Thanks Larry, again trying to move in another direction, we will see how it goes. I too was happy with the outcome. You haven't seen the last of the Twin jet 90. Think it will be a fun project for sure.
Thanks Larry, thanks for the mic feedback, I too am looking forward to the new projects, and finishing up the others, I just love finding these ole jems.
Great job troubleshooting. I see it takes a lot of work and know how to get old bikes running again. Interesting and a lot knowledge thrown at us again. Thanks!
Thanks for hanging out in the shop with me Kevin, I think this is going to be a great project. Think I will be making another wiring harness and may adapt a newer style regulator. Thanks for following along.
Thanks Carl, I think this is going to be interesting for sure. Cant find a lot on the AT-90 but there is some info coming in from viewers. Going to be a great vintage project for sure. Thanks for hanging out here Carl.
Thanks Travis, yes, I have to agree, very cool, I want to try to get this one back together, wiring is going to be the hardest part, I think. Thanks for the feedback on the mic. Thanks for following along with me.
Thanks Daniel, I think so too, I'm sure that it could use a tune up and a cleaning for sure, we will see where we go with this one. I agree those 2 stroke twins are awesome, got a couple more that I will eventually get to. But this one struck my fancy because I thought it was a YL1, turns out this is an early H2, some call it a AT-90. Going to be fun just figuring out what I have here. Thanks for hanging out in the shop with me.
Thanks Taylor, no not a YL-1, I thought so too when I saw it. But it is a Japan market bike, only sold in Asia. Some have told me it is a AT-90. It says H2 on the engine but YSC on the steering neck. However, both engine and frame have the same number. I know in 1970 there was a H2 90 twin imported to the US. But to my knowledge the YL-1 Twin jet 100 was the one imported here. I figure a GI brought this one back from Southeast Asia in the mid 60's.
Thanks buddy, I appreciate you taking the time to watch. This one is a lot different than the past projects. I actually have a couple more very similar to this one.
I love it. To see an old girl like this spring into life once more. She seems like a fiery little beast. Goodonyou Dale you are the two stroke whisperer. Do you think all that oil in the crankcases is gearbox oil through crank seals ? More twins and triples please
Thanks Kevin, yes, she is coming back from the abyss, It's a cool bike for sure. We replaced all the crank seals on this in one of the videos. She has a tight crankcase.
Hey Dale, great find. A forerunner of the RD twins that many people had a lot of fun with over here in the 70s and 80s. It's definitely not a UK bike, as we use miles-per-hour, even though we are metric on most other things. I may be able to email a resource to you which could help in identifying Yamaha models. I'll see if the link works. Good work puzzling out the wiring, she sounded like a 500GP bike at the end of the video! It's raining here in Oxfordshire too, first time in months. Best wishes, Dean.
Hey thanks Dean, I remember these too from my high school days, the YL-1 twin jet 100 was a popular bike then. They were very peppy. That is interesting that you still use MPH instead of KPH. I thought it was sounding pretty dang good myself. Think I will be making a new harness and may try to retrofit a newer style regulator. It can't be that difficult. Yes, the rain has been a gift from God. We received another nice storm last night. We are indeed blessed.
@@montana2strokeracer We got sprinkles-need rain in this part of Texas. Liked the "set the torque wrench to zero" (or lowest shaft setting ) advice you gave a few episodes back. I know you cycled the wrench and checked the PMEL sticker off camera-lol.
Thanks Andy is that what this bike is. An AT90? For the most part, it looks like the YL-1 Twin jet 100 of my youth. But it does have some differences. Thanks for the feedback, I appreciate you spending your time in my shop.
All that water in the oil doesn't damage the engine at all when you fired it up? Love your videos I have an at1 and at3 I'm working on and your videos are great!
Hi there, there wasn't that much water in there, but there was plenty of oil, I don't think the amount would cause any problems. You have to get whatever is in there out or you will never get it started. It was pretty drowned anyway. It just kept fouling plugs; it has to come out. Thanks for watching and best of luck with your projects, it's good to have you on board.
The little Yamaha twin is the Twinjet 100 (97cc) Yl1. The engine number is stamped on the crankcase and starts with L1. I have restored 2 of these little Yamahas to showroom condition which were introduced in 1966, the Yl1 E having electric start. They are a free revving fun bike and can reach 60mph plus. The 90cc twin model was different in that it had a tubular fame.
