1920s Racer Inspired Kart

[JR74Ford]

Hi guys

I thought I would make a thread on my wee project. It is my first build so appreciate any comments and suggestions. I am by no means an expert, I am just making it up as I go really.
This website has been a great help to me so far, hopefully it helps others seeing my pictures.

This is a kart for my son, here is the inspiration car. I am making it a front engine kart with a chain drive, the chain will travel down an off centre transmission tunnel (looking like the real car).

http://i58.tinypic.com/6zrc3n.jpg
http://i62.tinypic.com/2i74fo9.jpg

The frame

http://i59.tinypic.com/wtbtae.jpg

A bit of a card board mock up. The wheels are 17" motor cross wheels

http://i62.tinypic.com/zn6esy.jpg

I got my hands on a wee 2012 Honda CBF125 engine. Its a cool little fuel injected thing.

http://i61.tinypic.com/2eflydu.jpg

Making mounts for the leaf springs

http://i61.tinypic.com/33cy78p.jpg
http://i60.tinypic.com/a5kkch.jpg

http://i60.tinypic.com/seyijd.jpg
http://i60.tinypic.com/2ijoz11.jpg

The front axle

http://i59.tinypic.com/new7kn.jpg
http://i59.tinypic.com/2s60ll1.jpg
http://i59.tinypic.com/5vpxkk.jpg

The steering arms

http://i61.tinypic.com/1ikaip.jpg
http://i62.tinypic.com/33aazig.jpg
http://i58.tinypic.com/5fovh2.jpg

 

[landuse]

Last 5 pics

 

[Desertduler]

Now this will be a cool build to watch!

 

[JR74Ford]

Another cardboard mock up, the body will be thin ply wood and fibreglass.
http://i61.tinypic.com/4s1n4n.jpg

 

[JR74Ford]

Here is the rear axle, I just picked it up from the machine shop. The bearings and hangers have just arrived, I will mount them soon. Sorry for the small photos, makes it a bit hard to follow. I would make them bigger but the mods think we live in 1999.

 

[landuse]

Here is the rear axle, I just picked it up from the machine shop. The bearings and hangers have just arrived, I will mount them soon. Sorry for the small photos, makes it a bit hard to follow. I would make them bigger but the mods think we live in 1999.

No, the mods do not think we live in 1999. Not all of us have line speeds like some first world countries have. This forum might be based in the US, but a HUGE number of members are not US based. You think dial up died in the 90's...maybe....but dial up speeds are still around, that hasn't changed

All you gotta do is click on the thumbnail to enlarge it, nothing changes

 

[itsid]

Sorry for the small photos, makes it a bit hard to follow. I would make them bigger but the mods think we live in 1999.

linking to pictures is really the worst way of showing them,
it's annoying as ****, especially when the pichost has pop ups

embedding them in high resolution is viable and much better than just linking them, but then again that causes traffic and problems.
Some users occasionally (or regularly) use this website on a phone..
sometimes a pic is corrupted (traffic corruption) and the website can not post-scale it to fit the screen,
and then you have to scroll past that huge empty space..

And sometimes a pichost deletes an image and then it's gone..
and the post or thread you made might be rendered useless.

Attaching them here is the best option yet.
The images should be as well backed up and available as the post itself;
and it comes as a thumbnail, for you to click.
But I agree that the imagesize could be a little larger..
say the full 1500px allowed and not scaled down to 1000


And now back to our regular program...

I fell in love with Cyclekarts the first day I saw one.
it's great to finally have a build log for one

'sid

 

[JR74Ford]

Haha, yeah I was just being checky having a joke. The thumb nails are ok, it was just my way of apologising for the links (it was changed from embedded by mods). The mods obviously know the circumstances of the users best. Cheers guys

 

[B.M.800]

Looking forward to this. looks like a cool build!

 

[JR74Ford]

It rolls
http://i60.tinypic.com/n5luuq.jpg
Next job is to make the jack shaft.

 

[JR74Ford]

Here is the progress on the jackshaft, while the wee fella is young it will be in 1st gear only with the centrifugal clutch. Then when he's ready for all 5 gears in manual I'll lock up the clutch.
http://i57.tinypic.com/14adi4x.jpg
http://i60.tinypic.com/27xowea.jpg

 

[landuse]

Nice jackshaft setup

 

[itsid]

have you checked the numbers?

it looks like a 2:1 ratio for the engine out to JS in..
As far as I know
primary reduction is 3.35:1
first gear on a CBF 125 is 3.076:1

that's a 20.61 in the end...
which means to fully engage the clutch you need to rev up to 41218 rpm
So the clutch will spin nowhere near fast enough to engage.

max torque is at 6250 rpm max hp at 8000
and IIRC it's rev limited -I don't know when- but I assume 11500-12500 or something...

So I'd say either get a much smaller sprocket for the JS in (get the 20T for the engine and a 10T for the JS),
and try it in second or third gear if at all..

gear : ratio : expected rpm to fully engage clutch with 1:2 JS ratio
1     3.076     10304
2     1.944     6512
3     1.473     4935
4     1.190     3987
5     1.038     3477

'sid

 

[JR74Ford]

Wooow, cheers. Not much gets passed you!
I had checked the numbers, but I made a fatal mistake..... I didn't know about the primary reduction. I was planning on stretching the spring on the clutch so it engages at an earlier rpm but now the jackshaft rpm will me far too low.

I will have a play around with the numbers, see what sprocket sizes are available and what lower clutch engagement rpm is possible.

Have you adjusted clutch engagement speed before by messing with the spring?

Thanks for the heads up there, you sir are why forums are awesome!

Cheers, John.

 

[itsid]

Hm.. I never tried messing with the spring, no.

stretching isn't exactly an option, since I believe you have a max torque SS there,
and the spring runs in a groove inside the shoes, so correct length is important.

you could of course weaken the spring, but if I had to make a guess, I'd say the downsides are plentiful and the one upside can be bought ($11) here:
http://www.affordablegokarts.com/mm..._Code=A&Product_Code=SMFKT*&Category_Code=PCJ

Oh and I miscalculated.. a MT SS engages at 2200 rpm, I assumed just 2000,
so rpm need to be 10% higher than what I listed above

'sid

 

[JR74Ford]

I have started on the body, it will be covered in very thin plywood then glassed over the top.

 

[MrBracket]

Very cool, can't wait to see the body take shape!!

 

[JR74Ford]

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Fits like a glove

 

[Denny]

That is a sweet little cyclekart your building there! I can't wait to see it running.

Denny

 

[landuse]

You did some great woodwork there. What wood are you using?