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Post by dmartin95 on Nov 5, 2014 23:27:34 GMT -5
Anyone have information about stroker kits? Success stories, failures? I've been searching pretty heavily about stroker kits and I've came across a few things I could use some help on.... For starters, a Stock GY-6 has a 57.4mm bore x 57.8mm stroke = 149.6cc. Stroker kits are usually listed as + x mm with the x being the additional millimeters. I.E. a GY6 has a stock stroke of 57.8mm. If you add 3mm to the stroke (60.8mm), you will get (57.4mm bore x 60.8mm stroke) a 157cc. Okay, so here's where my questions start rolling out... Just as the GY6 has a stock bore and stroke, it also has a stock cylinder height (at least I think).... Now, I haven't seen any numbers from a repair/shop manual, but I tried figuring out the size by looking up stock parts. From what I've determined, the stock cylinder height is 89.5mm. However, a lot of the aftermarket performance BBK's I have came across have taller cylinders.... I've seen them as tall 95mm (cylinder height).... That is a 5.5mm difference. First question: Is there any room in a stock GY6 to add a stroker without shims/spacers? - I've seen some that are as small as 2mm stroke. Second question: Is it the case that performance BBK's that are taller than the stock 89.5mm cylinder have more room for a stroker crank? --- To further this question, if the answer is yes, does that also mean that if I got a BBK that was 4mm taller cylinder than stock, that I should get a matching 4mm stroker? Third question: Does BBK stand for Big Block Kit, Big Bore Kit or something else altogether?  Forth is about a specific stroker. It's the 8.2mm from Taida. Even though I have found this upgrade listed for a 54mm GY6, I've seen GY6 store owners say on these forums that they stopped carrying them because they were destroying people engines... However, you just never know if what you're reading is truthful or not.... Does anyone have any actual experience with this stroker kit? Taida GY6 +8.2mm Stroker Crankshaft (66mm)Specifications Applications: Stock Stroke: 57.8mm GY6 125cc Engine (152QMI) Stock Stroke: 57.8m GY6 150cc Engine (157QMJ) Stock Stroke: 57.8m Taida Stroker Crankshaft 66mm (+8.2mm)  |
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Post by rcq92130 on Nov 5, 2014 23:49:40 GMT -5
BBK = Big Bore Kit
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Post by RapidJim on Nov 6, 2014 10:19:27 GMT -5
When I built Alleys trike motor in 2011 he went with a 60mm stroke (+3). scooterdoc.proboards.com/thread/4577/pst-150-bbk-build as far as I know it is still running strong. I have not installed one but, I can understand the statement where other shops have had issues with a +8 sroker crank. There are other factors involved besides the stroke. That is a lot of added stroke to a 150cc. It is just like any other performance build, there are limitations to what you want to do. If I was building an all out and out race motor, I would consider trying the +8 crank, only because I would be out to win and there would be tear downs after every race or so to see what was going on internally. I would not recommend it for a daily rider. |
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Post by UniqueSP on Nov 6, 2014 11:27:06 GMT -5
I have installed every stroker for the GY6 150cc engine. Basically you have to use a spacer for 3mm and above. Reason is the piston will hit the valve head. Now there is a way around that but most dont know how to do it. You take the piston and have it shaved down and the valve seats made deeper. I have a picture of mine and i need to find it. Doing this yo wont have to use a spacer. It will work with both 3mm and 4mm. As for the 6mm I shaved down the piston and added a thin spacer. Issue i ran into was the 92 link timing chain i used was too long. stock chain would not fit. So i modified the chain tensior to make it a little longer and it worked great. Now for the 8.2mm is tricky. issue is because of the stroke is so long that during the down stroke the piston can come too far out of the cylinder and jam a piston ring causing failure. They do make Big Bore kits that have longer skirts or built in spacers specifically for the 8.2mm kits. Also when doing strokers you sometimes have to grind down at the oil pump area a bit so the rod does not hit it.
