Slow burn 5th gen build - old skool kool!

[Stray]

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: 

 

Or slightly lower pointing tail: 

 

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! 
 

 

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

 

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?  

[VFR750F3]

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

[trooper1999]

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.

[Stray]

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. 

[Stray]

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?  
 

 

 

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. 
 

 

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. 

 

 

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. 

 

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! 

 

 

 

 

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 but you don’t have to). Only 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! 

[Captain 80s]

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.

[bmart]

1 hour ago, Stray said:

Again, what do you think?  

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

[trooper1999]

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.

[Stray]

Another step forward in the VFR racer saga: Ducati rear brake installed with hose running through swingarm. 
 

Big thanks to the guys on the site who pioneered this setup. Whilst slightly different, mine owes y’all a massive debt. 

Parts used: 

- Ducati 848 caliper & master cylinder

- Ducati 916 brake rod and clevis

- Custom 7mm stainless pin and R clip

- 2 x Ducati 848 caliper hanger brackets welded together

- custom brake hose with heat/chafe shield to protect from exhaust heat and swingarm rub (105cm long with 90 and 20 degree banjos)

- rubber grommet for swingarm hole to minimise rubbing

Here’s the brake caliper hanger made up from 2 x Ducati 848 brackets welded together. Needed to lengthen the adjustment hole to match the VFR swingarm torque arm pin boss. It’s a couple inches closer on the Duc. 

Matching the two parts for tig was a

b1tch. 

 

Duc SSSA is surprisingly similar to the VFR unit. 

The VFR brake pedal pivot uses an odd 7mm swivel pin. The VFR foot peg bracket and pedal have a 7mm hole. The Duc uses 6mm. So I had to make a 7mm pin (couldn’t find one to buy) out of a M8 stainless bolt. Needs to be a long bolt with an unthreaded section as the threaded bit only has about 6.5mm of “meat” on it. 
 

Chucked the bolt into a drill and pressed a file against it as it spun to reduce the diameter from 8-7mm. Times like these  I’d love to have a lathe… Then drilled a 1.5mm hole for the R clip. Used a hand drill with tungsten carbide bit: love these drill bits! 
 

Tickled the bolt head with an angle grinder to finish. 

 

Drilled out the Ducati clevis to 7mm and we’re in business! 

 

 

 

Lots of hand filing and finishing later it was done. The Ducati master cylinder isn’t quite aligned with the brake pedal so had to file the lever down a bit to match.
 

The Brembo brake master also has smaller mounting hole spacing than the VFR’s Nissin unit. Had to bring the  VFR hanger holes “closer” by 5mm. Used a Dremel and rat tail file to cut the holes closer to each other and mounted the master cylinder with 5mm bolts (6mm heads would no longer fit in the holes). 
 

Here it is fully installed. 
 

 

You can see the custom brake line with 90 degree banjo at the top. Feeds into the swingarm hole on the right, near the right foot peg. 
 

Took HOURS to thread a wire through the swingarm and out that hole. Lots of swearing. And when I finally pulled the brake hose through, discovered it was way too long so had to buy another one and do it all again. Horrible job.
 

Existing drain hole under the swingarm had to be expanded (used a carbide burr in a Dremel) to let the banjo pass through. 
 

Heat shield on both ends protects against chafing, along with rubber grommet in the drain hole. 
 

 

 

 

Bottom banjo has a 20 degree bend. Next time I might go with 45 degrees. Left a bit of line inside the swingarm to account for pull at full rear shock expansion, like when going over the Mountain at Cadwell Park! 
 

For anyone interested, line is 105cm long, with 90 banjo on one end and 20 degree on the other. 
 

Here with wheel mounted and everything in place. 
 

 

 

 

[Stray]

I honestly don’t think this’ll work but was messing about with possibly installing ram air from a CBR600F4i. Picked up the air box and tubes on a whim - worth a try, no?
 

F4i tubes go over the frame and under the tank, which is notched to allow tubes to fit. No such luxuries on the VFR, although I could “modify” the tank seam with a hammer to make a bit more room.. 
 

