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Discussion Starter · #1 ·
The owner of the company I work for was admiring my CB160, and said he had this old Yamaha sitting in his shed that I could have for FREE. Being the kind of guy who'll take any old piece of junk, I told him to bring it in and i'd gladly take it off his hands!






Frame # Y28-7131
Engine # J5-7131

I'd like it if someone knowledgeable could tell me exactly what it is. It's a 60cc 2-stroke with Yamaha's Autolube oil injection. Just over 10,000 miles with no title. I can't find very much information about it on these here fancy interwebs. From what I can find, my best guess is a '64 or '65 YJ2.

First step is to get her running...

:D
 

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Nice freebie!! I've seen one or two of them on Craigslist before. I'll bet the chopper guys would love to have that tank..


GB :mrgreen:
 

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Discussion Starter · #3 ·
So who here knows about 2-strokes? The little Yamahopper will sit and idle nicely all day long, but bogs out when I try to give her gas. It's gotta be in the carb, but the little guy is too simple. It's got me stumped!
 

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I dont know what model you have but I'm jealous! You may need to adjust the oil-feed mechanism, as its probably mixing too much oil, but thats just a guess...wouldnt hurt to clean the carb though.
 

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Sensei
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It's a rotary valve model (carb on the side of the crank) and my thoughts were also that the oil injector could be a bit high.... However, don't adjust it untill you DO clean the main jet and get a plug reading.....Better a bit smoky than burning up...

By the way, I also now believe it's a YJ2 ... At first I thought it might be a YG1, but that's an 80........Yours is a 60...Right?
 

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I wouldn't worry to much about the oil pump setting, however it may be loaded up from old oil in the crankcase or the crank seals may have dried out from setting for so long, clean the carb, clean the points, new plug and and wind it up slow off idle hopeful it will clean out and run
 

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Discussion Starter · #7 ·
66Sprint said:
It's a rotary valve model (carb on the side of the crank) and my thoughts were also that the oil injector could be a bit high.... However, don't adjust it untill you DO clean the main jet and get a plug reading.....Better a bit smoky than burning up...

By the way, I also now believe it's a YJ2 ... At first I thought it might be a YG1, but that's an 80........Yours is a 60...Right?
Yep, it's a 60. I see they also made a YJ2S, but I can't find anything that differentiates the models.

I went through and cleaned the carb one more time tonight and everything seems to be clean and open. When I check my plug, it is kinda wet. I am getting a nice strong spark.

It's too late tonight (the old girl is pretty loud), but tomorrow i'll check if the wet plug is really oily or just gas. I am able to crank up the idle speed and get some high rpms, so i'm thinking maybe it is the oil pump, as that's controlled by a separate throttle cable. I'll look into turning that down. I run AMSOIL Dominator injection/mix oil in all my 2-stroke engines, and you can use that stuff sparingly (50:1) in everything.

Thanks for the insight, and i'll let you know how it goes!
 

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Sensei
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Could be it's not breathing well through that old airbox/air cleaner element...Have you tried running with the right side cover off? (carb open?) a restricted filter would make it rich....
 

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http://www.classicyams.com/

There's a YL2 at my work, soon to be getting a new top end. I think a thorough break-in regimen will be required for good customer satisfaction. ;) Also, a nice little YL2 TwinJet, soon to the shop bike.

Have fun...goggles req'd!

NE
 

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Discussion Starter · #10 ·
66Sprint said:
Could be it's not breathing well through that old airbox/air cleaner element...Have you tried running with the right side cover off? (carb open?) a restricted filter would make it rich....
Yeah, i have the cover off. I also made sure the muffler wasn't plugged. Alot of **** blew outta there when I first fired it up, but it's clean now. The exhaust port was really caked with crud too, but I cleaned that out and it didn't make any difference.

I'll be tinkering with it some more tonight.
 

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That's fantastic! Looks like it will clean up very nicely. All there and not too beat up.
 

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Nice looking bike! Looks like you now need to officially add it to the list in your signature! ;)
 

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Discussion Starter · #14 ·
redfalken said:
Nice looking bike! Looks like you now need to officially add it to the list in your signature! ;)
Done and done.

:cool:
 

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Discussion Starter · #15 ·
Tonight I loosened up the cable on the oil pump and there was no change. When I first started the bike I ran some mixed gas in the tank, until the oil line was primed and to make sure the pump was even gonna work, and I had the problem then. So i'm ruling out too much oil as my problem.

Now I think I need to look into the electrical system. I have a really nice spark, but I wonder if there's a weakness in the electricals somewhere that's causing a lack of juice under load. I know my battery is good, I put the new one from my cl70 with a fresh charge in it. One thing I noticed as I was checking some connections was that I have poor continuity between the frame (near the battery) and the wire that connects to the negative battery lead. Could this potentially be a problem? Next i think i'm going to try and find exactly where the system grounds to the frame and see if I can't get a better ground.
 

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If you ran mixed fuel similtaniously with the auto-lube that would mean a rich mix wouldnt it? Maybe try running the mixed fuel and dissconect the oil pump...does it have correct plugs? If they look new perhaps someone put in the closest ones on hand...
 

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Sensei
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If the exhaust port was crudded, you can bet the baffle (should be removable/cleanable) is just as crapped up......Plus, (I believe) the ignition should be a magneto/points deal.... Battery is just for lighting stability, acting as a "buffer" (or regulator) of the mags lighting coils output... But a good clean ground won't hurt.....
 

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Discussion Starter · #18 ·
There was no oil in the line from the pump when I first started the bike, that's why I ran the mix, and I couldn't get it to rev then so...
The plug is correct, according to a Yamaha site. It's a new B8HS.
The muffler is wide open, there is no baffle.

One more thing I notice when I check the plug, it is wet with little bits of crud. Perhaps I should pull the head and see if it needs to be cleaned up?

Thanks for the continued help, guys!
 

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rings are probably stuck from sitting so long, compression? know it kind of iffy on two-smokers but wouldn't hurt to check and new rings have never hurt a two stroke
 

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A two stroke DEPENDS on the pressure/flow regulation of the exhaust in order to properly scavenge the exhaust gasses to accomplish the passage of the fuel/air mix from the crankase through the transfer ports to above the piston crown.....An open pipe is usually injurious to a two-strokes performance..... I'd bet it would run better with a 8" long piece of tubing 1/2 the diameter of the existing hole wedged in/sealed on temporarily.... This is why two-stroke "racers" have expansion chambers to precisely "tune" the exhaust.....Without proper scavenging, some of each fuel/air mix "pulse" from the carb will be left down in the crankcase, eventually condensing back to liquid form and building up enough to stall the bike as there no longer is the correct volume below the piston to allow the engine to get a large enough "gulp" of fuel/air mixture to run on.......
 
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