Vince41

I'm looking for information to help me restore our Yamaha push bike, can anyone assist.
Brisbane Australia

Vince

55/Rad

Please tell us what you know and post some photos so we can help you out.

qcpmsame 

If its their full suspension Moto-Bike, with two shocks on the swing arm and sprung telescopic forks, they are kind of a niche collectible bike. They were way too heavy to race BMX on, but the adult pro MX racers liked to tool around the pits at motocross races on them. I remember a picture in Dirt Bike Magazine, about the USGP at Carlsbad, in early the 70s, showing Roger Decoster on one as he was cruising through the pits. Gerrit Wolsink won the GP btw. He took the first three USGP races.

Post some pictures here, as requested, they are a conversation piece.

Bill

thumpism 

When I was repping one of my dealers had one he'd found someplace and I was able to find him an original owner's manual for it. That was in North Carolina and he probably still has it. Neat little bikes.

repechage

In 1974 bike criterium races were held on the Carlsbad Raceway road course, the finish was at the 1/4 mile line.
Great course. Took a win in my category. Fun to watch the Motocross there too in prior years.

qcpmsame 

There are a lot of the old timers in MX that never got over Carlsbad being closed and the land developed. It waa a personal goal to ride there, but I was never any kind of threat to anyone. I had heard that the road course was host to some bicycle racing back in the day, just hadn't known what was there. I wasn't into road rashing at all, just a dirt rat kid that loved MX and D37 desert racing (RUTS member here, Masters desert class, 2008-2010.) Should have been born out there I guess.

Bill

Otis

When they introduced that bike, Yamaha sponsored a BMX racing series (I want say it was called "Gold Cup", but can't really remember?). They were held at high schools using the running track with a bunch of artificial barriers like wood "jumps", water traps, rubber cones etc. around the track. It was totally lame!

I do not think one person was actually riding a Yamaha Motobike as they were totally un-raceable. I was still on a highly modified Sting Ray. I remember getting a good hole-shot start and crashing almost immediately on the first "jump", which was basically a wood box with what seemed like 45 degree ramps. I think I hit it and just went over the bars instead of going up the ramp. Those were heat races and that was the end of my day. Totally lame....

qcpmsame 

@Otis I believe you are right about the series being the Yamaha Gold Cup. I know you are right about no one racing a Moto Bike in them. One local kid got one for Christmas '74, it lasted about a day before it started falling apart. The swingarm, shocks, and fork were poorly thought out and executed. That seat must have weighed 10# alone. Yamaha tried to remedy some of the problems but they faded fast. Kawasaki tried to break into the BMX area also, unsuccessfully.

Schwinn Stingrays with stronger wheel sets and handlebars ruled the early era, then Redline and Webco jumped into the scene and it was katy-bar-the-door. Those kids must have had legs like race horses, and lungs to match. Now its a science unto itself with the players in that species of cycling. Freestyle, Olympics, etc. The BMX Forum needs to take this one to a level that will possibly answer te OPs questions.

Bill

thinktubes 

Did a test ride on a Moto Bike at a Yamaha dealership. My dad had an MX-250 and we were there for parts. I remember it looked cool, but was heavy compared to my Stingray.

As a side note, I loved reading Dirt Bike magazine back in the mid-70s. Seemed like it was run by a bunch of long-hairs, who wrote some funny stuff.

And nobody was more stylish than Roger Decoster....

dddd

I sort of inherited a Yamaha MotoBike when my older brother moved out of my parents house in the mid-70's.


I remember the bike well, it had a 2-speed kickback hub which may not have been original, but which was most familiar to me from my Stingray-riding days.


It had some really, really heavy steel, dual-crown suspension forks that probably came from their JT1 Mini Enduro parts bins.
The crankset was cottered steel.
The swingarm pivoted directly behind the bottom bracket and used a simple 8 or 10mm pivot shaft against the plain steel, so that quickly wore out to the point that I would get wheel-hopping power slides out of it on pavement for fun.



