The differences between GRUBEE GT5 & PK80 & ZEDA 80 & engine costs and life spans

[gary55]

Ha, Gary, awesome job spending that money!
I guess my point is: there is no NEED to spend that much money, and no "justifying" it other than just that you want to.

I weigh 220 lbs (BLUSH) at the moment and a stock engine will pull me around fairly well.
Mind you, I have to pedal a bit on hills and starts, but that helps solve the weight problem...
Case stuffing, a larger sprocket and head mods will give some low end torque for those clutch starts and hills.
Porting, pipe and modifying the stock head will give power and speed (more rpm).
A look through the archives will outline details. (Gary is a big contributor)

For those who are new to this sport/hobby, no need to spend big bucks.
And these engines can last many 1000 miles, but not if you mod them for max power and rpm.
I'd suggest a good air filter and good quality oil and daily maintenance are the recipe.

Thank you. Agreed this is way more than mostly needed, but I've wanted one with this hub since the first bike I had so the either or fell to the either. I couldn't be more pleased. I got the bad ticker, no big deal but much pedaling just isn't in the equation any more. Now with a slight increase in blow down, a little port work, and squish adjustment this engine runs better than the ones I used to go all out on. You opened my eyes to that and you were right. Some of my mods. were canceling the ones that work. With this hub the hills that were once out of the question are not a problem today.

 

[Diamond Back]

Ha, Gary, awesome job spending that money!
I guess my point is: there is no NEED to spend that much money, and no "justifying" it other than just that you want to.

I weigh 220 lbs (BLUSH) at the moment and a stock engine will pull me around fairly well.
Mind you, I have to pedal a bit on hills and starts, but that helps solve the weight problem...
Case stuffing, a larger sprocket and head mods will give some low end torque for those clutch starts and hills.
Porting, pipe and modifying the stock head will give power and speed (more rpm).
A look through the archives will outline details. (Gary is a big contributor)

For those who are new to this sport/hobby, no need to spend big bucks.
And these engines can last many 1000 miles, but not if you mod them for max power and rpm.
I'd suggest a good air filter and good quality oil and daily maintenance are the recipe.

I think Steve nailed it on how to keep it cheap and reliable and to just have fun on a low budget..! Although I know Steve could build a kick ass rocket ship bike if he could pick and use any product out there if it was free and no cost to him..Hell we all could, all of you guys are great builders and we all have our different quirks..its what makes this such a great Hobby for us 2 stroke tinkerers !! I love putting in some elbow grease (porting & milling ect..ect)) and some aftermarket parts for performance and LOOKS.! We all Like to make our RIDES look UNIQUE and apart..I love the diversity in this Hobby..!!!

Please keep adding your thoughts to this post GUYS and FOLLOW "PLEASE" !!,,,, I love all the different opinions and a lot of you I have known for a while,, this is a good all around thread...!!

Here is a question for you guys.? I will have more technical spec and data later on this..
But why there so much differences between engines, exspecially in the cylinder port shapes and heights..
I looked down the cylinder on the PK80 with head off and noticed that when the Piston is at BDC the transfer port are only half way uncovered and thats at the ring height not piston top....and the exhaust port is only 3/4 uncovered..!!!

Is this why people do piston ramps.? but that dont change ring height... There is a 4mm gap at the base of cylinder if i lift it up to get all the ports uncovered all the way...I was thinking about making a spacer or a lot of base gaskets or get thicker gasket material and cut my own thicker base gasket..then there would be a huge gap at the top end and probably not even run do to big loss of compression...so was first thinking of using a TYPE "B" piston lower wristpin to raise piston to fill gap,,,,but DUHH STUPID, that would do nothing cause at BDC the ports would still only be half way uncovered..!!! SILLY ME
What if I made a thicker gasket and milled the the top of cylinder the the same thickness as new thicker gasket or mill top down to give me a .70 squish band and 135 psi compression..?? what would this do engine performance you think?? or would putting piston ramps in be faster and better solution..??

