll prefer a few sizes up, particularly on the pilot. Also make sure the engine compression is appropriate and that the reeds are in good shape.

Sounds like a faulty battery pack, but one other item of concern is the BMS in your pack looks to be rated for a max discharge rate of 30amps which is quite low. Bike should still move, but I'd expect it to stutter or cut in and out under full power.

FWIW when I bought my 315R the clutch dragged quite badly. Same day I bought it a fellow at a local event told me it was absolutely critical to run the OE spec gearbox oil. I switched to that and the clutch then worked wonderfully (I don't know what the previous owner had in it, but it looked clean coming out). So I would definitely suggest running the OEM fluid first-off.

Here's one I'd look at https://bicyclemotorworks.com/product/pocket-rocket-ii-52v-8ah-samsung-40t-lithium-ion-e-bike-battery/. You'd need to have him configure it as 7s4p instead of 14s2p (same number of cells so should be easy). At 4p it'd be 16ah. You could also have him customize with more in parallel to get more ah out of it.

BTW an hour of ride time on stock batteries with a 5yr old aboard is really good. I doubt you'll get more time out of it by replacing the stock batteries with new ones of the same capacity.

Hi, the first ones l think would be a direct replacement for the OEM Oset batteries (check physical size to make sure they fit), probably no better or worse. I suspect the 2nd ones would work, and they would be much lighter. The biggest concern is whether they can deliver enough amperage at peak demand. I'm not sure what the 12.5 Oset draws, but those batteries have a pretty low rating so it'll be iffy. The most straight forward upgrade imo would be a custom battery pack of Lion cells to suit it. Places that make battery packs for e-bikes can usually do one up for an Oset. For a 5yr old on a 12.5 I'd go pretty big. Probably 7s5p or 7s6p with Samsung 40T cells. That would give 20ah. Packs like this is what Boost does which many folks here recommend. I bought one from them, it wouldn't physically fit, and dealing with them was an exercise in frustration and misery and I lost money. That was years ago and they are still in business so presumably they at least some times manage to make packs that work. A quick summary of battery info is below in case it's helpful. When my son was on a 12.5 we ran a Lithium Ion pack in 6s4p of Panasonic 1850 cells (25.2v, 12ah) from a wreaked Tesla. We focused on small, light, and durable as he was 2 at the time. If setting up for a bigger kid it'd make sense to add some cells for more capacity. On his 20R we have a pack underway that will be 14s6p of Samsung 40T cells (58.5v, 24ah). Battery chemistry: Sealed led acid (SLA) [these are what I take out of Osets, ha!]: Pros: Cheap, simple, rarely catch on fire, easy to charge. Cons: Very heavy, voltage sags substantially when in heavy use reducing performance and range, physically large. Lithium Ion cylindrical cells (e.g., 18650 and 21700) [these are what I run in the Osets] Pros: High energy density, very long life (can re-charge thousands of times), cells can be configured to customize battery pack. Very little voltage sag so performance is quite good. These are what are in Teslas. As lithium batteries go, they are pretty durable and hard to catch on fire. C ratings are relatively low as lithium batteries go, making them ill-suited where huge amperage draws relative to amp hour of the pack is required (e.g., fast RC cars where we pull 300 amps from a 7ah pack). Much faster charge capability than SLA (can charge around 0.5 C safely, with good chargers and some cooling you can push it harder). The cells are physically pretty durable. It's relatively easy to find custom pack builders who will make you a plug and play system with BMS and provide a charger. Cons: Good ones are expensive, cheap ones are utter crap (never buy from China, they'll be Chinese fakes). You want Panasonic or Samsung. You need a Battery Management System (BMS) or very fancy charger to charge them. Ultimate results are all about the specific cells used and selecting the right one for the application. For most Oset applications Panasonic NCR18650Bs or Samsung 40Ts would be optimal. C rating for discharge and charge will be much less than LiPos. Building a pack from cells requires skill, a spot welder, and pure nickle and copper strips (sandwich them with Nickle on the outside). Compared to SLAs they are more sensitive and if you get something very badly wrong they can cause a fire. Lithium Polymer (LiPo) packs. [Note, I have lots of experience with running these in big/fast RC cars] Pros: Cheaper than good Lion packs. It's possible to have huge C ratings (note that most of the times these are hugely inflated so don't believe what the sticker says, especially if you are looking at really low end packs like those from hobbyking). These exist primarily for the RC car market and are available in a variety of pack size and configurations. Buy a few, solder up some jumpers, and you are on your way quickly and easily. Due to huge C rating it's possible to re-charge in <30 min. Due to huge C rating there's almost no voltage sag. Cons: Difficult to setup a BMS system, so you have to manually keep them happy, balance charge, and be super sure not to over-discharge (that will permanently kill them). Get any of the care and feeding wrong and there is high potential for them to go up in flames. They are often physically not protected, so in your install you have to make sure they aren't prone to physical damage. If damaged, high probability of fire. LiFeP04 Pros: These are typically configured in the same size/shape/voltage as car or motorcycle batteries, so it's an easy drop-in swap. Much lighter than SLAs and much less voltage sag. Physically you usually get the same amp-hour capacity for a given size, so upping Ah with these is difficult. Good ones usually have built-in BMS to protect things and the chemistry is relatively resilient, so fire hazard is low. Cons: Low power density for their size. You have to pay close attention to the included BMS to make sure the amperage capacity is there. Relatively expensive per Ah. Terminology S = Series P = Parallel Ah = Amp Hour BMS = Battery Management System Wiring batteries in series means connecting positive to negative and so on. The resulting voltage will be the voltage of the packs/cells added up. The Ah will be that of an individual cell. Wiring batteries in parallel means connecting positive to positive and so on. The resulting voltage is that of an individual pack/cell. The Ah will be that of the individual packs/cells added up. So 6s4p for example means 6 cells in series and 4 in parallel. If you do this with 3ah, 4.2v cells (very typical), the resulting voltage is 6 x 4.2v and the resulting Ah is 3 x 4.

Fwiw I race DH mountain bikes so have some practice with putting these brakes to the test Bedding in properly is absolutely critical to have them working well as is a good bleed. Look up SRAMs videos on YouTube for details on both. Sram code, magura and hope 4 pots, and Shimano saints are all largely equivalent in power. Sram and shimano are the most common and will be easiest to find pads for and get bled at the local bike shop if you don't want to do it. Srams are the easiest to bleed imo. Hopes are the most bling and imo have the nicest levers. Magura probably has the most progressive lever feel. Codes are a nice mix of feel, power, and ease of setup. I own all of them and if I were built a bike today it'd get code RSCs, but I'd be happy to ride any of these. 203mm rotors are the cheapest and most impactful upgrade. Get good ones, not Chinese crap from eBay. Note that Magura usually uses thicker rotors than the others and hope can have some specific fitment as well, so don't count on all calipers working with all rotors.

Thanks!

That's awesome and should drop some weight. Anyone have eye to eye and stroke on the 20.0? I'll try and measure sometime over the next few days if not. Perhaps there's also room to increase stroke and gain a bit of extra travel as well.

Any idea what the stock pack configuration is? Cell type and count? The tricky part of doing small lithium ions is it get tricky to deliver the amps with out stressing the battery too much. A good lipo will have no problems, even with very small, light packs. Samsung T40s with 3p would be 12ah and still have enough amps I think.

Awesome thanks so much.