$3000 CURSED Dirt Bike Blows Up Every Time It Is Rebuilt 

HELLO, 50 years ago I was a mechanic for Honda.and I discovered that my Wife's Kenmore dish washing machine with the powdered Cascade soap did a job so good on washing motorcycle engine parts that they actually looked like new. The wife got over it eventually... Back then a new Gold Wing cost 3 K. The dish washer had a disinfectant cycle that had a heater unit in the bottom of it that heated the water to 180 degrees.... After many uses it did not even leave an oil film inside...and the dishes came out sparking also. It worked on the block halves and every other part even the carbs. I got brave and washed other parts including a 4 speed Muncie transmission out of a Ford 427 Cobra Jet... I was never disappointed. Back in the day we also trimmed the skirts on 2 stroke pistons in the port area to build more crankcase pressure it got so radical that it would blow out the crank seals right out of the cases. We had to peen the cases with a center punch and install the seals with red lock tight to hold them....When we did this we put the seals in first before joining the halves....Our shop had our own racing team and the owners who were man and wife were both West Coast Enduro Champions...They had twin sons that were also racers....I remember when the first water cooled 2 stokes came out and how strange they looked....I think that was 1976? My personal ride was a 1972 Honda CB 750 K. I rode it for over 300 thousand miles until my second wife got pissed off at me and ran over my bike with my Dodge power wagon...I decided to move on to wife #3. Getting a new wife is easy, replacing something that you love is harder.

Damn man. Every video you put out teaches me something new....I deeply appreciate you sharing your knowledge and your attitude about it. Love it mane!

Great job on this one. This is why I watch your channel. Very interesting and thorough. Thanks again for your time today and enjoy your weekend.

I worked at a 2 cycle motor shop for a few years when in school and as a second job. What was done on a rebuild always included checking all surfaces for flatness. If it was a motor we had not built the cylinder was cut to ensure the top and bottom were perpendicular to the bore. Pistons were measured for diameter and cylinders were honed and checked with a bore gauge to ensure they were round and not tapered, it was also the way proper piston to bore clearance. I hope she stays together for you, looks like a fun bike, always amazed me how much power a 125 two stroke can make I get running a ball hone through if your putting in a new ring or have it apart to check wear or replace gaskets but once your buying a pile of parts it’s worth the time to go through more throughly.

Looking at the JIS screws for the shift shaft, it is apparent that people are not using the correct heads when tightening them. The US uses Phillips but Japanese bikes use Japanese Industry Standard patterns which are different and when you use a phillips #2 it does not get the full engagement resulting in damaged heads. You can also identify JIS by a dot usually stamped into the head

Great video joe. Ive been a rm lover for ever. Im 56 years old and had rms all my life. Such a good educational video for us. We thank you with your know how.

love how you show us all how todo everything you are doing in the process of doing it. favorite youtube channel by far. edit- never knew that grease trick with gaskets before today thank you 🙌🏻

A pressure check on any two stroke will help prevent failure on a new motor. A lot of comments on the lack of a crankshaft seal on here, by doing a pressure check on the motor after the rebuild you will catch mistakes like that. Hope you find that before it blows up again. nice video!

Back to the old tried and true dirt bikes. Another great video. Engine teardown, learning moments. Keep up with hard work and a variety

BRAVO, you didn't bury it. Love the engine rebuilds, always something to learn. Next we'll learn upgrading, maybe a 550 or 650 engine? You have the patience of Saint. I'd have used the hammer - not in a good way - a lot sooner

good thing you mentioned the 2 holes on the piston. i rebuilt my 125 recently and didnt know you had to do that. you just saved my ass!

im pretty much a amateur rider so 125s are about my speed, some of the more fun times in my life was on a rm 125. good detailed build man👍

The crush washers on the head can be heated with a torch and reused. It's called annealing. It swells them back to like new. Can be done a couple times. I like to lightly sand mine to make grooves as well.

Stator went on with no crank seal installed 😮that’s going to be a problem. Hope you catch that before you ship it out the door. 15:33.

