It's been on the Dyno, and...

[tony.mon]

Had some dyno time today at HM Racing, in Green Street Green, near Orpington (J5 of the M25).

I'd fitted a Factory Pro jet kit and wanted to get it set up correctly.

I chose the hottest day of the year so far, and humid as hell so as to minimise the peak horsepower readings- just so that I wouldn't embarrass any of the rest of you. Selfless or what?

Turns out that I'd got the main jets spot on, a 180 front and a 182 rear. But the larger pilot jets that came with the FP kit (#50) were over-fuelling the lower end, so they refitted the standard Honda ones (#45)and went two clips higher on the FP needles instead.

Here's the graphs:

The red trace is as I fitted the kit, the blue trace is after they'd sorted it.

And through the gears:

This shows a theoretical top speed (geared speed) of 165+ so I'll need to sort the gearing. Obviously it won't actually pull this, as there's air resistance to take into account.

Short VS Long intake stacks
A few people have tried changing from a short intake trumpet to a longer one- me included. Seat-of-the pants says it gives more low end oomph, and a bit of midrange, at the expense of a little bit of top end.

But I wondered how much effect it actually has, and so after they'd got the set up done I asked for another run comparing the short and long stacks. The rear one stays as a long one, which is standard.

Here's the hard evidence:

The RED trace is the short stack front, long stack rear, and the BLUE trace is with two longs.

You can see that it gives a noticeable boost exactly as per the seat-of-the-pants feeling, with such a small loss after 8900 it's barely noticeable.

The little dip around 4800 is an oddity, you usually see this on the standard setup where the maunufacturers try to beat emissions or noise limits, but this appeared after the setup was completed. However, it's certainly not noticeable on the road.

I certainly recommend HM Racing, they have a little rundown shack of a premises but dunarf know what they're doing!
Cost of this lot (with a couple of other graphs of intermediate phases) was £200 plus VAT.


FP kit was about £75, from memory, from Straightline Racing.

Does it feel better?

Oh, yes

[Seven Of Nine Firestorm]

Looks good there fella . Still trying to find someone to bore out the spare TB and have new butterfly plates made up bet it would suck in alot more air and yeald some good gains too.

[tony.mon]

Yup, that would do it. I'd be very interested in a way to fit movable stacks, like the new Yam M1 or the 1098/1198's have got.

Electronically controlled, for preference, but I suppose looking at the graphs I got you could have something controlled by the tacho output, set to come in at 8000 or thereabouts?

Although to be fair, it makes between 3 and 5 BHP difference, and so you might be better off spending the money going for high comp pistons and revised inlet cam timing and duration.

Mmmmm, a cam regrind, now that would be fun.......(slaps wrist) No stop it, you've already drunk the housekeeping and spent the mortgage money on that bloody bike etc, etc.

[sirch345]

Very interesting to hear all about your results Tony You did well with the FP correct main jets Interesting too about the longer front stack. Cheers for posting the graphs

Chris.

[Beamish]

Good info Tony, very inetresting.

[Pete.L]

Sweet!
Good results Tony Now get out there and rag it :wink2

Pete.l

[Kitch]

I have a Factory Pro kit in my garage if anyone is after one.

Roger at Revolution set mine up and fitted a Dynojet Kit, so this one is surplus.

£40 posted if anyone wants it, PM me.

[Gerrit]

The "longer" stack u are using...... did u just purchase another rear stack,and fitted that on the front? or did u have it custom made?

Also....Would it not make more sense to use the same size jets front and rear, I fail to see the point of different jet sizes -the rear cylinder running hotter !

It is not that one is riding in heatwave temperatures, and with the small tank, u have to stop sooner than later anyway and the bike will cool down

Your thoughts?

Gerrit

[tony.mon]

Stack- just bought a spare pair on E-Blag, so I have the choice of two shorts. two longs or one of each.
I've not seen any forum comments re using two shorts, so didn't bother dynoing that option. Let's face it, you didn't buy a vee twin for the all-on top end power, more the way it's delivered and the low/mid torque. So longer stacks makes more sense.

Some people have gone to the same on both (main jets) but Honda presumably choose to use two different sizes for a reason.

Lot's of Vee twins do the same, and some triples run a bigger jet in the centre to aid cooling.
I'd expect that's why it's done as standard.

Lastly, the guys at my dyno have loads more experience than me, and I'll trust them on this one.

[Max]

Stack- just bought a spare pair on E-Blag, so I have the choice of two shorts. two longs or one of each.
I've not seen any forum comments re using two shorts, so didn't bother dynoing that option. Let's face it, you didn't buy a vee twin for the all-on top end power, more the way it's delivered and the low/mid torque. So longer stacks makes more sense.

Some people have gone to the same on both (main jets) but Honda presumably choose to use two different sizes for a reason.

Lot's of Vee twins do the same, and some triples run a bigger jet in the centre to aid cooling.
I'd expect that's why it's done as standard.

Lastly, the guys at my dyno have loads more experience than me, and I'll trust them on this one.

I've been running 2 short ones for a few years, It still gave 104 at the wheel on Rogers dyno. I went for short as I've lowered the gearing to 15/44 and do often end up in the higher ranges, also the lower gearing gives quite an apparent jump in oomph anyway.

[tony.mon]

I might just try two shorts next time I'm under the tank.

Trouble is, although I felt a small advantage in low-end grunt with two long ones, without the back-to-back dyno I couldn't be sure until now.

But different days mean different results- when I had mine done it was a very hot day, and even if I go back to the dame dyno I might not get useful results.

I might just take the advice given and just rag it!

(even though my new daily commute is now so boring as to leave me wishing for a car, TBH, apart from the fact it would turn a 1 hour 10 minutes journey into a two or three hour one each way).

[Max]

I might just take the advice given and just rag it!

Definately the way to go