As of writing many people are at home during the Covid-19 lockdown. You might be a bit bored and wondering what to do. But for many, including myself, this is the perfect time to tinker. So I was wondering how I could improve the performance of my X-Max 300 a bit. I wasn't expecting earth shattering results, but I think I definitely ended up with something fun and noticeable. The upgrades are based around the following principles: * Reduce weight * Reduce air resistance * Get more air molecules into the engine * Get more fuel molecules into the engine * Reduce exhaust back pressure * Reduce losses Summary of upgrades: * Mivv Urban Exhaust (previously installed) * Dr Pulley 20gram sliders (previously installed) * X-Max sport screen (previously installed) * BMC Air Filter * NGK Iridium Spark Plug * HiFlo Oil Filter * Yuminashi 12 hole Fuel Injector * Air intake foam delete * Air intake snorkel delete * Secret upgrade MIVV Urban Exhaust A nicely made exhaust at a good price point, not too loud but much nicer sound. Should be good for close to a 1 hp gain and is also much lighter than stock. Here are a few more impressions: https://advrider.com/f/threads/new-xmax-300.1256178/page-47#post-35665243 Dr Pulley 20gram sliders This mod is to change the driving characteristics more to my liking, make it a bit more grown-up and long-legged. I have to say that together with the other mods on this page it's a really nice package and definitely no slouch. Here's a discussion about it https://advrider.com/f/threads/guide-how-to-service-or-change-rollers-sliders-x-max-300.1327105/ X-Max Yamaha Sport Screen It looks tiny but protects more than one might think. I'm 5'11 and wind hits in the sternum area below the helmet. So for summer it's great, more cool clean air and no buffeting. You'll need earplugs, but you should be wearing those anyway. As a bonus I'm pretty sure it has less air resistance than if you go the other way with a bigger screen and wind deflector etc. BMC Air Filter Should flow better the than the stock paper filter and be good for a few percent of performance, remember to spray it with filter oil. You could also make your own filter from a universal foam filter sheet for maybe $10 (ebay or amazon) if you modify the stock filter holder. This depends a bit on where you ride, if you ride a lot of gravel roads I might advice sticking with the stock paper filter since, while it is the most restrive, it should have the best filtration. But if you ride mostly regular roads you should be fine going to either cloth or foam filter, just remember to apply filter spray oil or it won't catch small particles as well. You can also use cloth and foam filter on dusty roads, just be prepared to clean them more often. Most enduro and MX bikes use foam filter so it's a good technology, just that they tend to need more frequent cleaning. Here's a link for the BMC one: https://www.omniaracing.net/en/filt...-300-2017-p-88389.html?currency=USD&pID=88389 NGK Iridium LMAR8BI-9 91909 Spark Plug I'm not sure if this actually improves performance but it should make for better cold start ability since Iridium plugs generally require less voltage to fire. I had some starting issues on a cold day last year so I wanted to change spark plug just in case, I might have overheated the previous plug a bit after changing exhaust (looked at plug). So if I'm going to change why not go iridium. I've also modified my cold start technique... so far no more cold start issues. HiFlo Oil Filter Had to change oil filter anyway. Maybe it flows better than stock but I wouldn't count on any difference. Another case of "why not". Yuminashi 12-Port Fuel Injector Now here's an interesting one, and this could potentially be a big topic.. but I'll try to keep it brief. Essentially 99,9% of fuel injected engines operate in two modes. They are either in "closed loop mode", or in "open loop mode". Closed loop mode is when the ECU reads the lamda sensor and adjust the Air/Fuel ratio accordingly. Open loop is when the engine follows the pre-programmed ECU map to the letter. The thing to remember here is that for cold starts, full throttle, throttle blips and high-revs essentially all engines run in open loop mode and won't use the lambda sensor. Then the engine typically runs in closed loop mode when it's at steady throttle and low to medium revs. This is why products like the "Malossi Lambda Emulator" typically don't do anything for max hp, it cheats the lambda sensor to get a richer fueling... but the lamda sensor isn't used by the ECU when at full throttle and high revs. So the only way to really get more fuel at high-revs, and max throttle, is to use an aftermarket ECU or something like a Power Commander which modifies the fuel injector pulse. Or.. you could do it a slightly sneakier way.. and use the stock ECU and signal but fit an injector which is slightly larger, which is what we have here. So since I was suspecting that my X-Max 300 was running slightly lean (looked at spark plug), and