Dude I just wanna say I love the videos and vintage bike's. I live n breath all thing's motorcycle. You remind me of myself going through everything, so I enjoy watching and seeing them come back to life keep it up brother 🤘

The times you use assembly lube and loctite, clean that lube out of the holes. It won't allow the threadlocker to cure rendering it useless. Same on another video were you got assembly lube on the rtv for case halves..that spot will leak eventually because rtv won't seal to metal with lube on the rtv

Air screw adjustments are also a good indication of the jetting. General air screw settings are 1.5 turns out. With the bike warmed up and idling, start adjusting the air screw until you achieve the highest RPM. Count the number of turns out and then you will know if your low speed is too large ie 2 or 2.5 turns out or too small, fewer air screw turns. These are just general rules of thumb but a good thing to have in mind. Additionally, if you spray carb cleaner around the sealing areas and you get a increase in revs, you have an air leak in that area. Lastly, it is always best to use copper crush gaskets on the head bolts. It looked like one of those washers was a steel washer.

Dremel with the scotch brite pads are awesome gasket removers after razor blades. Want it clean for no leaks.

Great vid. Always enjoy learning from you wrench’n on stuff…one thing I do for old gasket mat’l, is use a die grinder with a fine nylon pad & that old mat’l comes right off. Makes a slow tidious job go much quicker

I'll be 70 in a couple months and sure wish i knew about JIS screws in my 20's and since! I always had a hard time getting them out and ruined most of the heads. Love your videos

Wow, just started watching so I'm assuming you blew it up too? Idk yet but can't wait to see, thanks for the great content lately!

The rod bearing is gone and thats why there are dings on the piston . The new chrome or newer coatings on cylinders dont get honed. Clean and buff at most or the coating will get wrecked. These videos are really fun to watch.

that idle still sounds way to high

I admit I am addicted to watching you effortlessly diagnose and repair these machines. I can only make one suggestion related to a chain coming off a bike you were test riding...can you guess what i am thinking? Hint - its not running shoes. 🙂

lol I love that he says it’s running great. That bike is screaming. Can’t wait to see if it blows up at the end of this video cause it’s not going to last long.

You cracked me up when you said the previous owner had the motor lock up on him then you said...."so something happen there" lol

All that work this kid does on this bike and he doesn't know how to break it in no wonder why they blow up He's running it at full he's got a pinned it's crazy to even watch it hurts my head I can't imagine that this kid doesn't know how to break a bike in unbelievable😂

I feel I need to comment that the engine does not sound right . Check all settings are standard in carb . When you were fitting the ignition the left hand crank seal was missing , bike would run but poorly but if you removed ignition cover it would stop and not restart , I have seen this done !

Great bike, love the Suzuki 2 strokes... that crisp popping sound is unique. Great vid

That bike is a beauty! Sounds great too. I think Suzuki has the best sounding bikes

2:57-“yeah that rod feels good in there”😂

Yo 2vin awesome wort as always, so I’ve just rebuilt a rmz250 put oil in and started straight up, put coolant in and it went straight in the engine 😢 stripped it back down can’t see anything wrong all looks good and help guys 😩👍

I was gone say I’d resurface the head then you ended up doing it anyway not a big setback though! Great job on the rebuild and video bud.

Man, those birds in the background are going crazy :D lol

Cool! Take it out for a good rip now! Great video, thanks Joe!

It sounds like the old suzuki 125 I use to own. It was a lot of fun. One ring racing piston too. So its a ripper for sure! Its a pretty nice lookng bike.

Personally I think 42:1 is way to lean especially for a fresh rebuild. 28:1 is good for a fresh rebuild and 32:1 for regular riding.

Awsome video joe! Great job as per usual

you can get small brushes in packs of 50 or whatever and use those to paint on your grease, never seize, oil.. onto your gasket surfaces instead of the gasket itself and keep your hands clean. Good to hear the 2 smoke run.

I’ve just subscribed With all your videos. I feel pretty confident when buying a motocross bike for me and my boy for the first time thanks buddy👍

Love your videos man... keep them coming!!!!

