'73 Yamaha 175...creation?

Discussion in '2 smokers' started by lgottler, Sep 2, 2008.

  1. lgottler

    lgottler Been here awhile

    Joined:
    Aug 19, 2008
    Oddometer:
    149
    Location:
    SE Michigan
    Just trying to get into bikes a bit. Played around with a 125 Suzuki when I was 15 and thats about the extent of my bike knowledge. So, now at 30, I'm trying to get a bike together.

    I know very little about the history of the bikes, whats good, whats not. I know less about upgrades or must haves. What I know is what my goal is: I want a light dual sport bike with no frills. I want to put it on the back of my Jeep and carry it 8+ hours away then use the bike to tool around to explore an area. I wanted a bike that was low and light, something for trails, no jumping or flying down 2 tracks.

    I decided on an early Yamaha because it was rather light, low, and looked simple (it looked cool too). Out of the 3 bikes I bought for 350 bucks, I've decided to use the '73 bike as my "core", scavenging parts from the other 2 to create one running bike.

    I'm cheap. Lets get that out of the way first. I work at a metal shop making brackets, springs, tools, etc...my main hobby is my 4x4, which I build every accessory I can (including trans adapters, axles, etc..)and buy nothing, so I'm not as afraid of tearing stuff apart as I should be.

    I'm going to document my progress on this "creation" as much as I can and hope that if someone has a tip or two, they could chime in!

    Here is what I'm working with: Front bike is my buildup, blue rear bike is donor and the second pic down is also a donor bike.
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    I have 3 engines at partial points of disassembly. This was my main focus, if I didn't have an engine, I didn't have a bike. The "good bike" (I'll say that from now on) had piss poor compression according to the previous owner. So, he picked up a new piston/rings and found a head in good shape and set it on the motor, didn't bolt anything down.

    I've got 2 reed valve motors both not very nice inside the heads, and the one good head thats non reed valve. I take it there will be a performance loss by using the older style, but on the pluss side the reeds will not be an issue. So, I've already talked myself into using this one good head on the motor.

    I've got the parts laid out on a table for review.....
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    I tore the engine apart about as far as I want to go. The gears shift fine and there was only light rust around the connecting rod where they let some water seep in there. I flushed out the engine with some ATF and drained it and it feels tight.
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    I'm going to try to revive the old oil injection pump, all the bikes I had were blocked off in one way or another. I've got 2 actual pumps and I tore apart one of them and cleaned it up, it appears to function just fine, but I lost one spring.......about the size of a flippin' hair. I found one, but not the other. Note: Do not disassemble the oil pump without extreme caution and good lighting! I pulled the second pump out of the donor bike to borrow the missing spring to finish the rebuild. Also, some water got into this case and the external spring was pitted, I grabbed that from the donor too. I don't want a premature failure from a spring to kill my engine!
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    More.....
    #1
  2. lgottler

    lgottler Been here awhile

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    I pulled the clutch plates out and measured them up. I've got a bit of uneven wear, all are within specs, but some are actually thicker than the book says they should be! I'm not sure if I should just use it as is. I'm planning on tearing another clutch apart to see what those measure before I make a decision.
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    Oh, best damn tool ever! These bikes are all put together with phillips screws, I'm not sure why because they suck! I stole this tool from my father permanently. You strike it with a hammer and it rotates slightly at the same time. All the screws I was swearing at came out after a few taps with the hammer. I'm thinking of replacing most of the fasteners with allens, we'll see if I can scrounge some off the other bikes.
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    I put in a shot of my front and rear sprockets simply because I have no idea if they are worn or look OK. Chain is rusty in some spots, I was planning on just soaking it in kerosene and then oiling the snot out of it.
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    More.....
    #2
  3. bpeckm

    bpeckm Grin!