I think that the saddle was padded black vinyl with springs, and no struts of the type that Stingrays had.
I remember the thrill of bombing down this one fast trail through a local apple orchard in suburban upstate NY, it was good for that!

I later broke the lugged frame at the bottom of the seat tube, and sold the remains to another kid who had a neighbor simply arc-weld the failure point with gobs of welding overlay. I don't know how long that repair lasted, it was the last that I saw of it though.


I would become a teenaged dirt bike enthusiast out there and was lucky enough to have some local older teenagers drive me hundreds of miles to the Unadilla 250cc USGP to see Bob Hannah and Gennady Moiseev win the race overall and World MXGP title, respectively.
Moiseev passed away this year, in July, at the age of 69.

qcpmsame 

Sad to hear thar Guennady passed, I'm way out of touch with the sport now. I remember the hatred he got for the take out move, by another USSR rider on a KTM, on Jaraslav Falta (CZ) that cost him the 250 world championship, and handed it to Moiseev. Protested but upheld by a scared FIM official. Guennady was heading up a development program in Moscow in 2009, last time he was in the news.

Still have my last bike in the garage, 2002 YZ426 FP Yamaha, it could pass for new. My collection of Dirt Bike Magazines runs from V1 No1, June/ July 1971 through Dec 1979, complete. Rick Siemen was editor after about the second issue . He was dealing with strokes and cancer last I heard.

Otis

The hot set up So Cal Sting Ray: Dennis' Welding on Pico in West L.A. would cut a a couple of inches out of the bottom of the seat tube, heat the down tube to pull the BB shell up to the shortened seat tube and bird-**** weld it in place. Then cut the extra loops off the seat-stays past the seat-tube and double bird-**** weld all of that in place to re-enforce.

A cross bar would be bird-**** welded in place up by the head tube between the top and down tubes to strengthen that area and fill the hole that usually broke out where the seat-stays where attached to the down tube.

Then he would heat up the fork and take all the rake out of it.

The extra clearance from the shortened seat-tube allowed for a pair of Collegiate crank arms running the 39T inner ring. A 16T would go on back. The way longer length of these arms and bigger ring was a game changer when up against a stock Sting Ray!

Other mods were a rear rim laced to the front so you run the big Schwinn knobby fore and aft. Jr. Sting Ray handlebars and saddle, which were smaller. A cross bar was added to the bars after it installed in the stock stem. And the front of the saddle was sawn off up to the seat -post, then wrapped in duct tape. You needed this clearance to fit your knee across when doing fully stylized flat-track cornering!

The strut loop was sawn off where the saddle mounted in back, and then the struts were mounted to the inside of the saddle. About five hose clamps were added to the bottom of the strut mounts to keep them from sliding down while riding rough terrain and hitting the saddle after jumps. And you would trim the struts right to the clamp.

Of course a pair of surgical rubber donkey-dick grips and a Vise-Grip clamped to the seat-post for all repairs done in the field were the finishing touches. Was such a trick set up! Mine (which was in as parked shape from about '74) was given away a year after I moved out of the house a few years later. Every once in awhile I think about building a replica.

It was during this era that some of the really cool Dad's that raced motorcycles started welding up the straight tubed frames and that would become Redline's, the double clamp style stems, etc.

A lot of this happened at Palms Park in West L.A. close to where I grew up. There were races there on Thursday nights, and we lived there on our bikes all weekend.

Chombi1 

Wow, this brings back childhood memories from the 70's!
A kid in our neighborhood was everyone's envy as he had a Yamaha Moto bike, when everyone else "just" had 10 speeds....
Everybody was impressed when he used to ride wheelies on the street in front of everyone's house and jumped curbs with ease. He never let any other kid ride his bike, so there was a bit of envious hate he was producing. I don't think I can blame him, considering how prized and rare such a bike was to us kids back then
Sad thing was, about 10 years later, when he was riding an enduro style motorcycle down a city underpass, in the middle of the night, he hit a stalled dump truck....... died instantly with his head supposedly cut off by the impact (could be just street legend description from the neighborhood)...
I still wonder what ever became of that Moto bike......

qcpmsame 

@Otis You guys went much more into modifications than the kids racing our local BMX track, in NW FL. A few got into fabricating stronger forks and stems capable of clamping crossbar equipped handlebars. I remember using the surgical rubber grips on my 400 Maico square barrel, and on my Suzuki RM 370A. They had the lifespan akin to a fruitfly's time on earth on our bikes. First Redline frame I saw was a visiting kid that brought it with him on his family's vacation.

