66/80 cc Motorized bicycle engine geometries explained

[@1232sean]

Thanks for this explanation, Fred. Shed some good light on the differences.

[@kevinturner1234]

Thank you for the information I watched this video like two months ago to get some help before I bought my parts

[@eugenegriess1896]

Fred, thanks for this video. It helpede me alot! I have a mainstreem 80cc engine and ordered a new bottom end for it. (Got one with the ZAE 50 rod) Was clueless about it maybe having a different sized piston shaft and when I put it together the piston ws hitting the head. I did extensive research onit and you are THE only good source of information on it that I could find. I do not understand why these suppliers don't put this information on the ads.

[@hakkedbitchhh7686]

Thank you for sharing you’re knowledge Fred! I’m learning a lot from you!

[@scottlang7564]

Thanks Fred well done vid Ive read all the info on the engines I could fine but several things did not sink in till I seen it with my eyes and heard what you had to say.

[@bryduhbikeguy]

Thank You! If there weren't for you,I'dve missed 'casting flash' tips/points on the edges of the Intake port,I would never have taken the Head off my new Motor.I saw 'tips'on the inner side of the 'carrier/intake' port from the base in the Head too.I used a very Fine file and drew Back until all the fingers were gone,and a Minute bevel was upon every ports edges.No problems after I started it.Thanx again Mr,C.(btw,I used Molybdenum lube in bearings and on cylinder sleeve before bolting together)You know,but not some here,that Molybdenum soaks Into steel and reinforces it.

[@bryduhbikeguy]

I did this all in 2018,as I watched Most of your vids before I even unboxed my kit.Was here just after New Year,but I wanted to do it right.Thank You,Mr.C.Been running Super for 2 mnth.Is on Mongoose Mt.Bike,front spring/shock fork w/26"wheel.(Looks like Survival Bike).

[@jdeere2141]

Thanks...this really helps illustrate the differences in these little rascals.

[@mapbike]

Thank You Fred, Excellent explanation of engine types and the differences, I have a couple older 2009 & 2010 BGF engines, my oldest with around 1300-1400 miles on it has the rod with the loose pin bearing on crank journal, it is a real bone shaker though, horrible vibes, I think removing crank and truing it will help some though, spinning crank in case one can see the weights wobble back and forth so I'm sure a lot of the vibes are being caused by this issue alone. this engine is a 47mm bore and 40mm stroke but it is the old type with 6mm studs and the piston is much lighter and has a shorter dome. an odd ball thing nowadays. Thanks again Fred for the great info.

[@darrenmillion1432]

Fred I have a ZAF80 Rod Motor so you was right :D but I must say that my ZL rod motor is the best I have had

[@mapbike]

Just wanted toad here that I have an older bgf engine that has a rod marked ZAE 50 which has the narrow crank flywheel/counter weights, the rod is a bit thicker and has more of an I-Beam look to it, the engine this crank and rod came out of has the largest exhaust port and transfer ports of any of these engines I have ever had or seen, I actually got it back in 2010, the measurement between crank main journal and lower rod journal pin is roughly 3.75mm just like the newest "half breed" crank. Have you seen one of these Fred?

[@pauls5745]

I have that ZAE50 rod in my 40mm bore 48cc. it is a revvy mutha but it never had any torque even w/porting +pipe. really smooth runner I thought. maybe the ports on those ZAE species were just made for top speed haha

[@macmotorizedbike3834]

So which stamp rods have the strongest engines?

[@roostalion]

extremely helpful video thank you very much!

[@stingray300m]

I wanted to rebuild my engine and I bought a rebuild kit with the wrong piston the type b piston hits against the crankshaft and the engine will not rotate I forgot there was two diffreant pistons

[@DesertSessions93]

I have the ZAE50 engine and the thing is a power house. I can beat the tar out of it and it just keeps taking it. It impresses me to no end.

[@kelebemoloro4842]

where did you buy it from

[@DesertSessions93]

Just a random low $ kit from ebay.

[@WillB-lv1xg]

I took my engine apart and it has the ZAE 50 im replacing the crank with a 3mm stroker though. Ill still keep it though. I'm using a 48mm bore cylinder.

[@honorb4glory606]

I'm currently rebuilding my 48cc engine. It has a JM50 connecting rod. I'm putting in a ZAE50 crank and rod assembly, in combination with a high-compression, hemi head. I wonder if the thing will self destruct....

[@codelicious6590]

So with the type "B" piston its most likely going to be a gt5? I got it from Kingsmotorbikes and it was tagged, "Black Stallion". It needs some tlc but its ok for a $120 engine as it stands out of the box.