On my yz's I've always used a tach and set idle to 1000rpm, turned idle air in until rpm starts to drop then back out just until max idle is reached and give it an extra 32nd - 16th turn and then reset for 1000rpm idle. Makes it spot on w/no bogging down off ldle.

Those old 2 strokes were the way to go for dirt riding with their snappy engine response. I always preferred the smoother 4 stroke engines for street riding.

Good morning everyone!

BALLS TO THE WALLS: break-in ride complete (check)

Many modern small bore bikes have sub-sizes on the bore and piston. A letter A, B, C, or D is inked on the outside of the cylinder. Make sure you buy the correct piston. Aftermarket pistons usually don’t offer sub-sizes, and sell loose pistons, so I buy OEM.

Nice to see you clean the parts before install ! That's huge !

When I put my gaskets on I put a little silicone around the gaskets to keep them from moving when u torque the head down plus incase u need a little extra seal it’ll help but jst a tip I do when fixing my sleds after They overheated

We used to relieve exhaust port bridge a few thousandth s to allow for expansion on air cooled YZ and RMs before water cooled bikes. Looks like oil mix to lean and or main jet to lean to ruin rod bearings . RMs held up better than others . I worked at dealership in NY. Love 125 class . Fastest class.

Sold my 250f an got an 01 just like this did a restyle on it out the gate I love it so much lighter and plenty of power

Get a cricut machine and sheets of gasket material. I cut all my own gaskets in the shop 😁

Detonation on the piston and head.

I have a hot rods crank in my cr125, it’s ran good for the last year since I installed it. Just double check the trueness of cranks before install

TYVM allways well made and fun to watch (from Quebec Canada )

Outstanding video, great job. Fun to watch

The hole on the piston is to lubricate the small end bearing you forgot to put your crankshaft seal in

Good lad that sounds so so nice Keep up the good work love your video that you make From the UK

There's something about the sound of a performance two-stroke engine getting revved, if you can get it, put some Castrol R in the petrol as well, the exhaust smell is amazing

You always do a great job on your videos, One thing I have to say is, all that assembly lube in the threads, Loctite will not set if any oils are in the threads.. JS?! 😕

I had a few CR250's and had excellent results from running really good gas and Klotz Beanoil. Never ever had issues

Whatcha know, Joe..lool Don't feel bad. I had a similar experience with a 1978 YZ250. Wish I had it to diagnose now. Been a long time.

Was waiting for this video, Good job!

Yep the green scotch Brite would on nikisil,I have seen people use a ball hone and it works

I love his content don't get me wrong but he is a prime example that engines don't need to be perfect to run. There is a pretty big margin for sloppiness when it comes to engine building and I'm sure it surprises some people who watch his videos. lol

Thanks for the great vid Im having a hell of a time finding electrical parts for my 91rm 125 .I already bought 2 CDIs off of Ebay that dont work , Where do you get your ignition parts for older bikes

And better watch that high idle after you rebuild one that will cold seize that piston

Id say the last guy had a bad premix oil and not enough of it im 44 now and have rode my whole life and i only ever used either caster 927 or honda hp2 never had a issue or foulded plug with either and i love the smell of the caster oil lol

38:40 Turn the gas on then lean the bike over to the left until fuel pisses out of the vent lines, tgen pull the choke, give 2-3 slow priming kicks, then kick to start. When you lean the bike over it primes the engine so you kick less and it doesnt lean rev like mad on startup.

The "skirts" of the cylinder are the protruding sections at the bottom of the bore of the cylinder that protrude into the cylinder cases, (the bore skirt below the base gasket). I am a bit surprised the cylinder uses a bridged exhaust port. Most got rid of the bridge and went to sub exhaust ports for a wider port. That bridge design has been proven to be easier to seize at times, which is why you are putting holes in the piston. I think, to reduce the chance of seizure, the bridges have been made a bit concave, about .003" away from the piston/rest of the wall, to allow for expansion and not touch the piston.

Some top notch break in procedures you used..lol

Pro tip: grease up the mating surfaces with a small brush rather getting your hands covered in grease by greasing the gasket.

