dyno sheet

howardsmed

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I found this dyno sheet when i was tidying up the external hard drive

the engine is one i built for Steve Mann CRMC sidecar racer, this is about 6 years old now, the lower trace is using a Megacycle 25-020 cam, the higher trace is a Smedspeed 2.5 cam, which is the same cam but with some computer smoothing and more valve overlap. the lift and duration are exactly the same

the rest of the engine spec is 750cc, Wossner 9:1 compression pistons,533 rod length, Dell Orto PHF36mm carbs, and XV 750 valves, with a really good valve seat cut, the ports are completely stock

A year later we added a 3.5 cam, more compression from 10:1 compression JE pistons and got 76hp on the same dyno ( we always use TTS for dyno work)

two years later we built an 880 which got us 93 hp

just thought it might interest some people, not many peeps dyno their work
 

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Quite a result with unmodified heads/ ports! I see a torque dip at 4,1-4,2 k rpm. It would be really interesting to see curves from 2- 2.5 to 4 k. Basically see if this engine was somewhat streetable.
 
its a race engine, built for Steve Mann, BUT it did pull a sidecar and two people, and started and ticked over well, it is really just a street engine used for racing

the next iteration was more purposeful

the heads had a really good seat cut, using a Newan contour machine by someone who knows how to use it

six or seven angle inlet and full radius exhaust with ration 89/90%
 
You must be joking, Lenny Paterson of the Cylinder Head Shop is a crook, who talks rubbish ( see his website, bigging himself up) with worn out machinery, he sold the good stuff and now has a Serdi 100 with a worn spindle bearings, that doesn't cut properly concentric seats i have known him for 40 years, avoid like the plague

We use ( and still do) a high quality engine performance shop, the guy who runs it builds Subaru engines and has an 1100 hp one !

Serdi have recently announced a single point cutting head shop machine, that operates just like the Newan Contour BB machine. I believe they are £60K
 
You must be joking, Lenny Paterson of the Cylinder Head Shop is a crook, who talks rubbish ( see his website, bigging himself up) with worn out machinery, he sold the good stuff and now has a Serdi 100 with a worn spindle bearings, that doesn't cut properly concentric seats i have known him for 40 years, avoid like the plague

We use ( and still do) a high quality engine performance shop, the guy who runs it builds Subaru engines and has an 1100 hp one !

Serdi have recently announced a single point cutting head shop machine, that operates just like the Newan Contour BB machine. I believe they are £60K

That’s where my head went on your recommendation, Alsopp’s not Lenny Patterson.

Daniel.
 
I'm not well versed about cams. Just trying to learn the lingo. If lift and duration are the same how does one have more valve overlap? Lobes positioning slightly different?
 
Correct. And that is how most variable valve timing works (BMW Vanos in cars, some Ducati engines, etc (DOHC is required for this)
Little overlap at low revs, more at higher revs. Basically the best of both worlds.
 
Thanks for the heads up (!) regarding TCHS 😁
I am not a fan off slagging people off, BUT Lenny Paterson from the cylinder head shop is not a nice man, he is full of chat, but in the end he will ( if he can get away with it) do very sub standard work, he recently did a set of Harley Pan Heads for my friend at Wolverhampton, they were rubbish, in the end Lenny had to drive and pick them up, fix them and drop them back
he did a Triumph crank for us in 1983, he ran a firm called High Gear in Wimbledon then, the work was awful, he had to re-do that, we learnt then avoid him, there are lots of top class people doing cylinder head work in the UK, but he is NOT one of them
 
Very good info! I was close to sending my XS head to TCHS some years ago. Guess I should be happy I didn't 😁.
Anyway, do you think Virago valves are worth it, in a 750 for the street?
(With 34 mm flatslides, huge K&N filters on velocity stacks, single wall headpipes (approx 36 mm ID) and somewhat open mufflers)
 
The XV valves we have used a fair bit, they are +2mm oversize, which means that the seat ID ( the seat choke point) will be 89/90% of the valve OD. this gives 38.27 /38.7mm the stock seat id is already 37.72 which gives a high ratio of 91/92%

Yamaha no longer makes XV750 valves, the only reasonable ones are Vesrah, which we have used

