#6

[speedpro]

Back doing bits on the FZR. I decided to change the plenum inlet from the small tube and to mount a flange. To the flange I am able to mount a throttle body if/when I get around to it, or as in the photos just fit an airfilter for when I run it normally aspirated like now. This adaptor is 3D printed PETG and seems pretty tough. The inside steps down with a similar shape as the entry on Mikuni carbs. The outside is shaped to allow the fitting of the cap screws used to mount it.
In the future I want to try a single throttle body between the turbo and the plenum and I've been putting a bit of thought into the design. The way it is usually done with a disc mounted on a shaft has always looked like a quick and dirty way of doing it to me. I don't like the screws in the intake though I understand they very very seldom cause problems. The shaft with screw holes in it is also a weak link in my opinion. V-rods can have issues with the shafts for instance. Some sort of a slide valve was considered but I think stiction might be an issue and having it slide on rollers increases complexity too much. A ball valve has a few downsides for me as well. What I have thought of is having a shaft with a disc but made as one piece which would allow it to be aerodynamically shaped and also hopefully completely reliable. This would of course require a 2 piece throttle body which would simply be 2 pieces with a hole bored down the middle and a couple of holes for the shaft to pivot in. I really can't see why this hasn't been done before. Maybe I just haven't seen it.

[Grumph]

The reason you haven't seen it is because the myriad of subcontractors to carburettor companies can supply the split shaft and butterfly at a price and quantity you couldn't match with the one -piece. And designers of multiple carb/throttle body assemblies have to think about fit and tolerances with unskilled labour on the line.

It'll work. Either two identical cast/3D printed sides or one an inlet stub and the other a bellmouth. At this point I'd remind you that John Britten cast his throttle bodies in what was basically carbon fiber filler material. Ultra light and machined well. Dirty with dangerous dust though.

[speedpro]

Bit of a side note, the MB5 now has a new home

[speedpro]

Plenty of spare time so I have been learning Solidworks software. As an exercise I've designed and printed a throttle body that could be used on the bucket. The rectangular opening in the middle is 30mm on the sides and 36.58mm at the widest top to bottom. The round bits each end are the same size as the turbo and the other bolts to the plenum. The blade in the middle is aerofoil shape and the square section is shaped top and bottom to match the blade profile approximately so as to maintain a reasonably constant x-section for the length where the blade is. It needs rework if it's going to be made from aluminium and also needs to be split down the middle to allow for machining of the interior. The next struggle is getting a curve in the tapered sections at each end.

[speedpro]

The MB100 powered FZR chassis is slowly coming together. The engine is together and in the frame and I've been through my bins of bits and extracted a throttle body, clutch lever & cable, and chain. I also found the little sprocket required when running an MB engine which I have fitted after machining the sprocket mounting hub so the chain does not ride up on the sprocket bolt bosses. The chain I have is a crusty old RK 428H. I have links for other chains but this one has beefy side plated and none on the links I have will fit. I've also been through the carbs I have and they are either tiny or huge. If anyone can help with a carb in the range 24mm to 32mm, preferably 28mm, I'd be interested. Failing that I'll purchase a new 30mm Mikuni VM round slide. The 30mm looks to have a newer design body compared to the 28 and is also a bit bulkier which will allow machining for inserts. I'm also after a front master cylinder if anyone has one they don't want. If anyone has a link to one that works can you send/post it and I'll check that out as well. Thanks.

[F5 Dave]

I'll have a dig in carbs. There was a PWK I never got back, but might have bits for another.

[F5 Dave]

Meh pretty slim pickings these days, I sold a bunch a way back to release some funds.

There's almost a TZR carb but missing Float jet and seat, needle and emulsion tube but that will be it in the bag with a shroud fitted as experiment.

There is however an RZ carb by the looks so 26mm pj needs the pj tube or blocking off more like. Have a Yamaha reedblock needs reeds, heck I may have fibre ones now I'm back upstairs, and an inlet manifold.

Bah pic won't load will try on tablet later.

Anyways yours if you want it or either.

[speedpro]

There looks to be something usable in the carbs Dave. I'll give you a call tonight.

[husaberg]

There looks to be something usable in the carbs Dave. I'll give you a call tonight.

i think i might have a throttle cable to suit the long mount those TZR carbs normally have if it helps

[speedpro]

I've been slowly chipping away at the spare bucket. Latest little project was sorting out the gearchange. I looked at simply fitting a reversed lever but it would have been either too short or not left enough room for your foot. Modifying the original footpeg mount, footpeg, and fitting a lever got too hard real quick. I ended up making a new footpeg bracket and then making a whole new linkage. It all came out pretty good and I'm happy with it. Just need the welding finished on the lever as it is just tacked on to check placement.
The countersunk hexagon socket screw had the head diameter machined down and also a couple of mm taken off the face. The bush it fits into I then machined a matching recess. The screw goes through the 2 bushes and screws into the bracket and has a locknut on the back. The bushes when bolted together have clearance to allow the lever to pivot. One little problem which complicates adjustment is that each end of the rod has left hand threads to match the bits I had lying around. Also, I could probably bend the lever to completely clear the rod or what I might do is put a slight bend in the rod. It's a good grade of stainless so it won't affect the gearchange by flexing.

[speedpro]

It all went together quite nicely

[speedpro]

Carbs arrived from Dave today. I need to check for spares that I have but it looks like I'll end up using a Mikuni VM 28mm round slide carb, possibly feeding a plenum. I'll probably just get it going first.

[speedpro]

Carb from F5 Dave has cleaned up nicely. Ignition is fitted and the gear linkage is complete and ready to go.

[husaberg]

It all went together quite nicely

what sort of rose joint are those?

[speedpro]

what sort of rose joint are those?

As far as I'm aware they are standard off some Jap bike. No idea what. They come with a rubber boot over them.