Two Stroke Motocross

Two Stroke Motocross Forum => Vintage Two Strokes => Topic started by: citabjockey on January 22, 2012, 04:52:07 AM

Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 22, 2012, 04:52:07 AM: My latest bike. This one deserves a nice restoration. Hope I am up to it. Most of the parts are there, the rest are not that tough to find. Engine is stuck. So is the tranny. Fork tubes are probably a total loss, maybe the rear rim as well. Fuel, oil tanks have zero dents. No dents in the rear fender and pipe either. Just lots of corrosion.

Going to be fun!
Title: Another Vintage Project, 1968 DT1
Post by: VintageBlueSmoke on January 22, 2012, 09:59:38 AM: I had the (green) 100cc MX version back in the day and my grandpa had the enduro version of the same bike. Ah, the memories....
Title: Another Vintage Project, 1968 DT1
Post by: Coop on January 22, 2012, 11:35:02 AM: Looks like fun.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 22, 2012, 12:26:17 PM: I have worked on a later model before at work. They are pretty fun bikes once you get it going.
Title: Another Vintage Project, 1968 DT1
Post by: xandyx on January 22, 2012, 11:53:58 PM: Dude, that bike is awesome! I saw a rebuild/conversion of that bike to short track, it was absolutely amazing.

I'm gonna search for the rebuild and then i'll share with you!
Title: Another Vintage Project, 1968 DT1
Post by: xandyx on January 22, 2012, 11:56:55 PM: Found it! It was quick! eheh

http://advrider.com/forums/showthread.php?t=557469

Keep posting pics! I love project rebuilds!
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 23, 2012, 05:39:58 AM: My intention is to make it look as Yamaha intended. I have never done a show bike before but am hoping I will be up to the task. Here are a few shots of a '73 360 I cleaned up a couple years back:

Starting point. Pretty complete bike:

Taking it down:

After powder coat:

Fork cleanup:

New top end and other engine clean up:

Assembly:

Finished. There is no better bike for running errands around town or just cruising down a twisty country road with an occasional dirt road thrown in for fun:

I am expecting the DT1 to be a much bigger job and I have give it much more attention to detail to really make it right. I think its a good starting point, will know for sure when I get it opened up.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 23, 2012, 12:24:36 PM: Damn Great job with the one
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 23, 2012, 06:27:36 PM: Thanks for the nice comment. That one was a far easier job and is also a rider -- not intended to be a full restoration. The DT hopefully will be.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 25, 2012, 01:19:03 PM: I couldn't help but notice from one of the pictures the two spark plugs, whats up with that?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 25, 2012, 03:25:23 PM: Yamaha made a few models that had 2 plug holes. You could either carry a spare plug or install a compression release. The problem with that head on my DT1 is its not original. don't know if I am going to do anything about it. Others that know more than I are hinting that it may be a high compression model...
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 25, 2012, 04:57:40 PM: Its possible. So does the second plug actually spark and help fire off, or does it just sit there in the cylinder head and do nothing?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 25, 2012, 07:07:28 PM: Quote from: cnrcpla on January 26, 2012, 12:57:40 AM
Its possible. So does the second plug actually spark and help fire off, or does it just sit there in the cylinder head and do nothing?

