I am now a proud member of the "Shifty Fifty Club"! :vroom: My affinity for small displacement bikes has led me to acquire an even smaller bike for my collection. I've wanted one since they came out and I finally got my hands on one. (Although truthfully I'd rather have an AR50 or AR80 if one was available.)
As the sales guy who knows me said when I bought it "I'm really surprised you're letting this one into The House of Yamaha". :dawg:
It's in pretty nice shape with only 2400 miles and came with the owner's manual, tool kit, and a brand new 1982 dealer brochure.
I've been going through it as I do on all my purchases before putting many miles on it, but it's pretty darn fun to rip around the neighborhood! It needs a few very minor cosmetic fixes. The tires have to go! Knobbies on this bike is just plain ridiculous! I'm waiting for the correct size of ContiStreets to get back in stock (mid-March), and I'm currently in the process of blasting and repainting the front disc and rear sprocket that some tool decided to paint purple. :rolleyes: A new chain is waiting to go on as well to replace the gaudy yellowish/orange painted thing that's on there now. And I've already converted the tail light and dash lights to LEDs.
i love those! congrats!!! :olaf: :cheerleader:
I'm really trying to resist the temptation to throw an expansion chamber and a 70cc kit on it. I'd like to leave it stock since it's so original, but...
taking the stock parts off and storing them safely just preserves them. be responsible, fit the 70 kit and chamber. save the stockness... on a shelf. :devil:
I have to agree with the above, I love these little bikes and they are way more fun when they make a little noise..
DUDE!
Quote from: m in sc on February 10, 2023, 01:52:11 PM
taking the stock parts off and storing them safely just preserves them. be responsible, fit the 70 kit and chamber. save the stockness... on a shelf. :devil:
I assume this logic also applies to my AR and converting it to LC?
- correct. :cool:
Mark is right; 70cc and pipe!
I concur. 70 kit and a stinger.
- no vote on the stinger. :eek: :shocked:
Did a little work on it today. Media blasted the rear sprocket that someone had painted purple. Installed an OEM helmet lock for the missing one.
A while back I blasted the front brake rotor and repainted it black, and installed LED bulbs in the tail light and dash. Also replaced a bunch of small hardware and items that were missing like the red rear reflectors.
Still waiting on tires. No US stock on the ones I want. I was told by Continental that they should be restocked at US dealers by March 14. (actually not much of anything in stock currently in 2.50-18 or 2.75-18 that's a decent tire with a modern tread pattern).
Score! I have lusted for one of those for a long time, just haven't found the right deal.
One lives here. Fun little zip around bike.
Your MB still has the ultra rare left side battery cover.
Quote from: ~JM~ on March 28, 2023, 11:54:35 PM
Your MB still has the ultra rare left side battery cover.
Yes, it came with a a box of parts with the bike. Unfortunately, it doesn't stay on and was only stuck on there temporarily for the photos. I can't figure out why the battery seems to stick out a little too much and won't allow the cover to clip on properly. The battery dimensions are the same as OEM and the battery box doesn't look like it can be mounted any other way or be moved inboard at all. :umm:
throw an alarm battery in it, they are typically smaller and work awesome. :umm:
Quote from: m in sc on March 29, 2023, 01:50:21 PM
throw an alarm battery in it, they are typically smaller and work awesome. :umm:
Not sure an alarm battery would accomplish much. It may help clearance a little for the battery casing but I think the battery tray would still interfere and it wouldn't resolve the root cause. I need to figure out why the whole assembly seems to cause interference on what is believed to be a stock bike. I don't want to mod this one
(yet). And it's got a relatively new Motobatt in in it.
And the tire supply issue continues to drag on. :rolleyes: The ETA was just updated from 03/14 to 04/28. Ugh!
reach out to treatland, see i they have any tires on hand. I have a set of savas on the yl1, and had them on the G3, i know they are good up to 80 mph. 02
didn't know about the tray issue. weird.
