Drawbacks of aliexpress CNC heads?

Sharif

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May 28, 2019
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I was wondering if there is any draw back of the CNC cylinder heads being sold at places like aliexpress or ebay from china?

I am waiting on buying this, but before I pull the trigger on something more expensive than other parts I wanted to make sure if what I was doing is a mistake.

https://www.aliexpress.com/item/32846961375.html?spm=a2g0o.productlist.0.0.2fe64fa1WzibTV&algo_pvid=9ba4dbc7-fa96-4c25-a6b4-095923457047&algo_expid=9ba4dbc7-fa96-4c25-a6b4-095923457047-53&btsid=0d2043e9-1b01-43e6-b4b9-7df569a2d03b&ws_ab_test=searchweb0_0,searchweb201602_4,searchweb201603_52
Going with this in particular as I know the Gasket kit bundled will come in handy in the future.

My main reason to getting a high compression head is not for the increase in power, but reliability. Bigger heatsink, better heat dissipation with all that surface area. Just hoping it increase the lifespan of the engine and I will be lying if I didn't mention the aesthetic appeal is one of the reasons as well haha.
 


GreasyChris

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I ordered this one from this vendor. The spark plug fits very well and the chamber looks decent and workable. It was also shipped fast considering it's from China. Less than 3 weeks to Canada
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Sharif

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May 28, 2019
Messages
114
I ordered this one from this vendor. The spark plug fits very well and the chamber looks decent and workable. It was also shipped fast considering it's from China. Less than 3 weeks to Canada
View attachment 89875View attachment 89876
Thank you!
I am in Canada as well, personally prefer using Alliexpress due to their better shipping options. With that said, went through that seller's listing and found the same listing as the one I linked in this post and purchased it using standard shipping. 😁

Is there any power difference you noticed and how long can you leave the engine idle with that heatsink?
I usually turn my engine off with the kill switch when at a stop light to not let it get too hot.
With that said, left bicycle out in the rain last night when I was at work (it was fine when coming back home) put it under a tarp when I got home, but it was humid and still raining, things didn't really dry up. I am wondering if the new open air filter I got is the culprit. Currently at the DMV, when I was getting here I noticed I barely have any power (engine runs smooth just struggling to accelerate, especially any hill), disconnected the kill switch on the way here, but nothing changed. I did feel the power was slowly increasing as I kept driving (or imagined it) i already rusted out my Magneto in the past, but learned my lesson and sealed it up with RTV (including the hole) so that shouldn't be wet again, especially after all the previous rains I went through. Might just put my old restricted air filter back or just create a cover for the current one. Will find out on the trip back home, after waiting all this time at the DMV it should be dry by now.
 

GreasyChris

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1,209
Thank you!
I am in Canada as well, personally prefer using Alliexpress due to their better shipping options. With that said, went through that seller's listing and found the same listing as the one I linked in this post and purchased it using standard shipping. 😁

Is there any power difference you noticed and how long can you leave the engine idle with that heatsink?
I usually turn my engine off with the kill switch when at a stop light to not let it get too hot.
With that said, left bicycle out in the rain last night when I was at work (it was fine when coming back home) put it under a tarp when I got home, but it was humid and still raining, things didn't really dry up. I am wondering if the new open air filter I got is the culprit. Currently at the DMV, when I was getting here I noticed I barely have any power (engine runs smooth just struggling to accelerate, especially any hill), disconnected the kill switch on the way here, but nothing changed. I did feel the power was slowly increasing as I kept driving (or imagined it) i already rusted out my Magneto in the past, but learned my lesson and sealed it up with RTV (including the hole) so that shouldn't be wet again, especially after all the previous rains I went through. Might just put my old restricted air filter back or just create a cover for the current one. Will find out on the trip back home, after waiting all this time at the DMV it should be dry by now.
I actually haven't used the head yet its for another bike im building. I live in southern Ontario and it's been extra hot and humid here. I ride my bike every day to work and it's about 10km each way. I ride it hard all the time and don't shut it off ar red lights and it's never gone above 390°F that's with the stock cylinder head
 

Sharif

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May 28, 2019
Messages
114
I actually haven't used the head yet its for another bike im building. I live in southern Ontario and it's been extra hot and humid here. I ride my bike every day to work and it's about 10km each way. I ride it hard all the time and don't shut it off ar red lights and it's never gone above 390°F that's with the stock cylinder head
NL, St John's here. It's the complete opposite, it's rather starting to get cold, will drop down to 11 degree tonight. Turns out the issue from yesterday is a clogged exhaust.
Do you have a temperature probe of some kind on the head?
 

GreasyChris

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NL, St John's here. It's the complete opposite, it's rather starting to get cold, will drop down to 11 degree tonight. Turns out the issue from yesterday is a clogged exhaust.
Do you have a temperature probe of some kind on the head?
No, but when it was really hot out I would check it with a infrared temperature gun. Some of your performance issues could be related to the change in weather and cooler temperatures now. You may find you'll have to readjust your carb.
 

Sharif

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Messages
114
No, but when it was really hot out I would check it with a infrared temperature gun. Some of your performance issues could be related to the change in weather and cooler temperatures now. You may find you'll have to readjust your carb.
I experienced that during the beginning of summer when the weather was all over the place. Having a computer to adjust that on the fly would have been nice.
 

Sharif

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Joined
May 28, 2019
Messages
114
I actually haven't used the head yet its for another bike im building. I live in southern Ontario and it's been extra hot and humid here. I ride my bike every day to work and it's about 10km each way. I ride it hard all the time and don't shut it off ar red lights and it's never gone above 390°F that's with the stock cylinder head
I just received mine this week, just waiting to find some time to install it. How is it? Is the compression ratio greater than the stock head?
 

GreasyChris

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I just received mine this week, just waiting to find some time to install it. How is it? Is the compression ratio greater than the stock head?
I still haven't tried mine yet. Im going to have to modify it to fit on my bike because of the clearance issues. It's on my winter rebuild list. I am curious what you think of yours once you get it installed. It looks like the combustion chamber is bigger than stock so the compression is going to be a little bit lower. However the cooling benefits of the head outweigh the compression loss. The compression can be made up by milling the head down.
Looking forward to see what you think about it when you get it installed
 
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