New Pk80j 66cc Teardown

[210061741]

Hey Sportscarpat

Thanks for the reply. (sometimes i wonder if i dont get too deep into it.)
My wife says i have OCD "Obsessive Compulsive Disorder"

I got the PK80-J limited edition Slant head for a few reasons.

The 48cc grubee GT-2B barley fit in my bike.
So i knew if i wanted a 80 it would have to be a slant.
Needing a slant narrowed down what i could buy.

Then one day wile searching I see Pirate Cycles was getting a shipment of the 4th Quarter Grubee GT-5
A slant with the new carb and wider mounts and some other nice features.
When i saw that i E-mailed Justin to get one.

Unfortunatly when his shipment came in it wasn't what he expected.
Which is why i was considering the PK.
That i new nothing about.
It was easily available to me.
Justin at Pirate Cycles answered all my calls and e-mails promptly plus i'm on the east coast and took only 2 buisness days to get it via regular UPS.

So i took my chances just to see what i'd get.
I wanted the wider mount.
I wanted a Slant Head.
The price was very good.
I planned on tearing it down so i wasn't really worried about anything else.

All I know about the Grubee is what the Grubee ad said.
Sounds like a good motor.
I do know that it has caged rollers on the top and bottom end.

I was happy when i dissassembled the PK80-J for many reasons i've allready mentioned.

Especially the Crowded Roller Needle Bearing on the Bottom End.

There is a post out there that i cant find know that explained which bearings were the right ones.
I remember the needle count was much higher and wondered how they got so many needles in the cage.
Now i know.
There not in a cage thats how.

I like to run my motors up to 8000 rpm so thoose needle bearings are important to me.
I orderd 2 (Sthil 028 chainsaw) 10X14X13 needle bearings to replace my piston pin bearings.

The porting on the PK is huge.
And the Angle of them looks great.

Initially i will only be smoothing and polishing the ports slightly.
I don't think they will need much.

As far as what is more powerful i really can't say.

But this PK has all of the things you would find in a performance motor.
The rest is up to it's owner.

 

[210061741]

posted by Fabian originally
This is very interesting:

Re: Is there a difference between the skyhawk and the starfire

Quote:
Originally Posted by Hot Dog Piggy Tails
No actually there is a big difference first is the match as far as the transfer ports then there is the Quality of the lower end Bearing (23 Needle verses 16 needle in a poorly Engineered cast)
The Nantong Jiali Manufacturer is known as the better if not the best engine manufacturer exporting these and have lost contracts with people Because they refuse to Mass produce cheap engines.

If you've replaced A starfire with a Jet your Stafire was probably a 48cc'er thats about the only ones left. Also the Starfire is the factory that your Jet was Manued at..And if it is is out of one of the First two shipments of Jet Engine they have lower end problems due to the fact a Customer I wont say no names but is actually thier competitor convinced them to use a Poorly casted Lower end Needle casing. They all need replaced. As a matter of fact the ones that are correct and Have 23 needles are still on thier way too them. I never received the 16K Needle bearing with the problem because I have the prints too it and refused to Allow them every order to put them on the bottom of my Connecting rod.

I deal with this factory and its Management Exporter and are very good friends talking at least once a week.

Now that excerpt came from a diff site.

But i bet there are 23 rollers in that bottom end.

 

[Dilly Bar Rob]

210061741,
here is a link to the "report" from Grube that I mentioned before, just thought I would throw it out here, some might find it interesting to read (I did), there Is also some info on "PK engines" in it that we may find usefull...

Quotes-
"Engines sales from this "assembly factory" go to the Rico Group, California, Zone 8 RAW engines in California, WildFire in Ohio, and RuiHong in Canada." ....."Engines with PK on box come from this factory. Instruction sheets also are a dead give away for identification." - No doubt that the engines go to even more places then this. "RuiHong enterprises" for example IS zoombicycles.com & powerking(ebay) & gasbikeshop.com...

Personally I don't think there is ANY difference (quality wise) between the PK kits from different vendors (comparing kits from the same production run/date of course), aside possibly from packing & other minor differences (ie slant head or such). I don't think any vendor would get a discount on a batch of "blemished" engines or anything like that-that would mean that there is actually some quality control going on at the factory, which is doubtfull. I also doubt that any of the vendors could specify that they want a higher quality engine part in "their" kit (lets say the crowded needle bearing for instance). The manufacturer would probably tell the vendor that wanted a change "yeah no problem we fix in next shipment dont worry" over the phone, but in reality either do nothing at all, or holler out of his office window something like "hey frank, when that box of bearing run out you find different bearing to use, these no good".... This approach would of course result in all engines coming from the factory to have a bearing of that type after some point in time....


