Engine rebuild

[tony.mon]

You can slot the gears by hand with a decent file.
They're hard but not too hard.

I'll have a go on a spare engine setting up the all exhaust cam set (rather than one exhaust and one inlet in each head) and get them set up same as the Moriwaki or Yoshimura ones.
They must have done a bit of work testing out lobe centre positions to get it as good as they can, and that seems a good setting to copy

UPDATE:
Dyno booked for Tuesday afternoon, 15th March.

[sirch345]

Today I fitted the reground cams I had done last autumn.
They are about 1mm higher, with about 10 degrees more dwell.
I set them as per the standard ones, didn't degree them in, so may not be as good as they could be yet.

But rode it around for ten miles or so, TBH knackered so didn't want to be out for long.
Preliminary seat-of-the-pants impressions is that it's gained a few BHP, maybe five or so.
But it's more "cammy" so feels stronger at the top end but maybe less torquey lower down.

It might be just that in comparison to the increased top end the torque hasn't increased; we'll see what the dyno says.

I will dyno the bike "as is" to get a true comparison standard vs. reground cams, but then I will refit the long intake trumpet on the front cylinder instead of the standard short one currently fitted. I wanted to leave everything as standard as possible for realistic dyno numbers, but will add the longer one and a -4 degree ignition advancer once I've finished the comparisons.
That should get me some of the torque back again.

But a big improvement over standard, both in terms of power and driveability.

Dyno figures to follow, probably next week.

That's really appreciated by me for one, as it's much easier to see what's gained (or not which ever the case may be ) from each individual mod, thanks Tony

Chris.

[tony.mon]

Dyno runs today, at HM Racing in Edenbridge.

Wasn't according to expectations, TBH.

I'd fitted some reground cams, with about 10 degrees more dwell and 1mm more lift than standard, which should have made a difference.
But they really didn't have much effect, lost a wee bit of torque in the midrange and gained a couple of BHP at the top end.
I'd expected that they'd take power to around 118-120 BHP, maybe with some loss of torque, though.

Here's the printouts: Through the top five gears-


And Horsepower/torque curves-


As you can see, another 2.5 or 3 BHP, but at the expense of torque lower down.

They suggest that I refit the standard cams and increase main jet sizes a little to fix the wobbly line in the second graph in the blue trace at about 4000-4500 revs.
That'll give smoother curves, and with almost no appreciable gain at the top end, I'd rather have good full fat torque curves, mostly because that's where I normally ride, 3-5000 on the road.

But I'll fit the ignition advancer and refit the longer intake trumpets on both cylinders first, to see if that makes a noticeable difference.

The only explanation I can come up with so far is that the rocker arms are not acting at efficient angles, as I had to fit thicker shims than normal to compensate for the lower cam base circles- you can't get reground cams to add 1mm of lift without removing 1mm of metal on the base circles.

It might be that with some playing about with the cam timing I might get a bit more, slotting the cam sprockets is simple enough, but it would have to be trial and error, and these dyno runs keep costing me money.

It seems that something is holding the engine back form developing the power increase that the cam profiles should have been able to deliver, possibly a full system is needed, maybe airbox mods would help, suggestions on a postcard please.....

[benny hedges]

well there are peaks there of over 120 when you throttle back on, suggesting the mix is a little on the weak side up top imo.
did you get a fuelling run in?
you will reach a point where you just can't get any more air in and like you say, airbox mods, trial & error.
the cams you have are the same profile as std but higher lift??
if so it might benefit from a bit of light porting, particularly on the inlet side?

still nice numbers though

[Darknomad]

is it possible to supercharge vtr's or even a nos?

[tinysmall]

Lol. That just looks like it's ready to rip itself apart. How would you even ride that thing?

[tony.mon]

Lol. That just looks like it's ready to rip itself apart. How would you even ride that thing?

Carefully, if it's round corners....

Benny, re airbox, yes, I agree, seems that something's holding it back, so likely candidates are exhaust , porting and airbox.
Exhaust is standard downpipes, but cans flow freely enough, so maybe a larger diameter system would make a difference.
Can't afford a Moriwaki full system at the moment

Airbox?
Tried a modified airbox last time it was on the dyno, and it gave no improvement, however it had more volume but the standard intake snorkel was still in place. I'm thinking that the cross-sectional area of the intake, coupled with the fact that it has no clear route into the snorkel may be a factor here.

So to try this out I'm going to try to find a way to add some form of ram-air intake into the modified box, and see what that feels like. Hopefully fed from the triangular intakes already in the fairing. They don't seem to do much in the way of feeding air anywhere useful, to the rads or the airbox, so may as well put them to some use.