Awesome job! 👍 she sure sounds excellent after all the work put in. your videos never cease to amaze me. Though I didn’t see Vinny the lovable Pup make an appearance. My daughter just loves to see the little guy in your Videos.

2:56 that's what she said💀💀

You should hang a can of premix up above the bike and have a hose with a valve on it so you can test these bikes without having to put the gas tank back on. It'll make it much easier to see everything while you're still troubleshooting

Still idling like a dc10 lol 😅😂

He didn’t show it on video, but when putting the piston pin circling in, always put a rag under the piston in case the clips flys off and down the crankcase during attempt. Engine out yea you can try and flip it upside down. In the frame not as easy.

The inner clutch hub rides directly on the needle bearing? I thought there was a washer in between them?

Man I do miss that sound when you dig in and go

I had coolant coming thru stud as well on my LT..had it decked etc and solved the issue.. fresh washers etc

It takes a minimum of 3 minutes to warm up an engine. So adjustments to the carb and reving accomplish nothing before that time.

Love the videos man but Ya forgot the heat cycles man😂😂

Sounds amazing. Awesome job.

While I do enjoy fmf pipes, I find their suggested jetting to be off in most cases. I recommend jetting by the pro circuit jetting guide even if you have an fmf pipe.

I drilled an extra hole for my bridge port in my 77 RM. 125....piston.

My Husky liked to be seized a few times before it ran well at high RPM. Just used to wet and dry the scraped areas put it together. After a couple of times it would sound a bit loose when cold, but run reliably well when at racing temps.

you can drill a cup in every cracks end so its cant go forward,then take a grinder and grind the crack a u shabe so deep at you cant see any cracks lines, then you can use braising rod and braising flux or just use tic weld to fix all.

When lapping something (head) on a glass surface with abrasive or wet/dry paper, should use figure-of-eight motion, not circular. So as to change leading edge on the lapped part, avoid removing more material on one edge.

Love your videos pal, yet to say ,you've titled this one spot on , there is another vid on tube somewhere. It covers the history os susuki , and basically, they scripted and saved ,way too much. To the point they made careless mistake on their bikes !! So to you, good luck 🤞... look for video , history of susuki or something similar

the case area where the rod goes cracks on them little pieces chip off & that's what makes the piston lock up used to happen on my RM125 1999 too

Did you ever do an update video on that Niche big bore kit in that yellow 400ex? Just wondering how long it held up?

First thing I would have checked would have been if that cylinder had a plated or steel sleeve. I think the cylinder is the problem. It's probably warped and or egg shaped and it just chews up pistons and won't seal. Send the cylinder off and have a sleeve put in it and forget about it. While it's gone replace the crank seals. The high idle is definitely an air leak.

Hey Joe that other crank might make a good anchor for one of your boats

We always ran 3 heat cycles a half hour each with no more than 1/4 throttle on my race 2 smokers. And always run them rich during break in. Sick build though, takes me back to the smell the races used to have!

I once had an older RD500 4 cyl v-4 2-stroke and also ran into the issue with coolant coming from the upper head bolts. When I researched it it turned out to be because I had put the wrong nuts on. There were supposed to be domed nuts and not regular ones. With domed nuts the coolant stayed in the head. Very weird stuff.

Man I just love the sound of this bike. It brings back memories

Measure that piston rod,, yu know, the old one, the hot rod one. I'll bet you it's a 8th in. Longer. Plus, that "assembly lube" you use, I'm tellin ya, that's some good stuff man! That'll make your bike, once it gets broke in, run forever! I don't know what it is about that stuff but every dirt bike that I've built and rebuilt and use that stuff it just seems like the bike lasts forever. Now,, there's been times I haven't used it and the bike is you know, been wore out after quite a few races. But for some reason when I use that it seems like the bikes will just run better. Anyway ,,love your videos dude! These videos just show us how easy a little dirt bike can be your best bud!!!!!!!!!! 👍

Nice case.. great job finding that, they suck to find. Never to much when it comes to pre lube.

Clean bike sounds good to good vid and build keep up the good work

Exalent content joe as usual love watching your videos mate

I have a pal that am races this model bike. he loves it & has only rebuilt it a few times. he’s really fast