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Slow burn 5th gen build - old skool kool!


Stray
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Another minor bit of progress - initial trial fit of NSR 250 MC21 tail fairing (Chinese plastics) and cut down 5th gen seat. Still needs a great deal of sculpting for both seat and fairing, but it’s a cautious start. 

Now just need to settle on the rear fairing angle and build a subframe. Which one do you prefer? 
 

Slightly upward pointing tail: 

72CEDF47-0159-47AD-9190-763FCF824793.thumb.jpeg.ef31fa3c174eaeef946e528683c651a8.jpeg

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Or slightly lower pointing tail: 

FA1EA6E1-C1E0-442B-9311-F3A01A215999.thumb.jpeg.adb6422c24564799f04a49839dcb1602.jpeg

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The MC21 is a much smaller/narrower machine than a 5th gen and the tank is narrower too. The MC21 fairing sculpts inwards at the front and fouls against the 5th gen frame, making it impossible to line things up properly. 
 

So I cut the offending pieces off and straightened them with a heat gun, some old angle iron and a clamp. You can see where I cut them off in the previous picture; there’s a gaping hole just where the fairing meets the main frame. 
 

Below you can see the grey plastic piece sandwiched between two black angle iron pieces and a blue Irwin clamp. By the way, these Irwin clamps are amongst the most useful tools I’ve ever bought! 
 

BBC103A3-C38C-4E43-9445-FCE0D96B79EF.thumb.jpeg.7f06cc3bc89437427efe96c8be7da831.jpeg
 

Came out straight enough with minor ripples that will sand out. Can’t tell it was ever “sculpted” in the photo. 
 

AC7386AF-119B-46C8-A488-68A7AD2C92D8.thumb.jpeg.eb00afa2a1c167193b73b5e223ece1fd.jpeg

 

The idea is to glue them back on (solvent welding) but if I was doing this again I’d just have bent them on the fairing without cutting them out. 


Now can somebody please tell me why the MC21 has a NACA duct on the rear fairing cover? What purpose does that serve other than to let rain water in? 
 

And one more thing: why does the 5th gen have a sculpted crease on the tank (where the seat meets the tank) and no fairing to go there? It seems like they initially planned to extend the rear fairing and cover that hole where the rear cylinder is visible but then changed their minds. Maybe to let hot air out and stop the rear cylinders overheating?  

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Nice bits ie front and rear suspension. I can not wait till the finished product. Maybe shorty muffler no mid pipe though.

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If your still looking for seat ideas I've got a period RS850 seat you could try (Nottinghamshire based), that is true 80s endurance, take a look at my rs850 build page.

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On 6/19/2022 at 3:14 PM, VFR750F3 said:

Nice bits ie front and rear suspension. I can not wait till the finished product. Maybe shorty muffler no mid pipe though.

Thanks mate. Can’t wait to see the finished product either but my God she’s taking her time! 
 

On 6/20/2022 at 12:58 PM, trooper1999 said:

If your still looking for seat ideas I've got a period RS850 seat you could try (Nottinghamshire based), that is true 80s endurance, take a look at my rs850 build page.

Just saw pictures of your RS850 - got to be one of the most beautiful motorcycles I’ve ever seen! 
 

Unfortunately I’m now committed to the MC21 seat and am measuring up subframe parts. But I’d still love to see your bike in the flesh. 

 

I’ll be racing in Mallory Park on the 8th if you fancy coming for a jaunt. The Triumph, Norton and EMRA boys will be there - should be a hoot! 
 

Free to watch if you come early enough before the racing starts. It’s an odd circuit and you can only access it by riding the wrong way round the track. So once the racing starts there’s no way in until the next break. 

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Bit more progress, albeit minor. Got to measuring and designing the subframe.

 

For the record, the stock subframe sits under the NSR250 fairing. I’m using this as a guide/template to measure the new one before fabricating parts.
 

Was thinking about extending the seat to follow the tank crease at the knee - what do you think?
 

Also thinking of following that seat line with the fairing so it’s one clean line, parallel with the frame. This part of the 5th gen always seemed untidy to me, like they had a plan but changed it.
 

Again, what do you think?  
 

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I’ve even been thinking of covering that lower triangle on the tank (under the green pen) in the same material as the seat for continuity. 
 

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Here’s what the seat pan looks like in situ. Need to think about how I want to deal with the hole where the rider’s butt goes. Might just seal it with plastic plate. 

 

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Also got me thinking more about why the NSR cowl/cover has all these holes. Turns out the two on the side (where the blue end of the pen sits) are for a passenger seat pan that slots in. Will have to weld those shut. 
5CB0A533-223D-4CB1-9577-D6E3164337E2.thumb.jpeg.e89db0767a44c039a30fd140b8e5043b.jpeg

 

But what about the NACA duct on top (where the pointy end of the pen is)? What purpose could that possibly serve other than to let rain into the battery box? It’s absurd! 
 

I was working late at night and couldn’t break out the angle grinder so cut the ends of the stock subframe off by hand with a hacksaw. No joke, it took over 30 minutes (with cutting oil!) and I was sweating like a galley slave at the end! 

 

 

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Finally, if anyone wants to do this mod the stock subframe will fit if you cut the rear corners off like I did. You don’t have to even cut the Frankenstein bolt (I did buy you don’t have to). Not a very small part of the stock subframe shows (where the yellow pen is pointing) if you kneel down low. 
 

You’d have to weld on tabs for the fairing and lights but that’s easy on steel. 
 

Interestingly, the NSR fairing mounts are a hot mess. If you look at a stock NSR MC21 subframe you’ll see what I mean. I’ll have to recreate that hot mess of welded tabs to make this work...wish me luck! 

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I'm almost thinking making the seat smaller to match where you clearanced the cowl at the front.  Ending where the lower triangular portion of the tank starts.

 

I'm liking it in the direction you're going too, don't get me wrong.  But I think the seat will tuck in better without extending the where the crease ends.

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1 hour ago, Stray said:

Again, what do you think?  

I think that you must be retired! I barely have time to get fuel...

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On 6/22/2022 at 8:48 PM, Stray said:

Thanks mate. Can’t wait to see the finished product either but my God she’s taking her time! 
 

Just saw pictures of your RS850 - got to be one of the most beautiful motorcycles I’ve ever seen! 
 

Unfortunately I’m now committed to the MC21 seat and am measuring up subframe parts. But I’d still love to see your bike in the flesh. 

 

I’ll be racing in Mallory Park on the 8th if you fancy coming for a jaunt. The Triumph, Norton and EMRA boys will be there - should be a hoot! 
 

Free to watch if you come early enough before the racing starts. It’s an odd circuit and you can only access it by riding the wrong way round the track. So once the racing starts there’s no way in until the next break. 

Hi thanks for the offer of Mallory Park but I'll be busy, but I'm at a trackday at Cadwell Park on Wednesday 6th ( Moto Morini club) if your free pop along it's supposed to be a good day.

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