My first impression of the Grubee SkyHawk GT5A

The crank had shims on it so they mush do some shimming to the crank which is a good thing. I know my clone did not have any and has a lot of side play.

They now come with socket head (allen) screws but only where you can see them. The 3 behind the clutch are the old crappy screws but I have good ones to replace them with.

The guy that sold me this motor has been in contract as I knew he would as he has always tried to be helpful. Now waiting to see if Grubee will reply to the email I sent them.
Thanks all for the input.
 
How is the casting on the cylinder? I was probably going to do a minor port job anyways but I have a buddy that wanted a good reliable plug and play motor
 
I was about to order one of those kits since they are so cheap for better quality

I am still going to buy them as the castings and other things are better then the clones. All so will bolt up to much wider frames with out using a differnct mount. I am so glad I did not take others advice and run it before taking it apart or I would be doing in later and would be more costly. The eBay motor I have was just as dirty and gritty so all of them need cleaned before starting. I do believe this is why they recommend running way too much oil for break in hoping to flush all the grit and trash out. Any grit and trash is not good for any motor. Wonder if the 4 cycles have all the girt and trash? If I live long enough I will find out as build 3 is going to be a 4 cycle.
 
How is the casting on the cylinder? I was probably going to do a minor port job anyways but I have a buddy that wanted a good reliable plug and play motor

Then tell him to buy a 4 cycle. Other then the pitting cylinder casting looks good. Definitely have to match the booster ports between the case and cylinder like all of them. This motor of mine will be all tricked out and done properly before she ever fires.

I do want to say the sell Thomas has gotten back to me several times in the last hour about these problems. He is the one I bought this motor from.
 
When I build a motor there is not any scratching as I clean my cylinders well and do not have this problem. <SNIPPED>When I am working on motors that cost 5k to 10k to build I assure you mine do not look like these! I turn all the motors I built over many times checking things and on my motors I never have these scratches. <MORE SNIPPED>

I am not sure what all the trash is but it sure is gritty and should not be in the engine! If it was break in oil which I really do not think so it sure is the wrong lube to use! No it is just plain nasty as I do not have to put any grit in the motors I build to seat the rings. If you can find a genuine Grubee for just the motor pleas post a link as I looked for hours finding the best price I could find. whid for a whole kt was $144.99. Most are wanting $180 or more for them. Now the clones yes you can get them much cheaper. Thanks Steve for your input.

The Canadian supplier:
http://www.motorizedbicycle.ca/bicycle-engine-kits.html
sells the motor alone for $125cdn which is slightly over $100usd this week.
Last month they were selling for $115.

The streaks are from limited contact polishing and take a motorized high speed run up (+1500rpm) to show.
Turning the motor over by hand or even with a starter motor will form the streaks.
If you pulled one of those $5000 motors apart after 5-10 minutes run they would be there.
The streaking is even worse when you use moly coated pistons. Easy to look at the bore on 2 stroke rebuilds.

Factories do not use the same lubes as hand built assemblies, for many good reasons.
They typically wish to use a minimum and usually have an automatic dispersing and measuring system.
The assembly lube itself may be type of wax with an evaporative carrier fluid.
It is fogged on in a measured squirt, engine assembled, run up by an electric motor.
Better QC systems will check run up torque and compression (and oil pressure on 4t engines).
A drip of carrier fluid and wax may settle on the top of the piston with a bit of the phosphate ring coating.
The carrier fluid evaporates during shipment so that a waxy black deposit is left on the piston top.
I don't know if this is the case, but have seen it on other factory assemblies.

I spent the last 35 years working in industry. Machinist, millwright, electrician, quality control tech.
Currently I supply technical people to factories and troubleshoot difficult factory issues.
That the Chinese can build a $100 engine and ship it across the Pacific amazes me. We cannot do it.
It is not just cheap labour either. Labour is typically less than 10% of manufactured goods cost (typically 4%).
If you got the labour for free, it wouldn't take $10 off the price of these motors.

I don't mean to be an apologist for poor quality. I know why they are so cheap, and they won't be forever.
Enjoy them while they are here, for the price they are.
And the quality, or lack of it.

Steve
 
Last edited:
The Canadian supplier:
http://www.motorizedbicycle.ca/bicycle-engine-kits.html
sells the motor alone for $125cdn which is slightly over $100usd this week.
Last month they were selling for $115.

The streaks are from limited contact polishing and take a motorized high speed run up (+1500rpm) to show.
Turning the motor over by hand or even with a starter motor will form the streaks.
If you pulled one of those $5000 motors apart after 5-10 minutes run they would be there.
The streaking is even worse when you use moly coated pistons. Easy to look at the bore on 2 stroke rebuilds.

