My First MB Project

Discussion in 'General Questions' started by pessen, Mar 2, 2009.

  1. pessen

    pessen New Member

    So, I am about to embark on my first MB project. I thought I would start this thread to show what I am working on, and so that as problems arise I have somewhere to ask questions where people can see what I have done so far.

    I have a Diamondback mountain bike. I bought road tires for it but still have the mountain bike tires which I could switch back too if needed.


    I am ordering (hopefully today) the 80cc(66cc) kit from, I figured if I jack something up I would rather do it on a cheaper kit. Figure I'll upgrade once I know what I am doing more.

    I plan to just put the kit on my bike, and once I have an idea of how that performs, the first upgrades I might consider would be a new carb (Maybe a Dellorto?), and an upgraded tuned pipe. I like the Shifter Kit from SBP as well, but want to make sure my bike is working fine first before I put the $200 down on that.

    I live at 5200ft so I am not entirely sure how that will affect my engine or what problems might arise, guess I'll see once I get my engine running.

    I'll post updates once I get my kit and get started on my build. In the meantime, any suggestions would be welcome.



  2. bluegoatwoods

    bluegoatwoods Well-Known Member

    It's a nice bike. Ought to work well for this.

    You might want to consider different handlebars; something that gets you more upright.
    I suppose that's a matter of personal preferrence. but I think most MBers like to be more straight up.

    I don't think your altitude will be a problem. There are a few high altitude riders here.
    and I think they mostly say that they notice no difference.

    Good luck and have fun.
  3. pessen

    pessen New Member


    I got my engine a week ago or so, but was busy with school and work so didn't have time to start working on it. I have spring break this week so I am hoping to get my MB running finally!

    As I unpacked my kit I noticed that the gas tank has some noticeable rust on the inside. I know people had mentioned using KREEM to seal the inside, but I looked at a Motorbike store and the KREEM was like $35 dollars. Is there an alternative solution that might not cost so much? Is there anything wrong with leaving the tank as is and just installing a fuel filter in my fuel line?

    Just thought I would see what you all have found works best. Thanks!

    Looking forward to riding my MB!

  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Call bikeberry and get them to send you a gas tank that doesn't have RUST in it
    They say they offer warranty and RUST seems like a defect to me

    Do all their tanks have rust?

    I just got a tank that has a LOT of rust too and I am getting a replacement
  5. pessen

    pessen New Member

    Gas Tank Rust

    I emailed them and they said to simply rinse the tank out with gasoline, and that it should be good after that. I am not convinced that will completely eliminate the rust. Does anyone have experience with rusty tanks? Should I do as they say and use gasoline, or use KREEM to seal it, or should I insist that they send me a replacement tank?
  6. pessen

    pessen New Member

    Gas Tank Rust

    What do you all think?
  7. azbill

    azbill Active Member

    if you are still worried...
    put some small gravel in the tank, shake it pretty hard for a few minutes, empty rocks, rinse....repeat if neccessary
    should be good to go :)
  8. pessen

    pessen New Member

    Exhaust Pipe Fitting Problem

    I ran into another problem last night: I installed the stock exhaust pipe but it doesn't fit close enough to my bike, so my pedal is hitting it. I don't know if there is some way to bend or modify the pipe so that it will fit closer to my bike, and be out of the way of my pedals.

    Here are a few pics of how it is currently fitting:

    march 09 001.jpg
    march 09 002.jpg
    march 09 003.jpg
    march 09 004.jpg

    As you can see, if it fit closer to my frame it would be fine, but the angle on the engine mount makes it stick out. I guess I could cut the small tube on the exhaust, install it where I want, and then connect it with rubber hose/tubing.

    I had been considering buying a better tuned pipe, should I just go ahead and go that route rather then trying to mess with the cheap stock pipe?

    I live at a high altitude (5200 ft), what would be the best type of pipe to get? I don't really have much experience with them so I am trying to get some suggestions and hints. I would prefer something that isn't really loud (due to where I will be riding the bike I don't want to attract extra attention from the coppers).

    So, any suggestions on how to make my stock pipe fit? Any suggestions for a better tuned pipe that is quiet and improves performance at high altitudes?

    Thanks in advance!