[@integrationofmanandmachine4714]

i have AF80 connecting rod it is a long rod yes but i dont really know how it compares to ZAF80

[@amber6804]

I have the same problem

[@integrationofmanandmachine4714]

i threw that engine to my scrape yard 😂

[@TheFrank5767]

Originally the GT5 came with a 40mm stroke But the builder changed to the 38mm stroke more recently !All my GT5 engines are different, different cylinders and different parts depending on when they were made !the GT5 engine comes with the best cast cylinder and can be ported way!!! better than any other on the market and come with the 40mm intake ! most PK's come with the 38mm stroke but I got one with the 40mm stroke !They just mix and match parts at the factory ! I talked to the man at the factory a couple of years ago and he explaned the change from 40 mm stroke to the 38mm stroke !

[@apworksearch]

sound like to me the zl rod is the one to get where can i find it?

[@dakidp97]

Had one motor quite some time ago with a jsf50...Haven't seen this suffice since but always wondered what stroke was on it. Went to replace piston with a type-a (low pin)--didn't know then what I do now--and it cleared cylinder an easy 1/8"...tore this piston up quick. Assumed then because cylinder has 32mm intake and believed then that ALL 32mm intake cylinders had type a pistons

[@rickrocket2169]

Wow actually someone who is full of knowledge n has his shit together !!! U also speak well and have good mannerism - I have clicked on videos that have made me want to choke the idiot who posted it 0 understanding of the 2stroke combustion engine - thank you for posting a civilized video that could actually help someone understand what type engine we received

[@bryduhbikeguy]

The next post,from me of course,should read..triple 40.30 degree hill at 16mph torque with All stock.Gas 93 oct,syth oil.

[@jeffbicht8844]

I have a Grubee engine and the rod in it is ZAE80. not ZAF80. Motor was built in the lat 2015.

[@premiumcut6813]

I've never seen or heard of a zaf80, only the ZAE80, Why was the ZAE80 not included in this??

Did you find out anything...i have the ZAE 80 also...the engine is denoted as A80 on the pamphlet. I curious what stroke it has.

[@pauls5745]

other variants are popping up these days. 2 have a low-hole Type A piston with a ZMN80 rod that might or not have the GT4 cylinder. I want to get a sleeved 50mm jug, but it comes with high hole A piston and I dont have long rod bottom ends, but maybe i can find a matching piston idk,,

[@ChuckHaney]

When the video started and I heard the crickets I thought you added that audio to be funny. XD

[@BuildBreakFix]

2021 and 25,000 piston& rod combos later now remarked and branded lol like to see that video rofl!

[@enginelover1]

I found it better, that the bigend bearing will be with out a cage. I made the small top bearing from bronze! The standard type small end bearing with cage keeps on breaking, and there for every time scratching the bore. thanks for this video.

[@arthurclark563]

enginelover1 I had to edit my comment most of it was theory anyway and beyond all that nonsense I had absolutely no luck with the PK 66/80 it was far too heavy for my 8 lb.steel bike frame. Sense then I've held on a small version that runs extremely well with transfer and port enhancing and reed kit .

[@DopamineMafiaCo]

Digging your music taste, Fred :P

[@billaugustin1928]

The gomax pk80s I have been running have high hole pistons, I tried to put a low hole on one of them when I rebuilt the top end and it didn't work and was hitting the head, that was years ago and I always use the high hole now, even gomax claims their pk80s are triple '40s?

[@ChuckNorris-xs5gl]

It probly doesn't matter much but my engine has the rod that you're missing and if your wondering, the brand of mine is RAW

[@andybobandy9483]

Chuck Norris I also have it, amazon kit manufactured by a shandong hausheng zhongtian machine’s lol

[@francoreia8147]

I just got a motor from BGF 100cc high compression head . The rod is stamped EAF 80. Supposedly 50 mm bore I measure at like 49+ .Can find any info on it.

[@iceyaj3167]

now im totally confuse. i have a high wrist pin hole on the piston with the FM80 connection rod. the description on the engine i have said its a 40mm stroke. now you're saying its a 38mm stroke?

[@ryankeith5529]

Hello, could you possibly tell me how I can Identify what size motor I have. I recently bought one second hand and the only identifying mark I can locate is the number "50" inside the case where the magneto is located. I need to purchase a clutch kit and I don't know which to get

[@butre.]

