I’ve actually started to get feedback and to this day I have said the 30mm Mikuni carb is the best mod, I have had a fellow member called Paul do this recently and he has said it has been brilliant! The bike now runs how it should, such a smoother ride and acceleration! He has supplied me with pictures to give people a better idea and comparison between the Mikuni 30mm and the stock 26mm PZ26 carb, which essentially is a Mikuni 26mm copy. The 30mm unit is on the left:
Just to give a you a better comparison, here’s the stock end cap on the 30mm Mikuni on the PZ26 to give you an indication of size.
So it’s significantly bigger, and a simpler design. Upon receiving it the first thing is to re-adjust the pilot, from Paul’s experience he turned the screw for the pilot all the way in till the screw was recessed then turned it out by 1.5 turns. The main Jet varies depending on performance setup. The performance air filter should be a 42mm unit. If you have just a 42mm performance filter then opt for a 105 jet. If you have a performance filter and exhaust opt for a 110 main jet. On both setups we have found the needle needs to be set on the lowest notch (richest setting). So take the four screws off the new mikuni and replace the main jet with the size required.
The main jet is the big one in the middle, the screw on the right is the air & fuel mixture for idle, adjust this accordingly if need be by earlier settings in this article. Its then just a case of taking the fuel tank off. This is done by opening the passenger seat, this gains you access to the drivers seat where you undo the butterfly bolt, then undo the 13mm fuel tank bolt. Once undone, unclip the two side panels and lift up the tank and disconnect fuel lines. You should be left with this:
Undo the 10mm nuts from current carb and swap the carbs over as refitting is the reversal of removal (famous Haynes manual words). Wollah new carb is on.
Now you can stick on your 42mm air filter of choice and colour. One thing Paul did was disassemble the old air box and put the rear half back on to reduce splash and water to the new air filter. The new air filter will still be getting the same amount of air but it will be more protected. Which is pretty ingenious.
You will be however left over with a spare throttle cable from the previous carb, this engaged the acceleration pump on the stock carb. You can either tuck it or remove it. I’d personally remove it as I very much doubt I will go back to a 26mm stock carb and if anything does ever go wrong with the Mikuni I will replace like for like.
Hopefully this helps people with fitting and guiding people through to installing a new carb to their Lexmoto’s. It by far has been my best and favourite mod to the bike and I cannot recommend it enough! People like Paul cannot praise it enough!
I would like to thank Paul for supplying these pictures and aiding other people.
My XTR-S Project 
Do if I went from a 19mm to a 22mm carburater. What size jey should I use
Look at the stock size and just go up a few sizes, ie if 95, aim for about 100, its trial and error with jets unless someone has had an identical setup that’s been tried and tested and can testify it worked for them and even then you get people that retry the same setup and moan its incorrect.
I have an X18 110cc pocket bike. I just ported and polished the intake. And upgrades to an 22mm carb. What jet comes in a stock 22mm carb and what jet should I get for the best performance. I drag race the bike. We only travel 330ft. What is a good sprocket ratio for this bike.
Wouldn’t know what ratios or jets to recommend, if you wanted to maximise things then a dyno tune would be best with a arage who has the jets all ready, that way things would be much smoother but for a bike that size I’d say its somewhat pointless, but if its for competition then maybe it is worthwhile.
As for ratios I cannot recommend anything, I’d start with trying front sprockets as they are the easiest to swap and get hold off and try them out along with timing it, as with a set distance its hard to predict which way you need ratios to go, on the one had smaller sprockets would improve acceleration but you would be loosing valuable time shifting where as a bigger sprocket will kill acceleration but reduce shifts. There’s no way to know except for try and test different setups, once the front sprockets perfected then maybe knock a few teeth of the back to gain some acceleration back slightly.
The world of racing is a hard one as its down to trying different setups along with experience.
Hey mate,
I’ve been keeping an eye on your posts, glad someone is brave enough to try these mods out!
I’ve bought myself the mikuni carb and 42mm air filter but I seem to be having a little trouble with flooding at 20% throttle and the bike surging when at high/top revs.
I’ve got it on a 105 jet with The needle at the richest setting.
I don’t suppose you have any tips on what i could look at to sort these little troubles?
I was also wandering if there are any limiters in the exhaust that you know of?
Any helps appreciated bud.
Jimmy
Try middle setting on needle, and turn the pilot screw all the way in, then 1 and a half turns out. Sounds like a issue on the pilot jet side, sounds like possibly flooding out.
Stock exhaust is pretty poor build quality, but the biggest issue is the manifold, it has pressed bends opposed to mandrel bends, in mid-october a new manifold should be coming out. Apart from that there’s not really anything major in terms of restriction, except some poor build quality items.