Yamaha BW-80

[Sir Gumby]

Hi all,

I just got this bike from a guy at work. Its kind of a basket case. At least it was free...now I have a summer project, not that I needed another.

No spark..If anyone has any ideas on where would be the first place to check I'd be grateful. I did switch the spark plug.

Its also missing many parts that I will have to track down. and I have to do a bit of welding on the foot peg mount.

Thanks!

 

[Ding Ding]

The "Big Wheel" BW bikes are cool. Kind of a niche bike with the larger size tires. Similar to a Honda Fat Cat.

 

[sparkwizard]

If it were mine, I would look for a wire from the coil going under that flywheel. If there is a wire there, I would remove the flywheel and look for a set of points I could clean and adjust.

 

[Sir Gumby]

There’s another problem. the screws for the flywheel are totally stripped. I’m going to try to weld a bit of steel to them. To extract them, then just replace them. Otherwise I will get a lefty drill bit

 

[sparkwizard]

Did you try removing that nut in the center? The one that holds the flywheel on the crankshaft? Those screws took like they might be holding the points mounting plate to the crank case.

 

[Sir Gumby]

Did you try removing that nut in the center? The one that holds the flywheel on the crankshaft? Those screws took like they might be holding the points mounting plate to the crank case.

I'll try that, thanks.

 

[Sir Gumby]

So it looks like the motor related parts are compatible with PW80 parts, which is good. I wonder how much the pw80 changed from then to now, and if year matters.

 

[sparkwizard]

Do you know what year your bike is? Is there a YAMAHA tag near the front fork?
Can you read anything on that white tag where a headlight would be?

 

[Sir Gumby]

Yep, its 1986

 

[sparkwizard]

Should be pretty simple to find parts.

 

[Sir Gumby]

yeah I'm glad of that because I need a lot of parts.

 

[Sir Gumby]

I wonder If an exhaust pipe from a yz50 would fit. If it did I could save a few bucks

 

[Sir Gumby]

The "Big Wheel" BW bikes are cool. Kind of a niche bike with the larger size tires. Similar to a Honda Fat Cat.

Yeah and its not too small either which is nice. I fit on it good, Im 5'11". this is gonna be fun in the woods. I am determined to get it running

 

[sparkwizard]

Have you checked Flea Bay? If you know what year and model, you can keep checking and maybe get lucky.

 

[Sir Gumby]

Yeah I been looking for parts. my shopping list so far:

Exhaust pipe, shift lever, air box, left side engine cover, probably a gasket set, and maybe piston rings (guy who gave it to me said it smoked a lot)

 

[sparkwizard]

It's 2 stroke, correct? Rings would make it really weak and hard to start, but not really smoky. If it is 2 stroke, the oil is mixed with the gas. If the mix ratio is not right, you may get smoke. If the gas/oil mix gets old, same result....smoke.
Yamaha dealer MIGHT have some of those parts.

 

[Sir Gumby]

I'm 99% sure its a 4 stroke. seperate oil reservoir.

 

[Ginz61]

Two-stroke.

 

[Sir Gumby]

ok, thanks. How might I go about testing the oil system? I'd like to check that over. there are actually 2 oil reservoirs. one in the motor itself, ig for the crankcase, and one under the seat, oil that gets burned. I'll probably drain that.

Is there a way to adjust how much oil its getting? I suppose that could be the smoke problem.

I did start it for a second last night.

 

[Triley41395]

ok, thanks. How might I go about testing the oil system? I'd like to check that over. there are actually 2 oil reservoirs. one in the motor itself, ig for the crankcase, and one under the seat, oil that gets burned. I'll probably drain that.

Is there a way to adjust how much oil its getting? I suppose that could be the smoke problem.

I did start it for a second last night.

I'm going to throw in my 2 cents worth. I'd just do away with any oil injection system and mix it myself. Leave all the parts for the look. Alot of these older engines are getting harder to find parts for and it only takes one time for an oil injection to stop and you can be fried. Our old boat engine has a good injection system but it's unhooked and we just mix it up.