Cams stg1

[lloydie]

I'm just pleased that your on here (rodger) and taking part as the wealth of knowledge you have is second to none .


And you to tony :-)

[Roger Ditchfield]

Hi gs_l_r. In answer to you question regarding R&D of the VTR it was customary for HRC to appoint and financially support other people to try and develope new engines as well as themselves. They also like to do it on other Continents so they get feedback from sources and climates other than Japan. Mamoru Moriwaki was the established Japanese developer, Bob Hayashida (Big Valley Honda) in the US and while I was at the Suzuka 8 hour I was honoured to be asked to develop in Europe. Many aspects were investigated to produce a complete machine and Ti was one of them but collectively we decided the benefit was not worth the expense whereas we did want them in the SPs. Coating of parts was available then but still fairly little used in bikes. I built an engine using coated parts from a UK firm but the performance benefit was immeasurable but I was building race engines so the longevity factor of coating was not an issue. I have built engines since using Corrillo rods to good effect but could not do that when I was being paid by Honda but I did lighten the OEMs balanced the crank, lightened the flywheel etc. to good effect. In all R&D work you go from one end of the spectrum to the other so what became available on ST1, ST2 and ST3 was the result of exhaustive testing. There exhaustive tests on ignition advancing to suit each level of camshaft but this is another story! A word of warning - many "aftermarket" products are not subjected to this level of testing especially on low volume selling bikes like the VTR

[Roger Ditchfield]

Hi Tony and Guys.
The 2013 prices for cylinder head work on both VTR heads are as follows:-
1) Cutting 8 x O/size valve seats ONLY is £175.00.
2) Cutting 4 x O/Size valve seats INLETS ONLY is £125.00
3) Porting and Gasflowing 2 x VTR cylinder heads is £450.00.
4) Porting and Gasflowing 2 x VTR cylinder heads + 4 x O/size valves seats is £525.00
5) Porting and Gasflowing 2 x VTR cylinder heads + 8 x O/size valves seats is £575.00
These prices include return delivery to any UK Mainland address
I hope this helps in your deliberations
Roger

[tony.mon]

Took me a while to source some, but:

Naturally I weighed them as soon as they arrived....
Looks like I might need uprated inlet springs as well.
Ah, well.....

[VTRDark]

Ooo err oversize valves. Yummy yummy in your tummy. Well, in you engines tummy. So when do you think you will get around to fitting them. I would not have though that uprated springs will be as hard to source as the valves.

(:-})

[lloydie]

Springs and headers next then :-)

[tony.mon]

Ooo err oversize valves. Yummy yummy in your tummy. Well, in you engines tummy. So when do you think you will get around to fitting them. I would not have though that uprated springs will be as hard to source as the valves.

(:-})

I have a wee project on the go.
As well as the OS inlets, I am opening up the exhaust ports.
If you loom into the exhaust port one valve is directly in line with the port, but the other is hidden away, and the hot gasses from that valve have to come out, turn 90 degree, then turn back another 90 degrees before entering the flow of gases in the header pipe.

That can't be efficient....
So I'm trying to make the port oval, and larger.

Of course, that means chopping out one of the ex studs holding the header on; so a new stud, further out, and the necessary metal to mount it on is also necessary.

Lastly, opening the port out like this means cutting into the water jacket, and so that will need sealing up again.

It's a game for this year, but may not be finished in time for the end of summer,- perhaps ready for next year's drag strip messing about.
Gotta dyno each step first....

[VTRDark]

So I'm trying to make the port oval, and larger

I can't visualise the double 90 degree and how it routes without seeing it. But do you need to go larger as this will change the flow dynamics or is it a case of re-routing it and filling up the excess in the previous route. The same with the water channel, surely that will need to be re-routed to whatever it is cooling rather than being blocked. Would this not restrict the flow of water circulating or will it just take another path.

Just had a thought if you was to re-route the channels, you could then use some plasticine (if that how it's spelt) or play doh (that easier) to re shape things and then use a hose and water to test the flow. Sort of a poor man flow-meter.

Sounds like exciting stuff and you never know it might just end up improving things performance-wise. I've got to get a couple of heads to play with, maybe for next year. I fancy giving the high velocity porting a go using JB Weld. It will be interesting to see how you get on with the exhaust side.

(:-})

[gl_s_r]

The only reason I can see why the exhaust port is where it is and shaped as it is, is the fact they use the same head front and back turned around.. the rear one needs to be offset to the side to make room for the rear suspension (which is also offset sidewards to make room for the exhaust)...

If it come straight out from the middle (like the inlet) it would leave no room for the shock.. so thinking this may be a mod for the front head only or maybe both with a radical change to the rear suspension?

Tony, half way through the job you asked, will send some pictures when I finish it Monday.

[Roger Ditchfield]

Hi Tony, Just a word of warning. If you open the ports too much the gas speed will drop significantly and disproportionately even to the point that the bike can become "unfuelable" and "unrideable" even as a race bike. Remember you are treading a well worn path already trodden by reputable and experienced development tuners around the World including HRC. Everything that can be done has already been done but enjoy your experimentation. BTW there was even a conversion of the VTR into 500cc single like the HRD Vincent Comet. Good Luck. Roger

[tony.mon]

Hi Tony, Just a word of warning. If you open the ports too much the gas speed will drop significantly and disproportionately even to the point that the bike can become "unfuelable" and "unrideable" even as a race bike. Remember you are treading a well worn path already trodden by reputable and experienced development tuners around the World including HRC. Everything that can be done has already been done but enjoy your experimentation. BTW there was even a conversion of the VTR into 500cc single like the HRD Vincent Comet. Good Luck. Roger

Yep. Inlet ports are getting towards critical as standard, as I understand it.

The oval port idea is purely for the exhaust side, so that th ex port is to all intents and purposes centralised between the valves. Clearly if the port width is widened then it is easy to reduce the port height- same as the SP1 port, which is filled in to create a step in the head material, but not, interestingly, mated smoothly with the exhaust header itself. Wonder what the power difference would be if it was?
Anyway...

A game for another day is building a separated airbox for each cylinder so that the valve timing set 180 degrees out- a Big Bang engine, (as both cylinders would fire 90 degrees apart, then 630 degrees of rotation before anything else noteworthy happened...) might be fun to ride.

Sounds great when cam timing is set that way, but the airbox limits revs to 5K or so before the engine starts to complain, and I would like to have a little play on a properly-revving version- shouldn't be difficult.

Re the 500 single, good opportunity for thought games here- for example unless the crank was shortened you'd lose too much with oil drag, surely..... unless maybe you used the second cylinder as a rudimentary supercharger........But case thickness would then be over-engineered, and simply lopping a cylinder off would leave the remainder unbalanced, so (hang on a minute, I just remembered the 250 VTR version- wonder if that might provide a better chassis to carry it...Mmmmmmmm.
Leave that one with me......