DisTech's DR350 rebuild

Discussion in 'Thumpers' started by DisTech, Nov 27, 2009.

  1. BSR-1

    BSR-1 Adventurer

    Joined:
    Sep 13, 2008
    Oddometer:
    28
    I'm sure I'd posted before but I haven't been on in a while.
    It still remembered my login but my post count was gone.
    #21
  2. Phreaky Phil

    Phreaky Phil Long timer

    Joined:
    Mar 18, 2006
    Oddometer:
    2,939
    Location:
    NEW ZEALAND
    That is sweet too.!! I searched for info on the swingarm stuff. Apparently an RMX250 one will fit and I think some RM125 ones will but im not convinced its necessary. In my past experience the shock makes the biggest difference. Ive used Ohlins on several bikes and the difference is like night and day
    #22
    Jeff@TheQuadShop likes this.
  3. Phreaky Phil

    Phreaky Phil Long timer

    Joined:
    Mar 18, 2006
    Oddometer:
    2,939
    Location:
    NEW ZEALAND
    This bike only has stock swingarm but an Ohlins shock, and an RM front end

    [​IMG]
    [​IMG]
    #23
  4. Kawidad

    Kawidad Long timer

    Joined:
    Jul 9, 2005
    Oddometer:
    6,438
    Location:
    Central Coast, Cal
    That was going to be my suggestion. It will bolt up directly. The best option is to find a wrecked RMX, the later the better. 1997 and up? That's because they came with the RM forks, which also bolted directly up to the DR. I know you already have the boingers, but.............
    #24
  5. BikePilot

    BikePilot Long timer

    Joined:
    Jul 5, 2005
    Oddometer:
    11,961
    Location:
    Golden CO
    Its not a direct bolt up - the RMX swinger is designed to mount to the outside of the engine cases, using the engine cases as a stressed member. The DR swingarm is solid across the front.
    #25
  6. procycle

    procycle Long timer

    Joined:
    Jun 7, 2007
    Oddometer:
    7,855
    Location:
    Center of the DualSport Adventure universe
    Just getting the motor back together for the 2nd time.
    I blew it up on the dyno but that was after seeing 40hp :lol3

    [​IMG]

    [​IMG]

    To take advantage of the FCR37 you will have to do some significant porting work. The intake port is right at 33mm. Not much point in using a carb that is bigger then the port.
    #26
  7. BSR-1

    BSR-1 Adventurer

    Joined:
    Sep 13, 2008
    Oddometer:
    28
    Awesome results Jeff!

    any Idea what was the cause of the motor blowing?
    I mean, what will stop it from happening again?
    #27
  8. Fubars

    Fubars What would Scoobydo?

    Joined:
    Aug 20, 2003
    Oddometer:
    2,236
    Location:
    Ventuna, CommieFornia
    This thread has me jones-ing for a 350 right now. Forgot to mention--I like this workstand. I'd build one, but I'm in the middle of a 40mm WP conversion on my 650.

    #28
  9. procycle

    procycle Long timer

    Joined:
    Jun 7, 2007
    Oddometer:
    7,855
    Location:
    Center of the DualSport Adventure universe
    Definitely detonation. :puke1 It toasted the piston but didn't hurt anything else.
    It took several runs to get the jetting in the ballpark. Those early poorly jetted runs took their toll.

    I changed shape of the top of the new piston to give it a little more squish area - that should help.

    The thing that is most amazing to me is this motor was breathing through the stock TM33 carb, the ports had not been touched and the valves, seats and guides were all worn out.
    #29
  10. BSR-1

    BSR-1 Adventurer

    Joined:
    Sep 13, 2008
    Oddometer:
    28
    It sounds like there's quite a bit of untapped potential there.
    #30
  11. BikePilot

    BikePilot Long timer

    Joined:
    Jul 5, 2005
    Oddometer:
    11,961
    Location:
    Golden CO
    Procycle, awesome results! What have you done to the motor other than the big-bore?

    Judging from Gman's builds of these motors and my guess from fiddling about a bit with a stockish one, I'd guess there's a lot to be gained by making it flow better - larger carb, oversized valves and a much more aggressive cam. He also removed the counterbalancer for less rotating weight - claimed it didn't make much difference in vibs, but that's a bit counter-intuitive... I do suspect that with good stiff valve springs and Ti retainers you could probably fit a DR250SE ECU for a bit higher rev limit too.

    For that matter, what have to you done to the chassis? I find that my motor (stock bore, wiesco pistion, TM33SS, FMF Q, header weld ground down and ceramic coated, airbox opened up, properly jetted etc) will easily overwhelm my stockish chassis in most off road environments.
    #31
  12. procycle

    procycle Long timer

    Joined:
    Jun 7, 2007
    Oddometer:
    7,855
    Location:
    Center of the DualSport Adventure universe
    Everything else is pretty much stock. I bought the bike to use as a test mule. When I pulled the motor apart I was pleasantly surprised to find a White Brothers cam and aftermarket valve springs and retainers. Other than that the ports and carb are stock. The airbox is wide open and it has a Pro Circuit exhaust system. The chassis is completely stock but improvements there will come later - after the 480 kit development is done.
    #32
  13. DisTech

    DisTech Been here awhile Supporter

    Joined:
    Sep 3, 2008
    Oddometer:
    658
    Location:
    Seattle
    Thanks for the input everyone. Special thanks to Jeff for the dyno-charts!

    I know I have enough parts to make one good DR350, but in the back of my mind I keep hoping I'll end up with two.

    Got another '99 DR350SE head off ebay, hasn't arrived yet. Looked ok in the pictures.