I worked in a sweatshop type factory in central europe (czech rep.) for about a year and a half at one time. We made office furniture under the 3M & Franken brand names, also projection screens for french manufacturer "Oray" and others. We made metal shelving units (Raxa, Regalux...) that exported to germany and italy. Stuff from the factory was always labled as "made in france" or "precision made in eu". Quality was very inconsistent depending on how good of a nights sleep the workers had or how pi$$ed they were with the supervisors that day. Nobody cared at all, mainly the supervisors & bosses didn't. There was one guy who's responsibility was to ensure that the nuts, bolts & other hardware we were using was the absolute cheapest available. At one time part of my job was to check that shelving units looked "ok and well packed" whilst I piled them on pallets. I got in trouble for putting too many "bad" ones aside, supervisor said: "Oh if they don't like it they will just send it back (across half the continent....), don't worry about it. " Getting like 1/4 of a shipment back as defective was common. The defecteve units were torn apart, and what appeard good was re-used. Kept everyone nice and busy. After some point I couldn't take it anymore. I had to quit. Funny thing- nobody was ever worried about getting fired end execs. didn't seem to be worried about the company going out of business. The manufacturing prices must have been so low that the companys that ordered the products simply didn't care about the quality.

Just to give you an idea- if this goes on in central europe just imagine what goes on in china where the poor saps make even less money....

By no means is this supposed to mean that I have something against the PK engines or their distributors - on the contrary, mine also runs flawless, I am happy with it and zoombicycles services were fast cheap and excellent in my opinion. You wanted response so i just threw some out there :-D

Good to see that we don't have to pay a "premium" for a grubee. If only PK made a sleeved cylinder engine, that would be my wet HT dream

 

[sportscarpat]

210061741,
Maybe I should go back and read your other posts more carefully before I cover the same ground here, but I will ask anyhow. So, if Justin at Pirate Cycles did not receive the new Grube GT5 in his shipment, does he expect them in soon or is he not getting them at all? Were these just the pieces necessary to assemble this Grube engine or were they complete engines? I thought they were not going to be available as complete engines because they would not pass EPA. I could and probably will call Justin, but I am just beginning a second build so the engine purchase is still a few weeks out. By the way I live in California and a lot of the engine suppliers will not ship here. I bought the Grube because I could get it here in California.

 

[210061741]

Rob
Very good points.
Thats exactly why i took the motor apart. ( Personel Quality Control )
There was metal debris throughout the engine and some surfaces were nicked up but thats the worst i found.

What makes me happy is the fact that all the components in the PK are of similar design that you would find in a performance motor.

Maybe not the 6202 or upper needle bearings.

But to have the better bottom end, the nicer piston, and proper porting makes this a perfect Foundation for someone like me to turn it into a Real Quality HT.

Not much Different than what Rock Solid does.
They have to start with something.

With the exception to the complete Billet Machined Engine that has a $1500 price tag.

I could get prolly 20 PK's for that much dough and thats alot of miles.

Even at 4000 Miles each thats 80000 miles total.

I hope that $1500 motor goes 80000 miles.

Any way i love Rock Solids Parts and would love to have a Billet Head and a Ceramic Coated Piston.

But for the $99 bucks i spent i am very happy with the PK.

 

[Turtle Tedd]

210061741.....a lot of good info you have putting in here..The Turtle says ..thanks

 

[iron_monkey]

It was when i tried to put the PK bearing in the Grubee piston that i realized the Grubee bearing was 10MM wide and the PK was 13mm.
Obviously i'd prefer the 13mm wide bearing.
It was a little too big so i filed down the bosses inside the piston to give enough clearence. Put it back together and well see how it runs tommorow.
I can say one thing for sure.
I like the quality of the components in the PK much better than the Grubee.
But thats my opinion.
Most of the HT's ive heard have K16X21X10 for the crank bearing.
Thats what the grubee has.
The crowdede rollers are much better.
So is this PK

Funny this isnt advertised, this is actually solid improvement in the technical design of the HT (compared to all the previous hogwash that your brand is better than mine, etc but without having any real difference in the design).

The HT might actually be quite reliable if every supplier started making them like this; although no engine no matter how good can survive WOT downhill.

 

[Turtle Tedd]

Just ordered another motor for a spare...PK80-J limited edition..pirate cycles...better price for the whole kit than the (moter only) grubee gt2 48cc I am running now.....210061741..thanks again for the effort

 

[iron_monkey]

Well, I looked up the factory. Looks like Don Grube apparently tried to shut down exports from it because of shoddy practices and it wasnt complying with EPA.

www.birddogdistributing.com/images/YongXingReport.ppt

Ironically enough you're telling us this engine is much better built than the engines from Don Grubes.


Also, looks like my engine comes from the same factory as yours, if there is only one factory called 'yongxing'. I ordered mine from yxmzone.com. Although my engine is 1 year old and the spare upper bearing given to me is 10mm, not 13mm. Looks like they are evolving.

 

[Fabian]

Hi Rich

Great to see your teardown pics.

Wonderful to see that the factory has abandoned using a caged needle roller bearing on the connecting rod big end and converted operations to installing a crowded needle roller setup.

Just for your information, i have done exactly the same thing by stripping out needle rollers from the cages of two K16x21x10 needle roller bearings and squeezing as many as possible (with clearance) into the connecting rod big end, to make a crowded bearing system.
It was the only simple and cost effective way of doing things.
Assembling the needle rollers isn't difficult - just use bearing grease to hold the needle rollers against the inner wall of the connecting rod and slide it over the crankshaft pin.

Fabian