The drz400s rebuild, stronger...faster...somthinger!

Discussion in 'Thumpers' started by focallength, Oct 5, 2012.

  1. TipsyMcStagger

    TipsyMcStagger Long timer

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    Bookmarked this post a few years back.

    Tipsy
    #21
  2. focallength

    focallength You're Welcome

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    #22
  3. focallength

    focallength You're Welcome

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    so here is the score so , far. Im waiting for a puller for the fly wheel then Ill split the case. Initial inspection shows some slight play in the rod, which means shes shot. I ordered a complete hot rods lower parts kit, to rebuild the bottom end. The gears arent blue, but I wont know until I can split the case. So far no definitive causes, the cylinder does show signs of previous wear and oil could have slipped passed the rings. The cylinder is nice and flat, but the head is pretty well warped.

    Ill have the case honed just in case, so that both parts fit together perfectly.

    Now the cylinder is salvagable, Ill prob. send it off to cylinder works or millenium and have them hone and replate it. Still not sure if I wabt to go with a BB or not.

    The head is just a big paper weight, however there are signs of dirt being sucked into the valves, which is not that uncommon with a dirt bike. Just means Ill have to really check my air intake when I re install it. Most likely it happened over time, however I did notice that the FCR-MX carb dosent fit quite so well, so Im going to have to do something about that. Maybe find a airboot from another bike thats a little bit longer.

    So lower parts kit should be here tomorrow as well as the puller, in addition Ill replace the countershaft bearings. Heres hoping the gears are good. Stay tuned, sorry no pics, nothing new to show...

    I may pick up a kick starter kit though, should be easy to install with the engine in pieces...
    #23
  4. focallength

    focallength You're Welcome

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    Ok, one thing I wanted to fix was the fcr-mx airboot issue. Anyone who has one knows it barely fits and is prone to air gaps.
    so I bought a 2 inch rubber coupler, trimmed the inside of one side so the air boot fits. I also trimmed the tab and one row of the rubber rings. The carb fits in with a little gap, which is no biggie as the ring tightens it down nice. I cut the coupling to about an inch, you only need about an extra 1/2 inch to make it fit.

    [​IMG][/IMG]

    [​IMG][/IMG]

    [​IMG][/IMG]

    Oh, never look into a pumper carb and turn the throttle wheel
    #24
  5. Starchamp

    Starchamp Rebel Scum

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    Why not just get an E boot? MacGyvering is best left for trailside repairs.
    #25
  6. Starchamp

    Starchamp Rebel Scum

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    Agreed, mostly, and I wasn't referring to your exhaust tubing suggestion in particular, but rather the entire approach. I just think that with all the money being put into the engine, if it were my bike I'd not skimp on a $50 rubber boot (about how much they're going for on ebay, complete with entire airbox) and risk sucking unfiltered air into the works. To each his own, I guess.
    #26
  7. focallength

    focallength You're Welcome

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    Is the E boot longer? I just assumed the s and e boots were the same.
    ive never heard anyone suggest the E boot, if its longer and makes the.carb fit properlly ill get one.
    #27
  8. Starchamp

    Starchamp Rebel Scum

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    Yes. 4strokes.com offers the below as the complete list of parts needed for the FCR conversion, but you can probably get away with just the outlet boot:

    Suzuki Part Numbers:
    FCR Carb: 13200-29F10
    Velocity Stack: 13670-29F00 (plus gasket and 2 screws)
    Intake: 13111-29F00
    Outlet: 13881-29F00
    Clamp: 09402-58208
    Clamp: 09402-60208
    Throttle Cables: 58301-29F00

    But again, I'd just grab one off of ebay rather than go through Suzuki.
    #28
  9. focallength

    focallength You're Welcome

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    Ok, so I finally got the cs bearings in, going to split the case, soon. But I was thinking, the head got real hot and may have damaged the head bolt threads on the case. So...ill send the case halves ofg and get some timeserts installed. This will prevent any strippage of the head bolts when putting the engine together, plus if I go BB itll strengthen the case so the head dosent pull itself apart. $100 will make the engine stronger and give some peace of mind.
    #29
  10. focallength

    focallength You're Welcome

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    So, I think I finally have a solid number for a rebuild

    Bottom end $575 w/cs bearings
    cylinder, bored (434) plated with piston, clips/bearings etc... $450 (millenium, will ship a bored stock cylinder with a JE piston)
    head $575
    cams (hot cams) valves, springs etc...$625
    rebuild clutch $400
    timing chain,timeserts $175

    $2800, not including parts for carb.

