SV special build - S-pokey-V.

Ok mate thanks, As the ducati yoke I have already have a carby sv stem fitted but mines injection so I either need a bigger bearing or to swop the stem to a injection one

[millemille]

Clock mount complete, after several aborted attempts to try and squeeze everything in under the screen and not foul the bars/controls/cables/hoses....



Front mount for belly pan complete....



Took a bit of a punt on the belly pan mount as the bike was in bits at the time of fabricating it I couldn't check the ground clearance. With the rolling chassis back together and loaded in the van I took the opportunity to pull the forks down so they bottomed out....



..phew!

Been doing a load of work on flywheels and lightening them...

Before lightening...



After lightening....



I'll be running a 3 magnet flywheel, as there's no lights on SpokeyV, which is another 90 grams lighter.

Cam swap complete and thinner headgaskets fitted. Machined the thermostat housing for the Koso water temp sensor, as well putting an in-line fitting in one of the oil lines for the oil temp sensor, and put the cooling system together with the super trick Oetiker stepless screw clamps (as used in F1, MotoGP etc)...



Carburetors. Been giving them some thought recently. The consensus is that FCR's are a good thing on an SV. Was pondering whether they were worth it or not and had a look at the bespoke kit and what you got for your money. I was expecting that the setup would mimic the OEM setup, with some nice machined parts holding the 2 carbs together and a mechanical linkage so only one cable is needed.

Nope. 2 downdraft carbs and a load of cable splitters.

I used to be big into Supermoto's and know sidedraft FCR MX 39's are available for peanuts, comparitavely, because they get swapped out for 41's at the earliest opportunity and the rear cylinder on an SV is at pretty much the same angle as a supermoto single cylinder engine (obviously back to front inlet/exhaust wise...).

It might be possible to take 2 sidedraft FCR's and fabricate a set of inlet runners, similar to the Ducati air cooled SS/Monster set up, so that they fit where the OEM carbs and air box were.

I could spend hours and a fair bit of money mocking everything up but a friend has started doing 3D laser scanning, which allows an object to be scanned and then modelled in CAD. This is an Aprilia RSV frame he scanned for a 500cc 2 stroke project.....



..and he's scanned and modelled the OEM carbs and airbox and an FCR MX 39 carb and we're going to take a look at whether they could be made to fit in the same space envelope as the OEM set up and how convoluted the inlet runners would need to be.

This has put a temporary hold on the top fairing work - I'd got some quotes for getting mould made from the modified top fairing, around a grand for splash mould good for 6 or so moulding, but if the FCR's are going to be used I think leaving the side vents/gills in the fairing might be better so that they get as much air as possible.

[Nicky S]

Can't believe I've missed this. What a cracking build


Sent from my iPhone using Tapatalk

Just logged on for the first time in ages and read every page.


Top build. Amazing effort

[millemille]

Several hours staring at the computer screen trying to figure out whether the FCR's will fit....







The jury is still out, need to get some measurements off the frame to check clearances..

[millemille]

A cautious "yes" from the computer....

[millemille]

A definite yes from the computer....









The inlet runners have been designed to be fabricated from off-the-shelf straight and bends of ally tube. The issue with fabricating them is, even with gas purging, there will be some weld beading on the inside of the tube. CNC bending is an option, but is waaaaaaay spendy.

A twin pull throttle, like the old 2T bikes, with a set of Venhill custom cables will sort out actuation.

There'll also need to be a scavenger tank fabricated for the crankcase breathers which currently vent into the airbox. I'd like to have a go at using a frame section as the tank body, but don't think that's too practical, so am looking at something along the lines of the scavenger tanks used on supermoto race bikes, like this....



...but rather than having one of those horrible breather filters, and going everywhere with an accompanying smell of hot oil, it'd run a hose to drain the coalesced oil back into the engine, probably through the oil filler cap.

The carbs will also need drain catch tank, something like this but in ally and a whole lot more pleasing on the eye....



..and a heat shield between the carbs and the engine, with some smart gold reflective foil, to keep the carbs as cool as possible.

[millemille]

Ok, update time.

700cc pistons and cylinders bought on a whim as they were too good a price to ignore...



So much for limiting engine tuning in the first build.

Engine/bike stand knocked up - the idea is when the final build takes place the engine will be built on the stand and then the chassis built onto the engine until it can go onto it's wheels and the stand be removed...



The very nice and helpful folks at GMX fabrications built me a modified crankase breather scavenger tank with an extra inlet spigot on it and the breather spigot moved. I welded on a couple of brackets and it's now fitted...





Also got a GMX carb breather catch tank, which will fit on the other side of the engine....



...with a new mounting bracket...



Got the drawings for the carb inlet manifolds and have been trying, without success, to find a CNC tube bending company who will make them. Not given up yet, but looks like they'll have to be fabricated.

What has been bugging me is a problem with the frame/rear suspension.

When I'd been figuring out how to graft the CBR swingarm into the SV frame a road racing friend had measured up a whole load of angles and dimensions on his CBR race bike and I'd replicated them on the SV. But what I'd missed was that the CBR measurements were made with the bike on a rear paddock stand, so the suspension had sagged about 12mm at the back under the weight of the bike, whereas I'd been doing the SV with suspension topped out because it was supported by the foot pegs. This resulted in the back end being too low and the linkage tie bracket welded to the SV frame being in the wrong place.

I'd "fixed" the problem by making a pair of very short adjustable tie rods, replacing the Honda suspension linkage, to lift the back end......



..... but I'd always had the nagging doubt that the motion ratio was all over the place as a result of the linkage tie bracket being in the wrong place.

Well, it is. It's actually falling rate until about half way through the travel and then goes very steeply rising rate.

So I'm going to do another frame and get the rear suspension right.

And also take the opportunity to cut out the fixed swingarm pivot points and weld in machined adjustable pivot points so that I can correct the anti-squat characteristics with the steep angle the CBR swingarm runs at.

And also take the opportunity to modify the headstock to accept eccentric inserts that allow the head angle to be adjusted.

Plus a few other little bits and pieces, like fairing mounts and the way the chain roller is mounted, that I think can be done better/differently to how I did them the first time around.

I'm also going to have a set of adjustable offset yokes made. I'm hoping that a race bike collector I know still has his barn full of ex works SRAD parts and has a set of endurance yokes - as below, fitted to one of my ex WSB SRAD's I used to race - that I can borrow to scan/measure and tweak to suit the SV.

[maviczap]

Lovely!

[andrewsmith]

Lovely

sent with all the fury of a clogged drain!!