sean01
Legend Spanner Spinner
Ok just got a 67mm BBK and some extra's in the mail from Akunar in Thailand.
All Akunars bore kits are $125usd plus shipping which is usually around the $35usd
and since a fair few people buy from akunar but never review his products i thought id throw one up..
now this kit will make 186.85cc in a yx 150, 193.91cc in a 155zonger and 200.96cc in a yx160
Firstly the quality of the barrel looks good (brand new not reco'ed) and it even come with rubber dampeners in-between the barrel fins to try and lower some of the pinging noise these engines are known for..
and it actually look like one of the barrels used on the zonger 155
i have to add too that the quality of this bore kit compared to the ceramic kits available is far better
straight up i measured the sleeve OD and it is 71mm so cases will need to be bored at least 0.030 tho bigger or 71.07mm
the height of the bore from base to head gasket surfaces is 74.47mm
the piston is a cast flat top type with a 15mm gudgeon pin.
also there are 2mm thick pin boots so you can use the yx 13mm gudgeon pin in the 15mm piston..
the pin height with the pin boots included is 14.25mm
the 2 top rings are both chrome rings which is good as they last longer and can cop a pretty good flogging straight away.
both rings are marked so you know which is the top side of the ring and they also have the numbers 1 and 2 on them to show which ring is for which groove.
head gasket is made of copper and is 0.5mm thick and has a 67mm cylinder hole..
the base gasket is alloy and is 0.55mm thick and has a 70mm sleeve hole..(he has sent me the wrong one so i have to modify this)
ok this is probly overkill for the review but now onto the technical side of it for the odd person that wants to know everything about these..
and for those wondering i use a micrometer and an inside dial bore gauge
piston measures 66.916mm in the mic at the top of the skirt (just under the oil ring groove)
then measures 66.988mm at the bottom of the skirt
now the bore clearance im not 100% a fan of but should be it would be fine the way it is or you could give it a quick hone to suit your standards.. but im sure since akunar has been doing these for a long time now im going to trust what he has done..
ok at the top of the bore it has 0.0005 tho (half a tho)
in the middle of the bore it has 0.0015 tho (1.5 tho)
at the bottom of the bore it has 0.002 tho
im guess he does this for perfect ring seal as the skirt only comes up half way in the bore..
ok now i bought a cam off EPOD couple weeks ago but i needed springs, so here they are.
top set are heavy duty YX clutch springs
i will edit this post when i get time to check the valves installed height on a YX head and length of these springs on coil bind.
that way everyone can see how much lift these springs will handle..
unfortunately im unable to check the seat and coil bind pressure, but i may take them to the engine shop around the corner from me to see when i have time..
ill probably be installing this kit either this weekend or next on another miniriders members bike (176thumpy) it will be in a yx150 bigfoot with either a 28mm or 30mm oko, but we are still waiting for the carb and exhaust system from akunar..
so keep an eye on this thread as im going to include some extra info like compression ratio, piston deck height etc
oh and for my end thoughts..
All Akunars bore kits are $125usd plus shipping which is usually around the $35usd
and since a fair few people buy from akunar but never review his products i thought id throw one up..
now this kit will make 186.85cc in a yx 150, 193.91cc in a 155zonger and 200.96cc in a yx160
Firstly the quality of the barrel looks good (brand new not reco'ed) and it even come with rubber dampeners in-between the barrel fins to try and lower some of the pinging noise these engines are known for..
and it actually look like one of the barrels used on the zonger 155
i have to add too that the quality of this bore kit compared to the ceramic kits available is far better
straight up i measured the sleeve OD and it is 71mm so cases will need to be bored at least 0.030 tho bigger or 71.07mm
the height of the bore from base to head gasket surfaces is 74.47mm
the piston is a cast flat top type with a 15mm gudgeon pin.
also there are 2mm thick pin boots so you can use the yx 13mm gudgeon pin in the 15mm piston..
the pin height with the pin boots included is 14.25mm
the 2 top rings are both chrome rings which is good as they last longer and can cop a pretty good flogging straight away.
both rings are marked so you know which is the top side of the ring and they also have the numbers 1 and 2 on them to show which ring is for which groove.
head gasket is made of copper and is 0.5mm thick and has a 67mm cylinder hole..
the base gasket is alloy and is 0.55mm thick and has a 70mm sleeve hole..(he has sent me the wrong one so i have to modify this)
ok this is probly overkill for the review but now onto the technical side of it for the odd person that wants to know everything about these..
and for those wondering i use a micrometer and an inside dial bore gauge
piston measures 66.916mm in the mic at the top of the skirt (just under the oil ring groove)
then measures 66.988mm at the bottom of the skirt
now the bore clearance im not 100% a fan of but should be it would be fine the way it is or you could give it a quick hone to suit your standards.. but im sure since akunar has been doing these for a long time now im going to trust what he has done..
ok at the top of the bore it has 0.0005 tho (half a tho)
in the middle of the bore it has 0.0015 tho (1.5 tho)
at the bottom of the bore it has 0.002 tho
im guess he does this for perfect ring seal as the skirt only comes up half way in the bore..
ok now i bought a cam off EPOD couple weeks ago but i needed springs, so here they are.
top set are heavy duty YX clutch springs
i will edit this post when i get time to check the valves installed height on a YX head and length of these springs on coil bind.
that way everyone can see how much lift these springs will handle..
unfortunately im unable to check the seat and coil bind pressure, but i may take them to the engine shop around the corner from me to see when i have time..
ill probably be installing this kit either this weekend or next on another miniriders members bike (176thumpy) it will be in a yx150 bigfoot with either a 28mm or 30mm oko, but we are still waiting for the carb and exhaust system from akunar..
so keep an eye on this thread as im going to include some extra info like compression ratio, piston deck height etc
oh and for my end thoughts..
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