Good thing with doing all these bike builds I have accumulated a bunch of spare parts to experiment with.. and the GT5 cylinder has 2mm port difference in height if you read my previous comments...when the ZEDA 80 comes in I will measure and post those dimensions so we can compare all 3... I wonder what the best setup would be if i mixed and matched all 3 engines parts,,it would be a FRANKENSTIEN....""ITS ALIVE,,,ITS ALIVE..!!!"""""""""lol..haha.

Any thoughts guys, please?? ALSO not so sound rude or weirdo,, but can you guys start hitting the LIKE button next to reply please,,,only if you like...I am trying to get points for a trophy !!....LOL..LOL ... I know im weird...haha

THANK YOU GUYS FOR ALL YOUR COMMENTS AND HELP.....KEEP WRITING MORE AND FOLLOW,,I TRY TO WRITE @ TWICE A DAY

 

[Rusty_S85]

Holy cow... I bought a $200 Grubee with and extra $30 of gaskets and small parts, stuck it on a $50 used bike. modified the dickens out of it (at little cost) and ran it for a summer (at least 1000 miles) at 30-40 mph. How in heck are you dumping $1300 into a motorized bike?

Lot of it is shipping since I bought most of my parts off the web vs trying to source locally.

Plus paint I used it was right at $60 by itself for two cans of base coat and two cans of clear.

 

[Rusty_S85]

Ha, Gary, awesome job spending that money!
I guess my point is: there is no NEED to spend that much money, and no "justifying" it other than just that you want to.

I weigh 220 lbs (BLUSH) at the moment and a stock engine will pull me around fairly well.
Mind you, I have to pedal a bit on hills and starts, but that helps solve the weight problem...
Case stuffing, a larger sprocket and head mods will give some low end torque for those clutch starts and hills.
Porting, pipe and modifying the stock head will give power and speed (more rpm).
A look through the archives will outline details. (Gary is a big contributor)

For those who are new to this sport/hobby, no need to spend big bucks.
And these engines can last many 1000 miles, but not if you mod them for max power and rpm.
I'd suggest a good air filter and good quality oil and daily maintenance are the recipe.

That's my thing I am around 200 - 220 haven't weighed myself in years but I am working on losing the weight. How ever I am trying to find a happy medium for my heavy bike (wouldn't be surprised if the bike is pushing 70 lbs by itself without the engine) and my weight that is still capable of running around 30 mph but still be capable of pulling from a stand still.

That's why I am going to try my hand at hot rodding.

 

[Diamond Back]

I cant believe no one has replied or made a comment on my recent post,,, what would happen if i added enough base gaskets or a spacer to make the piston uncover the transfer ports and exhaust port all the way at BDC instead of half way uncovered stock,,, of course i would have to mill the head down the thickness off the extra base gaskets to maintain compression,,,,,,this changes port timing drasticaly..!!

or should I just ramp the piston and call it a day,,??? Every time I ever ramped the piston I always lose low end torque bigtime but gain topend power and rpm...

please read my post up above ,, i wanna hear your thoughts,,I know you guys have done both mods that i describe,,,so please help me out and save a piston and cylinder...lol

Can someone invent a left hand NUVincci HUB,,,,,would make a killing selling that in this market,,,I gonna make one and be on SHARKTANK...!!!

 

[Rusty_S85]

I'm still trying to figure out what mods to try. Going to be ordering my Zeda 80 hopefully this week if the boss will ever get off his lazy ass and actually make our checks out for last week.

 

[Steve Best]

The distance from the top of the exhaust port to the top of the cylinder where the rings sweep is what makes torque.
Minimizing this distance is trading off torque for breathing and rpm, hoping the gamble will return more high rpm hp.

With these bikes, I want torque, so I don't surrender any of that precious torque.
I really need it on hills, at low rpm and for clutch starts.
So how can I gain breathing and time for more rpm?
Go wider on the ports, especially at the top of the exhaust port and the bottom of the intake.

Ramping? It works and has some advantages over raising the ports.
It can radius the transfer flow over piston head and match the exhaust port roof.
What does a piston cost? $10? Buy several. How long does it take to swap a piston? 15 minutes?
Try ramping a piston, small at first, then take more and more off. Only this mod. Try it out. Test it.
Report back to us.

