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

Diamond Back

Active Member
Joined
Jun 11, 2016
Messages
137
I ordered the JET 80 and the SILVER FIRE 80 from GASBIKE. The JET 80 comes with the SUPERCHARGED CDI and looks like a GRUBEE GT5 cause it has a ROUND EXHAUST PORT and a 40mm INTAKE...

The other engine is the SILVER FIRE 80 from GASBIKE. The SILVER FIRE comes with the RSE REED VALVE 32mm bolt spacing. The engine looks like a PK 80 cause it has the rectangular Exhaust and the 32mm Intake...

I wanted to use the RSE REED VALVE with the SUPERCHARGED CDI on the GRUBEE GT5 Engine but the INTAKE Bolt Pattern is different,.. SO which set up would you use,, which is the better motor ????
I am going to update this thread when I pull the cylinder off each on to check on which piston and rod each one has...
 


gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
3,825
I ordered the JET 80 and the SILVER FIRE 80 from GASBIKE. The JET 80 comes with the SUPERCHARGED CDI and looks like a GRUBEE GT5 cause it has a ROUND EXHAUST PORT and a 40mm INTAKE...

The other engine is the SILVER FIRE 80 from GASBIKE. The SILVER FIRE comes with the RSE REED VALVE 32mm bolt spacing. The engine looks like a PK 80 cause it has the rectangular Exhaust and the 32mm Intake...

I wanted to use the RSE REED VALVE with the SUPERCHARGED CDI on the GRUBEE GT5 Engine but the INTAKE Bolt Pattern is different,.. SO which set up would you use,, which is the better motor ????
I am going to update this thread when I pull the cylinder off each on to check on which piston and rod each one has...
Sense it doesn't take long to swap out a engine You might want to try them both. That's the only way you will know for sure. I would almost bet you that the jet 80 with the 40mm intake runs better than the 32mm with the reed valve. Look at how the reed valve fits the engine, and how small it is. I think the restriction it creates in the intake cancels out the benefits of the reed.
 

gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
3,825
The reed would only be better in the low end I think.
On this bike my experience was no noticeable difference when I changed form a standard modified cyl. with stock intake and a dellorto sha 16 16 to a boost port gt80 cyl. and a rse reed. Their was some improvement with the larger reed intakes, but tuning in the carb. was a adventure. A skill I need to work on with carbs. I'm not familiar with.View media item 60095
 

Diamond Back

Active Member
Joined
Jun 11, 2016
Messages
137
So I did decide what to do... I am putting these two engines in two bikes that I am building for two different customers,, But I did how ever take the TOP ENDS apart on them to clean up and do some mild portwork and come to behold I did some measuring with my calipers and WWOOOAAHHHH !!!! What a difference between these to CYLINDERS ,, I will take more time and post the exact measurments on these two cylinders ( PK80 ) and ( GT5 ) if somebody on here would like me to just ask,,

I will also look on the magnetos and look at the production date of each engine as they are written on the coil wrapping on all engines if you didnt know already..

The GT5 has a ( AF80 ) stamped ROD, and the PK80 has a ( ZAE80 ) stamped ROD,, Both engines use the TYPE "A" piston with the higher wristpin location (more centered)...

The GT5 (photos 2&3) has the round exhaust port and the 40mm stud spacing and rectangular port..
All 4 ports inside the cylinder sit 2mm HIGHER from the TOP then the PK80, and the round exhaust port is smaller in width then the PK80 rectangular port,, But both intake ports are identical in size even tho the GT5 claims to be bigger with the 40mm stud spacing..!! and with the cylinder hieght and deck hieght being the same dimensions the GT5 would seem to have different port timing then the PK being that the transfer ports top edge is 35mm from the top of cylinder, and both cylinders on top are identical dimensions. ALL the ports sit 2 two mm higher then the PK80.. I am curious to see how each motor runs,, I am going to keep everything as close to stock and keep the differences the same,, I am not going to do crazy porting on these engines just a clean up.. Will let you all know the engine running characteristics in a few days..

AS for My Chopper Bike, I went to ZEDA MOTORSPORTS Web Page and called and talked to the owner.. After doing some research and talking with him I Order the New ZEDA 80 engine with the DIO Ported Cylinder and DIO 6 Carbon Fiber Reed Block assembly and the OKO Flat Side Carburetor and the engine comes with a nice Blue Billet Comp Head, Windowed piston and Ported cylinder and Blue Velocity stack air filter,, ITS a triple 40mm engine with the long Rod,,not a bad deal $250 for engine and full Kit and you can pick your back sprocket size,,although i already got the 1.5 hub adapter 36 tooth assembly..CHECK OUT THERE WEBSITE THEY HAVE REALLY COOL DIFFERENT PARTS AND GOOD LOW PRICES,,,,,say goodbye to Gasbike.net.....

pic#2 GT5 exhaust port, pic#3 GT5 intake, pic#4 PK intake, pic#5 PK exhaust port
IMG_20170818_151858.jpg
IMG_20170818_152039.jpg
IMG_20170818_152155.jpg
IMG_20170818_152143.jpg
IMG_20170818_152024.jpg
 

Rusty_S85

Active Member
Joined
Jun 8, 2017
Messages
943
So you got the case reed Zeda 80 or is it the cylinder mounted reed Zeda 80?

I was personally looking at going with a reed Zeda 80 since I want more low end power which will allow me to use a smaller drive sprocket. But I keep hearing the case reed is better but from photos it does away with the clutch cable mount.
 

gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
3,825
So you got the case reed Zeda 80 or is it the cylinder mounted reed Zeda 80?

I was personally looking at going with a reed Zeda 80 since I want more low end power which will allow me to use a smaller drive sprocket. But I keep hearing the case reed is better but from photos it does away with the clutch cable mount.
who told you the case reed was better?
 

Rusty_S85

Active Member
Joined
Jun 8, 2017
Messages
943
who told you the case reed was better?
I don't remember who it was but I was told that its not as restrictive and will make more low end power than the cylinder mounted reed. The Zeda 80 used to come with the reed free but I guess that was limited time. so now I would have to buy one separate
 
Top