Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Oh yeah I wasn't planning to cut the tubes at all - was just gonna cut the springs and put the spare on the return side, following this video:

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Definitely need to make a rear fender asap - worried about flinging mud into the carb as I'm riding. Trying to figure out how to work one with the big sprocket. Was originally thinking a sheet of aluminum like this:

ScreenShot2021-02-01at10.25.22AM.png

But making sure I account for the chain might be a challenge:

PXL_20210131_234616773.jpg

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> Colin Ratcliff Wrote:

> -------------------------------------------------------

> Yeah this is with the original intake (because the short one wouldn't

> work with the rear transmission). Power comes on quite high it seems -

> though I can't tell for sure with the red springs. Might toss on the

> blue ones today (I don't have the yellow ones sadly) and run it to get a

> better idea.

>

> It definitely had some running trouble - overheated, was fairly weak at

> super high rpms, and never felt SUPER powerful. I'm guessing those are a

> combination of:

>

> 1) needs to go more rich

>

> 2) might have an exhaust leak, sounded pretty loud

>

> 3) long intake

>

> So once the short one comes in I'm gonna test 'em both out and see which

> way to go. Also need to get some bigger pilot jets for the Polini

u need to gear it low! It’s insane, my stock engine reved like crazy I can only imagine that kit (edited)

Re: Crazy Custom Frame Hobbit

Idk what it is but the rear of that frame seems very dumpy, kinda too boxy? Like it’s a cushman or something. I think maybe it’s the furthest back triangulated frame member.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

I'm not sure what area you're talking about. I definitely still need to do work on the seat to get it to the same height as the tank etc, if that's what you're thinkin of. Or are you saying it's angled down too much?

Re: Crazy Custom Frame Hobbit

It’s the last tube in the V that meets the shocks.

Most frames have a curved member there or the V doesn’t go all the way down to the swing arm mount. Just fucks up a kick ass bike’s look in my opinion.

As well, the shocks would work better if the top mount was moved forward a bit more. In my experience, 45-60 deg is the best, but these are a lil less than 90.

Re: Crazy Custom Frame Hobbit

These are just my opinions. Everyone has some.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Hmm, I agree to a certain degree, but think the lines will come together once the butt-stop on the seat is in place, which will break up the top line of it. If anything I would change the front downtubes to be a bit more vertical, which would shift the visual weight forward.

I went off the lines of the VanTech frames, so it's definitely possible to make these lines work:

ScreenShot2021-02-01at11.09.55AM.png
ScreenShot2021-02-01at11.09.33AM.png
ScreenShot2021-02-01at10.25.22AM.png

Re: Crazy Custom Frame Hobbit

I think a trick to solve all of this without frame mods would be to extend the swing arm a few inches. It’ll help you from lifting the front too much as well and will make the whole thing look more balanced (front to rear) I know joes bike basically flipped at one point, and your butt is right on top of that rear wheel it looks like

Re: Crazy Custom Frame Hobbit

Fair enough. Just an opinion

Re: Crazy Custom Frame Hobbit

> Colin Ratcliff Wrote:

>If anything I would change the front downtubes to be a bit

> more vertical, which would shift the visual weight forward.

>

Yeah that would do it for sure. I try to equalize the gap front/back gap between wheel and frame for a visual balance if possible.

Re: Crazy Custom Frame Hobbit

Just do the aluminum sheet for the fender, once you get the speed bump on, that'll cover your ass from dirt. And water.

I think the frame lines look fine. Most of the old 50cc racers had their butts over the center of the rear wheel. With a tucked body position that puts your weight centered in the middle of the bike.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Dope, yeah I'm gonna roll with it like this and we'll see where it goes. There are some options to change the lines down the road etc (plus the wheelbase is long as all getup so I may want to shorten that at some point), but for now I'm extremely happy with how it feels and runs.

Also might be able to shift the tank forward an inch or so which would let me shift forward - right now it's back to allow the bars full turns, but I doubt they need that full kx80 rotation.

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> JBOT Admin Wrote:

> -------------------------------------------------------

> These are just my opinions. Everyone has some.

Talking to guy that actually took the words out of my mouth to explain the look of his bike but couldn’t agree with it....

Re: Crazy Custom Frame Hobbit

Uh wat?

Cut back on the meth plz

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> JBOT Admin Wrote:

> -------------------------------------------------------

> Uh wat?

>

> Cut back on the meth plz

I’m about 10 marijuanas deep stuck behind 6” of snow its comparable

Re: Crazy Custom Frame Hobbit

I think the swingarm is fine, maybe it’s just too tall still. The swingarm is like mad extended, its like when you raise or lower a car too much it really messes up the geometry and the extra angle makes the suspension act crazy. I think if it was closer to zero’d out like the original design it would be pretty much perfect.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

> Daniel '' Wrote:

> -------------------------------------------------------

> I think the swingarm is fine, maybe it’s just too tall still. The

> swingarm is like mad extended, its like when you raise or lower a car

> too much it really messes up the geometry and the extra angle makes the

> suspension act crazy. I think if it was closer to zero’d out like the

> original design it would be pretty much perfect.

