Quantcast
Jump to content

Hoping against hope that you will tell me that my '86 225 Moto4 is not as bad as I think

DaveswMN

By DaveswMN
in Yamaha ATV Forum

 Share

Recommended Posts

DaveswMN Newbie

DaveswMN

Posted
Posted

Pulled my '86 Moto4 out of shed where it sat for 20 years. I knew it smoked. checked it over a little put in gas and it fired right up!! 

Drove about 100 yards, ran about half throttle wouldn't idle.  Put on somenew parts, jug/piston and rings, carb and valve seals.

'went together ok, tuned it over by hand about 6 revs whick went well. Hit the starter it fired for about 6 revs and quit. tried it again fired once and then th sound of something slipping like maybe chain slipping over spoket.

Took cover off to watch cam sproket, hit starter again, heard same noise and the cam sproket was not turning but jumping a bit. Chain was still tight. You will probably tell me I need to split the lower case but hoping there mightbe something else.

I don't fully understand the chain tightener, the plunger only moves about 1/4 inch, should it move much more than that when off the motor and compressing it by hand?

Thanks for any thoughts.

Mech Grand Master

Mech

Posted
Posted

It's sometimes possible to remove the tensioner, drop the cam sprocket off the cam, let the chain off so there's more slack, then try to get the chain to go back on the bottom sprocket by manipulating the chain, possibly with a length of stiff wire down the hole levering the chain over. Then put the chain on the top sprocket, lift it onto the cam shaft but don't put the bolts in, check and redo the cam timing being careful not to bend any valves, then assemble it back up. If you can't get the chain on the bottom sprocket then yeah, you take the side case off again.

Stateing the obvious perhaps, but, you have to check the cam timing with the slack taken out of the chain and all on the tensioner side.

I'm not sure how much travel the tensioner should have, but it needs to be enough to take the slack out of the chain. It would be a good idea to figure out why the chain slipped. The tensioner has a ratchet mechanism, visually check the teeth  and pawl of that, and test it lightly, with big pliers perhaps, but only gently.. The other thing that happens is that people don't get the two slippers sitting in the correct places at the bottom, or even up the top on some models. If/when everything looks and tests ok then put the tensioner back in and turn it over..

DaveswMN Newbie

DaveswMN

Posted
  • Author
Posted

Pulled the cover,stator and fly wheel and found the chain off the sproket. Replaced, timed turned by hand. doesn't seem to have much compression. spun it with the starter and did not start. Checked the tappet gap and found them to be off from what I had set originally. Haven't been back at it but seems like I might run out of threads when I get back to adjusting the intake valve. Both vales seemed to be operating ok by looking thru spark plug hole. Hope to get back at it in a few days.

Mech Grand Master

Mech

Posted
Posted

You've got a bent valve or two preventing the valve from closing right down onto it's seat, and that's why the valve clearances have opened up and why there's no compression.

Head off again I'm afraid.

DaveswMN Newbie

DaveswMN

Posted
  • Author
Posted

I'm suspecting now that a valve is bent. If when I originally turned the engine over and it fired for about 4-6 times I heard something. If the chain was riding on one side of the chain and when it fell off the sproket could the valve have hit the piston and got bent?

GM, didn't see your last post about the bent valve until after I asked about it.

DaveswMN Newbie

DaveswMN

Posted
  • Author
Posted

GM, didn't see your last post about the bent valve until after I asked about it.

The original cylinder gasket had the open spaces on three of the holes and included an o-ring. There is no seat for the o-ring on the cylinder I bought and the gasket I bought does not have the open spaces on the gasket. Is this ok?

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing

  • Similar Forum Topics

    • HHurks
      CFmoto ATV Parts and Accessories
      By HHurks
      Yesterday I got a UForce 1000 as my first bike and I am wondering if there are any owners that could advise where I can find budget parts and accessories for it.
      I tried looking StarknightMT, but the filtering is a bit unreliable, so direct links or exact names are much appreciated.
      I'm mostly interested in sliders and side cases, but any advices for "must haves" are welcomed.
      Thank you!
    • KIWINZ
      Moto4 Shifting
      By KIWINZ
      Hello
      My son scored a free Moto4 - late 80s from the looks of it. I don't know anything else about its history as the owner wasn't there when i picked it up. Can't see the VIN number as its a bit rusty.  He cleaned the carb and then with some either it started and still starts first pull.  Its runs really nice - not rattles etc.  Goes forwards well and the brakes work fine so it looks like a keeper, However, we have only managed to get it into reverse once.
      1) it won't shift down into what seems like where first would be - 2nd and upwards only. The changes between gears is fine.  No crunching or missed gears - just no first gear.  2nd gears appears to be as low as it will go
      2) the clutch - when you hold the gear lever up or down works (only the second ATV we have had.  Other is a Quadrunner which doesn't have this feature)
      3) no neutral light - will start when no in neutral - should it do that?
      4) the one time we did get it into reverse the neutral and then the red (reverse) lights worked. Swapped easy between forward and reverse - when it went into second, it didn't return to first or neutral
      5) checked the clutch adjust on the RHS - seemed fine to me.  When i turned the screw back 1/8 it was where it was to start with.  Clutch doesn't slip.  The bike will move forward is all gears.
       