    Ordered a Renazco seat. All vinyl, black matte grain top, black pigskin sides and silver seams and logo.

    Finally connected with Jesse today and talked about his big bore kit and head work. It turns out it's a 455. Here are the details:
    • Aluminum sleeve nicasil plated, much lighter and dissipates heat better he says!
    • Stock DRZ400 piston, same deck height as stock dr350 piston.
    • Larger stainless valves, don't know new size yet.
    • Multi-angle valve job.
    • Clean up head for better flow.
    • MegaCycle mild cam.
    • Weld and modify rockers.
    • R/D valve springs.
    I really would like to go with the FCR37 and will probably hold off on the swingarm, but we'll see.
    #33
  14. Reposado1800

    Reposado1800 Juicy J fan!

    Joined:
    Dec 8, 2006
    Oddometer:
    5,828
    Location:
    5th and Main
    That thing is going to be a beast.
    #34
  15. BikePilot

    BikePilot Long timer

    Joined:
    Jul 5, 2005
    Oddometer:
    11,961
    Location:
    Golden CO
    Procycle,
    Great luck with the cam and such! I bet a larger carb and porting to match would free up the top end quite a bit. Surely the 33mm carb is strangling it a bit. A more aggressive cam might help with the detonation, but sounds like you've got that sorted with jetting.


    DisTech, the aluminum sleeve sounds promising! I've not used one on the DR, but they sure hold up well in my MX bikes.
    #35
  16. Mezo

    Mezo Banned

    Joined:
    Nov 17, 2008
    Oddometer:
    2,129
    Location:
    Brisbane,Australia.
    Man thats going to be nice bike, or should i say bikes :evil, better start the DR350 Builders "wall-o-fame".

    Do the first with the FCR37 (they are whey cheaper than the 39mm) and then go injection on the second, are you watching the FI DR350 thread on TT ?

    Get John to port your heads, grab a couple of Jeffs 480 kits when he`s ready.

    This thread will have everyone scouring the local paper for a DR350, mines the Quokka :D (whats a Quokka?) and there have been some very cheap 350`s for sale.

    Hey Distech, DR650 snob, very funny :clap

    The real funny thing was BSR-1 "Newbie" now that was funny. :poser

    Good choice of seat by the way, is it done by Chris?

    Suuuubscribed !!!


    :lurk Poprcorn muncher & all.


    Mezo. :thumb
    #36
  17. DisTech

    DisTech Been here awhile Supporter

    Joined:
    Sep 3, 2008
    Oddometer:
    658
    Location:
    Seattle
    I hope it is beastly, but managable.

    Yes, I hope so. I was surprised when Jesse told me that's what he uses, in a good way!

    1. Thanks, I hope the bike(s) turn out well and yes I would like to see DR350 w-o-f.
    2. I doubt it will be the first FCR37, but I am liking that idea. Yes I have been following msiddalingaiah's FI thread, but he tends to talk over my head on the subject. wildwestsydney's winter project isn't as flash but I sure could understand it better.
    3. I'm leaning toward Jesse's 455 because of the aluminum cylinder and because he will take care of the whole top end in one package (and I need to get my Two Brothers mid tube converted for a GSXR can on the DR650).
    4. There are still quite a few DR350's looking for a home.
    5. Ha! And I had to taunt you a second time!
    6. Yea, something funny there.
    7. Yes, Chris is the man. He is local to me so I drive out to his place with the pan and pick up the finished seat. He has a beautiful spread. When I ordered my DR650 seat I was getting pissed that you (on the other side of the globe) and mx_rob (on the other side of the country) got your seats before me! Ha! But Renazco seats are worth the wait.

    Glad you're on board!
    #37
  18. Mezo

    Mezo Banned

    Joined:
    Nov 17, 2008
    Oddometer:
    2,129
    Location:
    Brisbane,Australia.
    Duh !! Seattle/Washington !! fuck am i stupid or what, guilty as charged.

    My time in the US was spent on the west coast (San Diego) i need a holiday on the east coat, haa.

    Look the fuel injection thing is new to all of us, you have the brains to do it & there is heaps of support from the nerds (friendly petrol head nerds) if you try & get stuck those guys will help you all the way, msiddalingaiah even offered to sort the code for anyone wishing to give it a go :clap

    Im sure you have seen Rob`s new thread on the FI650?

    I need to learn this stuff, as do you, Lukas, Rob, etc etc, what i want to know is what color are you going to paint the frame? Zsss, or did you say that already? haa.

    Mezo.

    :lurk:lurk:lurk
    #38
  19. DisTech

    DisTech Been here awhile Supporter

    Joined:
    Sep 3, 2008
    Oddometer:
    658
    Location:
    Seattle
    Bought the '99 SE head (the one on the right) off ebay hoping it would be interchangeable. I knew the cams on SE's were different, but I didn't know how they were different. Now I do. Look at the sparkplug end of where the camshaft is supposed to stop. The '99 camshaft is about 0.375" longer. The bolt patterns look the same so it probably would be interchangeable if I had the entire top end and could live with auto decompression. The cam journals would need some work, but the other side is in much better shape than the '93. Dang!

    [​IMG]

    Probably pull the '94 head just so I can get rolling with the project and keep my eye on ebay for a proper head.
    #39
  20. DisTech

    DisTech Been here awhile Supporter

    Joined:
    Sep 3, 2008
    Oddometer:
    658
    Location:
    Seattle
    I'm not afraid of trying FI, but I'm not sure I want tackle it this winter. Black frame and white plastics!
    #40