My Suzuki DS 185

[b40rt]

Bultaco

[feetupfun]

7 hours ago, Ftwelder said:

I have three front MX rims, two are for conical so the third can't be easily used.  They are all marked 1.6X21 but vary in outside width from 2.1" to 2.5" on the outside. with the narrowest one being 1.75" on the inside?    What is typical? Why?

Untitled by barnstormerbikes, on Flickr

My experience is that the 1.6 stamping means 1.6 inches between the inside edges of the tyre seat flanges and is only important for knowing which size tyre clamp to fit.

If it was my build I'd use the lightest front rim I had. There was something of a technology race in the 1970s to make the lightest rims for trials bikes. The lightest I've found are Takasago rims from C and D model TY250s and the Akront trials rims that came on Spanish bikes from about 1974 onwards which was the rim design that the lightweight Takasago appears to have been copied from. The Akronts dent fairly easily and the Takasagos eventually crack at the weld.

Your photo rim looks like the TY250 C and D models Takasago front rim

 

 

[htrdoug]

4 hours ago, b40rt said:

Bultaco

Yea,but if fabricating seems like a good time to flip it for better cable routing. I like the cable in front of the forks for easier management.

[Ftwelder]

8 hours ago, htrdoug said:

Shouldn’t the brake backing plate be on the left fork leg?

I don't know. I did it that way so the large part of the axle tightened to the bearing race not the brake plate but that isn't much of a reason. Ill look closer today.

Edited November 22, 2021 by Ftwelder

[htrdoug]

I realize you are in deep but maybe a different set of forks? You could go to a set without the offset axle and fabricate some triple clamps that would give you the same geometry as a modern bike,and the greater depth of the fabricated clamps required for non offset forks would increase your steering lock.

[Ftwelder]

1 hour ago, htrdoug said:

I realize you are in deep but maybe a different set of forks? You could go to a set without the offset axle and fabricate some triple clamps that would give you the same geometry as a modern bike,and the greater depth of the fabricated clamps required for non offset forks would increase your steering lock.

That is how I ended up with this combo in a round about way. I wanted to try 67.5 head angle with 60mm trail. I also wanted fork crowns that had rake. The RL suzuki has 2 degrees but total offset was a lot which reduced trail so I made a Honda head tube and welded it on, added custom CNC Honda crowns and put on a 35mm Betor with same offset I wanted but it's length was too short by about an inch (Honda has long head tube) . A buddy offered the NOS 32mm Betor shown recently with extended stanchion tubes. If the 32 is too soft or flexible I think I have the correct 35mm tubes to assemble a longer version from a later Mexican made Betor fork from a Rokon.  I am flipping the brake to the left side. Much better thanks.

Edited November 22, 2021 by Ftwelder

[htrdoug]

Cool, carry on with your plans! Very interested in how this turns out😀

[Ftwelder]

I chose the Takasago front rim which is 1/4 lb  lighter than the DID but broke a couple spokes while dismantling. Because the Honda Reflex crowns are narrower than 84 KDX 250 I had to dish the wheel toward the drum by 7mm so I should order correct spokes.

Untitled by barnstormerbikes, on Flickr

Reading through the service manual I found inspection numbers for the big end bearing and mine is shot. I persuaded a cart racing buddy to rebuild my crank. He explained the process and offered to send some video. I should have done it myself but I am trying to stay focused. 

The cases have been repaired and I have never been keen on the look if of die cast parts so I ended up using a iron workers needle gun (at reduces air pressure) to blend the finish. My other options involved abrasive particles which are toxic to engines. I assume it will darken quite a bit.

 

Untitled by barnstormerbikes, on Flickr

Untitled by barnstormerbikes, on Flickr

I need to restore the brackets that the electronics mount to and complete whatever frame details remain. I hope to have it done in 45 days. Not sure if I should work on the bike or work on making money to spend on the bike.

 

Edited December 5, 2021 by Ftwelder

[Ftwelder]

I installed the bearings in the cases and the one that supports the counter shaft at the sprocket is a tiny bit loose. No play but not tight. Ill use some sleeve retaining compound to tighten it up.

Untitled by barnstormerbikes, on Flickr

One of the original coil mounts was missing so I deleted the remaining one and made two new ones. The tank tunnel is pretty narrow so I kept that in mind.

Untitled by barnstormerbikes, on Flickr

Untitled by barnstormerbikes, on Flickr

The next thing is the ignition system. I am going to try to make two into one with each system. This will involve soldering, volts and other things that I don't understand.

Untitled by barnstormerbikes, on Flickr

 

I have another with a good coil that I will attempt to splice in.

 

 

Edited December 10, 2021 by Ftwelder
details

[tony27]

The big coil isn't needed, it's the lighting coil

[Ftwelder]

17 hours ago, tony27 said:

The big coil isn't needed, it's the lighting coil

I wondered about that. Can one run those wires to a on/off switch and onto a small LED headlight?  I have a rectifier also.

I ran a test on my CDI unit and it failed. Based on my record of success with electrical issues, It's probably actually good.  I also have one from a '76 PE250.

I did a facetime session on two-stroke crank rebuilding (Thanks Scott!) and decided to do the crank myself and made a crank splitting fixture. It will fit 125mm crank wheels and a 50mm conrod. I added 160mm risers and a support on the backside.

Untitled by barnstormerbikes, on Flickr

Untitled by barnstormerbikes, on Flickr

My riding buddies have been asking me how the bike will be branded once completed. I like this Suzuki Genuine Parts logo. 

Untitled by barnstormerbikes, on Flickr

After some tweaking. I hope Suzuki doesn't get mad.

Untitled by barnstormerbikes, on Flickr

 

 

[stevec]

[tony27]

I doubt you'll be able to run a LED headlight from the 2 thin coils, they are what connect to the CDI so they won't be supplying constant power. The only testing I ever did on the CDI in my Suzuki ignition fitted to my 73 CZ380 Mx bike was substitution, testing the primary & pulsar coils are easy but I ended up ditching the system due to lack of spark that I couldn't find the cause of, I suspect a bad connection somewhere

[Ftwelder]

19 hours ago, tony27 said:

I doubt you'll be able to run a LED headlight from the 2 thin coils, they are what connect to the CDI so they won't be supplying constant power. The only testing I ever did on the CDI in my Suzuki ignition fitted to my 73 CZ380 Mx bike was substitution, testing the primary & pulsar coils are easy but I ended up ditching the system due to lack of spark that I couldn't find the cause of, I suspect a bad connection somewhere

My thoughts are that I may build a testing device that allows me to spin the fly wheel and run the magneto to see if I can make spark. It seems like a logical step and pretty easy to do in a lathe. It would be great to have ignition system that is known to be working. when I go to start it for the first time.

[htrdoug]

On 12/12/2021 at 6:03 PM, Ftwelder said:

My thoughts are that I may build a testing device that allows me to spin the fly wheel and run the magneto to see if I can make spark. It seems like a logical step and pretty easy to do in a lathe. It would be great to have ignition system that is known to be working. when I go to start it for the first time.

Just put everything together all oiled up and leave the cylinder head off, spin it with a electric drill . You can even set the timing dynamically that way. I just had to diagnose a Sherco 250 that was violently kicking back, broke the kicker even. I pulled the plug, highlighted the TDC mark they have and spun it with a strong electric drill. Saw it was firing 4 times a revolution, only way it could do that would be triggering off of the charging coils feeding back through the ground circuit into the trigger pickup circuit. yep, bad ground. Would have been sucky trial and error component replacement if I hadn't of spun it up, instead of recognizing exactly what the real symptoms were.