I'll definitely try it out before cutting anything - you may very well be right! I just am hoping to get the seat height to a comfortable level, and it's already pretty low for me. Could always do a more padded seat though - right now it's ~2"

Re: Crazy Custom Frame Hobbit

If you're gonna do much more than 30 MPH , you'll appreciate the longer wheelbase .

Form follows function , unless you're suicidal . Then whatever ...

Re: Crazy Custom Frame Hobbit

Tweaker trash /

It’s to wide for that look and feel those bikes were built like pencils and tapered

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Oh the wheelbase is already 54", so it's already up there with big motorcycles.

Agreed the frame is a little wider than I would have wished, but it's accounting for the width of the engine more than anything. I'd go an inch narrower if I ever redo it.

Just swapped the main to a 210 and it's so much more powerful but still too small, and that's the biggest that the VM20 goes! Hoping the Polini can reach the needed size, otherwise... bigger carb?

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /
PXL_20210202_010026805.jpg

Trying to figure out how to fit a short intake in this. Seems too tight to make it out the side?

Re: Crazy Custom Frame Hobbit

210 not big enough ? Get your jet bits out and make it what ever works best . ;)

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> Colin Ratcliff Wrote:

> -------------------------------------------------------

> Oh the wheelbase is already 54", so it's already up there with big

> motorcycles.

>

> Agreed the frame is a little wider than I would have wished, but it's

> accounting for the width of the engine more than anything. I'd go an

> inch narrower if I ever redo it.

>

> Just swapped the main to a 210 and it's so much more powerful but still

> too small, and that's the biggest that the VM20 goes! Hoping the Polini

> can reach the needed size, otherwise... bigger carb?

You probably need a bigger atomizer

Re: Crazy Custom Frame Hobbit

Are those the large hex or small hex jets?

Large hex goes up to 720. Treats has up to 280.

Re: Crazy Custom Frame Hobbit

I will say that a long intake will make your jetting really picky.

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Yeah trying to figure out how to tuck in a smaller intake - the other challenge with that will be testing it out. Right now it feels pretty darn good, particularly when not under load, and I don't want to modify the side plate if I don't have to.

It's the 10 pack of jets, so probably small ones. Either way I'll be going with the Polini so not gonna buy more jets for the VM20 for now.

Bigger needle jet (atomizer) is a good idea - if nothing else I'll change the clip for the needle.

But yeah, totally get that the intake is gonna be a problem no matter what and limit what I can get out of it. Just trying to figure out how to assess the worth of the work without doing it permanently

Re: Crazy Custom Frame Hobbit

Tweaker trash /

> Colin Ratcliff Wrote:

> -------------------------------------------------------

> Yeah trying to figure out how to tuck in a smaller intake - the other

> challenge with that will be testing it out. Right now it feels pretty

> darn good, particularly when not under load, and I don't want to modify

> the side plate if I don't have to.

>

> It's the 10 pack of jets, so probably small ones. Either way I'll be

> going with the Polini so not gonna buy more jets for the VM20 for now.

>

> Bigger needle jet (atomizer) is a good idea - if nothing else I'll

> change the clip for the needle.

>

I was talking about a larger atomizer for the jet but it seems the vm20 only offers one size 😔

That jetting seems crazy, u need to find a way to add fuel without going up in jet sizes...maybe a thinner needle I don’t know

Fucking carbs

Re: Crazy Custom Frame Hobbit

Colin Ratcliff /

Mayyybe but main jet is what effects WOT, which is where most of the issue is.

Re: Crazy Custom Frame Hobbit

If you could put a 24mm or bigger carb on it you’d be much happier. Oko, polini whatever. My fastest 70cc bikes have 24s and it’s night and day from smaller carbs. My tanks are usually 2 or 3 gallons so at 40mpg at 55ish you can still get places. 24mm on the tiny hobbit tanks sucks shit tho.

As to the side intake that’s the way to go. Do a straight shot into the reeds from a slight downward angle, just like 3/4inch from that sprocket. The tube will have to be cut at an angle to weld up with the intake plate above the reeds.

To figure out the angle cut a 24mm tube out of paper and cut the reed plate angle til it works. Then tape together. Then you’ll know where to punch the hole in the plate too.

Making paper or cardboard intakes rules to figure out dimensions before making out of steel if you haven’t done much parts building.. I have a weird design space in my head from years of experience that I explode parts in and piece them back together like that chess lady does in queens gambit playing chess on the ceiling... but I still have to make stuff out of paper for tricky angles to make sure shit will clear (edited)

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account