Jump to content

Recommended Posts

Here is the motor I started to put together this weekend. It was an rt 195. I sold the rt topend  when I got a deal on an rb20. The transfers were opened up considerably and the cases where welded for extra material and matched to the kit. I had an unused 62 mm stroke crank that was rebuilt, welded. All machine/welding, crank rebuild done by Adam Bower. I rebuilt the bottom end. I would have finished, but I cant find the case studs, so I had to order more. 

RB20, mammoth head, lth short intake, 62mm crank (cant remember rod length), rayspeed 46 tooth 7 plate clutch,  16 drive sprocket, old rayspeed close ratio gearbox, casa axle, slotted rear brake shoes, Indian12 volt elec. ign., lightend flywheel, jl mk4 race exhaust (modified by A.Bower from ts1 to fit rb)

20190610_113603.jpg

20190610_113732.jpg

20190613_111126.jpg

  • Like 2
  • Upvote 3
Link to post
Share on other sites
  • 5 months later...
  • 2 months later...

At the end of last years riding season I had what I thought was a blown seal. Bike idled fine but when put in gear and let the clutch out , the bike dies.  If I feather the clutch and get the bike moving, it would run but I had to really over rev it. So I pulled the motor, had a third transfer cut in the case and cylinder and while it was all apart had the seals replaced. I learned some new info and thought I'd share. I was told that the spigot (the bottom of the cylinder that fits into the case) on rb20's is a little on the thin side and on some kits can warp and go egg shaped and pinch the piston. During the cutting of the new transfer,  this problem was discovered on my cylinder.  It was slight and corrected with a hone, but is an issue that can happen again. If it deforms alot, it can seize the motor. The solution to fix the issue is to resleeve the cylinder and use a smaller piston. Thanks to Adam Bower for the work and info!

First, second and third picture is prior to 3rd transfer. You can see how thin the spigot is

Screenshot_20200210-092000_Chrome.jpg

 

Screenshot_20200211-074243_Chrome.jpg

Screenshot_20200211-074207_Chrome.jpg

20200209_102809.jpg

  • Like 1
Link to post
Share on other sites

I believe so, but the top end was entirely set up by Adam so he knows the details. I'm guessing it was finding the right combo of the 62mm crank, rod length and squish clearance to give timings of about 190, 130. I just did the bottom end. The bike is really light too. I'd love to run it on the salt. 👍😉

Link to post
Share on other sites
  • 1 month later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...