This is the life of having old 2-strokes. Haven't had to take out the engine of our 250RDLC racer. Yet. The RG250 racer has it's third crankshaft fitted. The T20 racer experienced a real detonation last race. A conrod made fruitless efforts to escape. Made a slit through the crankcase. Spent 3 hours on christmas eve taking it apart. Right cylinder had been riveted to the crankcase. But not to bad after all. Just a three piece conrod, a damaged piston, a scrap crankcase and two teeth broken off third gear by the conrod piece. Right cylinder and crankshaft possible to repair. So now in process to rebuilding the next T20 engine after it had a gearbox lockup. Wonder what will happen next racing season. Guess we will bring the trusty old CB250 with us as a spare machine.
The best engine family to work on. They come apart in big simple chunks unlike Suzuki’s of the same period which are an over engineered nail shredding nightmare.
Glad to see you are prepping your garage built leak down tester! Testing will help you to get to a really good rebuild. You will be very confident your engine is good to go. To finish your test you may wish to consider: 1. Adding a plug to block off the other intake boot. 2. adding an air gauge to monitor your air pressure over the 15 minute test period. 3. consider using tapered rubber pipe plugs to block the exhaust port flanges. These have an expanding screw so it is easy to get a good seal. Available where you got your pipe fittings. Sometimes called a "freeze plug". 4. keep the air pressure low. 6 to 8 psi, or .5 of a bar. Shut off the air. If the pressure drops, hunt for leaks. 5 test both cylinders by swapping the air fitting between the two intake boots, and repeating the test. A spray bottle filled with water and a few drops of dish soap can be sprayed on the engine to find leaks. Test the head gasket, cylinder base gaskets, intake gaskets, carburetor intake boots, exhaust flanges, and the crank seals. You will get bubbles at the leak. Fix the leak and retest. When your engine holds air for 15 minutes without the air pressure dropping, you are good to go. Don't forget your engine case sealant! Yamabond, Moto Seal, or 3 Bond 1211. Your choice. Check out the UA-cam channel "art & motorcycles" he has a video showing leak-down testing a Yamaha RD350. You may find it helpful. Have a Happy Christmas holiday.😊
@@RepairandRideout My pleasure. I have owned several RD's over the years, and I have a soft spot for them. Currently, I have a 350 YPVS in my small fleet of bikes. Always happy to help others keep their RD's up and running. They are fun bikes to ride. 😊 Taking your time on bike projects is the smart way to go. Enjoy your Christmas holiday. Looking forward to future videos from the heart of France.
Having had lots of Yamahas over 40 years the 'family resemblance ' with the engines are clear to see. There is even similarities between the 2 and 4 strokes. Gearboxes, clutches etc.
A great job building your leak tester! Wishing you a great holiday season. One brief idea for storage of parts from ongoing projects. We use "bakers racks" and aluminum baking sheets to organize projects. The idea is to stack parts as you disassemble the project. The racks are on casters and can be moved easily. The racks can be purchased second-hand. I'm in the States. I use Costco wholesale to access "full" and "half sized" baking sheets. We also used inexpensive oil absorbent mats to line the sheets. The overall footprint of the rolling rack is less than 4 sq ft. Just an idea. It just happens to work well for us. There is no way to attach a photo of this storage idea. Be good. Remain safe. Merry Christmas
When doing your leak down test - Remember the Gearbox is separate to the cylinder, so you need to do 2 tests one test for the Crankshaft Seals and the other test for the Gearbox and relevant seals, also you have 2 intakes so you will need 2 plugs to do both cylinders, From my understanding the cylinder crank case is under great pressure, but the Gearbox does not build much pressure if any at all so if say a seal went on the Gearbox all you are left with is an oil leak, But if a Crank Seal goes then it effects the Running of the bike and you certainly will know it !!! I think I am correct here however if I am wrong I am sure other people will correct me !! Have a nice Xmas and Drink too much !!! Malc
@@RepairandRideout As l understand it the lab seal allows enough space/time in the machined spiral so that the charge pressure from the other cýl prevents any fuel mix transferring from one to the other. This will not be the case when you test 'dry'.
Interesting for an old 2 stroker........way before your time. Dont change your filming style with the new camera, your videos are so easy to watch because there is no ridiculous swinging around of the camera. Millyard is the archetype.
This is the life of having old 2-strokes. Haven't had to take out the engine of our 250RDLC racer. Yet.
The RG250 racer has it's third crankshaft fitted.
The T20 racer experienced a real detonation last race. A conrod made fruitless efforts to escape. Made a slit through the crankcase. Spent 3 hours on christmas eve taking it apart. Right cylinder had been riveted to the crankcase. But not to bad after all. Just a three piece conrod, a damaged piston, a scrap crankcase and two teeth broken off third gear by the conrod piece. Right cylinder and crankshaft possible to repair. So now in process to rebuilding the next T20 engine after it had a gearbox lockup. Wonder what will happen next racing season. Guess we will bring the trusty old CB250 with us as a spare machine.
Good for you man. An Allen Millyard in the making 👌🏻
Thank you, not in my wildest dreams though
The best engine family to work on. They come apart in big simple chunks unlike Suzuki’s of the same period which are an over engineered nail shredding nightmare.
I remember back in the day we would modify rotary disc valve on the fizzy but Suzuki AP50’s were impossible
Glad to see you are prepping your garage built leak down tester! Testing will help you to get to a really good rebuild. You will be very confident your engine is good to go.