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    Apr 2, 2008
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    7,000
    Location:
    Road Island
    Welcome to the club... something tells me that you are capable of doing more "showing and telling", rather than asking..... :eek1

    It's a fun obsession.... we should all be so lucky as to have two donors for our projects!

    :wink:
    #3
  4. lgottler

    lgottler Been here awhile

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    I take it I need DOT approved tires and not these cracked ones on the bike....? Do they even make tires in a size for this bike? I'm missing my note stating the size, but I seem to remember 3.25x18 and 3.5x18.....
    #4
  5. bpeckm

    bpeckm Grin!

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    7,000
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    That, and get yourself some AeroKroil.... best nutrustbuster out there!
    #5
  6. lgottler

    lgottler Been here awhile

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    Oddometer:
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    Do the rear shocks go this way?
    [​IMG]

    Or this way?
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    #6
  7. lgottler

    lgottler Been here awhile

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    That I do have! I soaked all the bikes in it when I first rolled them in!
    #7
  8. lgottler

    lgottler Been here awhile

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    I'm probably going to ditch the stock air box....1)Dealer said the air filter was obsolete 2) I plan on accidental water crossings and I don't like the location of the intake.

    Anyone ever run something up between the speedo/tach? I'm thinking just some tubing right off the carb heading up towards the top of the gas tank. A small cone filter stuffed into a cup of sorts with an oversized lid to allow air in and rain away. I could run a "hard line", just thin wall tubing bent to shape, then squeezed flatter to tuck closer to the tank, use two rubber hoses to connect either end.....hmmmm.....its a ways off.

    [​IMG]
    #8
  9. Trailing Jack

    Trailing Jack Dr. Acula

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    Jun 1, 2004
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    1,172
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    Clearfield PA
    That way :lol3
    Springs on top.
    #9
  10. Solo Lobo

    Solo Lobo airhead or nothing

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    Mar 16, 2004
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    9,662
    Location:
    Shoreline, WA
    If you air filters are paper with a metal mesh core, the old trick is to strip off the old paper filter element, buy a new car filter (Chev V8 or the like) and take the new filter's paper element, strip it off of it's holder and glue it to the bike's old metal mesh sealing as you go with silicone....
    #10
  11. lgottler

    lgottler Been here awhile

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    That probably would have worked. A mouse was living in box air boxes and between eating the foam filters and peeing on the metal, there wasn't much left besides two orange rubber rings. :D
    #11
  12. Putts

    Putts Gettin' there.

    Joined:
    Aug 22, 2007
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    Holy Crapamoly! Nice first thread, mate! :thumb

    Pictures; grease; busted shit; sacraficial bikes; things put on upsidedown; it's got everything!

    :lurk
    #12
  13. lgottler

    lgottler Been here awhile

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    Thanks, I like pictures.....I don't have to type as much.

    Just got the engine gasket set in the mail today. Also bought some new levers, I don't like plastic ones...
    #13
  14. JWhitmore44

    JWhitmore44 pistolero

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    NW Kansas
    Looks like you are due for a new chain and sprockets. I always wanted one of these bikes when they came out. I picked one up a few years ago and seemed like when ever I wanted to ride it i had to work on it first. Sold it for what I payed for it and moved on. If I wouldn't have been so cheap at the time and dug up a carb kit it probably would have been fine :D I think you can still get the "universal" tires in that size from places like Dennis Kirk.
    #14
  15. El Guero

    El Guero V4 Whore

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    Iowa City, IA
    I remember putting a lot of work into a '73 Yamaha 125 just last year. It was a riot as a first bike but be warned... You are going to get bored REALLY fast unless you weigh 125 lbs. The 175 probably has a little more oomph to it so that actually might be pretty good around town :D
    #15
  16. lgottler

    lgottler Been here awhile

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    I scout trails in Canada right now in my Jeep, a top speed of 45mph with my tires at 5psi, if I could do that on a bike, I'd be thrilled!

    I may get this thing running and fall in love with exploring on it, or I might not like doing that on a bike. Its kind of a gamble.

