View Single Post
Old 03-02-2015, 11:10 PM
mapbike's Avatar
mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Good, two stroke motor kit.

Originally Posted by Eric2.0 View Post
Ok I give up..... what is a Pk 80 vrs Gt-5 engine?

I looked at Fred Chelmanskis(SP?) that guy is dedicated....expensive engine, but I bet you'll never have to get another.

Looks like my kit is coming from China, cause stock is out at the California plant. Not for certain, but I think it's the case. Gonna take forever to get here, don't know if I can wait that long.
We use these terms to describe the different geometries between the engines.

PK80 refers to a CG that has a 40mm stroke which uses a 110mm connecting rod and has what we call the low pin piston which just means the wrist pin sits below the halfway point between bottom and ctop edge of piston.

GT5 we use to describe the engines that have a 38mm stroke, use the 114mm rod and use what we call the high pin piston.

The engines you see some of call the Half Breed are engines that are 38mm stroke but use the 110mm rods thypically stamped ZAE50 and these engine use the same piston as the 40mm stroke engines but the crankshaft design causes them to actually be 38mm stroke.

The Half Breed is sort of a combo between the PK80 and the GT5 the main unique difference being the crankshaft in the HBreed.

This may all sound a bit confusing, but its really all fairly simple once you've had the different engines and seen how to identify them.

I have six PK80's, three GT5's and two of the Half Breed engines and a fairly good pile of

The GT5 I just got going recently that came from rose326a on ebay is an excellent running engi e, very low vibes, all the PK80 type that I got from thatsdax have been excellent running engi es and good balance.
some of the older PK80 engines had horrible balance but ran great at 30mph and below with a 36T sprocket.

the new dax engines are the GT5 geometry and he says the balance is just as good as the original PK80 type he sold for a couple or three years, I dont have one of the newer GT5 dax engines together yet but I plan to get that done asap so I can report on here what mine is like.

hope I didnt confuse or make anything seem complicated.

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
Reply With Quote