 

 

Even after such a modification, the tank would need to shimmed up a bit at the front. 
 

 

Put the bottom of the F4i air box in the VFR for trial fit and it’s taller than the original unit. Would need to be raised still further at the front to have tubes facing forward. 
 

Just to clarify, the air tubes are right-way-up but the F4i airbox is up-side-down in these pics. F4i draws air in from the bottom of the airbox and VFR draws air from the top. 
 

 

 

 

Question: does anyone know what the hollow “fins” on the air tubes do? My guess is the lower one collects water from wet intake air. The top one is just a hollow triangle with a little hole into the air tube. Does it regulate pressure or something? 

 

Air tubes too low and pointing downwards. 
 

 

VFR air box cover vs bottom of F4i airbox. Toying with the idea of grafting the bottom part of the F4i onto the roof of the VFR so I can run ram air tubes. Angles are all wrong though. 

 

 

Interesting how the F4i breathing holes are bigger than the VFR’s. The snorkel and flapper openings are about 30% smaller than the F4i air tubes. Bigger engine has smaller nostrils. Most obvious in the 3rd pic below. 
 

 

 

 

F4i velocity stacks (staggered heights) are also around 1.5mm wider than VFR at the bottom, and about 2.5mm at the top. Again, the bigger engine has smaller nostrils. 
 

 

 

VFR air filter is slightly bigger, though. 

[VFR750F3]

https://www.facebook.com/Metalscorpiocom/

 

He did it with a f4 tank.

 

I toyed with the idea with a F3 ram air just glass it in.  I bought one never finished.  

[VFR750F3]

BTW those extra boxes on the ram air help dampen the noise I think I read somewhere.

[Dangeruss]

It's always fun watching a project evolve, I wasn't sure where you were going with this at first, kind of like throwing stuff at it to see what sticks (suck it and see, as you say in the UK). It's starting to gel and I like the way you are following your own ideas and letting it organically develop. I have a lot of random parts around from similar 'physical dreaming'. When I did the RC51 tail for mine I dug up an LED CBR600 tail light that I already had from a previous aborted project that fit perfectly.

[Stray]

Stumbled over this on the interwebs: https://motoridersuniverse.com/b1311521

 

Really sexy looking 5th gen cafe racer. Fantastic bodywork but it’s all 3D printed one-off. Shame really as it really suits the bike. 
 

The builder is a great artist but poor mechanic. He could have taken the opportunity to improve the bike quite a lot but opted to just throw on the printed fairings. 

[Ughandi]

 

37 minutes ago, Stray said:

Stumbled over this on the interwebs: https://motoridersuniverse.com/b1311521

 

I've seen this build before on FB and instagram... killer looks, but I struggle to believe it even exists just because of the gorgeous quality of the photos (no casual phone shots - all professional). And there's no pic of the guy riding/ revving it, which is a sin on its own.

...maybe I'm just jealous too....

[JZH]

On 2/9/2023 at 5:39 AM, Stray said:

The builder is a great artist but poor mechanic. He could have taken the opportunity to improve the bike quite a lot but opted to just throw on the printed fairings. 

All show and no go!  

 

To each his own, as they say.  To me, it looks "distinctive".

 

Ciao,

 

JZH

[Stray]

Bit more minor progress: trying a CBR 600 front rad on for size with standard 5th gen catless headers. 
 

The CBR rad is bigger than the 4th gen units I’ve been eyeballing, and it’s curved to catch more air.
 

Problem is it also hangs down a bit more than 4th gen VFR models and will likely interfere with the ZX6R USD forks at full compression. Forks have about 10cm of travel so I used a chopstick to measure where the wheel/fender might go when forks bottom out. 
 

 

 

 

Thinking I’ll have to cut off the bottom 4 rows of the CBR rad and solder it back up. Solder rather than TIG as I’m worried welding will melt the flux bonding the core to the tanks. 
 

Unless you guys have a better suggestion? I’ve repaired oil coolers and rads with that “magic” alumiweld stuff. Maybe that’s the way to go. Will also need to solder/weld some new mounting brackets. 

