CR500 , 2 stroke hardtail chopper project

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

have fun,I'll stop wasting my time.

sorry, wasn't trying to curb your ideas. Just addressing them. I certainly haven't thought of everything on this build. I mean it, I really do prefer criticisms over compliments.

 

[firebane]

If a bike your building isn't causing some stir your not doing it right.

You sir are doing it right keep it up and keep showing your work please.

 

[Cafe Mike]

Re: CR500 , 2 stroke hardtail chopper project

That's fine mike, I don't want you to like it. After years of road racing on a track I don't find much thrill in pretending to ride fast on the street. So I ride smaller bikes. Before this I had a 50cc step-in scooter that was modified to do 80mph and would keep the front end if the ground until 40mph. But I'm sure thats worth farting on too. This bike will be around 75BHP and weigh around 165lbs. I can put my weight on my ass and don't have to stand up to ride it.

This bike wanted to be a chopper, that's just what motor and geometry and tires all said. I just wanted to build a sweet custom bike for the hobby of building bikes. The next project i have is a gt750 3cylinder water cooled 2 stroke. It really wants to be a 30's style big wheeled board tracker, maybe you like those better.



I am after all kidding. I took the time and read your whole thread.... The lyrical tongue master maybe witty with words. But you my friend are giving the big fu to the purists and square minded followers. I dig it. It's one of my favorite quotes- I never heard someone complain they had too much horsepower... Only thing I say is get a throttle tube that is lobed so it comes on small. Rather half half throttle than on off 1/4 throttle. I had a yz490 at 13.. Only two poeple could start it in the hood. And of it stalled, I pushed it home. Made me a better rider, and owning kx500's man I hope you have lots of boxers.. Depends ...
And yes let's build this board tracker... I'm game. Only after we finish this one. Hater motivation

 

[oldskool]

Re: CR500 , 2 stroke hardtail chopper project

sorry, wasn't trying to curb your ideas. Just addressing them. I certainly haven't thought of everything on this build. I mean it, I really do prefer criticisms over compliments.

let me start over,I am fabricator with 10 + years of experience. You have created a structural nightmare with the curved bottom rails and bringing all the forces to one point.I don't think you get that

 

[Cafe Mike]

Re: CR500 , 2 stroke hardtail chopper project

I'm gonna have to disagree. Seems to me the shape is solid. Egg shapes are just as good as triangles. And yes triangles are superior... But really I say that not knowing the tube i.d. Wall thickness or 4130, drawn over mandrel. Seam bent at Clr.

let me start over,I am fabricator with 10 + years of experience. You have created a structural nightmare with the curved bottom rails and bringing all the forces to one point.I don't think you get that

 

[oldskool]

Re: CR500 , 2 stroke hardtail chopper project

I'm gonna have to disagree. Seems to me the shape is solid. Egg shapes are just as good as triangles. And yes triangles are superior... But really I say that not knowing the tube i.d. Wall thickness or 4130, drawn over mandrel. Seam bent at Clr.

So,the lower half of an egg with the outsides fixed on pivot points with downward force to the center is solid?...ya,ok. if the top of the egg was there it would counteract it,but its not there. Conventional frames use the egg shape geometry because the major load is in the center of the frame. he has taken 2 eggs n put em side by side with the downward force in the middle of the two,which will make the eggs wanna roll. I'm totally into building crazy non-conventional bikes and its kinda my thing. Just tried to help him out n he'll understand why later.

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

let me start over,I am fabricator with 10 + years of experience. You have created a structural nightmare with the curved bottom rails and bringing all the forces to one point.I don't think you get that

Jun-yah what's the single point you are referring to? The "swingarm" section and backbone section gross each other, but both forces terminate at a different point on the frame. And those points are both braced as well. So other than the 12" of backbone I don't see a single point that your referring to.

I agreed with you on the gussets and triangles and shown I had already done them. But your information on arches is completely wrong. A parabolic (top) arch is far stronger than a straight line. How many straight line bridges do you see?? The inverted arch (bottom) is great for lateral forces. Like the ones I will produce when I wheelie this bitch out of a corner.

I can suspect the problem you are referring to is the ovaling of the tube that can occur from using a tubing roller. To solve that I used correct size dies and rolled the tubing slowly. I also sealed and filled the tube with sand so that it would retain is shape as I rolled it. I did get some ovaling when I was torch bending the tight radius on the end of the frame, but the axle plate makes that are strong.

I used .134 wall A513 dom tubing

 

[oldskool]

have fun with it

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

have fun with it

It'll be fun for sure. I just wanted you to clarify where you think it has engineering shortcomings.

