Cynic

Lol. Thats you doing it my friend. 2 Hours to strip. Hour messing about with the rebore. ie sending it away. Another 2 hours to rebuild with fresh coolant and gaskets. I would expect it to be under 500 from a good independant. But in the smoke. Who knows.

Nope, it is actually better as is than fitting a different piston and rings now. It would be like fitting a new chain to knackered sprockets. Your looking at maybe 100 quid to sort it, if your fitting a new piston you would be a complete plumb not to bore it, or if your really stuck, chance a good barrel and piston from a breakers.

Oh you tit, I know exactly how you feel cos I did the self same thing a few years ago, although in my defence the bulb in the oil light had blown. Basically start saving, you will have done irreparable damage to the rings and to some extent the piston. It will never be the same as it was but relax as there will only of been damage to the upper cyl, the bearings will not have run dry. You may well get thousands of miles out of it, or, it may go in 500. Chances are good if the bike is in good normal health that will just mean the rebore will be needed earlier. The small rattle is most likely the little end bearing, another casualty but will be ok if mildly irritating. Like I said start saving, the clock is ticking but only a little faster than normal, it is a 2 stroke after all.

Ok, comp is down. Do you know the mileage, the oil making little difference suggests its not piston related. Also the fact you have 2 cylinder heads makes cracks or bad gaskets unlikely again because the values are similar on 2 separate elements. And the big plus, no smoke. That to me says look at the top end (valve gear) for the compression loss, could you be out on your valve adjusting propping valves?, or maybe a valve failure somehow?, but again on both cyl. Could the rattle have been cam chain?, bad tensioner maybe?, if that chain jumped a tooth or just whipped due to the slack affecting timing slightly and you bumped some valves that would do it? I may be wrong, but that's my logic and where I would start.

Why laugh at a ybr 125. I have been riding for. Fk me! nearly 30years and have 2 175's and a 250. I have also seen a cb250n make a bloke on a fireblade look like he needed stabilisers. Had the dt since i was 17. Engine size has its place but if the bike works for you what the fk is it any opinion of others. Welcome. I would wager there are far more 125 riders here than you think.

Me? If it really wont budge, drill and tap a drain in the case you remove to change the filter. That sidecase is easy to modify it as its removable without too much headache, a nice 10 or 12mm set screw at the lowest easily accessible point, use a stainless allen headed one and cut a clean thread and your all fixed for peanuts.

Just last year i re did the top end on my tdr due to a piston ring peg not stopping the ring from rotating and clipping the port. After the rebuild she got a gentle see what falls off trip to my mums. All told around 10miles round trip. Then ridden normally. Two weeks later i set off on a 600 mile weekend away at squires. Running in is tripe. If it aint broke in the first 20 to 30 miles it wont.

Sorry kev. Looks like you have posted one of your selfie's.

Think your looking in the wrong place. Have you tested the voltage regulater. Little silver box. Size of a match box with a yellow and sometimes white wire mounted either on the frame near the rear upper engine mount or under the seat.

Using a very un technical assumption my totally factory stock tdr250 runs 210 mains. So its worth seeing what the 210 does. Esp as you have one. Then go from there. If the 210 makes it run like shit and chokes then it may be more ig based. Do you know the ethanol content of your fuel. Here in the uk there is regular unleaded that can be 10% ethanol. That means bigger jets as the ethanol increaces the oxygen content of the charge, (leaner) AND reduces the relative petrol quantity by the same %. Leaner still. Also chemically attacking any brass and some of your seals too as well as holding water. Why i use premium fuel here which so far is ethanol free and you can tell the difference.

Think your looking in the wrong place. Have you tested the voltage regulater. Little silver box. Size of a match box with a yellow and sometimes white wire mounted either on the frame near the rear upper engine mount or under the seat.

Maybe with fresh oil

Sorry that don't wash, the daily sucks but the sqires meet is fine I have been every year and I'm in Bugbrooke near J15 M1, your closer than me by 40 mins. You can ride up with me in September if you want. Rode via the peak district stopping for chips in matlock, rode all the way with Andrewelvisfan, he was on his SR125, worked out somewhere around 230 mls for the trip up. Brilliant, no motorway and some epic scenery. Met the others in Matlock, one of those being Blackhat. He comes down from bravehartland and has a 7hour trip.

Nah. They know for certain their stuff is worse than your bike mate. Now they want to see how badly they missed the mark on the 900.

I shouldnt worry. 12hp is not going to destroy the oil anytime soon. The black in the oil is dust from the clutch not engine gunk. That isnt metalic so will do nothing. The oil will be fine.

200..... fk me. We were putting 250's in some of the 'tuned' bikes we 'improved'. Our favourite was a take the powervalve assy from the left cyl of a 350 and use a choke cable to opperate it. Low for wheelies, high for speed. Long time ago now though. No wonder she blew at 200. Was that a factory setting. If yours was factory full power the carb will have a different needle and emulsion tube etc which will make it lower but i thought the full power bikes used 220's. Dont quote me though. Anyway if there is no specific marking on the head gasket and is identical from either side fit as you please.

Why does the oil need changing so badly. Anything worth using will safely do 1000's of miles. So long as there is oil in there you have no scorching hurry. I'm assuming its just over the respective change period, that's like the sell by date on tinned food, largely to cover the manufacturers arse with a change interval so short. You could run it on a salt pan at max rpm without problems. How long has it actually been in there and what mileage has it done. Its good to change it but doing bigger damage from getting antsy with it is not helpful.

Another manufactured moment for the camera?

So you say? Enough money in Hollywood to generate a conspiracy around conspiracies so the conspiracy theorists coming up with the conspiracies, would think they had the wrong conspiracy completely, the clue is that these 'sights' nearly always have an ORANGE glow. Need I say more?

Fuel injection wont work without it.

Ah, so the funny lights in the night sky was Holland landing after a day trip to Mars. That's why its flat, less drag during take off.

Seriously, so, an alien. That going by the size of our solar system, not even the galaxy proper would have to be able to travel faster than light, many times faster than light to get here. Why would they give 2 starry eyed fucks as to if we could see them or not. It would be like discussing nuclear fission with someone from the stone age.

Wont tell you much on a 4 stroke, the plug thing is more for 2 strokes. The carbon left by the engine burning it tells you what's up. Your not burning oil (I hope) so really you need to look at the OLD plug to tell you about the engine as the residue takes far longer to build in a 4 stroke, if at all if its running really well. Use the bike for a week then have a look.

You take the side case off for the filter( i think) You can drain it then. Need to be carefull and may be messy without somebody to keep the bike leaned over. But it will drain the oil.

There aren't any un expected springs in there, maybe a couple of circlips but they wont 'ping' off without your positive help. Use the manual, personally I have a turkey basting tin from the pound shop that I use for this kind of thing. not affected by solvent, easy clean and keeps all parts together. I also keep the plastic tubs from the Chinese. You know the ones the food comes in to keep small parts ordered. End of the day be patient and accurate it will be fine.