thanks krusty kritter

I picked up a '71 yamaha CT1 and the shifter wouldn't stay engaged. I did a
google (groups) search and found a March 2002 response you wrote regarding
the same problem. You wrote :
<The ends of the hairpin spring rest on the eccentric shaft...
This eccentric shaft, about an inch long, allows the shifter mechanism to be
adjusted, and its locknut can be tightened to lock it in place... I have had
the eccentric break off, and fall out... >

Sure enough, you were right on, the eccentric shaft was busted off and
laying on the bottom of the case. Thanks! You saved me a bunch of time and
aggravation.

walt

'71 ct1

'73 T140V

'91 FXR

 

I'm glad you found that write up helpful. I fixed two AT-1's that had
that problem, as well as my DT-1...

Can you kick start that bike while it's in gear?

The DT-1 had in-gear kick starting via an idler gear that had spin on
the end of the countershaft. Yamaha had three versions of this gear.
One had copper plating in the bore meant to act as a bearing surface,
the next version had a copper bushing, and the third version of the
idler gear was made of bronze. The cooper plated version was the one
that seized onto the countershaft, as I recall. I had to grind that
gear down and split the remnants with a chisel so I could split the
cases and replace the countershaft...

 

I haven't tried (in gear). I obtained this bike from a co-worker who had it
sitting outside last year because he had no where to keep it. He gave it to
me (as in FREE) and I reassembled the motor (he had the right case cover
unbolted and the oil pump cover off), I also heated up the brake lever and
shifter lever because they were all twisted. I followed all that up with a
good washing. I tried to start it and she fired up on the second kick. I
shut it down asap because i didn't know if the oil pump worked or if he
premixed the fuel. He had told me the shifter didn't stay engaged and that's
why he started to take it apart. I thought it was a busted hairpin but once
i tore it apart i found the broken eccentric screw. I ordered a new one
online and the clutch nut lock washer (and the eccentric lock nut washer,
bend the tab style)
Once I get all the parts, and case oil, i'll check the oil pump and fire it
up again. (i called him and he said it was working the last time he rode it,
hopefully it still functions)
Here are a couple of pics:
http://www.wallys-speed-shop.com/ct1case.jpg
http://www.wallys-speed-shop.com/AFT2.jpg
http://www.wallys-speed-shop.com/AFT1.jpg
(note the rear brake linkage, it is now UNDER the swingarm.)
She should be a nice little rider... even nicer 'cause it was free!

I'm hoping there are no more surprises, i really dont want to split the case
and bs with it, no time, i have to finish up a salvaged jeep wrangler i'm
fixing for the summer. The kid who owned the CT1 said it ran great a year
ago until the tranny shifter acted up.
Thanks again, i owe ya a beer for the heads up!
wall
ps. check out some of my crap on my website and sign the guestbook.
http://www.wallys-speed-shop.com

 

Such a deal! I wish somebody would offer me a free mid-1970's DT-2 or
RT-2, those were 250cc and 360cc models. Or maybe a DT-400. That would
be nice...

I used to hate those little CT-1's when I raced moto-X. They had enough
power and they had a shorter wheelbase than my DT-1, so they could turn
tighter corners and just go inside me in the hair pin turns...

I can see your bike does have the in-gear starting feature, the idler I
mentioned is between the kick starter mechanism and the clutch. It's a
simple affair to remove a circlip and inspect the inside of that gear
to see if it has a copper bushing or is one of the copper plated bore
gears. That type will weld itself to the countershaft if it doesn't get
enough oil...

Another thing I had go wrong under that cover was the steel pin that
the tachometer drive gear rotated on fell out, it was just pressed in.
The steel pin got caught by the big clutch gear and it was pushed out
through the gasket surface of the crankcase and the clutch cover, so I
had to pull the engine out and split the cases to replace that
crankcase half...

Keep your air filter clean, and don't allow any dust leaks if you ride
it off road as it was intended to be ridden. Small displacement,
high-revving 2-strokes will burn out the rod bearings if the air filter
gets dirty or leaks...

They need a light weight 2-stroke oil that's nice and thin so the rod
bearings won't skid when you first start the engine up from cold...

 

what would be the best way to check the oil pump? I was going to start the
bike, crack the banjo bolt that goes into the cylinder (while manually
advancing the pump- where throttle cable attaches) and see if any oil
trickles out. I'll premix some fuel with oil (just in case the pump doesn't
work)
if you have a better idea, lay it on me.
I never raced motocross, i used to borrow a friends RM125 along with the
brother in law's CZ 250, those bikes were a blast (of coarse that was almost
30 years ago). A few years back I bought a snowmobile, the acceleration is
incredible on those sleds. Once summer came, my harley fxr seemed really
slow. We added ross racing pistons, andrews cam, and re-jetted the carb. The
bike has a better response, but it's still nothing like a 2-stroke.

wall

 

Yes, that's a good plan. Mix oil with gas about 24 to 1 ratio so the
engine gets oil while you're bleeding all the air out of the injector
lines...

Yamaha engines didn't have pressure lubed crankshafts like Suzukis, it
just squirted oil into the intake port to get mixed with the gasoline
there, so pre-mix works good...

When you start oil-fouling the plug, you'll know the injector pump is
working good and you can stop pre-mixing...