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Post by jerseyboy on Jul 30, 2013 10:35:03 GMT -5
Hi guys!!
I am planning on doing a BBK on my 150cc one of these days and just wanted to see what works well for you guys.What head,cam,cylinder,carb,jetting,ect and the results you achieve.I do not want to waste $$ and time so am trying to look into this.
I want to get a 60mm kit so I dont have to bore..my carb is 24mm.Also I'm not looking to race around at 8K rpm all day,,I just want the extra power to be able to cruise with taller gears,,but I do want a worked gy6 motor.
Thanks in advance...
Regards
Tom
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Post by millsc on Jul 30, 2013 10:49:12 GMT -5
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Post by jerseyboy on Jul 30, 2013 10:56:50 GMT -5
[replyingto=millsc]millsc[/replyingto]Thats exactly the same kit I'm getting,,my question is how do we get the full efficiency out of that BBK,,cam size,head,valves,carb,jetting,ect...Id like to hear what some guys did to there motor to get great results,,throwing a BBK on and not doing anything else would be defeating my purpose...and just buying random performance parts to build a motor is not my thing either.
I was going to try keeping my 24mm carb(according to Alleyop is more than big enough)upgrade the cam and head,,after that I would think it might need bigger jets,,its a 45/118 now,,I have the free flow exhaust and UNI already.
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Post by millsc on Jul 30, 2013 11:12:46 GMT -5
I'm gonna run a 26mm carb uni pipe and maybe a four valve head gonna max it
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Post by jeepsteve92xj on Jul 30, 2013 11:16:06 GMT -5
45!
My Znen has a 38 and 118, 1" header shorty muffler, and a pod filter.
a BBK, big valve head and an A9 (?) cam seems like a good start.
IF I found someone fairly close, I could see getting the case bored for a larger BBK. Jim is on the kitty-corner of the state from me.
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Post by brandjur on Jul 30, 2013 16:12:25 GMT -5
I was also looking at that kit, but I purchased a 58.5mm NCY kit because the piston skirt goes almost all the way around. If you look at the "high compression" or "performance" pistons, you will see the piston skirt is cut out at the wrist pin sides. That means the piston will rock more in the cylinder. More rocking leads to more wear. I was looking for durability and longevity. If you are doing a drag bike or plan on rebuilding in less than normal wear time, then get the lighter high compression pistons. I also added an NCY 58.5mm head. If you do the 26mm carb, there are choke points in the spacer and the stock head. They both measure at 24mm. Now, as far as flow, yes these can be restrictive, but another way to get more air and fuel is duration. That is where a camshaft will work well. I haven't started the engine yet with the bbk upgrades, will probably finish up the build by tomorrow. Attachments:
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Post by jerseyboy on Jul 30, 2013 21:32:11 GMT -5
[replyingto=brandjur]brandjur[/replyingto]Very cool guys,,
Please post your results and what you used.
I am looking for more reliability,,but also want some power too!
I may have to go with a different piston,,will have to talk to Walter at Scooter Elements.
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Post by justin010304 on Jul 31, 2013 2:01:26 GMT -5
If you plan on doing anything over an A8 cam I would get KSPower (fender cycle) valve springs, they are rated to 11k rpm's and are designed to take high lift cams without any binding. I built my motor with NCY head, springs and valves. Used taida retainers and NCY cam. The intake spring binds slightly. So basically there products don't even work together. It was binding worse with the stock retainers. Spend the extra and just get KS power's springs.
I would recommend replacing the starter clutch with a heavy duty starter clutch, but be aware you need to practically split the cases to do this. At that point why not just throw in some bored cases and run whatever you'd like?
A stroker crank will help with your TQ which will help run a taller final drive gear set and still get out of it's own way. Go mild with 2mm and you can just stack your base gaskets and go.
Porting of your head is where there is lots of power to be made, if you can't do it, have somebody else do it. Achi from area 808 and Nick at KS power do amazing work.
Run a new heavy 4 or 8 ga. wire to the starter from the battery, it will help turn the motor over with it's new found compression. Also change out the ground wire from the battery with a better wire.
If you are really dedicated about longevity, have your stuff coated at swain tech to keep internal temps down, spend the extra money for an oil cooler, and don't be affraid to buy quality stuff. I figure its not that expensive to throw a new cylinder, piston and rings at it every other year. I have to rebuild my dirtbike every other month and it costs way more then rebuilding this scooter.
Hopefully that helps you out a little with some ideas.
