Curious about the engine, :question:

cannonball2 said:

The FM80 crank/rod are the 38mm stroke/long rod of the GT5. The piston should come to the top of the 40mm stroke jug, but wont travel as far down , maybe affecting timing. It would follow logic that the GT5 jug is timed for this crank. But who knows for sure? I don't do porting so Im not well versed on the subject. I posted further back pics of the GT5 engine I have and the ports with the piston at TDC/BDC. Maybe that will help you see what you have.

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Not to argue a point here but, the only jug that the piston in a GT5 will come close to the top of is a GT5 jug.

I just shaved 0.030 off of a GT5 jug today to get better squish on the GT5 Im going together with, the jugs for the 40mm stroke engines need about twice that much taken off then to get piston where it will have best compression.

there are a couple ebay vendors that sell GT5 type engines only and all there parts like pistons and jugs are GT5 parts.

when I get on my computer later I will post a couple links here to point to those parts.

cannonball2 said:

Thats another good thing to know. There is a GT5 specific jug then. So what in the world is the 1/2 breed supposed to run in? Or is it a detuned crank/engine?. If you look at Freds vid, rods grouped on the right are all the same length. The first rod is a ZL a common 40mm stroke rod. The ZEA50 rod he calls the 1/2 breed is the same length, so in effect it is a 40mm rod. SO it appears suppliers are exhausting their40mm rod stocks on 38mm cranks and just building what ever the engine turns out to be?

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No there not exhausting stock from the way it looks to me and the reason i say this is one simple factor that applies primarily to the Half breed engine and that is that the ZAE50 rod is a completely different rod than any of the other in shape and design, the only thing it has in common with the other short rods is just that... it is the same length but if you look is is a different rod and the only engines that use the ZAE50 rod are the half breed engines.

The 40mm stroke engine have NOT gone away, but evidently the 38mm engines must be a better deal for the vendors lately and thats why we're seeing so many of them coming over, when I had a legnthy phone conversation with Uane/thatsdax the other day I ask him about the 40mm stroke engines and he said he can still get them just the same as he did before, he just wanted to go with the current 38mm stroke engines this time around since they are well balanced also and some of his customers have requested them or like them due to the quicker spooling up into rpms that he said some of the racers had claimed.

The Half Breed/ Hybrid is just an added geometry that is not something new, I have one that I bought back in 2010, I didn't realize until recently what it was, but it is for sure a half Breed with the ZAE50 marked rod, only thing different about this old version is that it has narrow crank counters instead of the extra thick ones we're seeing with these Half Breed engines lately.

I honestly don't think anyone is thinning out inventories since the cranks and rods are completely different than are found in any of the 40mm stroke engines, these newer Hybrid engines are just a new mongrel type that takes from bot geometries to create what it actually is and that is a 38mm stroke PK80 40mm stroke variant, yes its a de-stroked 40mm engine plain and simple.

But who actually knows why they have go to this new geometry....?????

Biggest problem I see with the Half Breed is people having know way of knowing what they will get when they order from some vendors, at least in the past we kinda knew who had what, and we had two most common choices.
PK80 40mm stroke or GT5 type 38mm stroke, yes there have always been some variants even in these but now this Hybrid mongrel has added some unfamiliar flavor to the mix.

cannonball2 said:

So I just bought a GT5 off ebay on auction for $60 +14.99 shipping. Not a bad deal. This is from the same supplier my neighbor got his kit from. The same seller sells the complete kit for $118 shipped(USA) from time to time even includes a common digital speedo that is believe it or not shipped directly from China. These engines seem to be the new norm now. I see a bunch on the bay for sale.

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Yeah I've seen that seller on there, almost bought a kit a while back, but wasn't sure what the engine was so I went with a seller that specified the engine was a 47mm bore x 40mm stroke and ended up with a Half Breed...LOL!

That kit came from Hong Kong $119 free shipping but they changed all that and now shipping is through the roof, guess they didn't realize what it would cost to ship that over here, I must have bought the first one....LOL!

Hope the one you got turns out to be as good as the friends did, let us know.

Here is a link to where I got my GT5 Jug, they have the jugs and the pistons, they sell the "Stinger" engines which are simply GT% Skyhawk type engines and so there engine parts are actually labeled so you know what you're ordering.

http://www.ebay.com/itm/66cc-Motorized-bicycle-skyhawk-motor-cylinder-/221369946503

http://www.ebay.com/itm/80cc-Motori...-motor-only-complete-piston-set-/321415387043

Now this said, I have seen on this vendors site that they also sell the old style crank assembly with the Z-L Rod and the crank isn't drilled for better balance, as far as I'm concerned these should be used for trotline weights only, no way I'd put one of these in one of my engines...lol

But they do have other stuff besides GT5 only parts, good thing is that klike this junk crank (in my opinion) they do list what some of their parts will and wont work in, this crank is one of them, they say clearly in the listing this will not work in a GT5 type engine.
http://www.ebay.com/itm/80cc-Motori...9&pid=100005&rk=1&rkt=6&sd=321415387043&rt=nc

cannonball2 said:

Wow that is an old crank! You gonna change the wrist pin? Looks hefty enough to use as a steering king pin in a 65 F150-lol. I have bought from these folks before, apparently Miami is a big MB scene. The other place is MZmiami I believe?
Keep us updated on the jug and your mods to it.