I didn't want to fork out $300 for an aftermarket ECU, this is what I did. After the mod I noticed more aggressive throttle response, better torque and maybe more overall performance so I'm happy with the mod. This is the injector I bought: http://www.yuminashi.eu/300cc-12-holes-injector-xmax300/ Fitment was easy, didn't require any special tools and was done in 15-20 min while being careful, it actually looks identical to the original injector and like it was made in the same factory, just that it has a different code on it. Air intake duct (22) and foam filter (43) delete I believe the rubber intake duct, and extra foam insert, might a be a little restrictive and that it's mostly there for noise regulation, so I deleted them. If you're running on a lot of dusty roads probably don't delete part 43. I can't speak for performance increases on this mod alone but at least you can hear more intake sound and I think it's more responsive, so that's nice. It should help the engine breath more freely, but how much of a difference it actually makes I'm not sure. These performance mods are all about small improvements here and there which add up in the end. On some bikes the intake duct works as a resonator and helps mid-range performance, but I don't think that's the case here. And scooters use high revs for max performance anyway. Secret upgrade What you say? A secret upgrade? Well, yes. There is some potential for engine damage here, but also some potential performance gains. This secret upgrade might be revealed in the autumn after I'm fairly confident I won't get anyone else than myself in trouble with it. Conclusions It's hard to estimate how much of an individual difference these mods make, many of the individual gains are probably small. The exhaust I know makes a fairly big difference but the other are hard to estimate individually. What I can say however is that when taken together these mods make a quite significant difference to the X-Max 300 and makes it feel more aggressive, freer revving and freer breathing. The stock X-Max 300 is nice but quite laid-back, now with these mods the x-max 300 feels well.. almost aggressive. It's more responsive on the throttle and generally feels more eager to jump off the line and take off into the distance. I don't think this difference from stock is subtle at all but quite noticeable. So if you want to give your X-Max 300 a new and racier feel I recommend the mods above, I'm quite happy with the outcome and performance. We've made it easier for fresh air to enter the engine, easier for exhaust gases to exit and we've given the engine a few extra percent fuel to work with. So more air through the engine plus more fuel equals more hp. If I have to put numbers on it I'd estimate that the exhaust alone is good for close to 1 hp and the rest of the mods combined might be good for another 1hp, or a bit more in combination. So if the stock engine is rated at 27.6 hp I think now we're close to 30hp. By no means earth shattering but it's also about how the driving experience feels, and like I said I think there's quite a noticeable perceived difference here in responsiveness, sound and power. One also has to remember that on scooter with 27.6 hp an increase to 30 hp is actually a 9% increase, and I think that feels about right going by seat of the pants feel. For personally I'm very happy with the mods and have no thoughts about going back or regrets about the cost etc. A few extra notes on air pressure A tip for improving ride comfort without upgrading the shocks is to try lowering tire pressures a bit below the recommend. For me I've found that 1.9 bars for the front and 2.1 bars for the rear work well, that's about 27.5 psi front and 30.5 rear. Feel free to experiment here. As a bonus slightly lower pressure also aids stability a tad at high speeds. A few extra notes on rear preload Running a too low preload isn't nice, especially with heavy luggage or a passenger. However, there is some potential to play with the preload to alter the handling of the bike. In general a higher preload will make the bike sit more upright and makes it easier to turn, but can also make it more nervous at speed. On the other hand if you want more high speed stability you can try decreasing the preload. I personally like running a fairly low preload which sags the scooter and makes it more stable at speed. Note though that if you bottom out a lot the preload is too low for your weight and this will make the bike skittish and uncomfortable. An extra note on the handlebars In case you didn't know the X-Max 300 handlebars can be adjusted forward and aft in two settings and also rotated a little bit. If you're running a low sport screen I recommend the forward position, which probably is what many have as stock. And if my upgrades aren't blingy enough for you can also search all the upgrades available in Thailand and through Alibaba. Here are some examples: https://taiwanbigscootershop.com/collections/xmax-300?page=1 Have fun!