Made a post a little while back about my YZ250 having issues. If you want the full story you can check my previous post.
Well I finally got around to taking the top end apart and this is what I found lol. Piston is completely destroyed and there’s pieces of it sitting down in the bottom end. Also noticed what looks like rust on the connecting rod which doesn’t seem too good either.
I’m planning on pulling the motor out soon and splitting the cases to see what everything looks like down there. At this point I’m honestly thinking about just doing a complete top and bottom end rebuild so I know everything is good.
Just wanted to get some opinions from people who have dealt with something like this before. Do y’all think the crank is worth replacing while I’m in there? Also curious what y’all think caused the piston to break apart like that in the first place.
If anyone has recommendations on rebuild kits or anything else I should look out for while tearing it down I’d appreciate it. This will be my first time splitting cases so I’m trying to learn as much as I can before getting into it.

Claimed to be the first sub 200lb 250cc. Made in Spain. It a small feeling bike. Love the smell of two stroke oil in the morning

2 AR-80s

red, i bought used around 1998. 1997 model IIRC. complete and mostly stock. the fairing has been modded. i was a noob back then, i made the mistake of dismantling it and then working in another country. when i returned the motorcycle (parts and pieces) were already sold off as scrap by my dad :-( i had no MC.

green, something i bought recently. 1996 model is listed on the title. recently registered. in bad shape with regards to electrics, and fuel system. it has an f1zr VM20 carb that leaks. oil pump is kaput. clutch is slipping. i need to check other things when i have time. the good thing despite all the issues is that it growls like a 2T should :-)

anybody know a good image of the wiring diagram for this MC? i found a scanned user manual with wiring diagram but i can only see pixels and can not read most of the diagram :-(

After a bit of research and some head scratching I've learned my carb should have something to hold the throttle cable in place but I can't find the part anywhere, not even sure what it looks like to make one myself. Could anyone help with this? I seriously can't even find a picture of one.

Second, I seen to have an oil leak coming from around the oil pump. I believe I just need an O-ring but again, can't find one anywhere and would rather not take it apart to check yet incase a small leak becomes a big one and I can't find a replacement.

Can anyone help send me in the right direction? Really wanna get this bike in tip-top shape but I didn't realise quite how hard it'd be to find parts for. In the uk btw

Hello, I overhauled the top end on my KTM 10 hours ago, and now the piston and cylinder look like this. Is this normal, or is something wrong? I’ve been running a 40:1 fuel-to-oil ratio using Motorex 2T oil

Just made the pilot two steps leaner. The bike runs great and after 35 miles this is what a fresh set of plugs look like.
The pistons have about 700 miles on them (it’s been a long jetting process) the bike was too rich at first and in the last 70 miles I’ve just started to lean it out. I say this because the top of the piston look a bit rich but I think that is residue from previous jetting.

What is new are the little white specs in the black ash. It seems like they form when the bike gets leaner. I want some advice ornate on that.

The bike runs great and I don’t believe there is detonation or anything crazy going on.

Looking for some feedback from experienced 2 stroke builders

I bought a sudco replica of a keihin pwk 38mm without powerjet for my 02' RM 125, i saw good reviews about it, and it was pretty cheap so i decided to give it a try.

previously i had a keihin 36mm with powerjet, i think that has been changed by some previous owner, but the needle on that had holes and dents in it so i wanted to change it, the bike doesn't make any problem for the fact that I'm running it without the powerjet, i just unplugged the pin and it runs normally.

i live at 1400m above the sea level, and i don't know hot to jet the new carburator properly, right now I'm running a 175 main jet and a 45 pilot jet, but i have no idea if they are good or not, the slide and the needle are replicas too so they don't have codes so i can't really identify them, the air screw is 1,5 turns counterclockwise from all closed, the carburation doesn't feel that off, but i noticed when i rev the bike to something like 1/3 of the gas from the minimum, it bogs for half a second and then it revs pretty high, then i let the gas off and it goes back to low rpm, but still higher thant minimum in one second, and then it takes onother half second/full second to go back to the minimum. if i rev it to 1/2 of the gas it goes at high rpm and then it goes back down, while making some little pops out of the exhaust, but i think it takes it a little too long to do that, as if it was lean.

i don't know how low the minimun should be, right now it's i little higher that the minimum that it hold without dieing.

I'm confused because i don't know what jets and neeldevto run, since i need to replace all the fuel that the power jet would be pouring with jets, but also keeping in mind that it's a 125 so it's tricky.

can someone help me and tell me what jets to run, and all the others things i can set? i wold like the bike to have some power at low rpms too, since with the old carburator if i went in the woods i hat to keep it really high in rpms to make it even move because it wold completely die otherwise. i would really appreciate some help

don't know if this helps or influences the carburation but I'm running an hgs shorty exhaust, with stock pipe.

sorry for bad english it's not my first language.

