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Twinshock frame mods


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#1 neil0965

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Posted 25 November 2011 - 10:43 AM

Iíve read a lot about modifying a twinshock frame to Majesty spec, presumably the front tubes are straight forward but does anyone know how and where the back of the frame is altered?


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#2 feetupfun

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Posted 25 November 2011 - 11:41 AM

Front uprights shorten at bottom end. Rear uprights shorten at top end. Middle uprights shorten at top end.
There is nothing good or bad, but thinking makes it so

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#3 shedco

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Posted 25 November 2011 - 01:32 PM

Just a cut & lift job - dead easy.
If only!
As feetupfun says,

The front tubes were cut & bent slightly,
The two tubes in the middle of the bike were cut & bent slightly.
The rear tubes cut & bent slightly.

How much to 'bend a bit' is the difficult thing to find out!
Without a jig, it would be very difficult to do correctly.
Get it wrong, the bike would be out of plumb & on the p***!

A lot of effort for little return.

#4 woody

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Posted 25 November 2011 - 07:25 PM

The back end is the difficult bit. We've had a Majesty and standard frame next to each other and it is very difficult to see exactly how it was done, even with much measuring of dimensions. There was more than just shortening the rear tubes. Also, as the engine sits almost 2" higher, the frame behind the toolbox needs to be reshaped to accomodate the sparkplug, airbox rubber will no longer fit and needs shortening and the exhaust height needs reducing.

As said, a hell of a lot of work. You don't really need that much ground clearance either. You'd be better off just angling the dampers, although big gains could be had by just fitting an efficient set of dampers to the standard frame.

#5 neil0965

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Posted 01 December 2011 - 11:25 AM

Presumably the swing arm axel moves up 2Ē as well then?

#6 woody

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Posted 01 December 2011 - 10:23 PM

Probably but I honestly don't know.

You can see obvious differences in dimesnions and you look at one part and think 'that will affect that part as well', but when you measure them one is the same on both frames, the other is different and you just think, that can't be... As I said, how they did it was clever and not obvious.

Attached are pics of a standard bike and Majesty fopm same side and my old Majesty from the other. See what you can make of them. The front pipe on the first Majesty is standard TY Miller pipe which is why it sits too high on the Majesty in case anyone is wondering.

Look at things like height of front engine mounts to wheel spindle height, swingarm pivot to wheel spindle height etc.

Attached Images

  • majesty john.JPG
  • Yamaha1976_TY250.jpg
  • Majesty Yellow.jpg

Edited by Woody, 01 December 2011 - 10:29 PM.


#7 feetupfun

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Posted 02 December 2011 - 06:40 AM

Earlier this year, I actually went through the process of modifying a TY250 frame to make a replica of a bike which was built in 1976 and which used very similar ideas to what was done years later with the Yam frame Majestys. It was quite a learning experience and as people say, a lot of work to do it right. It took me 4 full working days to make the jig and do the basic frame mods. It doesn't sound much but that is 32 hours work and that does not include the myriad of other work that is needed to be able to complete the bike.
It is definitely not easy and I would agree quite impossible to do properly without making a jig first.
In the case of the bike I did, the target was to raise the motor 1 inch, and from all I have seen and read about the Yam Frame majestys, I would say that was the case with them too. The claimed 2 inch increase in ground clearance and steepened steering head angle were achieved via the combination of raising the motor close to one inch and the increased rear end travel raising the rear end of the bike. Having studied photos of Yam framed majestys with tank removed, I know by comparing the locations of the sparkplug tips relative to the horizontal brace behind the toolbox, that they had the motor raised the same amount or very close to the one I did.
I'm not keen to post up photos of how the work was done yet because that bike was built for a feature article in a magazine and it hasn't come out yet. I do plan on posting the photos up somewhere accessible later on.
There is nothing good or bad, but thinking makes it so

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#8 tee_why

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Posted 02 December 2011 - 02:21 PM

How much of this applies to the TY175 frame?

#9 woody

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Posted 02 December 2011 - 09:29 PM

Probably none - don't think they had anything near the mods of the 250

#10 b40rt

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Posted 31 December 2012 - 04:58 PM

I'm not keen to post up photos of how the work was done yet because that bike was built for a feature article in a magazine and it hasn't come out yet. I do plan on posting the photos up somewhere accessible later on.


Come on feetupfun, time to show the photographs, please.
Never argue with stupid people, they will drag you down to their level and then beat you with experience. Mark Twain


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#11 feetupfun

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Posted 31 December 2012 - 10:18 PM

Will do. Had forgotten this promise. Did anyone see the article in VMX Magazine?
There is nothing good or bad, but thinking makes it so

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#12 feetupfun

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Posted 31 December 2012 - 10:34 PM

Step 1 was move the front motor mount 36mm along the front downtubes

Attached Images

  • P1010211.JPG
  • P1010212.JPG

There is nothing good or bad, but thinking makes it so

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#13 feetupfun

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Posted 31 December 2012 - 10:41 PM

Then bend the front downtubes rearwards to put the front mount in the right spot in the horizontal plane. Frame-holding jig was made so the the seat rails are horizontal with the original frame, and they are retained horizontal throughout the frame changes (to preserve the original steering head angle).

Attached Images

  • P1010216.JPG

There is nothing good or bad, but thinking makes it so

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#14 jon v8

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Posted 31 December 2012 - 10:50 PM

This all looks horribly familiar ! :)

#15 feetupfun

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Posted 31 December 2012 - 10:50 PM

Then cut the mid and rear downtubes and fit a set of dummy cases so the rear downtubes can be shortened and welded.

For those who didn't get to read the article about this bike in VMX Magazine, this bike is NOT meant to be a copy of a Majesty frame. It is a copy of a bike built in 1976 in Australia by Peter Paice, who used the original bike to win the 1976 Aussie titles. It was a TY250B frame that was used. In my copy made in the late 2000s in these photos, the frame used was a TY250A.

If I was going to copy a Majesty frame, I would have cut the rear downtubes off at their top ends.

Attached Images

  • P1020219.JPG

Edited by feetupfun, 31 December 2012 - 10:52 PM.

There is nothing good or bad, but thinking makes it so

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