It does nothing -- that is until the primary plug fouls. Then you move the spark cap to the spare and ride away.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 25, 2012, 10:54:28 PM: That is actually pretty handy. I would keep it on there, it looks interesting and it serves a purpose, kind of...
Title: Another Vintage Project, 1968 DT1
Post by: VintageBlueSmoke on January 26, 2012, 11:47:06 AM: My '71 Bultaco uses both plugs. If you change the ignition, you can have them both fire. Had a Husky that way once too. My '73 Husky now has both holes but since it has a Motoplat (vice points) one plug is a spare.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on January 28, 2012, 05:09:47 PM: I've got a CZ125 with a twin sparkplug/twin fire head.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 28, 2012, 05:26:41 PM: 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?
Title: Another Vintage Project, 1968 DT1
Post by: riffraff on January 28, 2012, 06:03:52 PM: i always ran a compression release in my spare hole, that would be the one on the side, center hole for sparkplug
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 28, 2012, 08:27:45 PM: Does having both plugs firing make any kind of difference in the running of the bike?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 29, 2012, 05:21:48 PM: 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.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 29, 2012, 05:24:35 PM: 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...
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on January 29, 2012, 06:17:23 PM: A wire brush on a grinding wheel should take care of most of that.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 30, 2012, 04:26:31 AM: Opened the top end. Piston and bore look fine. Rings are free too.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on January 30, 2012, 04:29:12 AM: 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.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 01, 2012, 01:54:16 AM: 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...
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 01, 2012, 12:28:26 PM: I bet she doesn't want to shift because water got into the clutch or something and froze it there (Froze as in rust)...
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 01, 2012, 03:13:28 PM: 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.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on February 01, 2012, 03:23:55 PM: 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.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 01, 2012, 03:39:22 PM: 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.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 01, 2012, 07:41:25 PM: Quote from: cnrcpla on February 01, 2012, 11:39:22 PM
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.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 01, 2012, 07:44:19 PM: With everything original but restored what do you estimate one could go for?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 01, 2012, 07:45:43 PM: Quote from: cnrcpla on February 02, 2012, 03:44:19 AM
With everything original but restored what do you estimate one could go for?

I have seen them go between 5k and 8k
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 01, 2012, 07:55:40 PM: Wow, that's a good hunk of cash. Do they still make all the parts for them to?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 01, 2012, 08:01:31 PM: No. That's why. the bike was historic in that it was the first vertical single air cooled two stroke in a light weight chassis that made good power, was reliable, easy handling, had reasonable suspension. Oh, and it was not expensive. First bike that worked pretty good on trails and you could ride it on the road too. Everything before then lacked one or more of these characteristics. The basic layout of the bike is still in use today. Yamaha broke new ground with it.

This particular year had many parts that were changed in later models so these parts are even more rare. Check out the tach that is smaller than the speedo. One of those that someone finds stuffed into a box in an attic somewhere that is NOS alone would be worth well over $500. I think the dentless, 1 year only, exhaust pipe that came on mine would be worth more than I paid for the bike should I part it on ebay (which I will NOT do).
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 01, 2012, 08:18:46 PM: I see... Well it looks you have quite the "diamond on the ruff" with this expensive kind of project. Good luck with everything.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on February 02, 2012, 03:45:41 PM: I'd have to disagree with your assessment of the DT250.The small bore Hodakas, Zundapps and Sachs of the era had better power to weight ratios, the German bikes handled better with better suspension and all of them were as tough as the Yamaha. I think what distinguished the Yamaha was the advertizing hype that surrounded the promotion of the bike, that broke new ground.I agree as well that the Yammi made a fine street bike.

If you look at Greeves Enduros that predated the Yamaha there are more then a few design similarities.

125 Sachs of the late 60's were actually quicker then the DT.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 02, 2012, 06:29:54 PM: Points taken and quite true. Perhaps it was the marketing (or the low price, non-intimidating dealers, easy parts availability) but whatever the reason the DT1 really struck a cord and tipped the balance for a pretty large public acceptance of these bikes. As so many of them were sold -- esp the follow on models -- there are a lot of nostalgia buyers out there now that want to recapture their childhood. Hence the demand for these bikes seen today.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on February 03, 2012, 03:51:34 AM: The first DT's were very well made and much cheaper then the Euros. I personally really like the Ossa Pioneers from that era, they handled well and had reliable,torquey and fairly quick motors.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 05, 2012, 09:49:16 PM: Engine on the operating table now. Exploration into its "shiftless" nature should begin this week. Carb should be taking a swim soon too. Top of the piston says 71 on it, looks like its already 4th over. Oh well...

