Added one to the herd...and it's NOT a Yamaha

[m in sc]

if somebody gets me a battery cover i can draw it up in solidworks, then it could be 3d printed (not by me).

[SoCal250]

if somebody gets me a battery cover i can draw it up in solidworks, then it could be 3d printed (not by me).

Looks like someone is already making them. There's a guy the UK selling repros on eBay for $55 plug shipping. 
The last used OEM one I saw was going for about $80 I think.

[SoCal250]

Task list and progress:
 - Service and bleed the front brake system
 - Fix or replace leaking oil level sight and replace OEM clamp
 - Replace license plate mounting hardware (M6 Allen button head) -- not a priority. so I'll do it later when I can find black hardware.

Disassembled and rebuilt the front caliper. It was full of rusty colored fluid, had black powdery sediment in the bore, and the piston was corroded. Replaced the seals and piston, flushed all the fluid and then bled.

And I had attempted a fix with the oil tank sight by disassembling it and sealing the window with RTV since it's an obsolete part, but I think it's still seeping oil. I purposefully left the level low so it wouldn't drip everywhere. I'm going to need to find another solution. 

Added some pre-mix and fired it up. Did a short session of idling with the pump pulley wide open as per the manual procedure to bleed the feed line from the pump to the carb. It was nice and smokey with 40:1 mix and then the pump kicking in.
Then decided to go for a short rip around the hood. This thing is so fun! I can already tell the new tires are going to be nice and sticky!

[SoCal250]

Today I was able to get some minor tasks accomplished like readjusting chain tension, lubing the speedo cable, and re-verifying pump pulley setting. And after a short warm-up ride around the neighborhood I changed the trans oil, so it now has some fresh new Bel-Ray Gearsaver 75W. The old oil looked clean but smelled burned.

Then took it out for a longer rip and ended up flogging it for 23 miles. So much fun! It's happiest from 7K to 10K+. Below 6500 there's not really much there to work with.
I found that 1st gear is almost pointless and when in 5th I kept trying to shift into 6th. It's begging for a CR80 transmission transplant. On the flats it was pulling almost 55mph (if the gauge is accurate) and it was continuing to pull revs past 10,500. It's almost hard to keep from revving the thing to the moon. 

I swung by the local Honda dealer so I could show it to the parts guy who's been helping me with sourcing some of the small bits and pieces. He had asked to see it after it was roadworthy. 

[m in sc]

   sweet! i could barely just keep up w that on the Yl1   

sounds like a riot!  you're making me regret selling my 89 DT50.

[msr]

  sweet! i could barely just keep up w that on the Yl1   

sounds like a riot!  you're making me regret selling my 89 DT50.

I'm starting to regret that I didn't buy it from you 😭

[dgorms]

Treatland has repop battery covers,$35. Along with a ton of other goodies for MB5.

[SoCal250]

Treatland has repop battery covers,$35. Along with a ton of other goodies for MB5.

That's where I got my tires

[SoCal250]

Earlier this week I removed, disassembled, and ultrasonic cleaned the MB5 carb. To get the carb out the seat, fuel tank, battery, part of the airbox, rear engine mount bolt, and rear fender all need to be removed. What a PITA!
The carb cleaned up well but I forgot to get the "after" photo when it was clean, reassembled, and ready to go back in.
I discovered the float height is over spec but it's not adjustable, so should probably be replaced in the future. However the float set is NLA from Honda.
Replaced the O-ring gaskets and reused the existing jets since it was running great and they looked OK.




Also found out that some previous owner appears to have pried on the carb slide cutaway with a tool putting a few dents and knicks in it. Almost looks like a flat bladed screwdriver was used in the inner lip of the cutaway.


The bike runs great and starts first kick when cold (with choke) or when hot.

And then today was bitty-bike wash day
Tomorrow I'll be doing additional detailing and waxing both in preparation for the annual Extravaganza this weekend.

[msr]

Man. That makes me want to roll the AR80 out and spin it around the neighborhood.

There was an MB5 for sale near here a few months ago, but I passed on it. Now I'm wishing I hadn't. My wallet is glad I didn't, of course.

What a beautiful job you've done on yours, Russ.

- Matt