Nice video, I was thinking about building an engine up using a pistonbikes bottom end and one of your stage one cylinder bodies with a stage 2 head but wasn't quite sure which cylinder body or piston I needed. There's so much variation between these engines and it always has me confused because by the time I need to buy parts I've already forgotten which parts go with which engines.

[@joneserupinsmoke9161]

I have a 100 cc with 38 stroke 50 mm piston and it picks up quick as hell .I hit 43 rip pull all stock bur for some reason I feel it can do a lot more

[@YorHighness]

DontiZAE 80s have long Rods Type B pistons have a 40mm stroke?

[@Yukanhayt-Mhenow]

I keep having issues with my 66cc . . .it has a tybe B piston and a z-L rod, keeps seizing at high rpm even though the mixture seems good for it, plug is chocolate brown. . Noticed you divided the ZL from the type B, the only damage is on the lower half of the piston.. Looks like its melting and chipping away! Is that rod, piston combo wrong?

[@cfdalton1]

My rod say ZMN have you ever seen that before? The piston is a Type A, I can't find anything about ZMN rod length and I need to get a new cylinder body. Any help would be greatly appreciated. Thanks

[@Bull3tBikes]

where did you buy th motor

[@troycollins4051]

I have the same engine. It came with upgraded motor mount bolts and nuts. Fast stock out if the box.

[@blaze9000g]

This is weird cause I opened a motor I have and it's a zmn80 rod but a type b piston and I can't find much info either

[@joshuabalaam6356]

hey fred! quick question when mentioning fine thread you're talking every thread is fine?? on the gt-5

[@jcxstargazer]

So while tearing my engine down for port work. I seen I have a ZAE 80 con rod kind of copper color Has the type b piston So what type of engine would I have? Also I bought the engine from gasbikes.net. It was listed as a black stallion 66/80 cc

i think these are rebadged A80 engines...just a theory though.

[@honorb4glory606]

I'm rebuilding a 48cc engine with a connecting rod marked "JM50." I got a ZAE50 rod and crank assembly, and I think it will fit. I will also be using non-sealed crank bearings, with a metal shield on one side, and I'll be running Lucas high-performance 2-stroke oil. Anyone have any advice on any of this? Am I making a terrible mistake? Btw, I'm assuming open side of the bearing should face inward, right? Or does the shield allow enough oil through? Maybe it's there to prevent debris from getting in there?

[@mflbikes1870]

I have a 49cc with a zl crank, is it still a 40mm stroke?

[@ridefast591]

How bad is the non caged lower needle bearing...if I tune a motor with such a bearing is it a waste . .. my other motor has caged bearing and and it seems to hold up fine and I ride it hard and it hits high rpm. Just got one and wonder should I sell it or tune it as I can do most everything except dynamic balance and that lower bearing

[@upsidedown1986]

Good tips, thanks.

[@Jonszii]

Hi. Help me want to ask for a 48mm cylindrical piston and zae 80 crankshaft is not good because it comes out of the cylinder to the plunger 3-4mm short cranks should just do not know

[@NoboaIsrael]

Hey i got an orther its no over the table ZAE80 with motor is it?

[@Nextrevit]

Same here

[@KunioTaki]

These connecting rod doesn't affect the stroke I need a longer stroke, but it depends on the crankshaft are there different types of crankshaft?

[@WillB-lv1xg]

Jordán József mzparts miami on ebay sells a stroker crank the rod is 3mm longer so 41mm stroke. I bought one

[@robertharvey472]

I got a ZAF60 in one of my engine and Af80 in the other one??????

[@andybobandy9483]

Okay I understand the stroke is different but what exactly makes the crank case different between the one with the longest stroke with an engine with a smaller stroke? Head or block? I could figure it out if say this was a Honda but the more I try and learn the bigger the can of worms gets lol

[@joneserupinsmoke9161]

I mean really u would want a lesser stroke so return combustion rate is quicker right

[@codelicious6590]

I have one I just got with a type B piston, and a brass-colored rod stamped ZAE 80. What engine type do I have? I'm wanting to order a few things from CR machine but I need to know what engine i have.

[@premiumcut6813]

Cody Watson, I have a GT-6 with the same ZAE80 rod. I don't know what mm' s length it is yet. I do know it's from gasbike, if you find out what it is please post information. I will do the same . I have no time to rip it apart to measure it.

[@codelicious6590]

premiumcut6813 I've already put her back together, but if it helps any it came from Kingsmotorbikes.com I plan to order another one next week - it dis have the issue with the drive gear ( the little one behing the clutch cover) wobbling due to not being assembled properly, and I had to fix the gap between magnet and magneto, but its running good so I figure its the best I can do for the 130 price tag. I still do need to find out what actual engine it is however so I can order parts from CR machine. The ZAE80 rod.