 

[oldskool]

if i get a chance I'll draw it out,will be the best way to explain it. It will work the way its built and I'm not saying it's unsafe. My suggestion is for the longevity of your project. I never said a top arch is weak,I said you don't have one over the length of the bike. And when you do a bitchin wheelie(I LIKE BITCHIN WHEELIES,BTW) it will be fine,its the forces of when you land that come into play.

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

Yeah I didn't think you were hating on the whole project. Is love to see a drawing of the weakness you see.

 

[oldskool]

are you on instagram?

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

are you on instagram?

yes but I don't post anything but cute kid photos

 

[Brodie]

Re: CR500 , 2 stroke hardtail chopper project

I suppose I like that part too. I just don't like the part of humanity where we have to hate anything that is different than ourselves.

That part is called xenophobia Define:unreasonable fear or hatred of the unfamiliar (Webster's).

 

[xb33bsa]

no hate or fear ,here,only understanding
what is being built here is an extremly poorly thought out soon to be found out dangerously bad handling RECUMBANT motorcycle
and yes !!
it can be done it has been done,see pics ;D
and they CAN handle really well
but dude the geometry of you're cr500 is pretty far off the mark
tucking in the front end a bunch will help
and really must have a full seat with a seat back and the ability to distribute weight and force some weight/pressure forward into the pegs
in the end it is still a bit weird and not REALLY a proper sickle
but i am ok with that no hate
it has been done already, you are doing it wrong

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

Haha I think I'll stick to doing it wrong. A recumbent bike is not what I'm building. Your perception is based only on my seating position.

You are kinda correct though. The front end is not gonna like to be pushed into a corner while trail braking. But that's not what I am building it for, and that doesn't make it an improper motorcycle. If that was what defined a motorcycle we would all be riding modern sportbikes., but of course 90% of those bikes are not ridden properly, so what's the point.


Here's is photo of the last custom bike I built about 11,years ago, maybe it will impress you or at least justify my understanding of geometry. Its an XR250 4stroke motor shoved into a RS125 gp chassis. I like to believe dorna got the idea for Moto1 and Moto2 from my prototype design, but at least I did it before they did.

 

[fury413rb]

I dont get why so many people have a problem with a bike that isnt built for max handling. One look at the thing and you can tell you aren't going for laptimes here...

 

[teazer]

Fury,
The issue isn't race handling or no handling, anymore than it's race performance or less than stock performance. It's really an issue of how good or how bad and cafe racers tend towards the functional end of the spectrum for any particular bike and tend not to make changes that make a bike less functional than stock.

Bee,
love that RS/XR mix. Our RS was earlier than that. Guys in Australia were racing singles in other chassis a while ago too. One guy had a CR500 motor in and RGV chassis IIRC. Went like stink and weighed less than a dried up fart - or so he said. AHRMA guys have been racing TZ250 chassis with various four stroke single motors but rarely the 125/250 combo that Moto3 is.

 

[Beeweldmut]

CR500 , 2 stroke hardtail chopper project

Teazer thanks I'm not claiming I have the first moto3 bike. I just could not find anything similar when I researched it a dozen years ago.

You summary of the problem is right on. I agree that the tendency of cafe racers is to improve on stock configurations and components. I also agree that the tendency if choppers is to make them less ideal than stock. That being said a chopper is no less a motorcycle. My desire with this build was the challenge of building a custom bike. Not building a bike that was going to win the race out of the parking lot.

I joined this site because some of my friends were on it. I innocently posted a chopper on a cafe racer forum because I thought it had lots of custom home builders that would appreciate my work. I forgot that cafe racers tend to be clues minded about anything but cafe racers. Luckily there are still many people on this forum that like the project and want to see it updated. I'll continue to update and debate critics.

 

[Cafe Mike]

Re: CR500 , 2 stroke hardtail chopper project


Sick!!!!!! Must have been sweet to ride. You still got it?

Haha I think I'll stick to doing it wrong. A recumbent bike is not what I'm building. Your perception is based only on my seating position.

You are kinda correct though. The front end is not gonna like to be pushed into a corner while trail braking. But that's not what I am building it for, and that doesn't make it an improper motorcycle. If that was what defined a motorcycle we would all be riding modern sportbikes., but of course 90% of those bikes are not ridden properly, so what's the point.


Here's is photo of the last custom bike I built about 11,years ago, maybe it will impress you or at least justify my understanding of geometry. Its an XR250 4stroke motor shoved into a RS125 gp chassis. I like to believe dorna got the idea for Moto1 and Moto2 from my prototype design, but at least I did it before they did.