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Post by dmartin95 on Nov 7, 2014 10:04:27 GMT -5
I read your link.... That's awesome what you did to Alleys trike! I'm in Michigan which is not all that far away.... How much do you charge to rebuild one of these engines? |
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Post by dmartin95 on Nov 7, 2014 10:34:17 GMT -5
I have installed every stroker for the GY6 150cc engine. Basically you have to use a spacer for 3mm and above. Reason is the piston will hit the valve head. Now there is a way around that but most dont know how to do it. You take the piston and have it shaved down and the valve seats made deeper. I have a picture of mine and i need to find it. Doing this yo wont have to use a spacer. It will work with both 3mm and 4mm. As for the 6mm I shaved down the piston and added a thin spacer. Issue i ran into was the 92 link timing chain i used was too long. stock chain would not fit. So i modified the chain tensior to make it a little longer and it worked great. Now for the 8.2mm is tricky. issue is because of the stroke is so long that during the down stroke the piston can come too far out of the cylinder and jam a piston ring causing failure. They do make Big Bore kits that have longer skirts or built in spacers specifically for the 8.2mm kits. Also when doing strokers you sometimes have to grind down at the oil pump area a bit so the rod does not hit it. So, you're saying you can in fact use a +3mm stroker without having to use any spacers? Or are you saying you can go +3 if you shave the piston? That's exactlly the kind of info I was looking for.... Care to share where you got your numbers from or is it just from experience? A few of the BBK's I found seem to be components for a larger kit.... The skirts are taller and have matching strokers and heads.... F or instance, this HOCA 63mm has a skirt height of 92mm (stock is 89.5mm), and the HOCA stroker is a +2.5mm.... 2.5mm + 89.5 = 92mm stroke... And of course the HOCA head ported to match a 63mm bore. |
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Post by UniqueSP on Nov 7, 2014 22:00:24 GMT -5
with a 3mm you either have to use a spacer or shave down the piston. one or the other. below are pictures of my piston when i had it shaved down next to the exact same piston before it was shaved down. as for how i did it i took it to a machine shop in Puerto Rico and those guys already knew how much they wanted to shave down. I prefer Taida over Hoca.   |
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Post by dmartin95 on Nov 8, 2014 13:55:02 GMT -5
with a 3mm you either have to use a spacer or shave down the piston. one or the other. 2 questions: So, are you saying with a +2.5mm stroker you don't have to do any mods to a stock GY6? Also, the HOCA 63mm has a taller skirt (it is 92mm vs the stock 89.5mm), does that mean I would have a combined 5mm of extra space for a stroker? The math works out if there's an extra 2.5mm of space in a stock GY6... The largest spacer I found is 6mm... If there's already an extra 2.5mm of space, 2.5mm-space + 6mm-spacer allows clearance for 8.5mm Taida stroker... Now I know Taida (and Samurai) makes a 95mm tall cylinder, but Taida's is only for the 57mm B-block... If you wanna go with an 8.5mm stroker on a 54mm, it has to be the 95mm Samurai or use spacers.... If I do go with a stroker, I will make sure to match it up with its corresponding BBK.... I do not want to use any spacers... I see them as a potential fail point..... What is it you prefer about Taida over HOCA? They're both Taiwan made I think..... I clicked on your link to Unique scooter parts, why do you not carry Taida products if that is your preference? I too like Taida's line-up, they have the widest selection and the water/oil cooled setups are the best IMO. |
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Post by xyshannen on Nov 8, 2014 16:05:10 GMT -5
Hoca would be a Camaro Taidi would be a Ferrari.
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Post by alleyoop on Nov 8, 2014 16:38:08 GMT -5
My motor has the 62bbk which needed the case bored out and a 60mm +2.2 stroker crank and no spacers where required. I hauled my trike up to Jim (RapidRepair) in Wisconsin because he said his machinist friend has a the boring equipment and I could not find anyone in Illinois to bore the case out. Motor has over 6K with the build and still going strong runs like a scalped ape.
Alleyoop
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Post by dmartin95 on Nov 8, 2014 16:52:17 GMT -5
My motor has the 62bbk which needed the case bored out and a 60mm +2.2 stroker crank and no spacers where required. What BBK? Who was the manufacturer? Not all BBK's have the same cylinder height... For instance, the Hoca 63mm bbk has a cylinder height of 92mm and the Samurai 63mm has a height of a whopping 95mm! |
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Post by alleyoop on Nov 8, 2014 17:48:48 GMT -5
Buy the kit and not individual parts they do not tell you that information and they do not know for one, they just sell the stuff. Also if your looking at the 63mm and you have a 157qmj motor you should NOT get anything bigger than a 62mm with a 63 you will have very thin walls and hardly any meat lift by the stud holes and the cam and chain side. One guy already went through that and the motor blew apart, broke through several of the stud holes and the cam chain side.