Zero dents in the oil tank! Draining the rest of the injector oil. Don't think I want to save this stuff...
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 05, 2012, 11:43:41 PM: Is 4 over the most you can go on this cylinder?
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 05, 2012, 11:45:34 PM: Not sure. Probably ok for the jug but may be tough to find a piston and rings? That said the jug still has hone marks in it. Could be a new 4th over set would work just fine.

Quote from: cnrcpla on February 06, 2012, 07:43:41 AM
Is 4 over the most you can go on this cylinder?
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 05, 2012, 11:48:13 PM: Do they at least make the re-production pistons or one that will fit for you? Or are you going to have to look at some used part-out bikes online?
Title: Another Vintage Project, 1968 DT1
Post by: factoryX on February 06, 2012, 01:11:15 AM: http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=dt1+piston&_sacat=See-All-Categories
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 06, 2012, 02:43:07 AM: From that last post, up to 6th over available for this scooter. No Problemo!
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 06, 2012, 02:44:49 AM: Nice. So are you going to bore it over again, or is it in good enough condition to put a new piston and rings in and call it a day?
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on February 06, 2012, 03:42:11 PM: The piston looks like it has little blow by.Why not measure the top end, it may still be fine.I recently found an old KX and the top end is brand new.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 06, 2012, 06:18:54 PM: This top end is the least of my worries on this bike. As I can go up to 6th over there are plenty of options. The fork tubes, transmission, the seat, getting things rechromed, repainted, etc are going to be much larger road blocks.

If the piston and bore does measure up I may just slap it back in there. As Sachs says, it does look to be in pretty nice shape. As I can go up to 6th over there are plenty of options. Of course putting the existing piston back into a bike I hope to have "new" in most respects doesn't really feel "right"...
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on February 07, 2012, 03:32:55 PM: The cylinder liner gets awfully thin on those 5th and 6th overbores. On some of the old 360/400 Yamahas I've seen the hone break thru. to the alu. cylinder on the 6th bore.
Title: Another Vintage Project, 1968 DT1
Post by: cnrcpla on February 07, 2012, 03:41:38 PM: Sounds like maybe you shouldn't go for a 6th bore even if you had to.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on February 07, 2012, 03:51:28 PM: Right now the liner measures about 4.5 mm thick. Must have started out as 5 mm (its a 1mm overbore now). So that removed 0.5mm off of a 5mm liner. If I go to 6th over that will remove another 0.125 from it. Hard to say if that is going to make it break. A good question for my engine builder expert. Thanks for the heads up on this guys.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on August 11, 2012, 11:02:08 PM: Did some cleanup on the outside of the motor. Then started to remove some extras. Off comes the left side main seal:

Then the sprocket

Open up the clutch cover. On a mission to find out why it will not shift gears. Lots of sludge in there...

Take out the clutch and primary drive:

Then removed the shift shaft and actuators. The secondary actuator did not seem to engage the pins on the drum. After remove that gear I find that the drum refuses to turn. So I guess this is a split case job:
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on August 12, 2012, 03:35:12 PM: I just intercepted the remains of a 68 DT1 on the way to the dump.The motor is actually in nice shape.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on August 12, 2012, 04:40:31 PM: Score! You going to start a thread?

Quote from: SachsGS on August 12, 2012, 10:35:12 PM
I just intercepted the remains of a 68 DT1 on the way to the dump.The motor is actually in nice shape.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on August 14, 2012, 04:10:35 PM: Nope, other projects in the pipeline. I think I have enough parts to complete a 1975 Hercules 175 6A (rare bike) so that will probably be next.
Title: Another Vintage Project, 1968 DT1
Post by: citabjockey on August 14, 2012, 08:52:25 PM: Cool bike. Is that a 7 speed?

Quote from: SachsGS on August 14, 2012, 11:10:35 PM
Nope, other projects in the pipeline. I think I have enough parts to complete a 1975 Hercules 175 6A (rare bike) so that will probably be next.
Title: Another Vintage Project, 1968 DT1
Post by: SachsGS on August 19, 2012, 03:45:00 AM: No, it is a six speed and is a rare oddball - only produced for two years (74 and 75).