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Post by justin010304 on Jul 31, 2013 2:04:17 GMT -5
^Also, I didn't comment about jetting because there is no one size fits all for jetting. Not to mention you don't have a motor build set in stone yet. Buy a few different sizes and experiment.
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Post by jerseyboy on Jul 31, 2013 8:04:48 GMT -5
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Post by brandjur on Jul 31, 2013 12:03:06 GMT -5
When I looked at the A9 cam for the 139qmb, it didn't have higher lift. It had more overlap and duration (fatter valve opening). However, it is possible to get to the higher rpms with an A9 cam. I would only worry about valve float from 11k rpms if you plan on getting to 11k rpms. Jerseyboy, since you said you wanted reliability, I am assuming you don't want to hang around 11k rpm. So, valve float won't be a worry. Since you also said you don't want to open the case to bore it out, the 60mm should be the max. I went with 58.5mm because I wanted a thicker cylinder sleeve for reliability and heat. Even at 58.5, it gets thin. I started my build last night and it purrrs like a kitten. Will most likely take her out tomorrow. With a stock cam, 58.5mm cylinder kit, 58.5mm head, some restrictions removed from the airbox, I will start with a main jet ~110-120. Just an FYI, here is a comparison of the intake opening between the NCY head and my stock head (has same dimensions as 150cc GY6). Attachments:
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Post by justin010304 on Jul 31, 2013 13:46:38 GMT -5
Most of the heads you find are going to be made by the same factory. I would have no issue picking up that head, but of you put a cam in check to make sure the springs don't bind. It a common problem that people don't seem to know about. Also, port the heck out of that thing! I spent a couple hours porting mine, free HP! :-)
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Post by brandjur on Jul 31, 2013 14:19:36 GMT -5
That head doesn't look bad at all. I bought my NCY head because it was the size I wanted and it cost the same amount as that one.
Yeah, people don't know about the spring bind or valve float. But for most of people's riding habits here, it isn't an issue. We are talking about regular street riding and reliability.
I wouldn't port and polish the head unless you have done it before....but, it isn't a bad idea to clean up the casting from burs. You could make the head flow worse if you don't know what you are doing. If you do choose to do it, buy a kit with different grits. Think very very mild grits so you don't over cut. Or you can try the de-burr kit. Also, practice on the stock head you won't use.
Personally, I have done porting on half a dozen items from intake manifolds, exhaust manifolds, and heads, all for cars. There is a lot of time and calculations that go into porting. You have to scribe matching components and gaskets, you have to mark the thin areas of metal, and you have to make sure that your porting doesn't make the flow worse. You want the straightest bends with least friction. Larger ports aren't always better, especially if it creates a tighter bend. I didn't port my head because I didn't have the bits ready and didn't want to remove the valves as it is already assembled. Mine is a street rider, not track racer.
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Post by justin010304 on Jul 31, 2013 15:55:22 GMT -5
Very true, a flow bench would be amazing to do some tests on these heads, but I don't have access to one. I don't think valve float is much of an issue till you start playing high lift cams or doing top speed runs down hill.
Some more things to think about, I wouldn't worry about a high output coil, the stock one produces enough for good even spark.
If you go with a big bore kit that bumps up your compression (most do) I'd advise against a "racing" cdi box as the added timing with high compression can cause detonation.
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Post by jerseyboy on Aug 2, 2013 8:42:48 GMT -5
[replyingto=brandjur]brandjur[/replyingto]I want to get a big valve head also,,looking at scooter elements store he has this one a 61mm,will it work with a 60mm BBK? It says in his auction you can use thie head with a stock jug also,,so Im confused,,if i can use it what is the difference in using a matching head,,or will I benefit from getting say a 63mm head with the 60mm BBK,,you following me  Also looks like the intake is way bigger than a stock,,so what size intake manifold do I get so It will match up for max performance?? www.ebay.com/itm/GY6-150cc-High-Performance-61mm-Taiwanese-Big-Port-Valve-Head-NON-EGR-/310700590390?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item485732c536Here is a 30mm intake will it work with my 24mm carb and match up with the big head? www.ebay.com/itm/SCOOTER-150CC-GY6-NCY-RACING-HIGH-PERFORMANCE-30MM-INTAKE-MANIFOLD-/310716272169?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item4858220e29Yeah,,I dont want to tach more than 8K RPM,,just want to get there fast and if my top end is rated at 11k I would think the reliability would be there at 6-8K. Thanks guys,,you taught me alot so far about performance GY6 motors!! Tom |
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MJ, Orange coil, Blue Performance CDI (Orange NCY did not work), NGK Iridium, 5g Sliders