Quote from: m in sc on March 30, 2023, 11:57:48 AM
reach out to treatland, see i they have any tires on hand. I have a set of savas on the yl1, and had them on the G3, i know they are good up to 80 mph. 02
Good to know about the Savas. I saw those a while back on Treatland but was hesitant about them because I had not heard of the brand or any feedback from buyers about them. They're currently out of the MC7 but have the MC11 in stock in a 2.50-18.
See if your honda shop can get tires for a Dream 50. 2.50x18 Bridgestone bt39's that all ahrma racers use on little bikes. No they wont wear out in a month but have fun trying
Thanks for the tip. Another option to search for. I highly doubt my local Honda dealer will be able to get them. I was already in there checking on what brands they could get in a 2.50 or 2.75, but we'll see.
I looked up the specs on that tire. Interesting...race compound...hmm :devil:
BATTLAX BT-39 SS
Front/Rear 2.50-18 M/C 45L
Track Use Only.
This is a Track Tire that is sold through race-specific dealers.
Don't those MB5's rev. to 20k?
cliff
Quote from: automan on April 02, 2023, 04:52:12 AM
Don't those MB5's rev. to 20k?
20K? Not quite. I think if you hit 20,000 RPM you'd be backtracking to pick up bits of connecting rod and piston skirt nuggets off the street.
Redline is 10,500 RPM :burnout:
Funny, My sister-in-law texted me this a couple weeks ago.
Quote from: JBeasty on April 07, 2023, 01:10:48 PM
Funny, My sister-in-law texted me this a couple weeks ago.
Did you go get it? :haw:
Nah, one project at a time for me - to keep my wife from killing me.
Seem like a Honda mechanic told me a cr80 top end from that era would swap on to the MB5
FWIW, the stroke and the cylinder stud spacing of a CR80 Elsinore is the same but the transfers on the CR80 are much bigger compared to the MB5 and the case would need a fair amount of welding to seal the cylinder base. The mouth of the MB5 case would also need to be opened up to accept the lager CR80 spigot. It's doable, but not bolt on.
Quote from: Guygrrr on April 18, 2023, 11:59:41 PM
FWIW, the stroke and the cylinder stud spacing of a CR80 Elsinore is the same but the transfers on the CR80 are much bigger compared to the MB5 and the case would need a fair amount of welding to seal the cylinder base. The mouth of the MB5 case would also need to be opened up to accept the lager CR80 spigot. It's doable, but not bolt on.
Yeah, the CR top end requires quite a bit of work. Much easier to just bolt on an aftermarket big bore kit.
The CR80 trans is a straight drop-in though to upgrade to a 6-speed.
Quote from: SoCal250 on March 29, 2023, 09:43:30 PM
And the tire supply issue continues to drag on. :rolleyes: The ETA was just updated from 03/14 to 04/28. Ugh!
Well, it looks like I definitely have to move on from my tire choice that I had settled on few months ago after a lot of research.:rolleyes:
The manufacturer ETA has moved from March 14, to April 28, and now to May 29.
Guess I'm just going to pull the trigger on some Savas from Treatland. They seem decent and they're cheap. (and they have the Haase stamp of approval)
I bought a pair of IRC NR53 Zap 2.50-18 tires for our MB5.
Probably off of Amazon.
Progress made! Yesterday I mounted some new sticky Mitas (Sava) MC11 tires. :whoop: They went on really easily. It's so nice to get rid of those aged-out off-road Cheng Chins!
Also replaced the axle pulls with new OEM parts as the ones on the bike were crusty and one side had been modified with a welder by a previous owner. All new now...and shiny! :cool:
And installed the bead blasted and refinished OEM rear sprocket.
Next up is:
- Shorten the new chain and install
- Service and bleed the front brake system
- Install the new mini SLA battery
- Bleed the oil pump and adjust the cable/pulley
And lastly...let the terrorizing of the neighborhood commence! :vroom: :devil:
Foiled again by friggen USPS again! :bang: My special order part was apparently "Delivered to Mailbox" last Saturday when it was supposed to be delivered to the store by Mon so I could pick it up. No one knows what mailbox it was delivered to because the store doesn't have one, although the delivery zip code and the store do match. I figured "store pick-up" was the safe way to go to assure I would receive my part on time. Boy, was I wrong!
