opinions ?

[coley13]

i've pinched a picture from Mad dogs gen3 125 build....

first cut lower rails as per drawing completely and then-----

picture two tiny holes drilled both sides at the rear to prevent cracking and a pie cut to the front and two sides. I've exagerated the picture. Method would be to bend the down dube a couple of degrees further forward and then re weld. This would push the "Y" and lower radiators slightly forward and give engine clearance. I was thinking this would be a stronger section to modify and reweld but not sure changing the "PLANE" would be the smartest move.


Just after thoughts on this, pro's and cons. Would it work or be an engineering disaster.


PS. not interested in anything else "Y" height etc just moreso interested in the structual integrity of cutting and bending a frame in that location and fashion




Anyway, let us know what you think


Edit, just picture that with the "Y" still attached to the down tube

[Flatbiller]

I wouldn't do that if I were you. I had mine done the same way for my 250, got it all together powder coated the frame it was titties! Posted on here and 50 ppl who have done it the same way as me said there y cracked! I took there word for it and now I have to cut the whole thing apart again!

It was pie cut just like your thinking about! It won't work!

[coley13]

ok, thanks.....

i was looking other pics of 125, sorry i stole this pic aswell. led to believe it failed at the Y too.




Was wondering if these failures are due to the change in angle, hence my thought on changing the "PLANE" Further up from the "Y". The section looks like it would be sturdier.

Or maybe make a DIE and do a slightly curved boxed section using a press "IF" it can be suported. Kind of like cold roll pressing it. Not much room to work with up there though.

Anyway, just thinking out loud. Cheers

[coley13]

clamp method maybe ? just another thought. It wouldnt be as prenounced though. Looking at approx 20mm further forward at approx 150mm away if you where to look at the front engine mount location from a hypothetical pivot point of the clamp so the bend radius wouldnt be that much obviously.

[Flatbiller]

Um I thought you were going to cut in to the y and down tube with a pie cut and bend the y foward like your picture??? That's what I did don't do that. Is that your plan?
I'm not sure about a 125 frame... But that angle is extreme...

Hopefully some one will post that's done a 125 frame cuz I have no clue.

[Flatbiller]

DONT DO THIS!!!!!!!!!!!!

[coley13]

basically i was thinking the same, the only difference would be to change the angle further up away from the "Y" section in the beefier RHS section part of the frame.

So the heat effected area is not at The "y"

[coley13]

i've been thinking more of the bending method instead of the pie cut method... I did some rough measurements

20mm forward over 230mm distance. I havnt been to school for 20 years but i worked it out at roughly 9 degrees needed. i could be wrong

I'd be curious of bending stresses to achieve 9 degress over roughly 4 inches of RHS "thats the distance from the inner support to top of "y" with a gentle radius.


Maybe a better option ?????????????

[Flatbiller]

Dont pie cut anything! Lol that's how I got into trouble!

As far as I know on a 125 frame the y has to be cut completely out of the frame, the down tube trimmed for clearance and the y re welded over top of the downtube.

It's the blind leading the blind!!!!!! Just wait for some one with more knowledge to chime in b4 you hack the frame up.

[maddog1927]

I think AF's 125 build post is worth a read. If I was doing one without my billet wye that is how I would do it.

But I would never do a 125 again.

250 Algava style all the way. yea, I know every other post I write how much I like the algava style 250 conversions.

[AlisoBob]

I'm not feelin' it.....

[bearorso]

To reflect what another fellow said- "he'd not do a 125 again".

No offense to those that love their 125 conversions, I'd not do a 125, full stop. Plenty of 250 2ts out there to do - even here in OZ , where they don't grow on trees like in the US.

If you're determined on doing this (fair enough, determination and desire achieve many things), give thought to replacing the entire down tube / Y. Sure it might give you some fun and games with radiator mounts, but that can be solved.

My thoughts are : either a 'downtube and Y, and potentially the forward part of the cradle' in Plates, or new full cradle going to the plate DT and Y.

Nah, bugger that, here's something Much Better : a full new cradle to the original down tube, that has the following = the least fabrication of all. You could have a U, in either plate, bent U, or cut section of square / rectangle, placed on the front/ sides of the original down tube, to 'straighten' the downtube, then attach the new full, double bend cradle to both the DT extension, and the original DT. The original lower radiator mount could either be left in place, as part of the extension interface, or added to whatever you did. The original / interface is probably the strongest option.

Here's some pictures of how TM do their cradle and down tube set up on their alloy frames, for an example of a"full cradle":








I'm curious why you didn't do the steel TM frame you cut up - I was more than willing to help with that, as I told you. You would have had something unique, and in my belief, better than what you will end up with, with a Honda conversion. I've ridden the TMs, and the various Hondas people base their conversions on, and to me, the steel TM frames, especially, I think, are well suited to having a 500 2t in them. Probably not the thing to say here, but that's my take on it.