  9. fetor56

    fetor56 Guest

  10. pessen

    pessen New Member


    I hadn't seen that thread before but sounds like it should work. Now I just need to find someone who has a blowtorch, and a vice, and get my bike over there to get the muffler adjusted correctly. I live in an apartment so I am pretty sure I don't have those items laying around. :annoyed:

    I didn't realize how many mods and tweaks I would have to make.....not that I mind tweaking and whatnot but I want to ride my MB sometime this year!
  11. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    It doesn't look like your motor is centered on the front mount but your
    pics are small, dark and hard to see what is going on.....

    The header of your pipe should be much closer to the front downtube

    Do your pedals clear both sides of the motor evenly?

    The last pic doesn't even seem to show the motor mount attached to the front
    Last edited: Mar 24, 2009
  12. pessen

    pessen New Member

    My front downtube was too big for the motor mount to fit around, plus I have brake and gear lines running down bottom side of the front tube so I didn't want to mess those up.

    The motor is secure, I used the alternative mounting method they provided which is the metal plate with 3 holes, one to attach to bike frame, and 2 outside holes to attach to motor. My mountain bike already had holes drilled in the frame designed to attach a waterbottle holder, so I simply used one of those holes to screw the mounting plate into. I did some pretty good pushing and pulling on the motor and there wasn't much give at all.

    I am pretty sure the pedals clear both sides evenly, I will check again though. Even so, the amount the exhaust is off is way more than could be compensated for by adjusting the motor.
  13. fetor56

    fetor56 Guest

    If u have no need to "tool-up" or friends arn't convenient u could take it to a car exhaust installation shop....they'll do the job pretty cheap.
    You could try cold bending the exhaust but frankly i wouldn't recommend it.....too many horror stories.
  14. pessen

    pessen New Member

    I didn't think of that. There are several close by so I'll probably give that a try. Thanks for the suggestion!
  15. pessen

    pessen New Member

    Ready to Ride!

    Finally have the motor completely installed. Took longer than I anticipated mainly because this is my first build, though, I only had a limited amount of time to work on it being I am working and in school.....

    Anyway, I am hopefully gonna start her up this afternoon......wish me luck! :grin5:

    I'll let you all know how it goes....
  16. fetor56

    fetor56 Guest

    Good luck man...if i was there watching u i'de make sure to stand well back. :grin5:
  17. pessen

    pessen New Member


    So, I took her out to the back alley, put full choke, started peddeling and let out the clutch. And.....put put put....stall. Turns out I had to turn the choke down about halfway before it would stay started. Once I did that it ran like a champ!

    I let it idle for a little while and then tried to ride it slowly, but had my chain come off twice. Thats why I started out nice and slow. I think my chain is a little loose so I need to take a link or two out.

    Anyway, I am sure I will need to do a bit of tinkering before I am fully satisfied with how it is running, but boy was I excited when she finally roared to life!

    Thanks for everyone who has given input and suggestions so far, I am sure I will have more questions about tuning the engine for optimal performance so stay tuned!

    As Mountainman would say, I am finally riding that thing! :cool:

  18. pessen

    pessen New Member

    Performance Questions

    So, my bike is up and running, but I have a few questions for those of you who have ridden more than I have (which should be just about everyone).

    (1) My installation manual says to adjust the screw (~4-1/2 turns) on the carb so that the engine is running at ~1400 RPM. How the heck do you measure that? Is it just by adjusting it until the engine sounds good? I am still new to this so don't quite know if I am running mine at the right speed. It doesn't sound like it is running really fast or anything.....any tips for getting this right?

    (2) I initially installed the chain without the additional tension piece, but my chain slipped off a couple of times so I realized it was too loose. I took a link out of the chain but then it was too short and I couldn't get it reconnected. I then installed the tension roller and it works fine, but the cheap one that came with the kit is really noisy and I attract attention just pedaling with my motor off cause it is so loud. Has anyone made a custom tension piece that works well and is quiet?
  19. ENO

    ENO Member

    Hey Pessen..ENO (Down Under)..Have you ever thought of extending the exhaust pipe so it sits just under the motor and points backward..I took mine to the Muffler man and paid $30 AU to add a pipe and fit it..I never did like the look of the muffler in the stock shape or the placing. Have attached pic to show result...See ya

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