Modified Motorcycles

I have a long-term idea in which I'm working at a slow pace.
I want to make a HD sportster engine in order to use it in a street racer project.
I duplicated the main engine with some minor refinements.
Now I'm scratch building some other parts.
This entire project is in 1/12 scale so I cannot use the existing 1/8-sportster engine.
I'm carving a part in soap. Later I will make this part in resin.
I'm using soap because is easy to carve, retain details well and is cheap. Also in case of mistakes, I just can start over with not much investment lost.
Here are some pictures of my progress:
Here is the startup diagram, and a block of soap cut to shape.

Here is the part with some more detail on it.

Here is same part with a different background to show more of the details.

Still need to make it to fit with the other parts, but it looks good so far.
Does anyone have used soap for this purpose before?
If so, here are some concerns that I have that would like to get an answer from someone with more experience.
Would the soap cause a negative reaction to the mold material?
Does soap melt at low temp? Still don't know how to attach other soap details to the main part.
I might put those other small parts by melting it..like you do when carving wax.
Well, that's all, will try to post on a weekly basis

Edgardo

Here is my bi-weekly report
I'm doing the left cover of the engine
Initial section

Giving the basic form

Detailed part

still need some details like nuts and will make it thinner.
That's all until next week.
Edgardo

I normally stick with standard frame, rims, tanks, etc mods.
Haven't tried to do an extensive engine mod yet.

I prefer Aoshima Kits for doing choppers and streetbikes, they already offer a variety of "modified" Bike models that give you quiet a few parts for the spares box per build.

IMAI used to offer quiet a few Harley kits that were also nice to mod but they are gone now and it doesn't look like Aoshima(who bought their molds) is likely to re-release them.

IMO, Tamiya are the worst kits for modifying.

Weekly update:
Got engine crankcase and gear box and sandwiched between the two parts I was doing.
Here are three pictures of it.



I'll now do a silicone mold of the two parts. Hope Soap do not react badly with silicone.
Until next week.

Edgardo