Hi Sidney, nice to have you aboard, this particular bike is not a YL-1, if you follow the channel, I talked about this being a H-2 for the Japanese home market only, (also known as the AT-90 abroad) it was probably brought into this country by a G.I. that had been stationed in Japan in the sixties. This is indeed a 90cc, the head light emblem says 90, the speedometer is in KPH, not MPH. When I did the top end rebuild the pistons are 36.5 mm not the 38mm for the 100cc. The 90 that was imported in this country was the HS1, imported for the 70/71 years. This is a 1965, it does look like the Twin jet 100's that I rode growing up in the late sixty's early seventies. But the engine does say H2, and the frame says Y3C. You are correct about them being quick, spirited, and free revving. This one is only 8 HP but does run very good for that 8 hp. Thanks for hanging out in the shop with me.
@@montana2strokeracer In the case of the HS1B 90, I have noticed that checking to make sure the slides can move all the way to the top in the carburetor at full throttle provides a zippier feel! Mine will go almost as quickly as the twin jets; actually feels similar to my LS2 100, which is my quickest twin of this displacement, easily. The round tail light on these is an easy indicator of Japanese domestic market bikes, for sure. Nice find!
Hi Norman, yes, the full chain case does a good job of protecting the chain and sprockets, a good idea, but unfortunately most folks didn't like the look, so many were just thrown out.
Very cool! A 56 year old bike!! Love the way you figured out wiring. Well done, Dale. Looking forward to your journey with these. Is the oil pump working? Think I saw "auto lube" on a side case.
Thanks Jim, yep going to be interesting for sure, not sure if the oil pump works, don't think it needs one with all the oil that was in the combustion chamber. Yes, it has autolube though, I will get to it at some point. Its going to need a good hosing off, can't even see the oil lines.
Great job Dale. It looks like the wiring colors are going to be the same as the YDS3 that I have and actually pretty much the same as all the 60s and 70s bikes.
I was wondering, I just ordered a factory manual from Ebay for the US version. I do notice that grounds are brown and not black, not a black wire to be found on this critter. Is that the case on the YDS3's, just interesting to note the differences, I thought I would make a new harness and opt for a new style regulator.
@@montana2strokeracer The lighter of the 2 browns should be switched 6 or 12V. The red on the switch is direct to battery + and the blue should be head/tail light. dark brown should be turn signal lamps and dark green should be the other turn signal lamps. I always have to look up which is which R&L. The only black I remember is in the headlight bucket and has a big eyelet that fastens to one of the mounting bolts. It should have a 2 or 3 way female bullet connector on the other end. That's from memory of wiring my YDS3.
This thing is cool, right. I always wanted a Twin jet 100 when I was a kid. This is pretty darn close, at least its close enough for the girls I go with.
@montana2strokeracer New subscriber here. I'm trying to get a 67 YL1E back on the road. Having trouble with the autolube pump sending air to the right cylinder only. Tried 2 separate pumps, and properly bled each time. Primed the lines before reconnecting. And yet within a couple minutes of running, huge air pockets form in the outer (RH cylinder) oil pipe, starting right at the pump. New gaskets and seals on the pumps. Any ideas? Thanks for the amazing content on these older 2 strokes!
Well thank you very much, glad you could stop by man I love those YL1's, just nothing like that sound. It's hard to tell what your problem is, it sounds like you have all the bases covered. Its apparent that is sucking air somewhere, I would double check your plastic lines, could be a pin hole or a break somewhere, they are really brittle by the time they are 60 years old. Is the check ball and spring in the pump, that is your check valve to prevent the oil from running back to the pump. Best of luck finding the problem and thank you again for the kind words, and for subscribing.
@@montana2strokeracer Thanks for the reply! Yes, check balls and springs are there. Next weekend I'll be pulling the cover, replacing both clear lines and the black line from the oil tank with NOS parts. Will see what happens. Thanks Dale.