Oury, Jones. Doherty, or the stock Magura grips were used at one time or another, by most of us. I came to favor the file pattern of the Magura style, which is similar to my current Renthal soft, full file pattern grips. No ridges or ribs, or those horrid stock Japanese veined/ribbed street grips were comfortable. The Oury waffle pattern are pretty good too.

One thing Yamaha came out with for the Motobike was supports for the saddle. I have a feeling it was the result of the number of failures. Most of the ones around here, and that the adults sporting them, was to replace the heavy, grotesque stock saddle with one from a "ten-speed" bike. The pictures of Decoster and Brad Lackey on Motobikes, in the pits during GP races, had those saddle replacements.

Correction to my previous reply, Moiseev's first name should be spelled with a U, for some inane reason always leave out the "U". The spelling sans the U is prety much accepted now. Russian speakers, and linguists, grind their teeth about it, and our son is a linguist

Bill

obrentharris 

All these posts and no photo?


I borrowed this one from the internet...
Brent

qcpmsame 

Someone did a nice restoration on that one, it looks better than they did sitting on the dealer's showroom floor. Just looking at the shocks and the fork, brings back memories of how they pogoed, little in the way of damping in the units, if they even had oil for that purpose. Probably the same fish oil that Yamaha pawned off on everyone with their suspension for many years, it broke down before the bike's could be shipped seemed. Strange how the same companies could come up with the suspension parts they developed, and what is happening now with mtb and motorcycles.

Bill

Chombi1 

There was pretty much zero damping from "shocks" provided on most low end products from Japanese motorcycle manufacturers back then.....
Any sort of resistance from the dampers mostly came from the drag between the springs and the shock body and maybe from the dampers rod and seal around it. The damping oil, if any, was most a token item they add in, so they can call them legally as dampers..... they were that bad, and even as a kid who had a had a Honda DAX/ST75 mini bike back then, I knew the "shocks" that Honda put on my bike was just total crap!

bamab2

I had one just like the one pictured. My buddy had an orange one. I think his came with the single "ten-speed" seat. I really liked that bike. No racing just riding like a kid. The front suspension popped every time it extended to the maximum. It sounded like popcorn popping when we rode on bumpy trails. Good times.

qcpmsame 

You're preaching to the saved Chombi, I started out on an SL 125 Honda with the chrome swingarm supports on back. I thought I had died and gone to MX heaven when I took possesssion of my OSSA Stilletto 250. Betor rebuildable shocks on back and their forks on front as well. Spanish wonders that actually had damping and decent spring rates. My Maico was like nothing I had ridden with its forks and the Telesco gas charged shocks I used on it.

Come the RM series with Kayaba suspension and the advances in travel things were going sweet. Now its single shock, linkage rear suspension and USD forks both with rebound and compression damping that can be adjusted almost infinitely and modified to a fare-the-well if you have the bank account. What an advance from no damping circuits and thin fish oil with sealed bodies.

I got in on the beginning of forward mounted, cantilever, lay-down, etc shock mounting and frame-swimgarm modifications (FMS, in 1973-1975 dirt bike speak.) I did the rear frame modification to move the top shock mounts forward 4", and moved the swingarm mounts up 3-1/2" then added the Telesco gas charged shocks and springs which were longer to accomodate the change in their angle and installed the Fox Fork LT air spring kit with improvrd damping rods and valving. It made for a totally different way of riding.

Next chapter: Suzuki RM370A and suspension nirvana. But not here.