Porting? Already smoothed and ported the heads, but noticed that with the front head the ex valves aren't in line with the port, at least, one isn't. I smoothed the route out, and lightly polished, but maybe that needs a more aggressive opening up to allow both ex valves to flow freely.
However, I might then need to modify the front header, (make it an oval entry?) so that the gas is collected and routed into the downpipe with a minimum of interruption.

Lastly the peaks are only where the dyno op was clutchless-shifting, and the clutch slipped momentarily. It wouldn't transfer to the road. Realistic peaks were 116 and a bit.

[sirch345]

The only explanation I can come up with so far is that the rocker arms are not acting at efficient angles, as I had to fit thicker shims than normal to compensate for the lower cam base circles- you can't get reground cams to add 1mm of lift without removing 1mm of metal on the base circles.

It might be that with some playing about with the cam timing I might get a bit more, slotting the cam sprockets is simple enough, but it would have to be trial and error, and these dyno runs keep costing me money.

It seems that something is holding the engine back form developing the power increase that the cam profiles should have been able to deliver, possibly a full system is needed, maybe airbox mods would help, suggestions on a postcard please.....

Tony, perhaps not exactly what you were expecting, but still interesting all the same. I would be inclined to do what you suggest, as it won't cost you any money. Check to see at what degrees the cams are actually doing against the standard BTDC and ATDC measurements etc etc before going any farther,

Chris.

[Beamish]

Good figures there Tony I would be happy riding a Storm pushing out that curve , did you get an AFR readout from the dyno? granted it will be harder to tweak without injection and a PC but if its the A/F mix thats holding it back the dyno feedback should help out. Half the fun is in the battle for more power though, enjoy the ride

[tony.mon]

Yes, we did about a dozen runs as far as I recall. Only printed out the runs I posted, though.

Fuelling was nearly spot on, certainly perfect higher up but where there's a little wobble on the chart at around 4500 it ran slightly lean.
But only slightly, the suggestion was to go up one main size when I next have the carbs off and see how it feels.

Got loads of spare jets, so I'll try that in a week or two.

The other runs are saved by HM Racing for comparison purposes; if I find something that makes it feel stronger I'll trot off and get it measured again.

[MacV2]

; if I find something that makes it feel stronger I'll trot off and get it measured again.

Have you tried Viagra?

[Beamish]

Yes, we did about a dozen runs as far as I recall. Only printed out the runs I posted, though.

Fuelling was nearly spot on, certainly perfect higher up but where there's a little wobble on the chart at around 4500 it ran slightly lean.
But only slightly, the suggestion was to go up one main size when I next have the carbs off and see how it feels.

Got loads of spare jets, so I'll try that in a week or two.

The other runs are saved by HM Racing for comparison purposes; if I find something that makes it feel stronger I'll trot off and get it measured again.

Do you now struggle to keep the front down under hard accel? Must pull like a train, my SP had a longer swing arm so it wasnt such a wheely monster but my old Storm the one that that Dave wrecked ( ) used to wheely for fun, bet yours is a right handful now

[tony.mon]

I tend to ride over the front end anyway, unless I'm on long sweepers, and the practise I get playing on the drag strip teaches you how to keep the weight over the front end.
But first and second lifts up even with weight over the bars.
A touch of clutch helps it settle, and trailing the rear brake ditto.

But it sure goes light accelerating off corners, though, shaking its head all the time.
Keep you awake and interested.....

It's on old tyres at the moment, I'm thinking about a set of Sportsmarts for the summer and a track day I need to book before July. The old tyres don't help much either.

[bazza696]

I tend to ride over the front end anyway, unless I'm on long sweepers, and the practise I get playing on the drag strip teaches you how to keep the weight over the front end.
But first and second lifts up even with weight over the bars.
A touch of clutch helps it settle, and trailing the rear brake ditto.

But it sure goes light accelerating off corners, though, shaking its head all the time.
Keep you awake and interested.....

It's on old tyres at the moment, I'm thinking about a set of Sportsmarts for the summer and a track day I need to book before July. The old tyres don't help much either.

I can second the bike likes to rear its head, were following tnny on my bike and she still tried to lift after changing to 4 at 100.

Its a bloody animal compared to mine and mine is stock.

[tony.mon]

I can second the bike likes to rear its head, were following tnny on my bike and she still tried to lift after changing to 4 at 100.

Its a bloody animal compared to mine

-I have created a monster

Today I stripped and rebuilt the clutch to stop it slipping, used original Honda plates but with less wear than the set in there before.

Sorted!

While I was there I refitted the -4 degree Factory Pro ignition advancer, and removed the quieting gear on the primary drive.
No extra noise to speak of, and it feels strong, but as ever, the dyno will tell its story in due course.