Thanks Frank, I have been plagued with audio problems for some time, think I may have it sorted out. Rode had me send in my old one, they think it is a problem within. They will probably send me a new one. Nice folks there, seam interested in getting it fixed for me.
yeah simple but i always like to make it more complicated. i pour over the wire diagrams eventually figure it out. help to under stand the basics of what makes a motorcycle run. love the one wire stator to coil bikes the best.@@montana2strokeracer
with your expertise this would be a nice project on a 2 stroke that your going to keep. think it would be easy drill/thread/plug. many uses maybe to just see whats floating around in the crank case. @@montana2strokeracer
Thanks Mark, I know it was made there, but from what I was able to find out it was a Japanese local market bike. Do you concur with that? I had one viewer tell me that in England they still would have had a MPH speedo. Not sure about Europe as a whole. Just interesting to hear what others have to say. Thanks for following along with the channel.
But on the other hand most of Europe has been using kilometers per hour for well before 1968 Russia converted in I think 1925 the British empire was a holdout until 1977
That was one of the best videos I've seen in a long time dale , I like the outcome. Keep em running happy trails.
Thanks Larry, again trying to move in another direction, we will see how it goes. I too was happy with the outcome. You haven't seen the last of the Twin jet 90. Think it will be a fun project for sure.
Good morning Dale, your microphone is perfect. I also love the New old bikes that you'll be bringing back to life.
Thanks Larry, thanks for the mic feedback, I too am looking forward to the new projects, and finishing up the others, I just love finding these ole jems.
Great job troubleshooting. I see it takes a lot of work and know how to get old bikes running again. Interesting and a lot knowledge thrown at us again. Thanks!
Thanks for hanging out in the shop with me Kevin, I think this is going to be a great project. Think I will be making another wiring harness and may adapt a newer style regulator. Thanks for following along.
Extremely interesting Dale. Quite the find you have there.
Thanks Carl, I think this is going to be interesting for sure. Cant find a lot on the AT-90 but there is some info coming in from viewers. Going to be a great vintage project for sure. Thanks for hanging out here Carl.
Cool old yamaha! Mic sounds great. Looking forward to see the new bikes repaired.
Thanks Travis, yes, I have to agree, very cool, I want to try to get this one back together, wiring is going to be the hardest part, I think. Thanks for the feedback on the mic. Thanks for following along with me.
That thing sounds awesome Dale! Good luck with it and I look forward to seeing it in more videos. Gotta love the 2 stroke Yamaha twins.
Thanks Daniel, I think so too, I'm sure that it could use a tune up and a cleaning for sure, we will see where we go with this one. I agree those 2 stroke twins are awesome, got a couple more that I will eventually get to. But this one struck my fancy because I thought it was a YL1, turns out this is an early H2, some call it a AT-90. Going to be fun just figuring out what I have here. Thanks for hanging out in the shop with me.
Nice work Dale... your audio sounds great by the way with the new mic. Is that the YL1 model? Got to love the sound of 2 cycle twins!
Thanks Taylor, no not a YL-1, I thought so too when I saw it. But it is a Japan market bike, only sold in Asia. Some have told me it is a AT-90. It says H2 on the engine but YSC on the steering neck. However, both engine and frame have the same number. I know in 1970 there was a H2 90 twin imported to the US. But to my knowledge the YL-1 Twin jet 100 was the one imported here. I figure a GI brought this one back from Southeast Asia in the mid 60's.
Very cool 90. Mic sound is good
Thank you, sir, I think my audio problems may finally be a thing of the past. I like this bike, think it will be a fun project.
Sweet find
Thanks buddy, I appreciate you taking the time to watch. This one is a lot different than the past projects. I actually have a couple more very similar to this one.
I love it. To see an old girl like this spring into life once more. She seems like a fiery little beast. Goodonyou Dale you are the two stroke whisperer. Do you think all that oil in the crankcases is gearbox oil through crank seals ? More twins and triples please
Thanks Kevin, yes, she is coming back from the abyss, It's a cool bike for sure. We replaced all the crank seals on this in one of the videos. She has a tight crankcase.
Hey Dale, great find. A forerunner of the RD twins that many people had a lot of fun with over here in the 70s and 80s.
It's definitely not a UK bike, as we use miles-per-hour, even though we are metric on most other things. I may be able to email a resource to you which could help in identifying Yamaha models. I'll see if the link works.
Good work puzzling out the wiring, she sounded like a 500GP bike at the end of the video!
It's raining here in Oxfordshire too, first time in months.
Best wishes, Dean.