    I found some Kenda K270's that look like the right size. I've got no clue when it comes to tires and whats good and whats not. I guess I'll find the most aggressive DOT tires I can find that fit.
    #16
  17. lgottler

    lgottler Been here awhile

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    Last night I finished assembling the oil pump, mounted it in a different case cover, cleaned up a few odds 'n ends, free'd the stuck piston ring, assembled the head and finished packing the clutch.

    Out of all the clutch discs I had, half were cracked, the nasty old blue bike actually had the nicest clutches in it, probably only a couple thousand miles best guess. Went through all the rubber cusion/spacer things that go between the clutch pack and picked out the nasty cracked hard ones and replaced with the nicest soft ones. I smoothed out the rough edges on the part the clutch rides on, hopefully it'll result in a nearly perfect clutch action.

    I plan on torquing the head down and doing a compression test by hand....we'll see if I can manage that one...

    [​IMG]

    As far as tires go, I measured around the rear tire for clearances. I want the widest tire I can on the rear, I plan on hitting wet stuff and sand frequently so I think I need the flotation, same with the front. Its just shy of 1" on either side before I contact the swing arm on the back...

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    #17
  18. lgottler

    lgottler Been here awhile

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    Nope. Nada on the hand compression test! I managed to only get to 30psi.....by hand, cold, with a leaky seal on the tester....bla. I'll do it for real once its all together.
    #18
  19. lgottler

    lgottler Been here awhile

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    Aug 19, 2008
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    Its been a while. My car broke down so I had to fix that (head gasket), then we had a mini vacation (long weekend) so not much got done in the garage.

    I managed to set the points and just about wrap up the engine/trans.
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    I tore down and cleaned the carb up, I need to replace one O-ring then its done. All the bikes had junk O-rings, so no luck there.
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    I started on the cables for everything. I lucked out and I have a good clutch cable, good throttle cable, good front brake cable, and both the speedo and tach cables work. I had to lube 'em all up, but after working them all they work very smooth now without any binding. No frays are visible, so I'm just going to see if they last.

    The brake switch required some parts from the other bikes to get it working right and bolted up right. I'm soooooooo glad I have the other 2 bikes, cuz a bunch of this small stuff would be a PITA to find!
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    I took both seats apart. Looks like the hinges are different. So, I'll take them to work and sandblast both, grab the hinges and prop rod and rubber from the one and make the second seat work. I'll have to weld a few areas back together though. I think I'll just reuse my seats right now, its torn, but a bit of tape should keep it together until I see if I want more foam etc...
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    Other things: Looks like the sparkplug boot thingy won't fit over the spark plug head. Not sure why, but I'm going to stop at the auto store and see what they have. The front brake adjuster nut thing is screwed up on all 3 bikes. I'm either going to use the best of the 3 or try making a new one. Battery is shot, need another one. Cleaned up the chain, looks good, I put some light lube on it until I get it together and find out if its stretched too much or if it fits fine. Probably need a new oil pump cable.

    Lucas
    #19
  20. lgottler

    lgottler Been here awhile

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    Welp, I did the seat today after work. Sandblasted it, welded it, primed it, top coat, glued the seat down and put the old cover back on it. Turned out nice I think. A new seat cover would look nice, I'll have to see what is out there for these older bikes. (oh yeah, the pink sparkly shoe is my daughters....)
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    This little dohickey has got me stumped. I'm assuming the spark plug boot portion will only snap over the old style sparkplugs with the "threaded" heads??? Cuz it doesn't go over the standard plug I have. The autostore parts guy looked at me with a blank stare and suggested I try a new sparkplug......:slap:
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    And I spent about one hour looking for my rubber bushing package I bought. 10 pcs of the little rubber with metal sleeves used all over the bike, I bought one pack and I can't find it ANYWHERE. I'll be uber ticked if I need to go and buy another package....
    #20