That Boyesen crank case is pure class! Love the tank as well, classic lines. Looks like you have a great pit bike there that sounds great as well. And the cherry on the sundae is that you built the engine yourself, and you can't say fairer than that. Great stuff.

Good video. Watching engines being put together, even on something this small, is like artwork. Good job!

Please don’t delete this video I’ve watched it a dozen of time and it’s pure joy to watch it again and again.

My dad was a Honda Service Manager in the 70s and said that Honda tolerances were so good and their mating surfaces so nice that no coppercoat or sealant was required nor recommended. If you got sloppy with sealant and some small pieces broke off the "bead" inside the case, it could plug oil passageways and screw your motor. GREAT video. I enjoyed it!

I built this motor over the course of a few weeks in my spare time. I probably spent about 5 or 6 hours working on it totally. I can dissasemble and reassemble a Z50R engine in about 2 hours if nothing goes wrong. In this case I was spending extra time to film and work carefully. This entire engine could be built for about $2000, maybe less if you shop around. The engine was not seized, I just wanted it to be bigger.

The wrist pin retainer clips should be facing towards the top or bottom of the stroke so G force does not cause them to compress and come out

People who wear gloves generally make meticulous work,as it stems out from actual requirement and also from a psychology of self- discipline and neatness.Personally, I trust tutorials from gloved technicians/engineers.

most motorcycle cranks (like the ones on the crf and z 50's) are pressed from the factory. the 'big end bearings' are needle bearings that are captured on the pin of the crankshaft. usually 2 thrust washers, then they're all pressed together. So you don't install them at home, they come like that.

Thanks, I take pride in the work I do. The bike is a 1984 Honda Z50R.

Interesting music combination 😂 it would be great if you would talk a little bit while your doing your stuff

i am fifty two years old and had a 69 and a 71 honda 50 when i was a kid , love your videos , i think it would be great fun to build a little race motor like that ...

la verdad el mejor video de como armar un motor!!!!!! impecable!!!!!! ahora quiero desarmar el mio y hacerle todo nuevo.........ja...

excelente trabajo, mejor imposible, me ayudo de mucho. Gracias...

When I was younger, I was pretty quick to critisize when I felt the need. As I got older, wiser and more mature I learned to keep my negative thoughts to myself. The reason being- things are not always exactly as they appear. I had the misfortune of having some of my criticisms come back and bite me on my a$$. If I was some bone head with NO toys or NO practical experience, then what I'm saying might not carry any weight. Since I'm retired, having been a machinist (automotive and general machinist/welder fabricator), mechanic, etc... And after owning my share of neat mechanical toys (past and present- Corvettes, Camaros, Novas, Mustangs, Mopars), I can afford to run my mouth a "little". As of now, I've got 2 strokes and 4 strokes in my shop- I much prefer 4 strokes. I also have 2 Harleys, so I'm a fan of V-Twins. There's also a couple of 4 bolt 350s waiting on my attention- one is an aluminum head, roller motor going in a V-8 S10. I enjoyed the video! It may not be perfect. But then again, how many of you are perfect? How many of you know EVERYTHING? I certainly don't. If you don't like this harmless video, click on another one. Save your criticizm- use when it is really needed. The IRS certainly comes to mind. Benghazi cover up comes to mind, too.

i love working with engines and taking them apart and rebuilding them, fixing them.

this vid. helped me 2 years ago and now im planning to change my new acquired motorcyle some new clutch lining and spring. i can say this is helpful tnx man ...

The bike wasn't built for speed, it was built for the track. Going fast in a straight line is boring.

The sirclip is gonna fall out if u keep it sideways like that. Its suppose to he up and down because of the pressure its up n down. U seem like you know whag your doing tho

Yes. On a stock motor there is a screen right above the drain plug. There is also a centrifugal oil filter in the clutch itself. You must remove the right crankcase cover to get to both. You must also remove the clutch inner cover which has 3 or 4 Phillips screws depending on the year of your motor. The Takegawa clutch I installed in this video uses the screen above the drainplug in addition to a paper filter element. You must remove the clutch cover to get to the screen. The paper filter has

That is so cute. Look at that little piston!

KOOL BRO

you build a takegawa for a small motor like this?I expected to see a honda glx,maybe a crypton x but not this lol

The motor is really out of a CRF50. It revs super quick because there is almost no flywheel weight. The exhaust helps the sound also.