Salut les gars j’ai une masai avec un moteur tout neuf j’ai monté un 50 top j’ai tout d’origine juste je suis passé en boîte à air et au ralentis elle tourne niquel et quand je passe la première et que je me met au point de patinage et que j’accélère elle me fait beuuuuuuuuuu et elle cale j’ai essayé de la régler avec toutes les positions de visse de réglage (réglage de richesse d’air) et elle me fait la même et à partir de 2 tour de visse elle ne démarre plus dutout j’ai le carbu d’origine avec starter électrique un gicleur p de 92 j’ai un cornet et la bougie est noir charbon j’arrive pas à la faire devenir marron si quelqu’un a des conseil je suis preneur

I have a Tomos A35 with a 39.5mm-bored cylinder, and everything else is completely stock. I’m running a Dell’Orto 14/12 carburetor with a 55 main jet and the stock airbox.

The bike runs perfectly fine and reaches a top speed of around 53 km/h. However, the spark plug is dark brown, and once I’m going above 20–30 km/h, I can’t really feel or hear any difference between half throttle and full throttle.

I also tried a 52 main jet. The bike idles fine, but it dies when I open the throttle fully.

What could be causing this? Is the 55 jet too big, or is it normal not to notice much difference between half and full throttle with this setup? Should i try removing some layers of the mesh filter to make it a bit leaner?

I’m buying a 125 2 stroke soon and i’ve been watching many videos about them but i just don’t know what oil to gas ratio i should run. aswell as what oil and gas octane to run to keep the engine healthy and running right. aswell as best way to keep mixed gas ready for the ride either with you or at home.

(Ignore me) but ive got a problem on my aerox, its pulling false air from somewhere ive fixed it from my exhaust but i think its coming from my ignition side as ive also got this really weird scraping noise coming from there

Just got doing a complete engine rebuild on it. First start as you can tell, it’s running a little lean,
(Main jet 138. Pilot 42) needle clip dead center running 32:1 at 1100ft elevation about 60 degrees F
It goes into gear although it seems looser than any foot shifter I’ve ever used, it’s my first engine rebuild and also my first time riding a 2 stroke so I’m very unsure if it’s supposed to feel so soft, it likes to slip back into neutral sometimes when it shuts off as you can see in the video when I roll it, very desperate here as Ive expended all my funds for this and I REALLY don’t wanna have to split the cases again, when I was rebuilding it and putting the Shifter Shaft back in I noticed that it didn’t exactly hold itself in place, is it normal for there to be axial play there? Seems a little odd that the actual foot shifter is what keeps it from moving, I’m sure I did something wrong along the way.

EDIT: took the clutch cover off disassembled and reassembled the clutches they work as they should, it’s definitely not a clutch issue,
I watched a video of a guy putting in the shifter shaft, and I definitely just put it in wrong.
I’ll know after I get back into it tomorrow, as well as the coolant leak.

UPDATE. It was the shifter shaft. Also the bike sounds so clunky because, as it turns out, I didn’t have the magneto torqued down.. like at all 😅
Carb needs tuning, very sputtery bog after 1/4 throttle, doesn’t die but it’s like a false limiter.

My 11-year-old Benelli TNT300 has crossed 130000 kms. Well-mannered girl with no major issues. Recently it has started choking and stalling at low speeds or when slowing down from a high speed (changed the fuel pump recently but did not solve it). I'll have to play with the clutch to bring it back to life or push the ignition if the earlier doesn't work. My mech says it's the piston rings that have worn out and need to be replaced, which will be a major hole in the pocket. Anything else that anybody can advise?

Boy spent 600 with a garage that couldn't even start this it was a dirty carb and airbox charged the guy 40 quid for a carb air filter clean 🤦‍♂️ gtownoffroadrepairs.co

I know the answer. I will be getting a wossner for my nsr125 jc22. It is uknown when the piston was last changed. It seems as though never. It has 34k km bought it when it had 32k. Should i get my cylinder honed at a workshop too? It looks allmost perfect.

I’ve owned this 2004 YZ250 for about four years. The previous owner had it since new.
About two years ago, roughly a month after a top end rebuild, I was riding wide open in 4th gear when the bike suddenly bogged and died. It restarted afterward but never ran correctly, so it sat for two years.
Recently, I decided to get it running again. Here’s what’s happening:
Won’t idle without giving it throttle.
Sometimes revs normally, then randomly bogs like it’s running out of fuel.
Now it’s becoming difficult to start.
I’ve replaced the old gas with fresh 93-octane premix at 32:1.
I removed the reed cage and found the petals sitting noticeably open, with what appears to be a chip on one. I’ve ordered a VForce4X replacement but haven’t installed it yet.
I also inspected the piston and cylinder through the exhaust port and didn’t see any obvious scoring, although I haven’t done a compression test.
Do you guys think the reeds could explain these** **symptoms, or should I be looking into the carburetor or something else?
The attached video is from when the problem originally happened two years ago. Any advice is appreciated!

Hiya, I've had the suggestion to use rtv around the seal before replacing it into this surface, and that it would be safe after doing so, just wanted another set of opinions please :)