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I have bought from both of these vendors myself, I know some people on here have hated on them for selling cloned parts and I see there point, but it does keep prices down in some areas which can be good and bad depending on which end of the thing someone is on, I like to support the local originator of a part or piece when I can, but we all like to stretch them $'s as far as we can when we can also, so sometimes I tend to support the original and the clone if they are about equal in quality.

I like both of the major Miami vendors but I wouldn't buy everything they offer.

that piston is a high bin piston, which is what is found in the GT5 geometry type engines that has a 114mm length rod.

That piston needs to be used along with a lower that has either the FM80 rod or the ZAF rod the engines with a ZL rod or a ZAE50 rod are the 110mm rod engines and that piston wont work with them because the piston skirt will hit the crank when it rotates down toward BDC.

if the lower you have has a FM80 rod then that is the correct piston for it and you will need to either get a cylinder for a GT5 engine or have a good bit shaved off the deck of a PK80 cylinder that was designed for the 40mm stroke engine.

there are a few sellers on ebay that sell the correct jug for your piston and lower set up, Ill post a link to a complete GT5 top end kit for $30 shipped here in a bit when I have the time.

CarpsCustoms said:

http://motorbicycling.com/attachment.php?attachmentid=7647

http://motorbicycling.com/attachment.php?attachmentid=7

http://motorbicycling.com/attachmen...506471&stc=1&d=14244817930&stc=1&d=1424481787

Slanted teeth on the smaller drive gear means GT-5 type motor correct?

I edited to also ask about my piston, How can i tell if its a type A or type B?? I opened the intake skirt about 4mm and im planning on making a 2mm window on the exhaust side

& chamfering the dome ( 4-leaf clover like pattern )

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all of my engines pk80 and GT5 and the one Half Breed I have, have got theangled teeth on the crankshaft clutch side gear.

Here is a link to the cylinder you need, I know it has a new piston, pin, Rings and gaskets but its a whale of a good deal and this fella ships quick and you get what you order.

Based on the rod yousay your engine has and basex on the piston you listed pic of, there is no doubt that you have a GT5 geometry engine(high pin piston, 114mm rod overall 38mm stroke)

http://pages.ebay.com/link/?nav=item.view&id=281557627732&alt=web

Greg58 said:

Hey Map after looking at that link they call the tall pin piston the "a" type, the other site I found calls the high pin piston a type "b". So to control confusion when ordering a piston a person should measure the pin height and go by that instead of the type each vendor calls them.

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the vendor I posted the link to, is the only one I have found that has the type listed wrong, I've been meaning to contact the fella and let him know he has his piston oz and top end set labeled wrong but just haven't got it done.

But yeah measuring is always a good thing if you cant tell by just looking, I have ordered several pistons and other parts from this guy and if you order type B stuff from him you'll get parts for a 40mm stroke engine and if you order Type A parts you'll get GT5 or Current type Flying Horse 38mm stroke engine parts.

One other vendor that I know of besides this fella in Florida and bikeberry actually say what geometry engine their parts are for.

The Chinese sellers don't have a clue for the most part, and they just say 66/80cc OT 49/50cc to distinguish the parts, I have bought enough stuff that I know basically who has what type parts, but there are a pile of them selling stuff and its not easy to tell most times unless they sell single pistons.

I have found that when they sell single pistons you can go by what kind of piston they sell to have a really good idea what type engine is in the kit they sell, I always look to see if the single piston is a high pin GT5 type or a low pin pk80 type, if its a low pin type I know one of two things about their engines, either they're 40mm stroke or they're Half Breed 38mm stroke which use the same low pin piston.

But they don't list their engines right many times, the Half Breed I bought out of Hong Kong was listed as being a 47mm bore and 40mm stroke and when I got it the first thing I did was pull the jug to find it has the ZAE50 rod which makes it a 38mm stroke Half Breed engine and the piston like 1/16" or .062 from being even with jug deck when its at TDC.

some of them are for sure a crap shoot.

for example this seller has GT5 type engines and I know this from buying the replacement piston for their engines and it was a high pin GT5 type.

Im not gonna say this strategy is 100% fool proof but in some cases I think its a good way to know what they're selling.
www.ebay.com/itm/TOP-2-Stroke-Cycle...587?pt=LH_DefaultDomain_0&hash=item3f44bf612b