Getting an old bike to run

[R E A L]

As I was browsing the bike before I took some pics I noticed another sticker that said somthing about it being a 1979. and also on the side where the kickstart is right above where you put the oil in, there is a stamp thing that says "oil 500cc" any idea what that means? How do you post pics on here? i took one of the overall bike and then one of the VIN sticker.

 

[Jon K.]

Let's see . . .

. . . . . .oil 500cc. . . . . .

Hmmmm . . . . . .

I'm thinkin' two stroke!

Er . . . . Ummm . . . . R E A L; how do you know it is a four stroke?

Oh yeah; you gotta be a subscriber to post pics. If you don't mind giving me your E-mail address on this board; I will contact you and you can E-mail me the pic. I think it would be OK if I posted it for you.

Jonny

 

[R E A L]

uh oh, well, we dont mix the gas, oil goes in its own little thing, that is why my friend said its a 4stroke, or could it be an automixer? what would happen if i have 4 stroke oil in it and its a 2 stroke?

 

[R E A L]

REALSORRY5689@aol.com

 

[Jon K.]

REALSORRY5689@aol.com

OK! Will send an E-mail.

 

[Jon K.]

Jeff; what you have is an old two-stroke. Maybe an "Enduro 100" or something of that nature.

Someone will know for sure. 1972 sounds about right.

 

[Jon K.]

The VIN number appears to be missing due to natural causes. Maybe the cable rubbed it off.

Not to worry, certainly not stolen.

 

[R E A L]

hm 72..... on the side near the handle bars it says "This vehicle conforms to US EPA regulation applicable to 1979 model year new motorcycles" what does that mean?

 

[R E A L]

so should I change the oil to 2 stroke oil asap? or will it be fine to ride for now? Are you positive its a 2 stroke? and is there anything I should check just to make sure that the oil is mixing properly with the gas?

So is the surge of power we were feeling yesterday just the power band, since its a 2 stroke?

 

[Jon K.]

hm 72..... on the side near the handle bars it says "This vehicle conforms to US EPA regulation applicable to 1979 model year new motorcycles" what does that mean?

Oops; maybe '72 is a bit early. Not too far off though; my LT-2 had that same engine in it.

And yes; you should dump the four-stroke oil out of the tank, and change to two-stroke injector oil.

Or better yet; pre-mix the fuel. A 25 year old oil pump is certainly suspect.

You will find that the throttle cable splits off and goes to the oil pump. Still; a replacement cable should be available from Yamaha.

Once you determine for sure the model.

Hey! I found a pic of my old LT-2!

 

[R E A L]

ugh, well the guy that i got this bike from i am asuming that he replaced the throttle cable because the cable was very tight,(thats one of the reasons it snapped) but anyways, it didnt split off anywhere, so im guessing that might have been a big reason the bike screwed up in the beggining. so i guess its pointless to use that resevour. When i premix it, what mixture should i use?

If I start premixing it should I take all of the oil out of the resevour just incase it is mixing and so it doesnt put in twice as much oil?

Just out of curiousity, do 4 strokes have the reed valve thing that goes from the carb to the cylinder?

 

[gwcrim]

It's not a 4 stroke. Not remotely. The cylinder head would have cams in it and the pipe would look different.

I'm gonna say it's an MX80. I had an LT1, 100 enduro and it had bigger wheels. The MX80 was kind of the precurser to the PW80.

 

[JasonWho]

Could it be a GT80??

32:1 would be good if you skip the pump. I don't know how one would do that, though.

 

[mxmatthew]

hahaha yea i have that exact bike! '79 GT80 is what she be. just a more road version of the mx80. it is definitly a 2 stroke and it is oil injected so no mixing gas.

 

[Jon K.]

Sounds like we have a winner!

Matthew wins the prize!!

If we could convince Jeff to shine a flashlight around the lower perimeter of the cylinder (just above where it bolts to the cases), there might be found the CC displacement of the engine.

gwcrim; I've been wrong at nearly every turn of this post, but I will put my neck out one more time. I don't believe there ever was a LT-1.

Yamaha went from a HT-1 90cc (with a lay-down cylinder) directly to the LT-2.

Of course, I could be mistaken!

 

[gwcrim]

gwcrim; I've been wrong at nearly every turn of this post, but I will put my neck out one more time. I don't believe there ever was a LT-1.

Though this isn't my bike, it looks exactly like it. I'm 99% sure it's a 1970 LT1 100 enduro.

 

[Jon K.]

Hey; I found a cool link;

http://groups.msn.com/YamahaEnduro1968-1979/general.msnw?action=get_message&mview=1&ID_Message=671

Cut from the page:

HT1 90cc LT2 100cc Codes
IP: 64.233.106.148
Posted on January 12, 2004 at 06:08:59 PM by Rip City Mark

100cc Year Start Run # Finish Color
LT2 1972 LT2-000101 LT2-031280 Candy Green
LT2M 1972 LT2-100-101 LT2-104430 Candy Green
LT3 1973 LT2-035101 LT2-071760 Grape
LTMX 1973 LT2105101 LT2-113130 Silver Dust

Not that I can vouch for the accuracy.

Maybe the LT-2M was the enduro model?

 

[gwcrim]

If you remember what was going on in the '70s you weren't doing disco. Or something like that. Guess it musta been an LT2.

 

[SuperCam]

whoa that bike looks awesome ha ha!

 

[R E A L]

yay! we have a name for the bike now, thanks a bunch everyone. Now all I need to figure out is how to make it to where I pre-mix it instead. Mathew, where do you put your oil in at? is it on the right side next to the kickstart? or is that for gear oil? once I figure all the oil mixing stuff all i need is a new throttle cable and airfilter and fuel filter and the bike should be good, but it doesnt idle AT ALL. the second I let off the throttle it dies. any info on that?

 

[SuperCam]

check your idle screw, not sure where itd be, but mines on the right side. My 2 stroke doesnt Idle at all, but I race with it so I guess thats best.

 

[mxmatthew]

cant really help you on the idle issue, sorry. But the one next to the kickstart is for gear oil. The 2-stroke oil tank is under the seat and itll just have a little black rubber plug in the hole that you put the oil in.

 

[R E A L]

ok, so do I just put the same 2 stroke oil in the gears as I would when I start premixing it? I have tried the idle screw and I have a feeling that it is broken or somthing because I can turn it all around and it wont affect the idle or anything. Do you think that the idle thing is anything big to worry about? because I dont really mind just giving it a push start every once in awhile. mxmathew, does your throttle cable split off to go to the pump? because if so then I am guessing that my pump hasn't been working since the previous owner tried to replace the throttle cable.

Thanks guys,
Jeff

 

[R E A L]

I checked under my seat and there was nothing, at least I didnt see a plug. but there was a sticker and it said engine displacment: 73cc and it did say it was a 2 cycle, so I guess it could still be a GT80. maybe its not an auto mixer. mxmathew could you give me a discription of your dirtbike, like all the features?

 

[mxmatthew]

hmmm, well its out at my cabin but ill try. It basically looks exactly like the one in that first picture (silver one) but it had a headlight and signal lights (which i ripped off).

You have to put gear oil in for the gearbox. And im really cant remember off hand about the throttle cable thing, although im sorta thinking that it mightve branched off.

But if you dont have the oil pump you could try about a 30:1 mix. One time i accidentally ran it dry of oil :| (still ran fine after thankfully) but after that the oil pump wouldnt pick up oil so i just mixed some 30:1 fuel and rode around for a while till it started picking up oil again. Once it started picking it up boy did it smoke like a mother ;) . Hope this helps a bit.