Author Topic: Mountain 90 rebuild  (Read 3730 times)

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Mountain 90 rebuild
« on: November 18, 2008, 09:39:12 PM »
I broke the kickstarter shaft off on the oil injection 1966 mountain 90 that I was rebuilding.  I got a new one from Richard, tore down the motor and reassembled it with the new shaft.  After I got it together I mixed one gallon of fuel 20:1 with 2 stroke oil, added it to the tank and tried to start it.  I got it barely running with alot of smoke, and then I couldn't get it to start.  I am pretty sure that it was getting too much oil so I have cleaned out the mix fuel and added straight gas. I can get it started now but it runs poorly and still smokes alot. I probably have too much mix fuel still in the tank.  This brings me to a couple of questions.
1. How do I set up the carb?  The manual says to turn the air screw out 1 and 3/4 turns.  Does this sound okay for 3000' elevation.
2. Where should I set the throat slide to begin with? There is now reference to this in the manual.
3. How should I set up the oil pump for the oil injection system.  The manual suggested turning the adjustment screw out 3/4 turn past where the pin in the pump touches the cam plate.  This is too high for my bike.  Any suggestions?
Richard, I hope your new site works well, we will see if I get any replies.

Offline Mikey

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Re: Mountain 90 rebuild
« Reply #1 on: November 19, 2008, 09:40:24 PM »
I would think it would be carb problems or timing issue. Has it been sitting long? I wouldn't think it is a fuel ratio problem. Just my two cents.

Offline hmmmnz

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Re: Mountain 90 rebuild
« Reply #2 on: November 20, 2008, 12:37:09 PM »
i'd have to agree,
clean out your carb and try again,
im not sure how the autolube system works on bridgestones work, so can't comment on that.

good luck
mini buffalo (chibi copy) 68' mkII 200

Dave K

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Re: Mountain 90 rebuild
« Reply #3 on: November 23, 2008, 07:35:56 PM »
Could the transmission seal be bad also and the engine is sucking trans. oil out of the trans. and trying to burn it?


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Re: Mountain 90 rebuild
« Reply #4 on: December 01, 2008, 12:00:26 AM »
Dave K,
The more I think about it and mess with it the more I think you are right.  I think it is getting transmission oil and burning it.  If I take it apart and put new seals in it, what seals do you recommend that I put in?  It doesn't appear to be leaking any oil on the drive side. 


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Re: Mountain 90 rebuild
« Reply #5 on: January 09, 2009, 04:52:35 PM »
To answer your number 2 question "How do I  set up the throttle slide?" Turn the idle screw so that it raises the slide enough that you can see light come through from the other side.This works best with the carb off the bike.This should put you in the ballpark. 



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