To finish your test you may wish to consider:
1. Adding a plug to block off the other intake boot.
2. adding an air gauge to monitor your air pressure over the 15 minute test period.
3. consider using tapered rubber pipe plugs to block the exhaust port flanges. These have an expanding screw so it is easy to get a good seal. Available where you got your pipe fittings. Sometimes called a "freeze plug".
4. keep the air pressure low. 6 to 8 psi, or .5 of a bar. Shut off the air. If the pressure drops, hunt for leaks.
5 test both cylinders by swapping the air fitting between the two intake boots, and repeating the test.
A spray bottle filled with water and a few drops of dish soap can be sprayed on the engine to find leaks.
Test the head gasket, cylinder base gaskets, intake gaskets, carburetor intake boots, exhaust flanges, and the crank seals. You will get bubbles at the leak.
Fix the leak and retest.
When your engine holds air for 15 minutes without the air pressure dropping, you are good to go.
Don't forget your engine case sealant! Yamabond, Moto Seal, or 3 Bond 1211. Your choice.
Check out the UA-cam channel "art & motorcycles" he has a video showing leak-down testing a Yamaha RD350. You may find it helpful.
Have a Happy Christmas holiday.😊
Got it backwards....
Regarding motorcycles and art.😂
Thanks so much for your advice. I’m going to take my time testing the engine for leaks. Have a great Christmas
@@RepairandRideout My pleasure. I have owned several RD's over the years, and I have a soft spot for them. Currently, I have a 350 YPVS in my small fleet of bikes. Always happy to help others keep their RD's up and running. They are fun bikes to ride. 😊
Taking your time on bike projects is the smart way to go.
Enjoy your Christmas holiday.
Looking forward to future videos from the heart of France.
Have a great Christmas . Thanks for your stream . 👍👍👍👍
Cheers cbrider, you have a great Christmas too
Having had lots of Yamahas over 40 years the 'family resemblance ' with the engines are clear to see. There is even similarities between the 2 and 4 strokes. Gearboxes, clutches etc.
Evolution over many years. The engines went from good to very good between the 1960's and the 1990's when production ceased.
Quite a relief to see something I recognized
A great job building your leak tester! Wishing you a great holiday season.
One brief idea for storage of parts from ongoing projects.
We use "bakers racks" and aluminum baking sheets to organize projects. The idea is to stack parts as you disassemble the project. The racks are on casters and can be moved easily.
The racks can be purchased second-hand. I'm in the States. I use Costco wholesale to access "full" and "half sized" baking sheets. We also used inexpensive oil absorbent mats to line the sheets. The overall footprint of the rolling rack is less than 4 sq ft.
Just an idea. It just happens to work well for us. There is no way to attach a photo of this storage idea.
Be good. Remain safe. Merry Christmas
Thanks for your advice. That sounds like a great idea, I’m trying to be more organized in the garage! Have a great Christmas
Merry Xmas and thx for the update hope to c u in the new year
Thanks for watching. Have a great Christmas
You've had a pretty good idea with assembling engine before getting lost bolts washers etc.
I'm pleased I did it. Just arrived home from a few weeks in the UK and I've realised I've kind of forgotten what goes where on the engine
catch up with you in january and have a loverly xmas !
Thanks, have a great Christmas
When doing your leak down test - Remember the Gearbox is separate to the cylinder, so you need to do 2 tests one test for the Crankshaft Seals and the other test for the Gearbox and relevant seals, also you have 2 intakes so you will need 2 plugs to do both cylinders, From my understanding the cylinder crank case is under great pressure, but the Gearbox does not build much pressure if any at all so if say a seal went on the Gearbox all you are left with is an oil leak, But if a Crank Seal goes then it effects the Running of the bike and you certainly will know it !!! I think I am correct here however if I am wrong I am sure other people will correct me !! Have a nice Xmas and Drink too much !!! Malc
Thanks, great advice. I am hoping to test each cylinder individually to check there isn’t any leaking between them - if that’s the right thing to do?
If the labyrinth crankcase seal passes air to the other side, the other pot will need the same plugs to have a true pressure reading.
Are both cylinders pressurized equally and the labyrinth seal does not keep them under separate pressures?
@@RepairandRideout As l understand it the lab seal allows enough space/time in the machined spiral so that the charge pressure from the other cýl prevents any fuel mix transferring from one to the other. This will not be the case when you test 'dry'.
I didn’t know how it worked, thanks for letting me know.
Excellent. Thank you.
Thank you
keep at it lad ul get there all the best 4 2024
4:00 "Upscaled fizzie" It's 'Race Developed', I'll have you know!😛
😂
It would be sensible to fit the standard exhaust system and jet the carbs back to manufacturer's spec before proceeding to run the engine again...
Thanks for your comment, that sounds like a good idea
I made a longer reply about service manuals etc., but it seems to have disappeared, probably waiting for your approval...
I’ve not seen it? I lose replies from time to time for no apparent reason
Interesting for an old 2 stroker........way before your time. Dont change your filming style with the new camera, your videos are so easy to watch because there is no ridiculous swinging around of the camera. Millyard is the archetype.
Thanks for your comment, I try to limit the movement of the camera as it can be distracting to watch.
Allen Millyard.you are not...