So they've sent another one and the ETA is now 05/16, however now it appears that I'm going to miss the vintage show on Sun 05/14 that I had targeted. :rolleyes:
Quote from: SoCal250 on May 08, 2023, 10:46:42 PM
Progress made! Yesterday I mounted some new sticky Mitas (Sava) MC11 tires. :whoop: They went on really easily. It's so nice to get rid of those aged-out off-road Cheng Chins!
Also replaced the axle pulls with new OEM parts as the ones on the bike were crusty and one side had been modified with a welder by a previous owner. All new now...and shiny! :cool:
And installed the bead blasted and refinished OEM rear sprocket.
Next up is:
- Shorten the new chain and install
- Service and bleed the front brake system
- Install the new mini SLA battery
- Bleed the oil pump and adjust the cable/pulley
And lastly...let the terrorizing of the neighborhood commence! :vroom: :devil:
I see you used rim strips. I just ordered tires & tubes but figured I didn't need them because I have the mags on the 400. Should I have ordered them?
Quote from: JBeasty on May 11, 2023, 12:27:26 PM
I see you used rim strips. I just ordered tires & tubes but figured I didn't need them because I have the mags on the 400. Should I have ordered them?
They are a stock part on the MB5. The Comstar wheels have a weld bead down the center channel of the wheel. I'm glad I bought new ones because one was torn at the stem hole and in pretty bad shape.
I don't recall if the RD400 had them from the factory on cast wheels. I'd throw a set in there. They're cheap and will protect the tubes from any casting burrs and from rubbing. You may have some already in there and they can be reused if they're not damaged. A common substitute for the rubber strips is duct tape.
The only thing you're missing now is this sweet MB5 t-shirt that m in sc and I saw at the Eastern 2-stroke Rally this week: https://www.redbubble.com/i/t-shirt/MB5-The-Supersport-Single-by-RodolfoPrice/72787300.IJ6L0.XYZ
^ that's a cool shirt! :thumbs: Matt- always good seeing you and still a large turnout here at DG.
Here's pics of the 2 MB5's I rescued and then sent them on to new homes. Both colors issued here in the US.
Quote from: msr on May 12, 2023, 10:59:44 AM
The only thing you're missing now is this sweet MB5 t-shirt that m in sc and I saw at the Eastern 2-stroke Rally this week: https://www.redbubble.com/i/t-shirt/MB5-The-Supersport-Single-by-RodolfoPrice/72787300.IJ6L0.XYZ
Thanks! :thumbs: (bookmarked)
Quote from: Evans Ward on May 12, 2023, 12:32:11 PM
Here's pics of the 2 MB5's I rescued and then sent them on to new homes. Both colors issued here in the US.
Cool! (and of course, it's common knowledge the red ones are faster!) :wink:
Quote from: SoCal250 on May 12, 2023, 05:48:41 PM
Quote from: Evans Ward on May 12, 2023, 12:32:11 PM
Here's pics of the 2 MB5's I rescued and then sent them on to new homes. Both colors issued here in the US.
Cool! (and of course, it's common knowledge the red ones are faster!) :wink:
Thanks! :thumbs:And both sold to college students to ride on campus and keep the knowledge of 2 Strokes alive. :clap:
Quote from: SoCal250 on May 10, 2023, 11:29:14 PM
Foiled again by friggen USPS again! :bang: My special order part was apparently "Delivered to Mailbox" last Saturday when it was supposed to be delivered to the store by Mon so I could pick it up. No one knows what mailbox it was delivered to because the store doesn't have one, although the delivery zip code and the store do match. I figured "store pick-up" was the safe way to go to assure I would receive my part on time. Boy, was I wrong!
So they've sent another one and the ETA is now 05/16, however now it appears that I'm going to miss the vintage show on Sun 05/14 that I had targeted. :rolleyes:
My special order battery has arrived...FINALLY. Looks like it should do the trick. It's about 1/2 to 2/3 the size of the current MotoBatt OEM-replacement unit.