If you have Taky parts already, go with Taky parts. If you have a stock motor, the Taky parts are better, but they are more expensive. I like the TB parts for the average recreational rider, cheaper and just as reliable.

this called racing bike? its not even a bike :D sory i dont want to be negative but its funny :D nice video btw, i like it :) its a honda orion block am i right? a pit bike engine

Race? It's a tired 4-stroke.. Thats 2 too many! :-)

In this video, I'm using a TB 52mm piston for their Race Head, with the stock crank it is 88cc. The crank I have in it now is a 51mm stroker making the motor 108cc. In this video, it's around 10 or 11:1. With the stocker crank it's abou 11 or 12:1.

Alex almost a million view on this vid.. congrats I watched these vids when they first came out. Nice of you to take the time to show people the process.

Is this groove street from gta san andereas ?

Never use a hammer to put a bearing.

Intake valve? That hose is to help vent the crankcase. The stock breather works good for stock engines with a small piston. The larger piston moves a lot more air. Both breathers vent back to an oil catch can so no oil gets on the track.

perfect job, enjoy it to see how somebody does a good job in mounting an engine. the only thing I cannot do is work with gloves. I need the contact to the material. And I prefere 2strokes, thats more adventure and a screaming little motor makes more fun

that's not a race engine it's not even water cooled

what problem happens with cd 70 engine when its voice starts changing

You can also put the piston in the cylinder part way, then insert the pin. Great vid, cool stuff!

It is pretty funny and I usually get a good laugh at people who complain about little things I'm doing that have no affect on their lives. I'm glad you enjoyed the video.

technically you could race a motorized bicycle (it doesn't get smaller than that) and yet that motorized bicycle could be classified as a racing vehicle, so yeah, this is a racing engine, big or small Motorsports are Motorsports, so please stop talking about your penises, please. Nice takegawa Alex.

Yup 4stroke sucks

Just a little tip.... see the piston cir clip at 3:47.... if you place it with the gap either up or down, it will be less likely to pop out at high revs. Important on a two stroke but also on four strokes to. Just an observation from an old engine tuner.

Heat makes things expand. When you heat the case, the hole becomes minutely larger and allows the bearing to be installed more easily.

man i love learning how to do things from you videos it helps alot keep the good work up

That'd be a neat idea. Many years ago I built a go kart that was powered by one of my Honda 50 engines. It was my first project after buying a welder. It used the 3 speed and the auto clutch. But a machine that used the Honda trans as a hi/med/low secondary transmission and a Peerless as the primary would be pretty interesting.

I'm glad you enjoyed the video. Unfortunately, I cannot understant your question.

what a fantastic moto!! great video! Nice and clean work.

Excellent ,and that is a sweet looking engine...peace "

Awesome video. and a cool little bike too.

i love the pipe sound..its sounds like the old endurance pipe..

whatever you say man, i'm only 17 and here in belgium we're not allowed to have big engines at this age so i have one like this and i enjoy working on it, i'll go bigger later. have a great day

People doesn't like tu run in... but it's the most important thing in an engine!!!

I LOVE that bike. Great video too.

nice little engine - sounds like at least 15 hp well done

DAMN BOY!!!! Peeps better recognize this guys potential and helpful videos. Thumb up

nice work!!

Nice job on the video and assembly. Ever thought about packing the oil pump with petroleum jelly? It will prime and get oil pressure quicker, unless the pump is already located below the oil level and is submerged in oil? It will be interesting to see if you get into bigger engines down the road.

here is a tip that applies to all race engines, 2 or 4 stroke: always install the wrist pin clip so the ends are vertical. if you don't, it could pop off at high rpm. great video though!

Awesome! A complete documentary! Nice job! Try to make some more videos like this..

great vid.man u R really genuis...i like it so much thanx alot to share your smart with us.....

Look man, I keep in these mopeds tuning since I was 8... I have placed Takegawa covers at all moped engines, even if it was a Lifan (I hate them). I can't accept this Z for track use, because it is bored to start. Secondly, the carburettor you are using is an imitation from Keihin 24. I had a Honda GLX90 @57mm piston bore in ASSA alloy cylinder, with Kitaco cam (The 90s have the best cylinder head) but later I put on a Takegawa. I used an RD350 Carburettor made by Mikuni. It was nice machine.

Some very fine work indeed!

Awesome build and bike also!

As long as necessary to expand the metal so the bearing goes in easily. Time varies depending on what heat source you use.