[@shaunc4209]

@@premiumcut6813 it's a 38mm I have a gt7 not a bad kit but certainly going to be adding the mz65 muffler

[@VirantRoss]

Darren loves his ZAE 50s

[@macmotorizedbike3834]

😂

[@jonathanguillory8321]

R the fm 80 s a single piece cylinder?

[@sharktooth1985]

Mine says JS50?? On the rod

[@floridaboy9052]

I just bought a engine and it has a AF80 gold colored rod . What do i have?

[@willgarner42]

A china 49cc would be actually a USA standard CC of ?

[@thrifty9797]

I have a ZAE 80 rod, is that newer, or just something you didnt list.

[@johnbrevard5966]

Rock on (Far ahead Fred)!

[@whoFNcares83]

Nice video. Stumbled across your stuff looking for a definitive answer about axial play on crankshafts and how much is too much. Realizing what these engines are and what they are NOT, I've always been under the impression that if you can feel or see it absent a dial indicator that its definitely bad as a rule for all 2strokes. Well what i have is a bottom end of unknown origin with your mystery zaf80 rod and you can actually grab hold and cock the entire crankshaft to the output side where it seems to perhaps grab the poorly machined lip that you described in another video. I have neither puller nor access to a lathe but would like to crack the crankcase open. Are there any methods of doing so without causing damage? Also this particular engine is coupled to a type B piston by your standards. I've been burning day light for over 2 hours now just taking in all this good info you're putting out. Thanks for being that guy.

[@mattasticbmxss]

hey fred I have the zae 50 half breed where can I find someone with this engine. I forgot who I bought it from

[@francoreia8147]

Mine is marked AE80 on the connecting rod

[@joneserupinsmoke9161]

So what ones u think is the better

[@HLandsons]

Need piston type B where can I get one from

[@wesleystandard680]

I have a Z-L rod with a B piston do I have the wrong type of piston?

[@justinchampagne2818]

Do you recognize this kind of Rod ZMN 80

[@ryanm9924]

my rod says ZAF60 on it, what does that mean?

[@kylegreen3442]

What do you think about the gt6 motor? Are they good motors or not?

[@TRAXXASSLASH1256]

hello fred what size would be the piston rings for a type b pistion gt 5 motor

[@watermeloncooler9597]

47mm piston rings should fit if you’ve still got the motor after you commented 5 years ago

[@barty111111]

Hello Fred, can i ask you for the bottom conection rod bearing dimensions for the "half breed" engine ? Thank you very much !

[@turrettooling1968]

Hi Barty. The dimensions for the lower connecting rod bearing used in the half breed engine is 22 X 16 X 11 mm. It's a caged needle bearing. It's the same bearing that is used in the GT-5 engines and some of the new style PK-80 style engines. All the engines using caged needle bearings are the same. The only engine that does not use a caged needle bearing are the old style PK-80 type using the Z-L connecting rod.

[@barty111111]

Thank you

[@unemployedmechanics]

So is a ZAF80 the same as an AF80?

[@gerestevenson4484]

What does the zeda 80 have

[@robjohns5611]

how do i tell if i got a 80cc engine and not a 49cc

[@jeffsausser7439]

hi fred I have a con rod ZAF60

[@damnthiccassboye7138]

I have zmn80 rod and its for b type

[@sallyport5384]

Well explained Fred !

[@JS-fb6ww]

sally port, what kind of 66cc motor do you have?

[@BusyB07]

how can i tell which piston i have. i dont see many differences

[@mapbike]

Look at the distance between top of piston and top of pistons wrist pin hole' the GT5 wrist pin hole is like Fred mentioned and about center of the piston, while the Type A piston for the 40mm stroke engines and the 38mm stroke "Half Breed" engines has its pin setting a few m's lower which allows piston to reach correct height at TDC since the Type A " PK 80 engines and the HB engines has a shorter connecting rod. Hope this helps answer your question, and if Fred chimes in here he may make it even clearer and add some other measurements to held you out.

[@BusyB07]

mapbike ohh that makes sense, thanks map

[@mapbike]

7brandonc your welcome, glad I could help. take care and ride safe

[@Aaronzahller]

Does a zeda 80 motor have a type A piston?

[@turrettooling1968]

No. The ZEDA engine is not a PK-80. The ZEDA engine takes a type B

[@Aaronzahller]

Frederic Chelminski ok thanks!