I used to ramp a piston to get a measurement for raising an exhaust port. I don't bother raising exhausts now.
Ramping can disturb squish, but heck, which is the greater good? Perfect squish or cylinder filling?

 

[gary55]

I cant believe no one has replied or made a comment on my recent post,,, what would happen if i added enough base gaskets or a spacer to make the piston uncover the transfer ports and exhaust port all the way at BDC instead of half way uncovered stock,,, of course i would have to mill the head down the thickness off the extra base gaskets to maintain compression,,,,,,this changes port timing drasticaly..!!

or should I just ramp the piston and call it a day,,??? Every time I ever ramped the piston I always lose low end torque bigtime but gain topend power and rpm...

please read my post up above ,, i wanna hear your thoughts,,I know you guys have done both mods that i describe,,,so please help me out and save a piston and cylinder...lol

Can someone invent a left hand NUVincci HUB,,,,,would make a killing selling that in this market,,,I gonna make one and be on SHARKTANK...!!!

On the Zeda engine you will find that a lot of what you are talking about correcting is Done. Both the exhaust and transfer ports open far more than the gt5 or pk80.
Your piston labeling is backwards. A type has the lower pin B has the more centered pin. Google crmachine engine geometry.
Since I don't know if the round port cyl. has the same port mapping as the zeda I can't tell you if what your asking will be a improvement. Since your not building a shifter I would go with Steve's suggestion and just widen the intake and exhaust to about 24mm. If you ramp both transfers and exhaust you have changed nothing in port timing, aided the flow a little but lose low end power by shortening the time the cyl. is sealed. If you ramp or raise the exhaust only you get more RPM and less low end. To many variables to give specifics without eyes on.
A left handed nuvinci would give no gain in build expense cause you need gear reduction. The engine sprocket is to small. If the round port cyl. looks like the zeda cyl. below as far as the pistons relationship to the port windows I explained in your other thread how I set the engine up. Happy building. Something wrong with image loading. I'll try again later.

 

[Rusty_S85]

On the Zeda engine you will find that a lot of what you are talking about correcting is Done. Both the exhaust and transfer ports open far more than the gt5 or pk80.
Your piston labeling is backwards. A type has the lower pin B has the more centered pin. Google crmachine engine geometry.
Since I don't know if the round port cyl. has the same port mapping as the zeda I can't tell you if what your asking will be a improvement. Since your not building a shifter I would go with Steve's suggestion and just widen the intake and exhaust to about 24mm. If you ramp both transfers and exhaust you have changed nothing in port timing, aided the flow a little but lose low end power by shortening the time the cyl. is sealed. If you ramp or raise the exhaust only you get more RPM and less low end. To many variables to give specifics without eyes on.
A left handed nuvinci would give no gain in build expense cause you need gear reduction. The engine sprocket is to small. If the round port cyl. looks like the zeda cyl. below as far as the pistons relationship to the port windows I explained in your other thread how I set the engine up. Happy building. Something wrong with image loading. I'll try again later.

Which is why I personally have been looking at the Zeda engine, my problem is I don't know if I want to take the risk buying from Zeda Motorsport or going through another company. Just have a gut feeling this might be a repeat of the frame I bought from Raw-Motors. Would prefer to buy via paypal. Would also like to find some coupon codes but cant find none.

But from the reading ive been doing on the Zeda80 engine it seems even their basic $118 priced engine kit is superior than similar priced kits from other people.

 

[gary55]

Which is why I personally have been looking at the Zeda engine, my problem is I don't know if I want to take the risk buying from Zeda Motorsport or going through another company. Just have a gut feeling this might be a repeat of the frame I bought from Raw-Motors. Would prefer to buy via paypal. Would also like to find some coupon codes but cant find none.

But from the reading ive been doing on the Zeda80 engine it seems even their basic $118 priced engine kit is superior than similar priced kits from other people.

It's kind of weird they don't accept paypal. I think fro the $21 extra I would use bicycle engines. From what I have heard of them if their was a prob. you wouldn't even need to get paypal involved.