So the safe bet is up to a 62mm on a 157qmj and I can vouch for that.
Alleyoop
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Post by dmartin95 on Nov 9, 2014 15:37:12 GMT -5
Buy the kit and not individual parts What kind of kit are you talking about? One that comes with a BBK, Stroker, Head, Clutch & CVT etc etc... Or by Kit, are you talking about something like a BBK? I have no plans on trying to piece together a setup where I buy an individual piston, rings, cylinder etc etc... I assumed you had purchased a BBK seperately from your stroker.... Can you provide a link to the "kit" you bought? I've been thinking about that.... I have emailed a few suppliers and got the same feeling that they just sell the parts, and don't really know what they're selling... However, there are also vendors like scrappydog who aren't just "sellers", they're also enthusiast and actually know what they're selling. I wish I could just up and switch careers... Here in America, there is a huge lack of competent Chinese scooter mechanics and a lack of suppliers that know what they're selling...... Thanks.... I already had the same thoughts that 63mm would be some really thin walls.... I have only been linking to 63mm BBK's trying to find information about the skirt height in these BBK's.... I think the key to running a stroker successfully is making sure there's enough "meat" there to protect the head-cylinder-case from eating the piston....... I would never use a spacer unless it was a racing engine... When the piston rings in my scoot get weak and can no longer pass a compression I'm probably going to beef the ole havoc up... It runs so awesome now, I wouldn't dare risk tampering a perferctly good scooter for 5~10MPH speed increase... This is just me planning for the future... It's almost winter here in Michigan, all I have left is the forums and window shopping for the goodies!!! |
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Post by UniqueSP on Nov 10, 2014 21:19:52 GMT -5
with a 3mm you either have to use a spacer or shave down the piston. one or the other. 2 questions: So, are you saying with a +2.5mm stroker you don't have to do any mods to a stock GY6? Also, the HOCA 63mm has a taller skirt (it is 92mm vs the stock 89.5mm), does that mean I would have a combined 5mm of extra space for a stroker? The math works out if there's an extra 2.5mm of space in a stock GY6... The largest spacer I found is 6mm... If there's already an extra 2.5mm of space, 2.5mm-space + 6mm-spacer allows clearance for 8.5mm Taida stroker... Now I know Taida (and Samurai) makes a 95mm tall cylinder, but Taida's is only for the 57mm B-block... If you wanna go with an 8.5mm stroker on a 54mm, it has to be the 95mm Samurai or use spacers.... If I do go with a stroker, I will make sure to match it up with its corresponding BBK.... I do not want to use any spacers... I see them as a potential fail point..... What is it you prefer about Taida over HOCA? They're both Taiwan made I think..... I clicked on your link to Unique scooter parts, why do you not carry Taida products if that is your preference? I too like Taida's line-up, they have the widest selection and the water/oil cooled setups are the best IMO. Why dont I carry Taida Products? If you want to donate about $50,000 i will be more than happy to carry the brand. Its expensive. Those that sell it are the ones that buy it directly in Taiwan. There is no USA Distributor. Taida is an amazing brand. Very high quality. Hoca is a great brand but Taida is known for its racing products. |
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Post by UniqueSP on Nov 10, 2014 21:21:55 GMT -5
My motor has the 62bbk which needed the case bored out and a 60mm +2.2 stroker crank and no spacers where required. What BBK? Who was the manufacturer? Not all BBK's have the same cylinder height... For instance, the Hoca 63mm bbk has a cylinder height of 92mm and the Samurai 63mm has a height of a whopping 95mm! Not sure if your actually looking at parts for your scooter. Samurai which i have seen on partsforscooters.com website i believe those are for a different engine. www.partsforscooters.com/169-214_63mm_Cylinder_Kit like this one this is for a Yamaha Zuma. Not GY6 150cc |
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..BAD TO THE BONE..