[@Aaronzahller]

Frederic Chelminski so does it come with a balanced crank? Ive seen people with a balanced crank from the factory.

[@magdamolina3999]

What is better for max top speed the long rod or short Rod?

[@manueldealba4356]

Gracias

[@macknumber9]

You said the fm80 has 38mm stroke...i believe you are wrong. The fm80 should be a long stroke connecting rod and should have a 40mm stroke Edit: i guess my af80 is a long connecting rod...which correlates to high wrist pin piston and a SHORTER (38mm) stroke...for some reason i correlated longer connecting rod with longer stroke...maybe i stand corrected

[@stevetag2081]

Mine says fm50 so wich one is mine?

[@1strat275]

Same bro I will let you know if I can find out what the piston type is I want to put a performance piston in mine I think FM50 rods are newer

[@Aaronzahller]

I have a ZMN rod do you have an idea what engine it is???

[@turrettooling1968]

It's a half breed.

[@Aaronzahller]

Frederic Chelminski can you explain so i fully understand im putting a ported piston type A

[@federruchi6147]

ive got the 49cc engine (thats what the ad said) and it has the fm80 rod. is that possible? or is it actually a 66cc?

[@pauls5745]

you have 66cc. esp you can tell by 8mm studs bcs 48cc has only 6mm. also head bolt spacing is 42mm if you can measure that

[@YorHighness]

Those companies do this so you think its completly street legal. Its 66cc

[@adamcolbertmusic]

Same. I ordered a "48cc" engine but it wasn't until I ordered a new jug (which was WAY too small) that I found out I actually had a 66cc. And yes, likewise, I have a con rod marked "FM80" and it has a type B piston. I'm not sure about the stroke, whether it's 38mm or 40mm..... I've never measured it..... But the top edge of the piston is flush with the top of the cylinder.

[@cameron15yo]

i have a kit with a f80 rod whats that

[@turrettooling1968]

Yes. There have been several newcomers since this video was made. There are so many rods now, It's become even more difficult to keep up. The F80 rod is a GT-5 type engine. You must use a type B piston and it has a 38mm stroke. Be aware that some vendors do not know what kind of pistons type have and name them arbitrarily (MZ Miami) for example has the nomenclature reversed. For reference, you can go to my website to look at the pictures. www.crmachine.com

[@rexterrocks]

I'm keeping my rod statistics to myself, I don't like to boast.

[@ronduck2812]

Mine has af80 on rod

[@francoreia8147]

Mine is marked AF80

[@chrisswin8976]

I wish I knew what the bottom line meant

[@Adalbertomatos_]

Where u are Fred u no have no more Fred head ?

[@jaydee6616]

mines has zaf60

[@catweaselttv]

I have a ZAF80 😁

[@theintegrathatcould3171]

i have th zaf80 connecting rod!

[@turrettooling1968]

I've only seen that rod in the GT-5 type engines (38mm stroke, type B piston).

[@theintegrathatcould3171]

I'm watching your video now. And I have that connecting rod with a type A piston.. and it's hitting the head.. obviously found out why. My question is what type of cylinder do I need. If you know

[@turrettooling1968]

Yeah, that's the wrong piston. You need a type B. Some vendors are confused and name their pistons incorrectly. You've got a GT-5 engine. I sell top end kits for that type on my website: www.crmachine.com

[@mikeflores468]

Nathan hubis hey I have a ZAE80 connecting rod the Piston I'm about to put on there is a B- piston , when the original piston was in A-piston ,which got cracked plus I have a high compression aluminum head would something go wrong?

[@theintegrathatcould3171]

The piston probably hit the head and cracked it get the type b piston and you should be good. Just received my type b once I get home I'm going to put my engine together I will let you know what I find

[@chinno1234]

I have 1 ! It is ZAE80 not ZAf80

[@shaunc4209]

Do you have a gt engine kit because I have. Gt7 and it says the same thing on my rod I looked it up and it said it's a ballenced crank I believe is 38mm

[@ernestososa2892]

I have GT 6

[@justinchampagne2818]

ZMN 80

[@magdamolina3999]

U need u number i m Jorge matos i need a engine 80 cc zl o zae 50 how much only engine is for competition i have zae 80 i fix the top problem but the top is only 45 mph u need halfbreed rod rigt i wan i lees 52 mph how i can talk w u thank

[@ashley-marcuslind3922]

way to much blah blah...would have given 5 thumbs up if you where more informatively direct..