If you drill it with a hand drill, just step up the bit sizes instead of doing it in one go. Takes longer, but goes much smoother and you are less likely to burn up the bit.
helps to be a competent machinist like these guys, right? what about all the other problems w/the cranks; wobbley, out of true, etc? prolly the crummiest part on these motors is the abysmal stock crankshafts, right? i mean-how often do you get one that is put together right?
Acording to my calculation it should be somethink around 15g each hole so around 30g total, but shis is just calculated based on normal steel, I dont know the exact density of the chinese steel.
Nice work! Hey I had a very important question, I bought a used bottom end and I've had to do lots of things. The recent one being I had to split the case because of a leaking case gasket. I noticed that I have what appears to be a balanced crank, yae! The rod is an AF80. I was using a 49mm iron sleeve, but I was thinking I would have better balance if I used the regular 47mm piston, and use my G4 cylinder. I'm not yet hip to balance factors, but I was wondering if these balance techniques are primarily used for the normal bores size and pistons? Also it appears that the case was ported for a minarelli jug. I haven't ventured into that arena either, lol. Any help with your knowledge would greatly be appreciated, thank you. ☺️
only two. if your crank was out of balance you will likely feel it throughout the entire rpm range. if you're vibing at 30 its likely drivetrain or wheel related
Ok so if I mod my engine and it vivrates like no tomorrow. I can drill holes as such as you've done here an it will help or make.it smoother completely. Great informative video by the way Thanks for sharing
Will lighten the crank by drilling a small 3/16(etc.) at set intervals cause too much offset in vibration or increase the overall r.p.m. factor? Just curious if you have looked at that as an option? Thanks for sharing the information.
I have a crazy issue. Been working on a 50cc bike engine. It's been a disaster from the word go. What is the normal width of a 50cc crank From outside of bearing to outside of bearing? Mine measures 2.165". The problem being that the inside of the crankcase is only 2" give or take a few thousandths. There's no way in hell this will work. It had two thick gaskets on it when I got it and was a witch to turn, duh. So which part is wrong so I know which one to replace?
Acording to my calculation it should be somethink around 15g each hole so around 30g total, but shis is just calculated based on normal steel, I dont know the exact density of the chinese steel.
the idea is too NOT go all way through with the bit! china does 65 % balanced is ok... what he did was 85%/ whats more ideal is 95%... add 2 more holes... trick is same weight as arm+piston+rings.. as metal removed... machinist do perfect but cost same as could buy 3x new motors! unless bought titanium race parts.. forget it! 85-90 % you feel no difference- better gas + no vibration! Godbless
If you drill it with a hand drill, just step up the bit sizes instead of doing it in one go. Takes longer, but goes much smoother and you are less likely to burn up the bit.
And what about a YD100? Same exact thing? Because they're all not the same. Different weights.
I’ve also seen them do the 7/16 on both sides left n right 5mm deep as well idk the difference tho so…..
helps to be a competent machinist like these guys, right? what about all the other problems w/the cranks; wobbley, out of true, etc? prolly the crummiest part on these motors is the abysmal stock crankshafts, right? i mean-how often do you get one that is put together right?
I have a ld100 and I’ve ordered a Reed valve and windowed piston would you still recommend this?
Is this Ballance good for a Stihl head that has high rpm or do you recommend taking more off
so you don’t drill all the way through?
Acording to my calculation it should be somethink around 15g each hole so around 30g total, but shis is just calculated based on normal steel, I dont know the exact density of the chinese steel.
Nice work! Hey I had a very important question, I bought a used bottom end and I've had to do lots of things.
The recent one being I had to split the case because of a leaking case gasket.
I noticed that I have what appears to be a balanced crank, yae! The rod is an AF80.
I was using a 49mm iron sleeve, but I was thinking I would have better balance if I used the regular 47mm piston, and use my G4 cylinder.
I'm not yet hip to balance factors, but I was wondering if these balance techniques are primarily used for the normal bores size and pistons? Also it appears that the case was ported for a minarelli jug. I haven't ventured into that arena either, lol. Any help with your knowledge would greatly be appreciated, thank you. ☺️
I've used the AF80 rod with the 47mm cylinder. It's smooth as glass. Definetly recommend it.
Damn it's very hard to hand drill, dtm I know have a drill press but they don't believe in drilling the crank so they didn't service my crank 😔.
Is this for the 80/66 cc engine ?
Hello
I have only have a 3/8 bit can i drill two holes?
Do you sell them?
It’s 4 wholes 2 each side front n back or only two?
I have 80cc chinadoll n I when I get to 30 she does get a bit vibratey
only two. if your crank was out of balance you will likely feel it throughout the entire rpm range. if you're vibing at 30 its likely drivetrain or wheel related
Ok so if I mod my engine and it vivrates like no tomorrow. I can drill holes as such as you've done here an it will help or make.it smoother completely.
Great informative video by the way
Thanks for sharing
Did it work fine?
@@catsnponds5959 yes it works i did it with the head off from the top. the bike and hosed out the bits with a garden hose. Revs way better now
Could have bearings going bad too
what is the drill bit size in metric units. also does this work on any motorized bike engine?
That would be a 13mm drill. I recommend asking someone in a forum or following twostrokestuffings guide.
A half inch is 12.7 mm
Will lighten the crank by drilling a small 3/16(etc.) at set intervals cause too much offset in vibration or increase the overall r.p.m. factor? Just curious if you have looked at that as an option? Thanks for sharing the information.
Yes it's just that simple. Its not really a high tech job to balance china doll. Thanks
I have a crazy issue. Been working on a 50cc bike engine. It's been a disaster from the word go. What is the normal width of a 50cc crank From outside of bearing to outside of bearing? Mine measures 2.165". The problem being that the inside of the crankcase is only 2" give or take a few thousandths. There's no way in hell this will work. It had two thick gaskets on it when I got it and was a witch to turn, duh. So which part is wrong so I know which one to replace?
I completely ruined my motor😅
How do you know how much weight to shave?
Acording to my calculation it should be somethink around 15g each hole so around 30g total, but shis is just calculated based on normal steel, I dont know the exact density of the chinese steel.
my bicycle engines crank 15.77mm thick, do I still go 15mm deep?
the idea is too NOT go all way through with the bit! china does 65 % balanced is ok... what he did was 85%/ whats more ideal is 95%... add 2 more holes... trick is same weight as arm+piston+rings.. as metal removed... machinist do perfect but cost same as could buy 3x new motors! unless bought titanium race parts.. forget it! 85-90 % you feel no difference- better gas + no vibration! Godbless
@@chrisstokley7687 Okay but what about a YD100? There's really not much videos on it, and I honestly can't be bothered taking the crankshaft apart.
What about a 52 mm? I have a phantom
Well he did say China doll motor
Maybe check with manufacturer and see if you can find out approximate balance
The perfect balance in a crank?? Definitely not! This actually can be done perfectly, but something called maths is required.