      Any help would be appreciated
       
      Thanks
       
      Andrew
    • tin
      My Moto4 project
      By tin
      A few weeks ago, I foolishly asked my girlfriend about a quad that's been sitting under a tree at her parents' place for 25 years... This thread will be a sort of log of my attempt to resurrect it. I'm actually a computer guy, not a mechanic, so this will be quite conical for some of you, I'm fairly sure 🤣
      So far I've found out it's likely a 200. Not sure what year yet... The frame has a serial of 53J-001343 (I think). Engine appears to have the same number.
      We inflated the tyres on Saturday, which were still up today, so that seems a win. This also confirmed that the wheels do turn, as it rolled back into its 25 year old indentations as the 4th tyre started coming up.
      Oil looks used but otherwise OK. I'll change it if I actually get it running, but looks good enough for attempting to start it up again.
      Fuel tank had.... something in it. It smelt more like old stagnant water than fuel of any sort. Drained that out and flushed some clean fuel through to be sure.
      Fuel tap was jammed in the off position. WD40 and some force got it free. Did that after the fuel hose was off, so hopefully the carb isn't full of whatever it was in the ttank.
      Engine turns fairly easily with the rope start. Made typical exhaust puffing sounds.
      Unfortunately the rope mechanism was not fully rewinding, so I was limited to about half its length... And today it jammed fully pulled out. I attempted to remove the rusty screws, but one stripped it's head out. So for now the rope rewind is jammed.
      Spark plug connector seems possibly burnt inside. Black crap on both the plug and up in the connector, and the connector doesn't seem to actually stay on.
      Throttle lever is stuck fast. See photo for possible reason... Cable also feels jammed. I assume the throttle itself is jammed. That'll be fun given my skill level.
      Electrical stuff all seems dead. No headlights. No starter. No indicator lights. Could be a fuse. Could be bad connection. Not something I'm too worried about at this point.
      Front brake handle works. Parking brake clip thing was bent out of shape, but that's now fixed and working. Front brake only works on one wheel. Other one seemed rusted in place (off). WD40 and hammer got it free, although still stiff. Cable might be broken as it doesn't move at all when the handle is pulled.
      Rear foot brake works but needs adjusting.
      Other handlebar lever doesn't budge. Not sure if that's a clutch lever or rear brake... If this is the 200 version, I gather it's got a centrifugal clutch so it would be a brake lever... But I'm not yet sure exactly which model I'm working with. And the cables all disappear under the plastics and fuel tank and I didn't bother trying to trace where it goes yet.
      Thats probably about it for this post.

    • ATVcenter
      CFMOTO owners - How's parts availability in your area?
      By ATVcenter
      Hey everyone,
      I'm seriously considering a CFMOTO 600 Touring but keep hearing mixed feedback about parts and dealer support depending on where you live.
      Before I pull the trigger, I'd love to hear from actual owners:
      - How long do parts usually take if your dealer doesn't stock them?
      - Have you had any warranty work done? Was it smooth or a headache?  
      - Does your dealer provide decent service, or are you stuck doing everything yourself?
      The value proposition is hard to ignore - seems like you get 30% more features for the money compared to the Big 3. But I'm trying to figure out if the potential service headaches are worth the upfront savings.
      Would love to hear real-world experiences, especially from owners 2+ years in. What should a potential buyer know before committing?

    • dink1970
      Can Am Parts and Accessories from UTV Wolfpack
      By dink1970
      Explore your Can Am Parts and Accessories from UTV Wolfpack. We have a great selection of products for the Maverick XRS 64 and  Maverick XRS 72 Accessories.
       
      https://utvwolfpack.com/shop/can-am/

COMMUNITY SECTIONS

ATV FORUMS

QUADCRAZY MEMBERSHIP

Be a part of best online community of ATV riders and join thousands of people who love ATVs! Share your ATV photos, videos, ATV rides, get help with your ATV and more. Not a member?

SIGN UP TODAY

ADVERTISE WITH US

FOLLOW US ON

  • Automotive Webmaster
×
×
  • Create New...