My VFR
It's like this - bikes come in all shapes and sizes. I've had several over
the years, with various degrees of success and fond memories...
I also had this bike tuned a little...
Well, at BikeNet I was
always
getting asked about getting more power out of motorcycles, and I always
ended up giving the same advice, namely start with a pipe, air filter
and jet to suit. Well, I decided to put my money where my mouth is, I'd
had the NC30 for a while now, and I didn't want to get lapped at a track
day at
Goodwood.
Right, off to Dynotech in Basingstoke.
First though, a quick word about dynos... they all read differently (a bit
like all bikes make different power curves), so get all your work done on
the same dyno, so you can see changes. I know a recent Grey Bike article
claimed 64bhp for a piped VFR, I think they had an optimistic dyno, not
more rear wheel power. Just for comparison, on this dyno, little Keith's
full race ZXR400 makes 72bhp.
The first thing I asked the guys to do was to shim the valves and balance
the carbs, then do a run, so we had a baseline to work from:
Well, a few notes here... 59bhp from a 6 year old 400 of uncertain history
is very good (well, I was pleased... I was afraid that they were going to
call me up and tell me that I'd bought a hound that produced 20bhp and
needed a lot of work). The bike felt really strong from 6,000 revs, and
I'd always suspected that it was climbing out of a hole from 5,000 revs.
I also found that I rarely held on to a gear above about 12,000 revs,
prefering to change up, even though the red line's at 14,000 revs, but I
hadn't realised how fast the power fell off after the peak.
The first modification the boys did was to add a new silencer (full exhaust
systems for the VFR400 are
really
expensive, as there's a lot of intricate pipework to get the left exit)
made in aluminium by ART... I could have got the carbon fibre one, but I
thought the ART one looked more standard. This involved hacksawing the old
silencer off, but they do sell an adapter to put the old system back on,
should you want to. This made the bike sound a lot better (before the
loudest sound was the gear driven cams!), and saved a fair amount of weight.
It also produced this dyno chart:
Well, 60 and a bit bhp is good, but the main points to note are how much
smoother the bit between 5 and 6,000 revs is, and how much better it holds
on to the power.
They then added a K & N air filer (this involves sending the old filter to
K & N, who cut out the paper and replace it with their own filter material,
to save them the cost of producing the plasticwork to fit your airbox) and
jetted to suit. Here's the chart:
As you can see, this has smoothed out the curve even more. Anyway, here's
the comparison BHP curve:
And here's the comparison torque curve... you can see the difference that
the work's done in the midrange (which, let's be honest, is where most of us
ride most of the time anyway).
On the road this is translated into a much smoother bike... my riding really
went to pot, as the bike would pull better lower down and higher up I was
always in the wrong gear, but I'm getting over this... it's surprising how
much you learn to ride around the bad bits. The major difference is 2 up,
when the bike accelerates better on faster bits of road... on my, ahem,
private racetrack, yes, that'll do it, where I used to hit 105mph before I
had to brake for the corner I now get to just under 115mph. Overall it was
worth the money I feel, and has put the sparkle back into the bike... I
think it's worth looking into a bit of tuning rather than upgrade to a
bigger bike.
There were dyno shops closer to me than Basingstoke, but I've met the guys
there on several occasions, and they've never told me how stupid my questions
were... I've also seen their work and I trust them to do a good job and deal
with me honestly.
If you want any dyno or tuning work done, and you're in the area I'd suggest
you call Dynotech in Basingstoke, as they're good guys. Tell them you read
this on the Internet, as I don't think they believe it really exists...
|