[coley13]

I'm not feelin' it.....

Not sure what you mean Bob ? The angle ?

[coley13]

To reflect what another fellow said- "he'd not do a 125 again".

No offense to those that love their 125 conversions, I'd not do a 125, full stop. Plenty of 250 2ts out there to do - even here in OZ , where they don't grow on trees like in the US.

If you're determined on doing this (fair enough, determination and desire achieve many things), give thought to replacing the entire down tube / Y. Sure it might give you some fun and games with radiator mounts, but that can be solved.

My thoughts are : either a 'downtube and Y, and potentially the forward part of the cradle' in Plates, or new full cradle going to the plate DT and Y.

Nah, bugger that, here's something Much Better : a full new cradle to the original down tube,that has the following - the least fabrication of all. You could have a U, in either plate, bent U, or cut section of square / rectangle, placed on the front/ sides of the original down tube, to 'straighten' the downtube, then attach the new full, double bend cradle to both the DT extension, and the original DT. The original lower radiator mount could either be left in place, as part of the extension interface, or added to whatever you did. The original / interface is probably the strongest option.

Here's some pictures of how TM do their cradle and down tube set up on their alloy frames, for an example of a"full cradle":








I'm curious why you didn't do the steel TM frame you cut up - I was more than willing to help with that, as I told you. You would have had something unique, and in my belief, better than what you will end up with, with a Honda conversion. I've ridden the TMs, and the various Hondas people base their conversions on, and to me, the steel TM frames, especially, I think, are well suited to having a 500 2t in them. Probably not the thing to say here, but that's my take on it.

I'm not really in a position to convert one at the moment, basically just asking questions, thinking, learning. I've already got an 07 125 which i purchased soley as a 125 for ST riding not for the purposes of converting it, but you never know the bug might hit and may aswell be prepared if it does. I know a 250 frame would be better and swap everything over, would need to find one, need to get it shipped over here etc and it all adds up finacially $$$$$. This may sound silly as 2002 - 2007 are same generation i'd still want it to be a 2007 model and to pick up an 07 250 frame will be even harder get my hands on.

Regarding the TM, would of loved to of kept it. The department wouldnt cover logistics costs when we transferred to the east cost. My other bikes took priority sadly. 8K in expenses and they wouldnt throw a bike in the back of the truck. i didnt have room in the trailer and i wasnt making a 3000km round trip to get it, sold the engine and some other stuff, i kept the ohlins complete front end and shock, billet parts brakes etc, jammed all that in the boot of the car

[AlisoBob]

I'm not feelin' it.....

Not sure what you mean Bob ? The angle ?

Everything...

The look, the angle, the stressing of the cradle when bending it like that.

If this was 3 years .... then o.k. 3 years ago there wasent the support that their is now.

Eric and Paulie both can sell you complete cradle replacement pieces for 125 chassis conversions....

Why even dick with all that pretzle making .....

[100hp honda]

i think TTM was on the right track with 125 conversions. i would look how he did it

[AlisoBob]

Fuck-face Fachar didnt replace the crable, he scabbed on like S/H still does.

Paulie and Eric dont......

[AlisoBob]

Like it!!

[Gravel Scratcher]

[quote="coley13"]



thats as crooked as a


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as Bob said there is a heap of better options around that will give you less problems in the long run

[100hp honda]

anybody that reads this forum knows theres several ways to convert every year chassis. one method not necesarrily being better than another but just another way to get from point A to point B. this aint about mike being a scamer. all im saying is his 125 conversion was nice. im sure eric or paules is nice also.

[coley13]

I'm not feelin' it.....

Not sure what you mean Bob ? The angle ?

Everything...

The look, the angle, the stressing of the cradle when bending it like that.

If this was 3 years .... then o.k. 3 years ago there wasent the support that their is now.

Eric and Paulie both can sell you complete cradle replacement pieces for 125 chassis conversions....

Why even dick with all that pretzle making .....

If i'm not mistaken that pic you quote was built by Eric "cmotodad's bike " and has since broken at the "Y" and has been redone with billet i believe. Hence starting a thread on opinions, Not so much pretzle making, understanding the angles, loads, bending, heating etc what affect/or negative effect a certain method would have



Prebent cradles would be great, i've only seen one for a 450 so far, it would need re bending for a 125 chassis.... i agree though it would be easier......

The bike above broke, there has to be a reason why? It looks like the cradel was completely replaced... Is it because of the down tube angle? The point of this thread, is there a way of changing it with NO i'll effects?


edit - http://bannedcr500riders.com/board/view ... highlight=

looking at the pics it was not a complete cradle

[Flatbiller]

Didnt cmoto say that his 125 conversion cracked the y?