Slowly plugging away at the remaining tasks. Still have these items left:
-
Shorten the new chain and install - Service and bleed the front brake system
- Install the new mini SLA battery
- Bleed the oil pump
and adjust the cable/pulley - Correct front tank mounting bolt issue (re-tap frame holes?)
- Replace license plate mounting hardware (M6 Allen button head)
Got a little more accomplished today. Every step of the way reveals new issues and results in further disassembly and labor time.
- Service and bleed the front brake system
- Install the new mini SLA battery
- Install inline fuse holder (OEM one is missing in harness)
- Replace oil supply hose from tank to pump and install new clamps
- Bleed the oil pump and adjust the cable/pulley
- Correct front tank mounting bolt issue (chase frame hole threads with a M8x1.25 tap)
- Replace license plate mounting hardware (M6 Allen button head)
A little more progress, but uncovered another little issue along the way. Found out that the oil tank sight glass leaks. Of course this was discovered after pouring 1/2 liter of oil into tank and bleeding the pump. And to top it off...the sight glass is discontinued and unavailable. Of course it is! :bang:
Task list and progress:
- Service and bleed the front brake system
- Install the new mini SLA battery
- Install inline fuse holder
- Bleed the oil pump
- Fix or replace leaking oil level sight and replace OEM clamp
- Replace license plate mounting hardware (M6 Allen button head)
During the pump bleed process it became clear that Honda engineers should have paid attention to how Yamaha designed their 2T pumps with respect to bleeding and maintenance access. I don't think Honda could have made it any more difficult to access the bleed bolt and to reinstall it. What a HUGE PITA! And the oil just runs down all over the pump, the top of the engine under the carb, and then down to the center stand. The service manual says to put a rag under it but there's not enough room for a rag big enough to soak up much oil. Not a very good design to say the least. Glad it's not a frequent task. (Knock on wood, at least I hope it doesn't become something regular.)
One came up for sale near me. Any opinions?
https://albany.craigslist.org/mcy/d/earlton-1982-honda-mb5/7626085924.html
Quote from: 1976RD400C on May 28, 2023, 06:10:52 AMOne came up for sale near me. Any opinions?
https://albany.craigslist.org/mcy/d/earlton-1982-honda-mb5/7626085924.html
Oh man, that's a nice one! :nana: And the price is a steal!
BUY IT!Super low miles, and from what I can tell in the photos it looks to be in excellent condition.
It looks 100% complete. Still has the ultra rare (and commonly lost) plastic battery cover. And it's still got the front reflectors on the forks that are impossible to find because they are NLA. And the mirrors and signals are all intact and OE. Paint and seat look to be in perfect condition (except for one scratch on the right side of the tank). All the stickers and warning labels are still in place too.
If that was near me I would be in my truck right now driving over to get it!
if somebody gets me a battery cover i can draw it up in solidworks, then it could be 3d printed (not by me).
Quote from: m in sc on May 30, 2023, 05:21:18 PMif 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.
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. :whoop: 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!
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. :thumbs: The old oil looked clean but smelled burned.
Then took it out for a longer rip and ended up flogging it for 23 miles. :olaf: 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. :dawg:
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.
:clap: sweet! i could barely just keep up w that on the Yl1 :dawg:
sounds like a riot! you're making me regret selling my 89 DT50.
Quote from: m in sc on June 08, 2023, 11:57:55 AM:clap: sweet! i could barely just keep up w that on the Yl1 :dawg:
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 😭
Treatland has repop battery covers,$35. Along with a ton of other goodies for MB5.
Quote from: dgorms on July 01, 2023, 04:34:42 PMTreatland has repop battery covers,$35. Along with a ton of other goodies for MB5.
That's where I got my tires
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.
20231003_142151_MB5_carb1.jpg
20231003_142311_MB5_carb2.jpg
20231003_155517_MB5_carb3.jpg
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.
20231003_140705_MB5_slide.jpg
The bike runs great and starts first kick when cold (with choke) or when hot. :thumbs:
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.
20231005_141139_wash_day.jpg
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