 

The inlet and outlet are in the right locations but those 90* spigots will have to come off and be replaced with straight hose unions.
 

 

Bottom left outlet is just above the lower rows I plan to cut off - lucky. 

 

View from above and through the frame (airbox and throttle bodies removed). Gives an idea on where I’ll mount it - where the original oil cooler bracket used to bolt up. 
 

 

 

Haven’t figured out where to mount the bottom. Was thinking to use the valve cover bolts but worried about that tearing up the rad. If it’s fixed to frame at the top and to the engine at the bottom, there will likely be some play, no? Doesn’t the engine vibrate/move independently of the frame? So as the top (frame) mounts stay still, the bottom (engine) mounts will vibrate violently and tear up the rad. Or am I wrong? 
 

Has anyone seen a radiator mounted to both the frame and engine at the same time? Is it safe to do? Am I overthinking it? 

[The Phantom]

Some of the OzVFR guys were running a communal 4th Gen trackbike a few years ago, and decided to experiment with ram air - using the ducts above each front indicator. Around Eastern Creek (now Sydney Motorsport Park) the bike simply would not rev past 6-7k, so they ripped it all out and went back to keeping the litre bikes honest.

 

If you look at Kawasaki ram air you'll see that they include pitot tubes to tune the intake, so that the carb runs at the same air pressure as the airbox, I imagine that without adding something like that you will not do much better than the OzVFR guys.

[Bren]

Didn't someone have a Rad made once on here? Didn't cost toooo much if I remember rightly, might save you some trouble. 

[Stray]

Thanks Phantom for reminding me about the Ozzie boys who tried ram air on their 4th gen - remember reading about it a couple years ago. 
 

The 5th gen has injection: does that matter? I’m looking at the F4i setup and there doesn’t seem to be any trickery on it to help equalise pressures. Just the long snorkels and a water/sound trap. Was going to transfer all that wholesale. 
 

Also thanks Bren for your custom rad suggestion. Trouble is nobody makes anything in the UK any more, and if they do, it’s brutally expensive. Any suggestions about where I should look? Or should I just take a hacksaw to the CBR 600 rad? 

[Stray]

Another small step forward with the airbox. More of a stop-gap until ram air is sorted: an open lid box! 
 

Mohawk was gracious enough to send me one of his open airbox lids to fit on the race bike. And I butchered it even more! 
 

 

I’ve basically just cut everything off except the rim that holds the filter. If she can’t breathe through this then she’s really not trying…

 

Used a Dremel cutting wheel to start, shaped with die grinder and hand files, and then ran a heat gun over the sharp bits to smooth them out somewhat. It’s rougher than a badger’s bum but does the job and nobody will see it. 
 

Pictures mounted on another 5th gen as the race bike doesn’t have throttle bodies on yet (watch this space for 6th gen throttle bodies). 
 

Incidentally, that Pipercross air filter was a real pain to fit. Was about 4mm too long and kept popping out of the grooves. Had to tighten one screw at a time whilst poking a flat screwdriver down the side as I went along. Took over 30 minutes to force that air filter in and I may still have pinched some of the rubber in a few places. Let’s hope the filter media is better. 
 

Open air boxes were popular with the RC30 so let’s see. 

[Stray]

 

Looks wise, what do you think of this? Bikini fairing plus bug spoiler - no full fairing. 

[Bren]

8 hours ago, Stray said:

Also thanks Bren for your custom rad suggestion. Trouble is nobody makes anything in the UK any more, and if they do, it’s brutally expensive. Any suggestions about where I should look? Or should I just take a hacksaw to the CBR 600 rad? 

Sorry don't remember who did it, I think he was in Australia - "Keef" maybe? Rings a bell.

[Ughandi]

16 hours ago, Stray said:

Open air box

That intake noise ought to sound heavenly

[Stray]

On 2/14/2023 at 5:55 PM, Ughandi said:

That intake noise ought to sound heavenly

At 8,000rpm it’ll suck in pigeons 

At 10,000rpm it will suck in clouds

At 12,000rpm it’ll suck me in, roll to a stop and tip over on its side…