In middle of a rebuild ktm 125sx top end. The new piston say I need to drill 2 holes. Is it necessary?? I dont race just ride around with my kids and wife. Any advice would be greatly appreciated thanks
Usually pistons will come with holes drilled already. I've never had to drill holes in a new piston and don't advise doing so. Are you sure it's the correct piston for the bike?
@@Dragonpops I did get the right size piston. You can never go wrong with the part #. I didn't drill holes just put it together. My first top end rebuild . Did everything I was supposed to do. Has way more compression (but not too much) antifreeze is holding at the same level. So far everything is good. Thanks Had to edit I did drain the transmission fluid flushed it and put new. I love it
I’m just a guy that builds motorized bicycles but I do two-stroke Only the reason for those two holes is if you have a split exhaust for so if your previous person did not have two holes do not have to drill it but if they did you need to drill them with that does is it lubricates and caused a little bridge of your exhaust port so it doesn’t swell outwards and cause a seizure however you will have better compression without drilling those two holes which also means Moreheat You can keep it like it is but I won’t ride it no more than 1520 minutes at the most 20 minutes at the most so get you a drill bit that is smaller than the bridge about the same size as the previous two holes can be bigger as long as they’re not bigger than the bridge and drill those two holes in the same spot or even put them closer together and add a third just make sure to smooth them out with a piece of extra superfine sandpaper when you’re done so they don’t have burrs on the edges kind around those edges off where you drilled on the edges of the circle
I use forged pistons and they last a shit load longer than cast. I go 200 hours with forged pistons in my 250 2 stroke. Never had a forged piston fail. Ive blown up a lot of top ends and they were ALL cast pistons and well under 100 hours.
@@Dragonpops I have never actually seen an engine with a cold siezed forged piston. That is probably some outdated myth from something that happened one time with an improperly designed forged piston in some highly abusive application back before engine parts were designed as well. Although yes they do require good luhrication. I run a fat oil mixture. I saw a study on oil migration in 2 stroke engines, and it is drastically faster with rich mixes.
@@hrbestalkinme3690 actually it happened to me on my previous YZ with a Wiseco forged piston, just didn't warm up as long as I should have. And there are tons of other people that have had the same issue so definitely not outdated or a myth. Forged pistons expand at a different rate to the cylinder. My video was not promoting cast over forged at all, just showing how much difference a good lubricant makes.
Firstly, mineral oil cannot provide the protection and cleanliness that a high quality synthetic oil can and it is destroyed by heat much easier. Secondly, running at 20:1 with any oil will foul the spark plug, form high amount of deposits in the combustion chamber and power valve, and make lots of smoke. All of these will be even worse if you use mineral oil.
Best lubrication comes from Castor Oil, the hotter Castor oil gets the better its lubrication properties get, downside is you get a lot of carbon build up, doesnt burn clean, so more maintenance required.
All motocross bikes technically have racing engines which always require frequent rebuilds if used as intended, 250f's require even more frequent and much more expensive rebuilds when raced. Slow riders can go 100 hours without rebuilding, but a pro racer needs a rebuild every 5 hours or so
@@2smoker311 sorry kid, it simply doesn't work that way. Internal wear increases exponentially with load, rpm, heat, etc and simply adding more oil cannot solve the problem. Adding more oil than optimum just leans out the mixture, reduces power, fouls spark plug, builds up carbon deposits, and clogs power valves . Go do some reading on 2-stroke racing engines before your next reply
Really thats only for race bikes. I use mine for trail riding and I rebuild it once a year. Its really not that big of a deal, I can do it in an hour or two. Its like 200 bucks total.
Motul 800 number 1
I must have 300-400 hours on a ktm85 piston & I'm on the pipe more often than not. I always warm her up real easy though before she gets the stick.
What fuel retro do you recommend after a fresh piston?
I hope my insides look like that after lubricating myself with Motul. #nowgoride
In middle of a rebuild ktm 125sx top end. The new piston say I need to drill 2 holes. Is it necessary?? I dont race just ride around with my kids and wife. Any advice would be greatly appreciated thanks
Usually pistons will come with holes drilled already. I've never had to drill holes in a new piston and don't advise doing so. Are you sure it's the correct piston for the bike?
