Mikuni

[piranha-bro2]

I think there's more pleating evident in that early fitment pic - the OD of the Sudco FCR stacks is over 80mm curving into a 39mm venturis. My hope was that the large ID tube would create minimal interference to the intake air dynamics, especially with the two large DNA filters. If I could find a way to run smooth tracts I would, but as with everything I make, I endeavour to retain functionality - so easy on-off for access to and removal & refitting of the carbs. TBH, I can't tell the difference by seat-of-the-pants in performance whatsoever from the open stacks - dyno says drop from 74 to 71hp, main jet down from 165 to 160. Still retains the massive spread of power and linear torque curve.

If this were a race motor I would leave them off - but then I'd also fit larger ID headers and maybe a hotter cam and and and ... As is I have clean air going in and awesome usable power. In the 3500km I've done on the SFQ several hundred have been in really shitty weather, some dirt roads and with filthy gritty road vapour in abundance. The thought of it sucking that crap in scares me.

 

[Vince]

Braver than me, I have been waiting to test the harder rear shock springs on my 3c for months now. It rained constanty so I wait for my backyard to dry out and get Mowed and just as it does the bloody rain starts again. We have a forecast weeks worth of Sunny weather so maybe soon. BTW I really wanted to run a standard Airbox with the Mikunis on my 3c but its inlet has so much downdrauhgt the way its ported it just wont fit so its DNAs for me.

 

[piranha-bro2]

The ultimate mod for an SF would be a space frame to free up that intake area and allow a still airbox. Maybe in another life - what I've got more than satisfies me ... like Craven Special Mild (we old Oz and NZ readers will remember the ads ... Jack Thompson on the jet boat!).

 

[Andy]

The ultimate mod for an SF would be a space frame to free up that intake area and allow a still airbox. Maybe in another life - what I've got more than satisfies me ... like Craven Special Mild (we old Oz and NZ readers will remember the ads ... Jack Thompson on the jet boat!).

Obviously not old enough... I followed the rothmans rally and the benson & hedges cup

 

[bazzee]

The ultimate mod for an SF would be a space frame to free up that intake area and allow a still airbox.

Or perhaps a trellis frame a la TRX850, or KTM 790 Duke?

 

[sfcpiet]

Did someone mention smooth hoses?

piet

 

[Paul Marx]

A lot of writing for results that can't be felt when riding.
Paul

 

[sfcpiet]

A lot of writing for results that can't be felt when riding.
Paul

Well, not as long as you're not willing to exploit them. Gotta go over 4500rpm once in a while for that... you do know Laverdas are capable of higher revs, Paul? Matter of fact, healthy engines seem to enjoy them!

piet

 

[Paul Marx]

Well, not as long as you're not willing to exploit them. Gotta go over 4500rpm once in a while for that... you do know Laverdas are capable of higher revs, Paul? Matter of fact, healthy engines seem to enjoy them!

piet

Well Piet, Quentin wrote that he couldn't feel the horsepower difference between straight or banana inlets on the road.
I regularly go over 4500 when I need to overtake on a straight bit of road but there's rarely a vehicle I need to overtake or a straight bit of road.
The occasional tractor.
Not my fault.
And the roads are pretty bumpy.
Paul

 

[ozijotati]

A space frame twin for you Quentin. Built by Andreghetto with an electronica motor. Beautifully done.
Tom

 

[piranha-bro2]

A lot of writing for results that can't be felt when riding.
Paul

It's called 'a discussion', Paul. Or is there some other reason we're all on this forum?

 

[piranha-bro2]

A space frame twin for you Quentin. Built by Andreghetto with an electronica motor. Beautifully done.
TomView attachment 91741

Awesome, Tommy! Would love to chew the fat with Andrighetto ... even better, take it for a spin. Maybe in my next life I WILL go the next step I've leaned towards retaining the heavy SF frame because I believe it helps in absorbing the vibes - which regardless of what we try to do, are an unavoidable part of life with a parallel twin without a counterbalance setup ... rebalance, different balance factors, 270, 360, lightened ... you're going to get the vibes somewhere.

The beauty of a race bike is you can tune the vibes out for the rev range you need to extract the best racetrack performance. Harder task on a road bike that you want to be able to tootle around on or tour on one day and wring its neck to max revs the next.

 

[piranha-bro2]

Did someone mention smooth hoses?

piet

Nicely done, Piet. My first iteration was indeed smooth silicone tubes, but the angle is so acute it was very difficult to A. fit them and B. keep them in place. I doubt very much the dyno would show any diff between the flex tubes with DNAs and the silicone tubes with same. 3hp drop is more like the fact that I've gone from open stacks to a filtered 'closed system.

 

[Exmoor beast]

A space frame twin for you Quentin. Built by Andreghetto with an electronica motor. Beautifully done.
TomView attachment 91741

The orange one needs an oil cooler for a mouth!

 

[Exmoor beast]

I have used OSMA guttering that is the exact size for flat side Mikunis -comes in grey/ black/white various bends 90, 112, straight socket - perfectly smooth internally and can be plastic welded.

 

[sfcpiet]

Nicely done, Piet. My first iteration was indeed smooth silicone tubes, but the angle is so acute it was very difficult to A. fit them and B. keep them in place. I doubt very much the dyno would show any diff between the flex tubes with DNAs and the silicone tubes with same. 3hp drop is more like the fact that I've gone from open stacks to a filtered 'closed system.

View attachment 91742View attachment 91743View attachment 91744

They’re actually bent velocity stacks Quentin. Intake shape may not be anywhere near optimal, but a helluva lot better than the stock bellows.

Moto Guzzi Lemon MkIII for anyone interested.

piet

 

[piranha-bro2]

I have used OSMA guttering that is the exact size for flat side Mikunis -comes in grey/ black/white various bends 90, 112, straight socket - perfectly smooth internally and can be plastic welded.

I played with poly plumbing pipes but no go - the external part of the Sudco stacks on the FCRs are sort of rectangular with rounded corners. hand¥ stuff, the old poly pipe - it's in place at the filter end of the flex tubes to take the ID out as wide as poss for the DNAs. I also made instrument bodies out of it for my std ND gauge gizzards for the other SF.

I could probably find some sort of smooth insert for the flex but I'm more than happy with the setup, compromise as it may be. Every time I ride it I worry about losing my bloody licence as it is - and it's not as if there are flat spots or dips in the power curve because the pleats are playing havoc with the airflow!

 

[Paul Marx]

It's called 'a discussion', Paul. Or is there some other reason we're all on this forum?

Discussions have a beginning and an end.
Otherwise it's a bridge afternoon, with tea and scones
Paul

 

[Andy]

Mmmm scones...
Does the jam go on first, or the cream?
Discuss.

 

[Exmoor beast]

Mmmm scones...
Does the jam go on first, or the cream?

Here is the Devon flag to help explain. Devon/ Somerset Cream on first , obviously then you’ve got those Cornish heathens that try to balance the cream on the jam- this is patently wrong. France has neither Tea or Scones..or toilet seats for that matter..