1973 643 hydraulic drive questions

R

rxwarriorgod

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Bitely Michigan
hello I recently bought a 1973 Yamaha 643 hydraulic drive snowmobile and AM wanting to get running is there anything you have to do after it has been sitting for a long time like change hydraulic fluid things like that any help would be greatly appreciated thank you
 

I think it would make sense to change the hydro fluid, probably takes dextron ATF but don't quote me on that. Other than that the normal stuff you'd go through on any sled like clean carbs, check all the bearings etc. And post some pics! I've never seen one in person.
 
YooperWoods said:
I think it would make sense to change the hydro fluid, probably takes dextron ATF but don't quote me on that. Other than that the normal stuff you'd go through on any sled like clean carbs, check all the bearings etc. And post some pics! I've never seen one in person.
Click to expand...
it is not mine its a friend of mines he said it starts but was wondering if we had to do anything special before we get it moving I'll post some pics very soon
 
First thing ... DON"T trust the auto lube on this model ... I don't know why , but the 643's ive picked up are seized , or
have been mixed ..... If it seems to work , maybe mix a good 100/1 synthetic and make a mark on the tank and see
if it is going down after 5 or 10 gallon of fuel...
Fluid is dextron ... if you don't see any water / white clouds in it ... run for a few minutes and check again.... no sign of water , just run
the oil that is in it,,, More guys have had trouble after changing it as it a stink of a job to keep out air bubbles...
Water will boil and force out the oil from expansion ,,, air bubbles do the same ....
Maybe check the chaincase .. but I don't know how ...lol ... the window clouds over so you cant see in with a mirror and
and a flash light ....
The centre drive cog get old and fragile ,,, don't tow any trucks out of ditch ,,, check general track condition ,, check exhaust for mice evidence
as they can stuff it full of seeds and nest... they also get around mag cylinder and stuff collects in duct ahead of it..
...
They don't steer well ,,, so much track pushing ahead and not a lot of ski pressure...and week spindles (don't add spacers)
.
maybe borrow a battery from a lawn mower ,,, that steel rope isn't as happy when it is this cold...
...
i'm not expecting any problems if the engine performs , the rest is age and luck related...
If you somehow wreck that converter , I have a spare ...
..
I start it in neutral , warm a bit and then shut it off ... just before it stops turning over , clunk it into gear...you wont need low..
Saves a lot of metal crashing... will start all day after warm ,, in gear..
Have a lot of fun,,, it is very different to ride,,, no jerk , just a whiny belt.
Ron
 
Have paid more for less but don't need another right now , that far from me.
..
That frame sure buckled at rear... a parts machine as noted . An un seized 643 is uncommon ... the GP motor is a better
donor for a 650 thunder jet as the EW doesn't have same output on crank shaft...
...
Same tunnel punch as EW433 but the bolt pattern is different on the chain case ....found out the hard way... lol
Ron
 
10 Years ago I would have chased it down , but after bringing home about 32 plus fluid drive yams ... I now watch more for the
"cream of the crop" machines .. something better than I already have,,, but at least 6 of them came after I said NO MORE ...lol
Ron
 
35 years this summer ... she is my navigator and realizes these trips are as close to a holiday as it gets ...
On the hottest days of July 06 , we left near Toronto , to midland MI , upper , eagle river , Mi st paul , Crosby , Hibbing , Thunder bay, Polaris ville,
Winkler MB , Altona . ND ..back to Mi Stpaul ,, wild cat mountain in Wisc , back to Midland MI and home ,,,
11 days , during our anniversary , I recall about 4500 miles ,,, two sleds from MI , one dropped Charlie Vall , two left in Thunder bay to get later,
2 on truck which got 4 home.. Saw every collection except museum in St Germain ( closed ) on the way.
Turned around in fall and got 1 from near Maryland over a weekend... Good thing USA gas was cheap ...lol
Ron
ps ... she doesn't need to ask permission when she buys new plants (her hobby)
 
HYD UNIT UNASSEMBLE.jpg
Other than some snap rings and an oring , this a convertor from a 74 TL433F.
SLIDE RAIL 2012 005.jpg
Since most are rusted out , they end up in the "parts" piles ,,, there are as many handle bars , and
fluid units as suspensions ... about 15 of them , mostly 75 and 77's. .. you can never have enough spares...
and at the failure rate on convertors of near zero ,,, about a thousand years worth.
Ron
it's a nostalgia thing for me
 
