RD400s

Discussion in '2 smokers' started by cc-rider, Aug 24, 2013.

  1. cc-rider

    cc-rider Adventurer

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    Guess I should introduce myself,,,I am 2smoker from Ohio.

    I joined this site a long time ago but I just so busy with everything going that I only lurked around.

    As far as 2 strokes I enjoy building and trick'n them out for that rush you get when it's on the pipe.

    My 1976 is my favorite bike

    [​IMG]


    My 1978 Is the quickest one get on the pipe at 6500 rpm and signs off around 9500

    [​IMG]



    Have a great weekend
    #1
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  2. volkrt

    volkrt Adventurer

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    welcome and nice rides..I like the 78 the best...needs some graphics tho :)
    #2
  3. Nadgett

    Nadgett Obnoxious, dimwitted blowhard

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    I had one. It was a lot of fun.

    [​IMG]
    #3
  4. Brad-Man

    Brad-Man Been here awhile

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    Welcome cc-rider:

    I had a '75 RD350 new in '75, am currently riding a '74 RD350 and doing a ground - up on a '75 RD350 (not the same one).

    It will be getting a mildly ported 400 engine w/Pro-Flo chambers and an MZB/Zeel electronics.

    One of these days I'll post some pics.
    #4
  5. cc-rider

    cc-rider Adventurer

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    Nadgett, love those '79 Daytona's..

    Brad-Man that's the fun of these things, building them. :-)
    Are you working with Lynn Garland at Vintage Specialties for the porting?
    Lynn is a top notch guy.

    Volkrt, funny you should that. The yellow has always been a shade or two off so last week I started sanding it for repaint. I'm thinking blue with white rally stripes plus adding a white "Yamaha " decal to the tank.

    Once that is done I'm putting it up for sale.
    #5
  6. Brad-Man

    Brad-Man Been here awhile

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    I have been down to Lyn's several times.

    The first was to have him supervise me tearing down the '75 engine and evaluate the crank/rods (both needed work).

    Next time was to evaluate a 250 crank/rods that I got for next to nothing (both needed work) and a RD400 crank/rods (good!) so I decided to go with a 400 engine. Since this isn't a race bike, I figured that the bigger area under the curve would better serve my ~250 lb frame.

    Last time was to actually put together the bottom end after he put new bearings (all four) on the crank for the 400 engine.

    We kept up a running conversation and I learned a LOT from Lyn.

    I am a member on 2 2 stroker sites and always send people east of the Mississippi to him if they are north of Atlanta or in the Atlanta are for crank work.

    He no longer does porting.

    A great guy and as stand-up as they come.
    #6
  7. cc-rider

    cc-rider Adventurer

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    Brad-man, your are exactly correct about Lyn..

    I knew he was getting of some porting work but mostly the 90deg stuff was hurting his wrist and hand.

    I have done several machining jobs for Lyn, mostly cutting combustion chambers and squish angle on his 400 and also did something to Paul's 250 just cant remember what that was now..

    Every time I have been to his shop it was hard to pay attention because he had a couple really nice bikes catching my eye. LOL

    Have fun doing building your bike, hope to see them here or on one of the 2 stroke forums.

    -Buddy
    #7
  8. Brad-Man

    Brad-Man Been here awhile

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    I'll be posting pics everywhere for people to see.

    I already have threads about the project on USA2Strokers and 2StrokeWorld, but haven't updated them recently - I'm about to get the oil tank, side panel and gas tank painted.

    The chassis is already together and I am waiting on a machinist friend to make a jig to center dowels from my specs.

    I forgot to mention that the heads had already been reduced to 25 cc and squished by MBSteve.
    #8
  9. cc-rider

    cc-rider Adventurer

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    MBSteve does great work from what I have seen.

    What are you doweling, your heads? If that the case you can borrow mine.

    [​IMG]
    #9
  10. cc-rider

    cc-rider Adventurer

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    I pocket mill a cavity for the dowel to sit in. I tram the center of the bowel and the cylinder the way the center lines are exact to each other and of the sleeve is what aligns it to the cases.