@@Dragonpops I did get the right size piston. You can never go wrong with the part #. I didn't drill holes just put it together. My first top end rebuild . Did everything I was supposed to do. Has way more compression (but not too much) antifreeze is holding at the same level. So far everything is good. Thanks
Had to edit I did drain the transmission fluid flushed it and put new. I love it
Drill the holes!
I’m just a guy that builds motorized bicycles but I do two-stroke Only the reason for those two holes is if you have a split exhaust for so if your previous person did not have two holes do not have to drill it but if they did you need to drill them with that does is it lubricates and caused a little bridge of your exhaust port so it doesn’t swell outwards and cause a seizure however you will have better compression without drilling those two holes which also means Moreheat
You can keep it like it is but I won’t ride it no more than 1520 minutes at the most 20 minutes at the most so get you a drill bit that is smaller than the bridge about the same size as the previous two holes can be bigger as long as they’re not bigger than the bridge and drill those two holes in the same spot or even put them closer together and add a third just make sure to smooth them out with a piece of extra superfine sandpaper when you’re done so they don’t have burrs on the edges kind around those edges off where you drilled on the edges of the circle
I use forged pistons and they last a shit load longer than cast. I go 200 hours with forged pistons in my 250 2 stroke. Never had a forged piston fail. Ive blown up a lot of top ends and they were ALL cast pistons and well under 100 hours.
Yes forged pistons definitely much stronger, but still require excellent lubrication especially since they can cold seize very easily!
@@Dragonpops I have never actually seen an engine with a cold siezed forged piston. That is probably some outdated myth from something that happened one time with an improperly designed forged piston in some highly abusive application back before engine parts were designed as well. Although yes they do require good luhrication. I run a fat oil mixture. I saw a study on oil migration in 2 stroke engines, and it is drastically faster with rich mixes.
@@hrbestalkinme3690 actually it happened to me on my previous YZ with a Wiseco forged piston, just didn't warm up as long as I should have. And there are tons of other people that have had the same issue so definitely not outdated or a myth. Forged pistons expand at a different rate to the cylinder. My video was not promoting cast over forged at all, just showing how much difference a good lubricant makes.
What about running a mineral oil but it a high ratio like 20:1?
Firstly, mineral oil cannot provide the protection and cleanliness that a high quality synthetic oil can and it is destroyed by heat much easier.
Secondly, running at 20:1 with any oil will foul the spark plug, form high amount of deposits in the combustion chamber and power valve, and make lots of smoke. All of these will be even worse if you use mineral oil.
Best lubrication comes from Castor Oil, the hotter Castor oil gets the better its lubrication properties get, downside is you get a lot of carbon build up, doesnt burn clean, so more maintenance required.
From south africa?
What do you mix fuel to oil ratio??
Probably straight gas if hes replacing it every 12 hours.
What oil ratio did you run at for those 24hrs?
Christopher Ramnauth, 40:1
Dragonpops and what kind of max rpm does that turn?
Its a standard 125 so around 12000rpm max
Dragonpops ok cool, I race karts and own a rotax 125cc but it's single speed and revs to 14000, wanted to compare top end interval times
I don't understand these bikes, who would want to rebuild a bike every 20hrs?
All motocross bikes technically have racing engines which always require frequent rebuilds if used as intended, 250f's require even more frequent and much more expensive rebuilds when raced.
Slow riders can go 100 hours without rebuilding, but a pro racer needs a rebuild every 5 hours or so
@@Dragonpops Surely if you mixed like 25:1 you could get 500hrs out of an engine
@@2smoker311 sorry kid, it simply doesn't work that way. Internal wear increases exponentially with load, rpm, heat, etc and simply adding more oil cannot solve the problem. Adding more oil than optimum just leans out the mixture, reduces power, fouls spark plug, builds up carbon deposits, and clogs power valves . Go do some reading on 2-stroke racing engines before your next reply
Really thats only for race bikes. I use mine for trail riding and I rebuild it once a year. Its really not that big of a deal, I can do it in an hour or two. Its like 200 bucks total.