Another Vintage Project, 1968 DT1

[SachsGS]

I've got a CZ125 with a twin sparkplug/twin fire head.

[citabjockey]

So for those that have twin fire heads, can you feel any difference if you disconnect one of the plugs? How much difference does dual firing plugs make?

[riffraff]

i always ran a compression release in my spare hole, that would be the one on the side, center hole for sparkplug

[cnrcpla]

Does having both plugs firing make any kind of difference in the running of the bike?

[citabjockey]

I cannot speak to motorcycles but when I was flying small airplanes those engines always had twin ignition systems. Part of the engine run up includes shutting one down and observing the RPM drop. If excessive then you would not fly. The drop was typically a bit less than 5% so a 2nd plug -- in those engines at least -- had less than a 5% advantage with two plugs firing.

[citabjockey]

I had a few minutes last night. Curiosity got me to finally remove the mag cover:





Looks like I get to start dealing with a *touch* of corrosion...

[cnrcpla]

A wire brush on a grinding wheel should take care of most of that.

[citabjockey]

Opened the top end. Piston and bore look fine. Rings are free too.

[citabjockey]

Electrics need some work here and there 



Carb throat and slide are not too bad



So it would seem the water did not make it into the crank cavity (maybe). Will remove the piston tomorrow and also try to dissect the carb.

[citabjockey]

Time to reveal the stator. Removed the nut and lock washer from the shaft. thread in the flywheel puller. Took a bit of finagaling to get it to start but the left hand threads in the wheel appear to be intact.



Did not bother to put a wrench on it, went straight to the big boy tool. Set on low. Pulled the wheel off with no drama at all. Nice.


Stator appears crusty but basically intact.



Going a little less Cro-Magnon on the stator screws...




Stator is out.





With the ugly magneto off the engine, the crank now turns nice and smooth! So far no sign of water visits to the crank cavity.  Still have to figure out why she doesn't want to shift...

[cnrcpla]

I bet she doesn't want to shift because water got into the clutch or something and froze it there (Froze as in rust)...

[citabjockey]

The clutch is turning now with the kickstarter -- which also turns the crank. So I don't think it has anything to do with the clutch. Of course the plate ARE probably stuck together but thats another issue.

I have a feeling that there is a broken spring in the shift actuator or something stuck or broken on the actuator arm in the transmission such that it will not engage the shift drum. I will find out after I get the engine out of the frame. You can move the shift lever up and down to its travel limits but it never seems to "grab" anything to move it.

[SachsGS]

Usually during the course of a restoration you find out why the previous owner parked the bike in the first place.I'm restoring a TM 250 and it is one of the most badly abused bikes I have ever worked on.

[cnrcpla]

It looks like you might be splitting the cases then, because that seems to be the only way to accurately diagnose and fix this issue.

[citabjockey]

It looks like you might be splitting the cases then, because that seems to be the only way to accurately diagnose and fix this issue.

On these motors, most of the mechanism to move the shift drum is under the clutch and outside the center cases. If I can find the issue there then I may skip the split.

As far as the PO parking the bike, what happens in bikes this old is the owner got tired of it and just stopped riding it. THEN the rust starts to take over. Apparently there was water in the mag cover. So far none in other critical areas. The bike is looking far better than I expected it would (being 45 years old). That said it is going to be a pretty big job.

There is one of these on ebay right now:

http://cgi.ebay.com/ebaymotors/ATENTION-COLLECTORS-One-most-popular-motorcycles-Yamaha-ever-built-/320839950539?pt=US_motorcycles&hash=item4ab38d20cb ]



Link is HERE

It is a VERY nice bike but some of the work and/or components used are not to the original bike which in some cases tends to reduce the value. Will be interesting to see what it goes for... Right now the bidding is pretty near my build budget limit for mine.