    Here is a before head

    [​IMG]

    And After

    [​IMG]
    #10
  11. Brad-Man

    Brad-Man Been here awhile

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    I actually have a damper for a press (rubber cylinder that is the right size that I have a 16mm machined bolt and the jig and a big washer to tighten down and center the jig on the cylinder and the jig has replaceable drill bushings so I can drill and ream to size the dowel holes in the cylinders and heads.

    I have a shorter 16mm bolt w/ spark plug threads that threads into the the spark plug hole in the head to center the jig to the head. (Since the combustion chamber is centered on the spark plug hole.

    I am going to use 1/4 " dowels in the location the locating holes are in the cylinders for the head gaskets w/an interference fit and ream out the holes in the cylinder head to .251".

    Just waiting on the jig now.

    Then I get to install the right side (pump primary drive and clutch and install the MZB/ZEEL and wire to get it going (assuming paint will be done this week).

    Just in time for nice fall weather to ride in around Atlanta, GA....!
    #11
  12. Motomedic

    Motomedic Over-caffienated Raconteur

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    #12
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  13. PJay

    PJay Any bike, anywhere

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    I used to have a race RD400 that I would go tormenting TZs with in the fairly early days of Post Classic racing in NZ; here it is going in to the hairpin at Paeroa street races 1998:

    [​IMG]

    Twin discs on the front and braided brake lines made for a power of stopping (and fork compression).

    Built up wire wheels, a lot of chassis mods, pipes made by Wobbly Wright, huge carbs, ultimately in post-classic racing Banshee pistons, ported to suit of course, and a hell of a lot of other engine/clutch/gearbox mods.

    We found the easiest head modification was to put RD250 heads on it to replace the bloody great buckets that are the standard RD400 combustion chambers. You get squish and compression all sorted with very little need for other modification, but the fins look strange above the RD400 barrels. The look doesn't matter a hell of a lot when you're getting a reliable 65rwhp.

    I still have an original standard RD400 roadster in the shed.

    [Edit] To the OP: do those pipes make yours really peaky? Mine on the dyno had +50 rwhp from 5,500, +55 from 6,500 on up, +62 from 7,500 to 8,500, fairly flat torque curve from 6,000, too. I never bothered revving it beyond 8,500, and it was geared to suit. The thing's still buzzing around somewhere, AFAIK has never had a rebuild since I gave it to an employee in 2004.
    #13
  14. Motomedic

    Motomedic Over-caffienated Raconteur

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    I've not had this one in a dyno. Not a whole lotta bottom end, a decent midrange a great big wallop on top from the Moto Carrera pipes.
    #14
  15. PJay

    PJay Any bike, anywhere

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    Yeah, exactly what the pipes look like they would do.

    Whereas the OP's ones in the second pic in the first post on this thread look like they'll make it go nothing nothing nothing BAM!
    #15
  16. JHG67

    JHG67 Adventurer

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    I rode RD's during my high school years (250, 350, 400's as well as an RZ) Loved them all. One thing I learned, when riding at speed ALWAYS cover that clutch!!!
    #16
  17. Mobil1

    Mobil1 Long timer

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    :fpalm
    #17
  18. PJay

    PJay Any bike, anywhere

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    Do you know, I've raced TD, TR, TZ, RD and RD LC machines, and the only one that seized was a TZ when my dumbass mechanic (me) forgot to tighten the nuts holding the water pipe fitting on to the head and it spilt all its water.

    Even then, it kept running until the pistons holed as well.

    I learned in that event that a water temp gauge won't show a high temp when the sender is not in water...
    #18
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  19. JHG67

    JHG67 Adventurer

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    Ya, I'm quite sure my 250 seized due to my dodgy mechanical skills at the time (first real foray into jetting for pipes and filters on a 2-stroke street bike). Not to mention most of the RD's I had were rats, pieced together from bits of this and that and some old race bike parts thrown in for good measure. At that age I did what I could afford.

    My RZ350 however, I still think the guy who bored the cylinders set them up a tad tight on the clearances (I gave in to his insistence that they were set up correctly) and given that, perhaps I should have given a bit more break in.

    And yes, they still ran but something about bits of piston banging about inside just freaked me out. Over time my tuning/mechanical skills improved and so did the reliability.......funny thing that!?
    But then, once bitten twice shy as the song goes.......

    I still loved lining up and smoking (pun intended) most of the interceptors, Gpz's and Seca's of the day. Great times indeed!!
    #19