RON HYDRAULIC YAM said:
View attachment 57666
Other than some snap rings and an oring , this a convertor from a 74 TL433F.
View attachment 57667
Since most are rusted out , they end up in the "parts" piles ,,, there are as many handle bars , and
fluid units as suspensions ... about 15 of them , mostly 75 and 77's. .. you can never have enough spares...
and at the failure rate on convertors of near zero ,,, about a thousand years worth.
Ron
it's a nostalgia thing for me
Click to expand...

I've been looking for "how it works" google and such on these beasts but haven't found much.

Yeah it sure looks like a torque convertor. Neat.

Thanks for sharing the pics.
 
Another picture of one out of a sled DISPLAY HYD FRONT VIEW.jpg
...
As far as sleds go .... I have hauled home 8 or 9, 1975 TL433G 's ... one has a reasonable frame but far from GOOD...
I would like to find one that the belly isn't punched in , the stirrups are attached , and when remove the seat , you don't see
the track ..lol.. I do know of such a machine here in Ontario , but it was his Dads and Dads gone and sled is staying ... He knows
it would get a good home but so far it already has a good home ..
75 STRATFORD OFF TRAILER - Copy.jpg
The 75's were the only ones with out red stripe somewhere ..
Ron
 
RON HYDRAULIC YAM said:
Have paid more for less but don't need another right now , that far from me.
..
That frame sure buckled at rear... a parts machine as noted . An un seized 643 is uncommon ... the GP motor is a better
donor for a 650 thunder jet as the EW doesn't have same output on crank shaft...
...
Same tunnel punch as EW433 but the bolt pattern is different on the chain case ....found out the hard way... lol
Ron
Click to expand...
Hey Ron I finally get to ask my Yamaha questions I hope you can answer. I have an ew 643b and out of all my sleds it's the best runner I got up until my current problem. I've never had really a problem with the fluid drive except it got hot on the trail one day and I figured out I needed a new radiator cap for the transmission system and all was good. I use it all the time for trapping up here in Hayward. The oil injection has always worked LOL now I'm going to take a second look at it after reading your post. Cuz I've had this sled for probably 15 years now and it's always ran great except for a hiccup at idle after I changed the points but never changed the condensers( don't aske why). It was a 1 owner sled I got out of cable with the original owners manual and all the notes from the Yamaha dealer in it. I figured out the pick up at the end of last winter changing the condensers the two ignition coils were barely connected and the wire was just vibrating back and forth but it still ran good so I changed condensers and lost the flywheel in that and the process and I think I soldered it bad so now I have no spark so I was hoping I could just change it to electronic ignition that would be awesome put new condensers in the end of last winter and never started it cuz I couldnt find the flywheel nut. condenser and I would like to change it to electronic ignition. This is probably my favorite vintage sled so far cuz it always starts and runs perfect and my daughter's love driving it . and One year when the rest of my machines were down I drove it all winter trapping and it was awesome up here in northern Wisconsin. So I got an 80 540 XLV and a 87 540 2 up, can I use ignitions from one of those and how do I change it I'm not sure what exactly all I need to change any help would be appreciated , I'm half ski Doo collector also and love LOVE my rotary valve torque monsters. my daily driver is now the on the 2nd of the same sled from 99 cuz it just rips so damn hard.( I wish I could find another one too so black Betty doesn't get all the miles ). So the real problem is I cannot find a seat cover for this damn ew643b. I don't want to pay a fortune either and I do have lots to trade as I'm a prof. Wood carver/log home builder from AK. A place in Rice lake wanted to charge me like 7 to $900 to make one, any chance there is a NOS one laying around for me anywhere!?!! cuz they don't exist my friend bought one once for his gp433 on ebay and it was for my sled and cut it up to fit his but this was before I owned mine and I was sick to my stomach after I bought mine when he told me that!! Lol Scott was a HUGE Yamaha collector, but he passed away last year. Sorry for the long post but I've been putting of doing research on this sled and saw your post so had to join and sitting in the hot tub this morning at -10 f I finally got the time! I'm up in Hayward if u wanna come up and ride!
 
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