BrickBuildingFox

Finally, after many trials I made some progress to make the gearbox and kickstart work smoothly :) also I make the first iteration on the chassis. The video demonstrates the kickstart mechanism... https://bricksafe.com/files/BrickBuildingFox/tc19/20210113_213538_1.mp4 There is enough space in the chassis to fit the fake engine and gearbox... it will be next step to merge them.

Very impressive!

Very cool B-Model. I like the way you build the tracks. First they look very similar to the original, and second, they seem to be a better design than 42100 especially when moving over bumps. Are you planning on making instructions?

Thanks! I am very happy with the new nose design as well. Only th foxtail need to be a little higher in the end. Yeah, unfortunately the lower swingarm sometimes detaches if the forcing on the front wheel is too strong. That's one issue i need to fix... Another is the gearbox and kickstart mechanism. This gave me some headaches the last days. This is what came up with so far: Lots of troubles though: The engine is misplaced one stud off center, the stability could be better and the kickstart (read handle) stands too far out, because the mechanism is too wide :( Good side: the high gearing ratio of the kickstart makes the engine turn several times. This gives a nice feeling and sound :) so I hope I can keep it.

I added the clutch and a 2-speed gearbox. However, as you can see from the previous post, the cylinder hub had a small inclination. I thought it would look better, but I found it is impossible to connect the crankshaft with the gearbox in a stable and legal way :( Therefore, I decided to go with a vertical cylinder hub (see picture below). Next step will be to add the kickstart and optimize thr frame of the gearbox.

Have you tried this: http://www.ld4dstudio.nl/ I never tried this one, because it only runs on windows. But LDCad, which was produced by the same guy is very amazing.

I like that spirit! I'm looking forward to see a working 2WD

Looks quite like the original. Very cool!

Yes, you're right. I made a new design of the front suspension, lights and also added the engine. Next step will be to marry front and back.

I made some progress on the frame and suspension. It is far from perfect, but a good base to continue. Next step is to fit the engine and clutch inside. While browsing the instructions of the BMW (42063) I found that bevel gears are used instead of a chain to drive the bike. I like it and adapted a similar solution. Here are some pictures:

I didn't finish my 42100 yet, but it behaves similarly at stage 1. I didn't notice the difference to the app display. So I think its ok. My model turns even less in reality, but I already played with the new powerfunctions before assembly... so I think its weak batteries

You can use the original instructions... just look at them in a mirror ;-) The boring thing about building cars is, that you build almost everything twice (only mirrored)

Very cool use of the curved fender parts... really looks like a cobra

From my experience, the friction strongly depends on how strong you bend the pneumatic hose... I hope it will work in the final assembly.

Thanks! I was not aware of this interesting mechanism of BMW motorbikes :-) Maybe I will go with this, then I don't need to buy more things... My apologies! I started today and build the 2-cycle engine and a concept for the clutch. I decided to go with orange color with some white... like a Fox :-) For the Kick start mechanism, I only play with some gearing ratios... 1:15 means ~4-5 rotation per kick... guess that should be ok. For the clutch mechanism I put a string through the hose... works better than I expected :) This is the engine... quite big, but in comparison to the "Fat boy"-engine (which is a V2 where each cylinder has a similar displacement compared to this one) so it should be still in reasonable proportion to the tires...

See all pictures of progress. This is my first contest and also the first motorbike I will build... So I am very excited. My current plan is: - use the tires of the "Fat Boy" creator model... those are the only suitable ones I have - orange or lime color... haven't decided yet - single 2-cycle cylinder (build out of technic parts) - kick start mechanism with working clutch - 2 speed gearbox (if still space is still available) I have no technic bike set, so the front suspension might be a problem. I haven't decided if I buy the Ducati (to use its parts) or just the order some springs from bricklink: either the 11L from ducati or the 9.5L used for other bikes. Which ones would you recommend? Wish you all happy building and happy holidays!

There is the linear relationship between the RPM of the motor and the torque. The new powered up motors have a rotation sensor to measure speed. This can be utilized for torque detection and control of another motor to change gears. I assume that LEGO uses this in the Volvo 6x6 (set 42114), which has the automatic 3-speed gear box. This would be straight forward solution and very comfortable for a RC-car. I attached a small "Powered up"-program it shows the current speed of the motor in variable "a". It decreases, as the load increases and thus "a" could be used with a if-condition to drive the gear switching motor.

Another difference I discovered is that the XL is much less noisy compared to L...

This is fantastic! Thanks for sharing the journey of developing the gearbox and improving it step by step. I'm a big fan of your scientific approach to lego technic.

You could use two diffenentials to create a straight line of motion as explained on this site: https://groups.csail.mit.edu/drl/courses/cs54-2001s/dualdiff.html Just noticed, those motors should have the orientation sensor so it should be possible to adjust the speed by dynamically in the powered up app...

@jam8280:thanks a lot for the pictures and additional explanation of the suspension! I think with this knowledge it is possible to build a similar suspension system...

Wow that's a great idea for a MOC. Thanks for sharing. I already put it on my ToBuild-list. Are you planning to make instructions? I would like to see some pictures, especially about the suspension, since it seems to be very difficult to implement.

Very creative solution to make the tiny V2 moving. Impressive!

WOW, I am a big fan of the original piece but this is way better!

CaDA has a major part of their instructions available on their official website: http://en.doubleeagle-group.com/cada/list.php?pid=108&ty=25 Maybe in future, they will upload the ones for @brunojj1 great model as well...