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1987 Yamaha BW 80
http://pilotodyssey.com/PO/viewtopic.php?f=5&t=4475		 Page 1 of 1
Author:  finallygot1 [ Tue Aug 05, 2008 11:04 pm ]
Post subject:  1987 Yamaha BW 80
I picked this bike up today as a project for my kids. It won't start so I will have to do some trouble shooting on it.

The Good:

All the plastic is in good shape.
It is complete.
The motor (( Internal Combustion Engine ? )) is not seized up.
It has spark.
The tranny shifts in gear smoothly. Hopefuly it will do this when I getting it running.

The Bad:

Seems to have low compression. I got about 35 PSI on my gauge, but I could not get it to tighten up. I will have to look for a different gauge with shorter threads.
Gas leaks out of the float bowl tube.
Rear tire needs to be replaced.
Front brake lever is broken.
Chain is rusty.
A few bolts for the plastic is missing.
Handle bar is tweaked.
needs new grips.

My first thing to do is to verify the comression and get that to spec. Hoser can you work magic on this Engine like you did for my Pilot? If so I will be PMing you about at least getting the cylinder bored and honed to spec. Then I need to take the carb off and find out why the float is sticking. Gas pours out of the tube while I am trying to kick or push start it. Hopefully that won't need replacing.

I got a feeling I will be spending some money to get it reliable again.

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Author:  hoser [ Wed Aug 06, 2008 5:42 am ]
Post subject: 
That thing is so cute!


Have a manual? That would be the first thing I bought :-) Try your local dealer they might have a used one from the shop they will sell cheap.

I am not sure if I can bore a cylinder that small I would have to look at it, going by memory the former owner of the boring machine said he could do Honda 50 cylinders so many I can?
Author:  Lonerider [ Wed Aug 06, 2008 7:17 am ]
Post subject: 
Kewl find!.....you sure it is for the kids? :-)
Author:  finallygot1 [ Wed Aug 06, 2008 7:47 am ]
Post subject: 
It came with a Clymer manual and I started reading through it last night. hopefully over the next few days I will get a chance to really start looking over it. I will see if Ican find a factory service manual somewhere for it as well.

I got to admit I wanted it more than my kids. I had to throw the kids in there so my wife would not complain. :-)
Author:  DC [ Wed Aug 06, 2008 12:51 pm ]
Post subject: 
I got one just like it only Red.... its been sitting in my shed for about 6 or 7 years now. Cool little bikes, they make a great pit bike. All the motor (( Internal Combustion Engine ? )) parts are identical to the PW80 so there are lots of little hop-up goodies available from pipes to Engine internals if that's what you want to do with it...
Author:  finallygot1 [ Wed Aug 06, 2008 9:17 pm ]
Post subject: 
I verified the compression today. The best reading was about 35 psi. I knew then I had issues so I pulled the cyl to find a broken ring. It scratched the cyl some and of course the piston is toast. I am surprised it turned over so easy. Hopefully it can be bored. yamaha has pistons from stock 47mm up to 47.5mm. after that I will have to use the Wiseco's or some other piston I see at rockymount called Pro-X?

Hoser, if you can work on a 47mm bore let me know. I have it boxed up and ready to ship USPS if you can do it. I put the cyl, head, and piston in the box.


These are the best pics I could get with my cheap camara.

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Author:  hoser [ Sun Aug 10, 2008 10:05 am ]
Post subject: 
Hi, sorry for the delay, the smallest cylinder bore I can hone is 60.35mm I can bore smaller I just don't have a hone small enough to finish the job.
Author:  finallygot1 [ Sun Aug 10, 2008 7:42 pm ]
Post subject: 
That's OK. I dropped it off at the local bike shop after getting some positive feedback of the guys work. The cyl was on its second bore of 47.5mm. He thinks he can get it cleaned up at 48mm. The rings gaps were not installed centered on the locating pins. He believes that caused the failure. I hope to get it back next Wednesday or Thursday. All my other parts are on order so I should have it running next weekend if I am lucky.
Author:  finallygot1 [ Thu Aug 21, 2008 9:55 pm ]
Post subject: 
I have been doing a lot of cleaning and replacing bad parts while I waited for my cyl to get back from the shop. I got it back today and got the bike running. My exhaust gasket is bad and I forgot to order a new one. I only ran it for a couple minutes since the gasket was leaking badly. Hopefully the local shop will have one in stock so I can get break in done and turn my daughter loose with it. The only big thing I still need to fix are the steering stem bearings. they seam a little loose.

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Author:  finallygot1 [ Fri Sep 05, 2008 10:28 am ]
Post subject: 
It is finally back together and my daughter loves it. the compression topped out at about 145. It even moves my big butt around pretty quickly. Now I need to find another one for my son. The only thing I can't find are new decals for the gas tank.

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