Factories do not use the same lubes as hand built assemblies, for many good reasons.
They typically wish to use a minimum and usually have an automatic dispersing and measuring system.
The assembly lube itself may be type of wax with an evaporative carrier fluid.
It is fogged on in a measured squirt, engine assembled, run up by an electric motor.
Better QC systems will check run up torque and compression (and oil pressure on 4t engines).
A drip of carrier fluid and wax may settle on the top of the piston with a bit of the phosphate ring coating.
The carrier fluid evaporates during shipment so that a waxy black deposit is left on the piston top.
I don't know if this is the case, but have seen it on other factory assemblies.

I spent the last 35 years working in industry. Machinist, millwright, electrician, quality control tech.
Currently I supply technical people to factories and troubleshoot difficult factory issues.
That the Chinese can build a $100 engine and ship it across the Pacific amazes me. We cannot do it.
It is not just cheap labour either. Labour is typically less than 10% of manufactured goods cost (typically 4%).
If you got the labour for free, it wouldn't take $10 off the price of these motors.

I do know why they are so cheap, and they won't be forever.
Enjoy them while they are here, for the price they are.
And the quality, or lack of it.

Steve
I hear yah!!! The only other engine that is this cheap are the predator engines. Quanity over quality, Chinese always beats everyone on price and sometimes quality
 
The Canadian supplier:
http://www.motorizedbicycle.ca/bicycle-engine-kits.html
sells the motor alone for $125cdn which is slightly over $100usd this week.
Last month they were selling for $115.

The streaks are from limited contact polishing and take a motorized high speed run up (+1500rpm) to show.
Turning the motor over by hand or even with a starter motor will form the streaks.
If you pulled one of those $5000 motors apart after 5-10 minutes run they would be there.
The streaking is even worse when you use moly coated pistons. Easy to look at the bore on 2 stroke rebuilds.

Factories do not use the same lubes as hand built assemblies, for many good reasons.
They typically wish to use a minimum and usually have an automatic dispersing and measuring system.
The assembly lube itself may be type of wax with an evaporative carrier fluid.
It is fogged on in a measured squirt, engine assembled, run up by an electric motor.
Better QC systems will check run up torque and compression (and oil pressure on 4t engines).
A drip of carrier fluid and wax may settle on the top of the piston with a bit of the phosphate ring coating.
The carrier fluid evaporates during shipment so that a waxy black deposit is left on the piston top.
I don't know if this is the case, but have seen it on other factory assemblies.

I spent the last 35 years working in industry. Machinist, millwright, electrician, quality control tech.
Currently I supply technical people to factories and troubleshoot difficult factory issues.
That the Chinese can build a $100 engine and ship it across the Pacific amazes me. We cannot do it.
It is not just cheap labour either. Labour is typically less than 10% of manufactured goods cost (typically 4%).
If you got the labour for free, it wouldn't take $10 off the price of these motors.

I don't mean to be an apologist for poor quality. I know why they are so cheap, and they won't be forever.
Enjoy them while they are here, for the price they are.
And the quality, or lack of it.

Steve

Steve,
You can buy just the clone motors for as little as $80 shipped. So does this mean they should sell people junk???? Guess I am just too old as i remember when people took pride in their work like I do. This day and age just screw who you can but I sleep well as I know my work is right!!!!!!

Steve I have pulled down a few of my motors after running for a short time just to look and I assure you none of my cylinders and sure as hell did not have any marks but where the ring gap was and I could wipe that off this is the difference between a well built motor and poor workmanship!!

Others want to run grit and trash in their motor go for it but I will no and I will not build any motor that way!!!!! This is how I have been when I built my first motor over 45 years ago. I have too many years in building motors and I know the way things should be done as I take pride in my work. I have see some others bikes here and just understand why they have problems just looking at them. But hey do what makes you happy I do.

I agree Steve the Chinese have no pride. Look at the CJ motorcycle they made for years now out of business they were junk from the first one to the last.
 
Last edited:
Steve,
You can buy just the clone motors for as little as $80 shipped. So does this mean they should sell people junk???? Guess I am just too old as i remember when people took pride in their work like I do. This day and age just screw who you can but I sleep well as I know my work is right!!!!!!

Steve I have pulled down a few of my motors after running for a short time just to look and I assure you none of my cylinders and sure as hell did not have any marks but where the ring gap was and I could wipe that off this is the difference between a well built motor and poor workmanship!!

Others want to run grit and trash in their motor go for it but I will no and I will not build any motor that way!!!!! This is how I have been when I built my first motor over 45 years ago. I have too many years in building motors and I know the way things should be done as I take pride in my work. I have see some others bikes here and just understand why they have problems just looking at them. But hey do what makes you happy I do.

I agree Steve the Chinese have no pride. Look at the CJ motorcycle they made for years now out of business they were junk from the first one to the last.
How can you tell if its a clone
 
Folks buy what ever motor you want and if you want pour a hand full of dirt in it as some say it hurts nothing BULL s**t!
 
Back
Top