[coley13]

yes

[bearorso]

Like it!!

Yes, a single cradle rail, either side is just such a clean way to do it.

Last year I had a variety of PMs with another fellow from here, showing / encouraging him to do this. Something Different. I'm not sure what he did.

If you can find (and surely, it can't be hard to find, any one of thousands of workshops in the US) a good tube bender, the 'double bend' cradles would be The best looking , and very strong, set up. Other than plated Ys and cradle - but I freely admit , that's just me being a goose and wanting to see My own (over)workmanship.

The downtube on the TMs is a special piece, as you can see, that makes it a very simple joint, from the welding perspective, but the cradles to the std downtube, with plating mirroring the cradle / downtube interface on the TM, would produce a beautiful and very strong conversion, that would virtually duplicate it.

I've sworn off doing anymore conversions, for the time being - and my mates that wanted them have all got theirs out of me. I've very little time to do extra things, for the next year, again, especially if some business comes through from my recent trips to the US. The "keep me sane" ( or is it, Drive Me Nuts?) project for this year will be a (well, probably 3 different versions - 1 for my frame, 1 for a std steelie rear end plastics, and perhaps one that will take later side panels and rear guard) monocoque subframe and airbox set up ( Bite Me ,Sean !!!:lol: ) like the early 80's works Hondas, just as I did with my drop tanks. But, if another old friend pulls the pin on his 4t, I think the double bend, full cradle, is what he's going to get. That, or nothing. That ultimatum, should sort the choice out for him .

[bearorso]

To reflect what another fellow said- "he'd not do a 125 again".

No offense to those that love their 125 conversions, I'd not do a 125, full stop. Plenty of 250 2ts out there to do - even here in OZ , where they don't grow on trees like in the US.

If you're determined on doing this (fair enough, determination and desire achieve many things), give thought to replacing the entire down tube / Y. Sure it might give you some fun and games with radiator mounts, but that can be solved.

My thoughts are : either a 'downtube and Y, and potentially the forward part of the cradle' in Plates, or new full cradle going to the plate DT and Y.

Nah, bugger that, here's something Much Better : a full new cradle to the original down tube,that has the following - the least fabrication of all. You could have a U, in either plate, bent U, or cut section of square / rectangle, placed on the front/ sides of the original down tube, to 'straighten' the downtube, then attach the new full, double bend cradle to both the DT extension, and the original DT. The original lower radiator mount could either be left in place, as part of the extension interface, or added to whatever you did. The original / interface is probably the strongest option.

Here's some pictures of how TM do their cradle and down tube set up on their alloy frames, for an example of a"full cradle":








I'm curious why you didn't do the steel TM frame you cut up - I was more than willing to help with that, as I told you. You would have had something unique, and in my belief, better than what you will end up with, with a Honda conversion. I've ridden the TMs, and the various Hondas people base their conversions on, and to me, the steel TM frames, especially, I think, are well suited to having a 500 2t in them. Probably not the thing to say here, but that's my take on it.

I'm not really in a position to convert one at the moment, basically just asking questions, thinking, learning. I've already got an 07 125 which i purchased soley as a 125 for ST riding not for the purposes of converting it, but you never know the bug might hit and may aswell be prepared if it does. I know a 250 frame would be better and swap everything over, would need to find one, need to get it shipped over here etc and it all adds up finacially $$$$$. This may sound silly as 2002 - 2007 are same generation i'd still want it to be a 2007 model and to pick up an 07 250 frame will be even harder get my hands on.

Regarding the TM, would of loved to of kept it. The department wouldnt cover logistics costs when we transferred to the east cost. My other bikes took priority sadly. 8K in expenses and they wouldnt throw a bike in the back of the truck. i didnt have room in the trailer and i wasnt making a 3000km round trip to get it, sold the engine and some other stuff, i kept the ohlins complete front end and shock, billet parts brakes etc, jammed all that in the boot of the car

Ahh, fair enough. Moving across our country is a bitch of a job, and those that require you to do it always fall short of what is actually needed.

I'd say you could have got a fair amount of money for the TM - sell it to Karters?

It's funny, standing back from things, can help - I'm referring to myself here. As I said, projecting a straight line down from high on the downtube, to a cradle made for the bigger engine, would be the go for a 125 frame. So long as there are no wheel contact issues, mudguard perhaps, but that wouldn't be a deal breaker. I think, though I could definitely be wrong here folks, that the 125 frames actually have a slower steering head angle than the 250s, and perhaps a shorter swingarm , as well?

Have a squiz along the lines I've suggested - I think you'll end up with a Good Thing. Just piss of the lower cradle, and fit a new one.