Hey thanks Dean, I remember these too from my high school days, the YL-1 twin jet 100 was a popular bike then. They were very peppy. That is interesting that you still use MPH instead of KPH. I thought it was sounding pretty dang good myself. Think I will be making a new harness and may try to retrofit a newer style regulator. It can't be that difficult. Yes, the rain has been a gift from God. We received another nice storm last night. We are indeed blessed.
@@montana2strokeracer keep on keeping on my friend. I'm enjoying the ride along with you.
Enjoyed the clip .
Thanks Cliff, were you a recipient of the recent rain fall there? We finally got some the last two nights; we are feeling blessed for sure.
@@montana2strokeracer We got sprinkles-need rain in this part of Texas. Liked the "set the torque wrench to zero" (or lowest shaft setting ) advice you gave a few episodes back. I know you cycled the wrench and checked the PMEL sticker off camera-lol.
Love the AT90, tank & seat look original to me. Microphone sounds fine
Thanks Andy is that what this bike is. An AT90? For the most part, it looks like the YL-1 Twin jet 100 of my youth. But it does have some differences. Thanks for the feedback, I appreciate you spending your time in my shop.
@@montana2strokeracer I think so. It sounds great, reminds me of being young
All that water in the oil doesn't damage the engine at all when you fired it up? Love your videos I have an at1 and at3 I'm working on and your videos are great!
Hi there, there wasn't that much water in there, but there was plenty of oil, I don't think the amount would cause any problems. You have to get whatever is in there out or you will never get it started. It was pretty drowned anyway. It just kept fouling plugs; it has to come out. Thanks for watching and best of luck with your projects, it's good to have you on board.
I used to own a 1967 Yamaha Twin jet. I paid $399.00 for it brand new. My twin brother and I shared it. We paid for it with our paper route
Nice, cant even buy one in ruff shape for that these days. Bet you guys had one heck of a time on that bike. Thanks for stopping by the channel.
The little Yamaha twin is the Twinjet 100 (97cc) Yl1. The engine number is stamped on the crankcase and starts with L1.
I have restored 2 of these little Yamahas to showroom condition which were introduced in 1966, the Yl1 E having electric start.
They are a free revving fun bike and can reach 60mph plus. The 90cc twin model was different in that it had a tubular fame.
Hi Sidney, nice to have you aboard, this particular bike is not a YL-1, if you follow the channel, I talked about this being a H-2 for the Japanese home market only, (also known as the AT-90 abroad) it was probably brought into this country by a G.I. that had been stationed in Japan in the sixties. This is indeed a 90cc, the head light emblem says 90, the speedometer is in KPH, not MPH. When I did the top end rebuild the pistons are 36.5 mm not the 38mm for the 100cc. The 90 that was imported in this country was the HS1, imported for the 70/71 years. This is a 1965, it does look like the Twin jet 100's that I rode growing up in the late sixty's early seventies. But the engine does say H2, and the frame says Y3C. You are correct about them being quick, spirited, and free revving. This one is only 8 HP but does run very good for that 8 hp. Thanks for hanging out in the shop with me.
@@montana2strokeracer In the case of the HS1B 90, I have noticed that checking to make sure the slides can move all the way to the top in the carburetor at full throttle provides a zippier feel! Mine will go almost as quickly as the twin jets; actually feels similar to my LS2 100, which is my quickest twin of this displacement, easily. The round tail light on these is an easy indicator of Japanese domestic market bikes, for sure. Nice find!
Well she lives. Sounds good.
Yep, but she almost drowned.
The enclosed chain case would have been nice on the YL1s, as well!
Hi Norman, yes, the full chain case does a good job of protecting the chain and sprockets, a good idea, but unfortunately most folks didn't like the look, so many were just thrown out.
Very cool! A 56 year old bike!! Love the way you figured out wiring. Well done, Dale. Looking forward to your journey with these. Is the oil pump working? Think I saw "auto lube" on a side case.
Thanks Jim, yep going to be interesting for sure, not sure if the oil pump works, don't think it needs one with all the oil that was in the combustion chamber. Yes, it has autolube though, I will get to it at some point. Its going to need a good hosing off, can't even see the oil lines.
Great job Dale. It looks like the wiring colors are going to be the same as the YDS3 that I have and actually pretty much the same as all the 60s and 70s bikes.
