Posts
42
Joined
11/19/2023
Location
Commiefornia, CA, USA
bike was using VP Racing T2. apologize, these are just parts of the piston, were taken with a borescope.
also, came across this FTC Decarbonizer (i believe it's an additive), supposed to clean up/remove carbon. has anyone tried it? wonder if this works, also, if it does starts to take off carbon, if the carbon flakes off, wouldn't that possibly cause some of it to get stuck between the piston/rings and score the cylinder?
What bike and how does it run?
2021 YZ125, i bought it used in oct of 2023, the seller bought it new in late 2021, he has multiple bikes, claimed this bike was for his young son and he just doesn't like riding it, so supposedly 10 hours. It has original tires, clutch and flywheel covers, wear wise on them, seems like he's telling the truth of the hours. the only things he changed are a bigger rear sprocket, silencer, header pipe, grips and seat cover, did a cold compression test, came out to 180 psi. I only had the chance to test ride it when checking it out and when i got home, rode it up and down a block length a few times, runs well at semi low speed, idles perfect, have not yet gotten a chance to ride it WFO. here's the bike. also there is one long black mark in the cylinder, can't tell if it's just a stain mark or scored.
Definitely more soot than on my yz125 pistons. It has probably run mostly on low rpm & load so cold & rich mixture causing much soot. Nothing to worry about I think.
that makes sense 👍🏻
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Probably 10 hrs of lugging, bike looks fantastic!
guess the seller was telling the truth 👍
anyone have an answer to the FTC Decarbonizer question from my first post and/or the cylinder mark question from my 2nd post (i am thinking if scored, it should go all the way down)?
I have never used something like that...the mark is interesting, but could be made to look worse by being up close. If it was me, I would get a new top end just for peace of mind and you can really inspect things. If that mark can be felt with a finger nail, then it will probably require attention.
Definitely needs some jetting if you are going to run T2. The mark is nothing, cosmetic.
jetting is bone stock, when i went to check it out, unless he changed the plug, it looked good from what i recall, cause yamaha's manual suggested plug BR9EVX, which has been discontinued, the replacement is BR9EIX. the seller ran nothing by T2 from the get go, his main concerned was detonation. me, i'm just gonna used premium 91 pump with stabil storage. all my previous bikes i had ran 91 pump (or whatever octane the premium was back then), but those days were before they started adding ethanol.
Just checked the plug, seller did change it to BR9EIX, probably fouled 1000 plugs before i bought it. 😆
this bike is for my noob young son, he's gonna be slow as molasses for a short while, he'll be using motul 800 2T, probably at 50:1, until he gets faster, after that, i'll change his jetting if need be.
These bikes respond amazing to jetting.
i got the same bike, seller bought it brand new, sat in garage for 2 years unridden, once i do break in, i'll change jetting.
I wouldn't use the decarbonizer. Just jet it right and run it. If you are really bothered, just buy a bade gasket wnr rings and manually clean the top end.
Don't worry, just go ride
"lugging"
i just thought about that, it had a shorty silencer, probably mostly ridden on tracks if not completely, the front number plate, upper forks and protectors all have tons of tiny dings everywhere, probably from lugging behind everyone else, getting roost constantly. lol.
I don't think it was lugged. The way the piston looks it never ran right. The carbon will not be an issue going forward.
lugging, i think INeedaNewUsername meant just going too slow most of the time to burn off enough of the oil .
what you said, if so, on my brand new one, i was cleaning out the carb from sitting with original dealer gas for so long and changing out the jet block gasket to JD's, found that the float height from the factory was at 6mm (my son's bike is probably the same), JD Jetting said that's how they come from the factory, they said it should be at 8mm. question is, aside from jetting, I assume a rich float height can/will cause extra carbon?
before, when i get a brand new bike, i just ride it and do basic backyard mechanic work when needed and learn more as i go. but now, i find learning more mechanical stuff work fun also.
I would start with the PC specs and adjust for local and fuel.
well, need to set float height properly first, otherwise cannot do jetting properly.
sorry, but what is PC?
Pit Row
Pro Circuit, they have a great setting.
oh cool page, ty.
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