    Will get a drz w/13.5 compression, 434 BB, stg 1hot cams, kibblewhite valves, hot rod bottom end, complete new clutch, strengthend head bolts.
    #30
  11. KLXmcrider

    KLXmcrider Been here awhile

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    I'm feeling a little envious of your rebuild. I want something similar so I'll be watching
    this thread , day dreaming as always........
    #31
  12. focallength

    focallength You're Welcome

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    Crank is being replaced, whole new hotrods bottom end, the onlything that may remain are the gears, (if their good, which they look ok from what I can see, ill know by friday )and countershaft, everything else is new (bearings/seals). The timeserts are just insurace, dont want to break a headbolt, it is possible, so better safe than sorry. Especialy since I wont know until it happens then id have to tear the engine apart again, $80 to be safe is money well spent. Plus those threads will never break with titanium inserts. Ive had a bad experience with a head seperating on a bigbore and ive heard enough war stories...not dealing with that crap again. Ill most likely even order some better head bolts, if im building this thing I might as well make it unkillable.


    [​IMG][/IMG]
    #32
  13. focallength

    focallength You're Welcome

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    Sorry for the delay, got the cases back yesterday, bottom end is together and in the frame.

    I had the timeserts put in, they were drilled a little deeper so I can put in longer head bolts. Maybe overkill but better safe than sorry.
    Replaced all of the seals, bearings, the bottom end is brand new aside from the gears, they were in good shape. New hot rods crank.

    Next is a 434 bb kit, just send the sleeve and for $419 I get a bored out sleeve, piston and rings.

    The big hurt is the head, itll all be brand new, a blank head is 575

    I need to replace the clutch and basket another $400

    And ill get new bigger radiators to support the bigbore and increased compression as well as the hot cams.

    Pics soon...
    #33
  14. focallength

    focallength You're Welcome

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    Im going to try out mylers for the radiators. They sell oversized radiators for 135 so i ordered one to make sure it fits ok, ordered the millenium 434 bb kit.

    They said it should fit ok with a clarke 3.9 tank. They look great and the added cooling should help with the 434 kit , increased compression and hot cams. I should have the radiator thursday and the bb kit some time next week.

    Ill get lots of pics as the parts roll in.
    #34
  15. focallength

    focallength You're Welcome

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    Ok, got the cylinder and piston installed
    Millenium, with je piston 434 kit.
    126/focallength/2012-12-19121132_zps0d198887.jpg[/IMG]


    [​IMG]
    Painted the cylinder red, for a little pizazz, lets people know theres a little something special inside.
    Gapped the top ring 0.02 mm smaller for a bit more compression.

    I bought a new radiator to test it out, very well made, sides twice as thick as stock. Myers super cool radiator
    Ill buy a new left one from them too. They say they can rebuild one of their radiators for iirc $45, even if its pancaked flat. The sides are easily twice as thick as stock, if not more.. I dont see them crushing, unless ran over by a dumptruck.
    [​IMG]
    Im buying parts for the head, all kibbewhite, just trying to score a new head

    So heres the score, hot rods bottom end, millenium bb kit with 434 je piston, myers super cool radiator. Kibblewhite springs/valves, fcr carb.
    Titanium timeserts, with a little extra length for some uber head bolts.
    All new gaskets and bearings, plus oil jet.
    #35
  16. bobfab

    bobfab Long timer

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    :lurk

    If my DRZ motor ever dies ill be heading a similar route!
    #36
  17. rgp332

    rgp332 Been here awhile

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    Check out Evans coolant to replace the antifreeze,cools alot better and wont boil over ! Use it in a 2stroke I have that was running hot in the slow stuff after that no problem !
    #37
  18. Bobby Ginger

    Bobby Ginger Cat Herder

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    Just found this, picking up a DRZ tomorow. If I ever have issues this will be handy.
    #38
  19. focallength

    focallength You're Welcome

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    so a little update, got a new head and all the parts for it, except the hot cams which are on back order for a month. i just need the clutch primary gear and plates. a left radiator and right radiator sensor. i got a e model air boot and throttle cables for the fcr. aside from the cams and clutch primary gear i just need to order a header, ill prob. get a fmf powerbomb. so the parts are trickling in slowly and ive been organizing them and double checking. ive replaced almost every single part on the bike with new,oem or aftermarket. school has the bike on the back burner but ill get pics up as soon as everything is in.
    #39
  20. larryboy

    larryboy Chopper Rider

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    I would highly recommend that you waste a few gaskets and check your valve squish, you know, modeling clay and check for proper valve to piston clearance.

    Stiffer valve springs I hope?
    #40