Whats wrong with this little yamaha motor?

porsche4life · porsche4life's Garage

I have this little 1971 Yamaha Mini enduro 60 that was my first bike. I havent ridden it in probably 4 years and I decided i would see if it would start and well it just started running this blue green oily/gassy smelling substance out the side of the motor(see pics). What is wrong with and how hard would it be to fix or rebuild this motor. Might just build the whole bike i have all the parts.

pwd72s · 09-04-2008, 03:53 PM

looks like leaking 2 stroke oil to me...

porsche4life · porsche4life's Garage

Where from up inside there I wonder. I know we have never been in the motor and well when i was riding it i was so young that i didnt mess with the oil at all. I do know that this bike has an oil tank on the other side and you dont have to mix the gas and oil like you do with some 2 strokes.

pwd72s · 09-04-2008, 04:00 PM

It's been a long time since my Yamaha 360 days...early 70's. But I'd suggest removing the seperate oil tank, check out the direct oil system. Looks to me like a leaky seal in that...

porsche4life · porsche4life's Garage

Thanks i will try that. Anything up in there that all that oil will have hurt?

Tim Hancock · 04:06 PM

My best "initial"guess at this point would be a leaking float needle (due to old shiit gas) which allowed the crankcase to fill with gas/oil mix which then leaked through the magneto side crankshaft seal. "Might" be able to simply drain the gas tank, clean the carb, remove the excess oil from the mag cover.

A leaking crank seal on a 2-stroke is usually bad, but on that little Yamaha, you might be OK.

EDIT: PWD72s is probably right, assuming the leaking oil does not smell like gas.

pwd72s · 09-04-2008, 04:04 PM

Quote:

Originally Posted by porsche4life

Thanks i will try that. Anything up in there that all that oil will have hurt?

Not that I know of...hell, it may have helped your engine as a corrosion prevention

Dunno where, but you may try to find at least an exploded parts diagram before you dig in.

porsche4life · porsche4life's Garage

http://www.bikebandit.com/houseofmotorcycles/yamaha-motorcycle-jt1-1971/o/m7330
Like that? I have it off and apart already. I have pics to upload later.

Bob Goding · 09-04-2008, 07:13 PM

Clean it up,empty any remaining oil from the tank and run it on pre-mix.

porsche4life · porsche4life's Garage

My dad has suggested that. If resealing this pump doesn't work that is plan b. Any suggestions on what mix to run?

nota · 09-04-2008, 07:58 PM

50-1 is standard

pwd72s · 09-04-2008, 08:02 PM

My chain saw likes 4 oz. to a gallon....but maybe a bike should be more oil? Just guesswork here.

Man, I wish computers were around when I was riding dirt bikes...those exploded diagrams are great!

Good luck!

charleskieffner · 09-05-2008, 05:43 AM

first yer sitting on quite a collectible bike. second i used to have posters of that damn bike plastered all over my room as a kid. third i almost got juan for my birthday until some idiot smacked a tree, killing himself, not a block away from our cabin in pinetop arizona about a month before my b-day. im still pissed off at that lil bastid for screwing up my life by killing himself! man just think of all the chicks i could have had if i had that bike back then. i probably should sue that kid for a lifetime of misery i had all because i had to wait until i was 18 to buy a bike and even then my folks were pissed and mentioned that moron in their warnings to me about dirt bikes.

anyway if its like all the bikes i get to freeking deal with that are barnrats.............its more than likely the crank seals took a crap and are leaking thru. this is real common on bikes from any country that sit around for years and the seals just rot away from lack of TLC.

when we store a concours bike for display............no oil/no gas/no fluids. that way seals are new, stay new and if bike is to be used we just put fluids back in and off they go into the wind.

any lil bike any mfg 3 wheeler/quad are worth their weight in gold nowadaze. look at what honda mini trail 50/70's go for from the 1970's.

sammyg2 · 09-05-2008, 07:51 AM

Is it 2 stroke oil or transmission gear oil? You should be able to tell the difference pretty easily, gear oil will have more of a sulfur smell and will be much thicker.

On the pre-mix I'd run 40 to 1. It'll smoke a little at idle but any leaner would be hard on the top end.

BTW, When I was a little kid I had a poster of that bike on my wall. I dreamed about it, I wanted it sooooo bad. It was all I could think of. Unfortunately my parents didn't have discretionary spending for that kind of thing, I didn't taste fast food until I was almost a teenager.

I finally got a used YZ 125 years later, lots of mowing lawns, paper routes, and saving up birthday checks from grandma. IIRC I paid $110 for it. Mucho bucks back then.

dhoward · dhoward's Garage

It's green, it's 2-stoke oil. If it's a leaking injection circuit, you should be able to fix it pretty easily. Keep in mind that if it's the oil circuit, you may not be getting lube to the crank and cylinder, so I wouldn't run it that way.
That old a bike may have run 32:1...

dhoward · dhoward's Garage

WIth oil pooled around the the stator like that, it might be the crank seal, which would cause the engine to run lean...
That looks like an awful lot, unless it's been going on for a long time.

porsche4life · porsche4life's Garage

Nope just started that and it hasnt been run at all that way.

3.2 CAB · 09-06-2008, 10:39 AM

When you were playing with it, did the oil leak appear after trying to kick start it? If so, the crank seal probably was stuck to the crank, and when the engine was turned over, the seal was torn.

cashflyer · 09-06-2008, 12:21 PM

A bike that old would not have been running 50:1 oil mix.
I mix 32:1 in my 74 Yamaha DT360.

Tim Hancock · 09-06-2008, 01:08 PM

I have owned 2-strokes nearly my entire life. I have used many different brands (Klotz, Golden Spectro, Yamalube etc) of 2-stroke oil over the years, especially during my serious MX racing years.

Several years ago after running my previous favorite Yamalube for quite some time in my Ultralight, some local ultralight guys convinced to start using Amsoil synthetic as they had been running it for years, it is relatively inexpensive, it is sold in many stores, it is mixed 100/1 which means you have to carry less of it and most importantly to me, several of these guys had ultralight engines with 300+ hours on them without being rebuilt.

Since I made the switch (8-10 years ago), I have used it exclusively in EVERY 2-stroke I own with no failures. (old and newer motocross bikes, snowmobiles, chain saws, weed eaters, ultralights etc). I simply dump one of these little bottles into 4-5 gallons of gas and forget about it. I think my ultralight engine calls for a 40:1 mix and various dirt bikes and power equipment all have different requirements, but the synthetic Amsoil mixed 80-100:1 works great in all of them and trust me, I run my equipment very hard. I typically run my ultralight at 6500-6800 rpm and on occasion all the way up to 8000 rpm. I have over 200 hrs on the engine and all of the time other than taxiing has been at well above 6000 rpm. My current MX play bike is an old 125, so when it gets ridden, the throttle remains pinned most of the time.

Many companies make good 2-stroke oil, but when I find a product that works and it proves itself over time to me first hand, I stick with it.