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Author Topic: The Yamaha BW80 - fat tire'd fun!  (Read 19756 times)

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Offline Makin Treehugrs Mad

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The Yamaha BW80 - fat tire'd fun!
« on: May 13, 2011, 07:40:25 AM »
79cc, 2-stroke, reed induction, 3-speed, auto clutch, oil injected. What a great little bike! I got one of these back on December 7th 1985 brand spankin' new. It's what got me into bikes. I rode that thing for almost 3 years before I outgrew it & started breaking stuff on every outing. I sold it to some lucky bastard for $150 back in '88. :bang: My first foray into the want ad realm too ....

Anyway fast forward 20 + years later. I went on an eBay buying spree around '07-'08 & bought every BW80 I saw. One I restored for myself to rip around the neighborhood on. Has 148 psi compression, Boyesen reeds & a FMF pipe. Will just about pick the front wheel up! Not bad for an auto-clutch. I've fixed up & sold about 5 of these .... and some I've bought back & re-sold.

The motors are indestructible on these ( unless you forget to fill the tank under the seat with 2-stroke oil ). They run forever. Of the 15 or so of these I've owned, most are only on their 2nd bore. Some are on their 3rd or 4th, and my keeper was on the original piston & rings when I bought it, now on it's 2nd. Very simple design & esy to work on. You can literally rebuild one of these in 15 minutes! Most of the parts are shared with the PW80, so parts are everywhere. The exceptions revolve around the fat tires of the BW: gas tank, seat, fenders, & transmission countershaft. There are some small differences inside the carburetor too, but a PW carb will work just fine on a BW.

As of now I have 8. I gotta get my ass in gear & get some of these running & sold .... but anyway, here's some pics:

Here's how the restored one started out:


The goodies -- Wiseco piston & bored/sandblasted cylinder :


Looks a little better now:




Part of the collection:
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #1 on: May 13, 2011, 07:46:14 AM »
Forgot to add:

The first one came out in late '85 as an '86 model. They were made in '87 & '88 ... then none for '89 ... then the final one in '90, which is blue/white. '87 & '88 models are mega rare - I haven't even seen one for sale .... and if I have, the guy didn;t know what year the bike was he had. I think '88 was the first year of the blue ... but could be '87. Not sure on that.

They also had a 200 which came out in '85, then the 350 which I believe came out in '87 or '88 - they didn't make the 350 long, & you'll pay for it's rarity  if you want one.

These are the best bikes on the planet (especially the 80's) for having a few with the fellas & ripping around your yard!  :mrgreen: :cheers:
« Last Edit: May 13, 2011, 07:48:27 AM by Makin Treehugrs Mad »
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Matty

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #2 on: May 13, 2011, 09:12:58 AM »
YES!  As an RV90 owner I automatically love BW80's.  People dont get how fun bikes with big tires are until they get on one and ride it.

The grins per mile ratio is hard to beat!

I'm really jealous of the fact that there is an actual aftermarket for them.  There is none for the RV90.
« Last Edit: May 13, 2011, 09:20:04 AM by Mattydiah »
75 Kawi F11 250 - Vintage Supermoto
72 Suzuki RV90 VanVan - Visit the VanVan Wiki!
1972 CTRV90 (CT90 Engine in RV90 Chassis)
2006 Suzuki DRZ 400SM

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #3 on: May 13, 2011, 03:54:44 PM »
Yeah, the grins per mile ratio is extremely high!  :mrgreen: :thumbsup:

Luckily they share lots of parts with the PW ... otherwise I'd be in the same boat for hop-up items. The pipe took some work to get it on there right ... and the silencer still isn't 100% straight. Was meant for those skinny tires ... but it sounds great & really woke the engine up.
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline m in sc

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #4 on: May 13, 2011, 07:54:37 PM »
buddy of mine had a 200.. hell he still might. felt like you were always steering in sand.. lol. neat bikes though
get off my lawn.

Rock Hill, SC

Offline DPeanut

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #5 on: May 15, 2011, 07:49:57 PM »
These things are an absolute hoot! I had a 350 for a while, and it was such a tank! The only downside to it (and all of the mid - late 80's Yamahas of the off-road variety)were the weak tanks that had turned a gross yellow.

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #6 on: May 15, 2011, 08:12:51 PM »
Yep - that's a Yamaha staple. The yellow tank. :lol:

That one I restored during better financial times, & put a NOS tank on it. I'm embarrassed to even say what it cost ...  :suicide:  but it looks sooo much better.



Some people take matters into their own hands .... and it doesn't turn out well. Check this one out - one of the worse ones I've bought:


 
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #7 on: May 19, 2011, 11:37:05 PM »
Finally got some free time to throw a couple of these together. Installed a couple top end kits I found REAL cheap on eBay. So cheap that I had to chamfer the ports, cut slag out of the combustion chamber, & scrape machine tool trash out of the exhaust port. :laugh: Took the plastic off that ugly one in the pic above & gave it some paint. Then disassembled the other bike & found the reason for the low compression. Wrist pin bearing grenaded & lodged needle bearings between the rings & cylinder! :haw:

Never know what your gonna find with these. :lol:



RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Sam Simons

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #8 on: July 02, 2011, 05:01:27 PM »
Good write up,MTM. I think there's still a market for them yet today.....lotta fun!

Sam in IN

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #9 on: July 11, 2011, 07:24:49 PM »
Those are MINT!! :swoon: :thumbsup:
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Sam Simons

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #10 on: August 27, 2011, 11:33:54 AM »
Thanks,MTM. I have a question for you-do any of your BeeDubs have that high rpm 'stutter'  common to the PW models? I'm still trying to find out more about eliminating that.....There's
tons of discussion about the PW in regards to the stutter,and even they can't agree on the source or the 'fix'....Some claim there's a rev limiter,and go on to claim that  by disconnecting a wire,it's cured..Others  claim to have eliminated the prob by de-restricting the intake,exhaust and rejetting....I've done all of that,and while much improved,it's not completely eliminated.
   Your thoughts ??

Regards,

Sam in Indiana

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #11 on: August 28, 2011, 02:53:53 AM »
Honestly I've never heard of it, nor have I experienced it. Maybe the lighter PW is able to spool up into the red zone? Not sure there. I've had a couple that broke up at high rpm, but that was usually due to a loose wire or bad plug.
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline Sam Simons

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #12 on: August 28, 2011, 08:41:25 AM »
 OK....Well,in the BW's case,it all may be corrected with de-restricting the intake & exhaust,and rejetting. I doubt that the BW's had any sort of rev limiter,because early PW's are said not to have them either... One fella on Thumpertalk has done some extensive development work on PW engines,and believes that the engines design(tiny carb,intake,ports) limits it to a max of 6500 rpm......a lot lower than I thought.

Offline Makin Treehugrs Mad

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #13 on: August 29, 2011, 04:42:46 AM »
That sounds about right. These were just designed for trail use anyway - makes decent torque considering it's size & RPM limit. :thumbsup:
RD350A with B cosmetics
RD200 (in need of lots of my time)
Several '86 Yamaha BW80S 's
'01 KDX220R (sold ...to pay for RD rebuild!)

Offline HerrDeacon

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Re: The Yamaha BW80 - fat tire'd fun!
« Reply #14 on: August 29, 2011, 05:38:51 AM »
Sorry but a bit off topic. I know TW stands for Trail Way and BW is Big Wheel, what does PW stand for?