Sweet video. Nice honda

this was the most helpful video i found thanks for taking your time to do this from this my bike engine had been rebuilt and will be seeing if it runs tomorrow thanks again, Danny

My chinese 90cc is now 110cc with a 125cc head, using the 90cc cam sprocket. The carburetor is a OKO-24mm, I think it has about 10hp at 9500 rpm.

Dude really good job, makes me wanna tear into my Atc 70.

What a cool video, better than trying to read "Zen an the Art of Motorcycle Maintenance".

Awesome video. Nice job on the motor rebuild. Keep up the good work!!!! :))

Freeze the part that goes inside and heat the part that goes on the outside, then slide them together quickly. Don't tap anything with a hammer. If this doesn't work, you'll need to take it to a shop that can press it together correctly.

Seeing your hard effort paying off-great!

Cool dude. Sounds great too.

You should change your crankshaft recommend Takegawa ( Don't go for the economy class, recommend the 54mm with the chrome connecting rod) Also recommend buying a head with bigger valves that uses ball-bearing camshafts (Cdi Head that comes with the lifan 125 engine should be fine after port and polish), and adding a r20 takegawa camshaft. and you really should buy a 28 mm carb when using a Piston over 54 mm recommend a Keihen PE 28, or a PWK 29 (PWK is better but hard to find in the US) Cheers!

It may look that way, but in reality my motor was built with Honda CRF50 cases, Trail Bikes top end, Takegawa clutch, Kitaco IRK, Honda ATC70 trans, and a genuine Keihin carb. Nothing Chinese/knock off.

A nice tidy old z. Very cool.

wasnt expecting that little engine to sound so good at 7:42 nice bike!!! just needa work out the rear fender before its gone from the exhaust!

Nice bike, Sick video dude, great entertainment with the volume UP! =)

your work is awesome!!!

It's strange the type of people you find on youtube... They'll insult you and/or your mother but in the same breath, also bitch about you not wearing a helmet for a slow test ride to the end of your street. Anyway, great video. Wish more people took the time to put quality vids like this, up on youtube.

Very interesting video you got here, I like to put all my nolts and bults on a cloth as well, keeps everything nice and organized :) I use instead of a torch a hot air oven wich i put to 120-150 degrees celcius, this way you evenly warm up the entire engine casing. Dont worry though this way is fine to :D Greeting from Holland.

If it has sat for a while, those carbs gum up quick and those damn pilot jets have a VERY tiny hole, that easily clogs.

this video brought up some sweet memories excellent mate

nice vids man.. you need to make another one for drag racing... just like mine.. awsome ride dude!!!

very very nice job, but you just miss one think to show, the clutch!!!!!! excellent job!!!!!

I forgot to record that. It was done on a different day.

el mejor video que vi de un armado de motor felicitaciones

learned lots of things by watching this video, thanks my friend

Brother, greetings from Argentina. good job

Очень круто! Приятно смотреть на хорошую работу!

Thanks for the video man, you have showed me how do pretty much do anything with these motors! you have the best vids on you youtube!

great skill my friend , i loved the vid , so cool

Very very good job..👍👍👍

@MrIptamenos To install it all you do is tighten the nut. That pulls the crank into the flywheel. To remove it you need the correct puller.

You're AWESOME AlexMan !

great video man. know nothing about these little things but t was a really good video.

Circlip opening should be up or downward facing, they can pop out when installed sideways like that.

Gotta love how such a small engine revs up. Japanese man... They know the way :)

se trata de uma moto .... prefiro carro .... mas nao posso deixar de comentar que esse cara é um tremendo PROFISSIONAL .... very god job !

Please don't be rude. I'm sure he does know how to race port a cylinder head, port match an intake, and swirl polish valves. I'm sure he can convert a 6v case to run 12v ignitions. And I'm sure he knows how to convert a 6v right case half to mate with a 12v left case half. And I'm sure it's second nature to him to make an XR75 swingarm fit a Z50R frame, despite the numerous complications. And I don't even have to mention how to shorten BBR forks, everyone knows that.

Very nice video Dost

looks awesome mate

Not every bit of the bike's completion is shown here. It would be quite boring. This is meant to show a time lapse of an engine going together, not the lengthy process of porting or anything else. Would you enjoy watching me cut something, test it, cut it some more, fit it again, and repeat this over and over until it was right? That's what I have to do, but it doesn't make an interesting video to watch. I'm glad your son can do all this, and doesn't waste his life on video games. Good job.