I was wondering, I just ordered a factory manual from Ebay for the US version. I do notice that grounds are brown and not black, not a black wire to be found on this critter. Is that the case on the YDS3's, just interesting to note the differences, I thought I would make a new harness and opt for a new style regulator.
@@montana2strokeracer The lighter of the 2 browns should be switched 6 or 12V. The red on the switch is direct to battery + and the blue should be head/tail light. dark brown should be turn signal lamps and dark green should be the other turn signal lamps. I always have to look up which is which R&L. The only black I remember is in the headlight bucket and has a big eyelet that fastens to one of the mounting bolts. It should have a 2 or 3 way female bullet connector on the other end. That's from memory of wiring my YDS3.
@@montana2strokeracer Making a new harness is probably the best solution.
great job dale considering the bikes age and condition its sounds pretty good I'm sure u will strip it down and overall engine hope so anyway
Thanks Mark, not sure were I'm going with this one yet, but more than likely I will, It's just too cool not to. Thanks for hanging out with me.
now your talking, fun riding collectable bike for sure. love to save these odd ball motorcycles.
This thing is cool, right. I always wanted a Twin jet 100 when I was a kid. This is pretty darn close, at least its close enough for the girls I go with.
Never will forget the first time i rode one. I thought 💭 this is fast for a 100. I bet that 90 i cool
They really are cool bikes, nothing like them today.
@montana2strokeracer New subscriber here. I'm trying to get a 67 YL1E back on the road. Having trouble with the autolube pump sending air to the right cylinder only. Tried 2 separate pumps, and properly bled each time. Primed the lines before reconnecting. And yet within a couple minutes of running, huge air pockets form in the outer (RH cylinder) oil pipe, starting right at the pump. New gaskets and seals on the pumps. Any ideas?
Thanks for the amazing content on these older 2 strokes!
Well thank you very much, glad you could stop by man I love those YL1's, just nothing like that sound. It's hard to tell what your problem is, it sounds like you have all the bases covered. Its apparent that is sucking air somewhere, I would double check your plastic lines, could be a pin hole or a break somewhere, they are really brittle by the time they are 60 years old. Is the check ball and spring in the pump, that is your check valve to prevent the oil from running back to the pump. Best of luck finding the problem and thank you again for the kind words, and for subscribing.
@@montana2strokeracer Thanks for the reply! Yes, check balls and springs are there. Next weekend I'll be pulling the cover, replacing both clear lines and the black line from the oil tank with NOS parts. Will see what happens. Thanks Dale.
flea bay,has some stuff new seat cover and repop service manuals, actually cheap!
Yes, I noticed, I spent some time on their last night and your right, seems to be a lot of goodies on there.
audio sounds very natural easy to listen to. of course my 80 year old ears arnt that reliable.
Thanks Frank, I have been plagued with audio problems for some time, think I may have it sorted out. Rode had me send in my old one, they think it is a problem within. They will probably send me a new one. Nice folks there, seam interested in getting it fixed for me.
electrical is part of ebay sellers stuff. PDF/or CD not a book. very reasonable prices.
Thanks Frank, I will be looking into it. But it really looks cut and dried. Pretty simple electrical on these old bikes.
yeah simple but i always like to make it more complicated. i pour over the wire diagrams eventually figure it out. help to under stand the basics of what makes a motorcycle run. love the one wire stator to coil bikes the best.@@montana2strokeracer
why dont they have a crank case drain plug?
Wouldn't that be nice.
with your expertise this would be a nice project on a 2 stroke that your going to keep. think it would be easy drill/thread/plug. many uses maybe to just see whats floating around in the crank case. @@montana2strokeracer
Howdy!
Whats happing Frank?
Maybe it needs air, open throttle
Still have some work to do to it, converted it to breaker less ignition, wow what an improvement.
I guarantee you it came from Japan originally ! 😉😅
Thanks Mark, I know it was made there, but from what I was able to find out it was a Japanese local market bike. Do you concur with that? I had one viewer tell me that in England they still would have had a MPH speedo. Not sure about Europe as a whole. Just interesting to hear what others have to say. Thanks for following along with the channel.
@@montana2strokeracer yes it most certainly could have indeedede been a Japanese market bike...
But on the other hand most of Europe has been using kilometers per hour for well before 1968 Russia converted in I think 1925 the British empire was a holdout until 1977