collapse

www.dimecitycycles.com


www.restocycle.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.bisonmotorsports.com

www.speedmotoco.com

www.cognitomoto.com

www.townmoto.com

www.sparckmoto.com

www.Moto-Madness.com

www.pistonsociety.com

www.steeltowngarage.com


Author Topic: RD400 - Back from the Dead  (Read 9942 times)

Offline Ryan Stecken

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 1779
Re: RD400 - Back from the Dead
« Reply #10 on: May 30, 2017, 11:39:25 »
Subscribed!
make sure you exchange the rotten crank seals too!

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #11 on: May 30, 2017, 13:25:53 »
Subscribed!
make sure you exchange the rotten crank seals too!

Purchased and on the way!  ;)

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #12 on: Jun 04, 2017, 03:07:45 »
As always... we begin with the carbs. Popped them off, and gave them a rigorous boil in lemon juice... So clean you could eat off'em now.

Popped off the reed valves... seems the reeds are a bit slack. Might be normal, will have to check the manual. Then I took the heads off. To my surprise, the pistons look fairly new... both have different gaskets, and both have different numbers stamped on them... could be one is OE? I cant tell. 

Some minor concerns started bubbling up once the motor was coming apart... mainly, the pistons are loose in the cylinders... front to back and side to side... about .010 to .020...

Im going to pop the rings off and check them in the bores... also going to read up on the clearances in the manual... hopefully all is well ... ?

Offline teazer

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8248
Re: RD400 - Back from the Dead
« Reply #13 on: Jun 04, 2017, 12:17:47 »
Those are 1mm oversized Wiseco pistons with very few miles on them and rocking at the top is not an issue. Pistons have a taper and are smaller at the top than the bottom and smaller again between the ring lands.  Check the clearance between bottom of the piston skirt and the bore.  Wiseco use different clearance than stock cast pistons.

Reeds tend to do that so get a set of new petals. Call John at Economy Cycle and see what he has for a stock motor. There are a few choices.  The only ones I don't like are Boyesen.

With barrels off, you could go ahead and port it and have the heads machined.  Chuck Quinzler in FL can advise you what he would do to keep it stock but better in terms of porting.  His work is really first class. There are others who can do porting work too.

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #14 on: Jun 04, 2017, 13:19:17 »
Those are 1mm oversized Wiseco pistons with very few miles on them and rocking at the top is not an issue. Pistons have a taper and are smaller at the top than the bottom and smaller again between the ring lands.  Check the clearance between bottom of the piston skirt and the bore.  Wiseco use different clearance than stock cast pistons.

Reeds tend to do that so get a set of new petals. Call John at Economy Cycle and see what he has for a stock motor. There are a few choices.  The only ones I don't like are Boyesen.

With barrels off, you could go ahead and port it and have the heads machined.  Chuck Quinzler in FL can advise you what he would do to keep it stock but better in terms of porting.  His work is really first class. There are others who can do porting work too.

Thanks! I can just now see the "1.00mm" stamp!

Can I check the clearance as I would by the manual?

Stock specs:
Piston ring in groove should be <.05mm gap.
Ring end gap in bore should be 0.3-0.5mm.
Cylinder bore clearance piston at the skirt with the piston 3/4" down from TDC should be <.035mm.

Thats pretty much all I have to go by. Are there Wiseco specs on their site?

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #15 on: Jun 04, 2017, 14:20:35 »
Nevermind... found this:

Offline teazer

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8248
Re: RD400 - Back from the Dead
« Reply #16 on: Jun 04, 2017, 16:55:02 »
That's teh place to start.  BTW, how did you clean the carbs?  What I am really asking is did you check each and every passageway by blasting cleaner through it and comparing both carbs?  A dip and boil does not always clean out the tiny drillings causing people to lose their minds thinking the carbs are perfect and sometimes they are not.

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #17 on: Jun 04, 2017, 17:20:47 »
Of course! Compressed air, cleaner, and wire.

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #18 on: Jun 05, 2017, 23:50:19 »
Potential bad news... Took everything apart... here are my measurements :

Left Cyl:
Bore - 65.05mm
Cyl Clearance - .005"
Top Ring Gap - .040"
Bottom Ring Gap -.040"

Right Cyl:
Bore - 64.72mm
Cyl Clearance - .003"
Top Ring Gap - .017"
Bottom Ring Gap- .018"

So the right is on the cusp, and the left is bunk... probably a lean condition on the left side, or a terrible machining job.

Anyhoo... Wiseco makes 1.50 and 2.00 over bore kits... $300, plus machine shop work... this bike is getting expensive!

Looks like they only have the 2.00 in stock, too... may be the last ride for this pony...

Offline teazer

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8248
Re: RD400 - Back from the Dead
« Reply #19 on: Jun 06, 2017, 00:02:41 »
I would get a set of rings, check the gaps and as long as they are big enough put it back together. The difference in bores is a bit wider than I would expect, but not the end of the road.  Those numbers are not perfect, but probably closer than many bikes on teh street.  Cold it may rattle a little but it's a two stroke, they are supposed to make noise.