Chombi1 

Wow!, Ossas, Maicos,.... I could only dream of riding those bikes back then less owning them.....
The closest I got to an "off-road" bike was my Honda 1974 XL100, that I had to share between two other brothers, because our father did not want to buy us the Elsinore 125 or 250M that we were craving for back then.....my dad was strictly a road biker and he considered motocross, or anything approaching it, as a sort of hooligan motorcycle sport.........he did not like two strokes, either....
Eventually bought the motorcycle that I really wanted when I graduated college and started to work, after a few years saving for it.....A 1988 Honda Hawk 647GT...... been a roadie since then (Now riding a VFR750), but I had played with the Idea of either buying Ducati Hypermotard.... or a C&V motorcycle that I can restore, like a Yamaha XT500 or a Honda XLR650 that I could set up as a classic Baja racing bike....twin driving lights up front, full bush bar and light protection, aftermarket shocks (Ohlins?), front and back, Akront aluminum rims, jumbo plastic tank, number plates, high rise, Ti, aftermarket pipe,....etc....etc.... Now you got me started thinking.....

thinktubes 

Avoid the XT500. My dad had one and it was a miserable beast.

I remember that it had a little window on the cylinder head because you had to position the piston correctly to get it to start. It had a comprssion release that was also involved in the starting process. My dad developed ar really strong right leg trying to start that SOB. Wouldn't start when it was hot, which was always since it was a big bore single. He ended up selling it after 6 months.

AngryFrankie

Great memories of my moto-bike, just like the one in the pic here but with the other option 3 corner seat. Yes, heavy, but a blast to jump off of things. I actually took the shocks off of a Yamaha enduro 125 carcass that belonged to my brothers friend. It raised up the rear a bit, but man I'd wheelie off of outdoor terraced planters and stuff. One day I got home and it was sitting there with no shocks. I guess he needed them back. :-\
I broke it repeatedly and my dad's buddy who could weld repaired it, until the time he said, 'kid, don't break this again. This nothing left to weld I've fixed it so many times.'

2cam16

Always dreamt for one of those when I was growing up.
Hannah and deCoster were my favorites!

Chombi1 

I was a fan of the likes of Yvon DuHamel and Marty Smith......
Roger DeCoster was just too perfect, almost Teutonic in the Euro sense, so I did not get too excited by him. He was just too predictable and perfect. Sort of like the Ingemar Stenmark of motocross. I saw DuHamel and Smith as scrappy underdogs that had to try much harder to win, so more exciting to watch.
I kinda lost interest in motocross after Bob Hannah started beating everyone on his Yamaha, a brand I considered the arch enemy of the Hondas my family had at that time....... Honda just did not have any answer to him.....

dddd

I was sort of fascinated by dirt bike suspension and later would be among the early adopters of suspension on my Pro-Flex bicycles.


What I remember about the dirt bikes in the 70's was that a suspension that seemed to work about right, and with correct adjustments, could change from Dr. Jekyl to Mr. Hyde after a hard lap or two as the dampers became hot. I've never noticed this effect on a bicycle, but on a 250cc moto like my Elsinore or MX-5, the back end could go into a hop where the rear wheel was suddenly bouncing a couple of feet left and right, with the rider struggling to maintain control of the thing.


The cheapest fix for this was a pair of double-walled S&W shocks which had a concentric Freon cell bladder compensating for the oil volume change of shaft displacement without allowing any mixing of the Freon with the oil. I was fairly light and remember only having to change back and forth between 80 and 90lb springs for tracks with different jump heights, with the softer springs giving much better uphill traction on rougher surfaces.


The Moto-Bike had no rear oil damping but did have oil in the fork. I don't know where the oft-repeated "fish oil" story came from, but I would bet that it was just a combination of insult to a feeble suspension and an expression of anti-Japanese sentiment that motorcycle magazine writers eagerly played to.


Thanks for posting the picture, I'd forgotten how "right" that these things looked! I'd never seen this strutted saddle arrangement, and the one that I got to mess with was orange instead of yellow and pretty well used already.