I usually use a valve size to bore ratio of 52% for street bikes, it stops over--valving the engine, race bikes we run 55%

when Yamaha stopped making oversize valves i designed some slightly oversize valves which return the seat ID percentage to what it should be, they are +1mm inlet and + 0.75 exhaust, these are made by G&S who make valves for Cosworth, they are one piece stainless forgings, plasma nitrided stems, with stellite tips where the tappet adjusters runs. They took me 5 weeks working with Andy Grenside to get them dead right. they are also 0.0003'' ( 3/10 of 1 thou) bigger stem diameter, which tightens up the stock slightly loose stem to guide clearance

On the inlet the smallest part of the induction system is the carburettor size, so the velocity ( and flat slide carbs are excellent in this respect) is very high 550ft/sec at the redline, making the seat iD larger will not effect the low speed running at all, with ALL valve changes the real trick is to get the very best valve seat cut you can find, old machinery just cuts bad seats, a lot of our race success was 100% repeatability, we knew the valve seats would be the same as the time before, so we could see the effect of a cam change alone

What cam are you running ???

your engine build sounds like the sort of one i recommend for street use, not too much exhaust is one of the ways to get good bottom end, i have just reduced the pipe diameter on my 535cc SR500 from the usual 45mm to 41mm

hope this helps

Howard
 
@howardsmed

You could reduce the inner header diameter even down to 39mm if you'd use a 3stepped header opening up to approximately 42-43mm's. Of course depending on what cam and set up you use on the SR.

55% ratio sounds about right but eg on an 535 Sr you could go (given correct cam choice) Up to 50mm's without loosening anything, given the camshaft has 13mm and up valve lift.

On my XS 880 i was playing around with calculations and figured that even for a hot street engine with a high lift cam 44-45mm intake valve diameter should be sufficient but will need necessity of putting head on my mill to reangle the valve guide bore angles and seats.

My personal opinion, if please not be taken as a critic (!), is that i have in all my years of porting, not found any gains on radiuses valve seats.

Personally I'm for my part am very happy with my Hunger equipment which is admittedly slow in operation but cuts very precise seats and gives one the whole liberty of adjusting seat correction angles.
(Basically i got the equipment back then cuz i was fed up in not getting what I wanted or worse not what I wanted and bad quality:laughing:)

Kind regards from Italy

Christian
 
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Hi Christian

SR500---the 41mm is the OD, all tubing in the UK is measured on OD, so yes the internal diameter will be the same size as the exhaust port at 38mm, then after about 300mm, up to 44mm, or if i can find tubing in 40, 42, and 44 as you say a 3 step header

SR500--i dont want bigger valves, i am not after top end, my absolute redline is 7000rpm, if i want to go fast i take another bike out instead, i want really strong mid=range, here is head i welded up last week, and the +6mm raised port, which i need to weld a bit on and then final finish

XS880-- the valve seat wont handle anything bigger than 44.8mm, Halco used to fit these valves ( made by Andy at G7S) for 1000cc engines, we finally ended up with 92 rear wheel hp, @7600rpm, that was with XV750 valves

XS880--we have used fully radiused exhaust seats for so many years, we always cut a 6 or 7 angle ( not radius) for the inlet, it works for us, so we keep doing it. Just started work on a bored and stroked XS-908 which uses stock deck height ( no stroker plates, longer cam chains, etc) it will be 83 x 84mm, it will use Smedspeed 41.75mm inlet valves, the calculated Mach speed at 7000rpm is 0.6 and 630ft/sec, we will build it and see what it does, we want 80hp, but 65 ft/lbs torque over a wide rpm band

with my SR500 head, i had two options for the squish, spin the head in the lathe and cut an 11 degree "dome" and do the same to the Wiseco 9:1 piston, OR mill a flat on the piston, i decided to do the latter, just like you do

it was such a bother dealing with Megacycle, and I have a dealer pricing arrangement, that i spoke to Ken Newman and we designed a computer designed, smoothed copy of the 251-40, it is basically our 2.5 cam, with quicker ramps, and more lift, and much cheaper too

thanks for your email


Howard
 

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@howardsmed

Hi Howard,
For my part i mostly had very good experience with Megacycle (thus the dour family) but I used to live for years around their neck of the woods so communication was always somewhat easier.

Regarding the combustion chamber I'd recommend you going, depending on Ivc, to go with the conical squish as one can, depending again on Ivc up to 13:1 with the usual common US profiles, and with 535 you will get anyways not much beyond 12:1.

Btw: what cam profile are you planning to use (doooh reading helps, sorry my add) ?
Edit: 140ish

I'd highly recommend though to cut a lil bit more around the sides of the SSR in the combustion chamber as otherwise the straight squish walls will mask the intake valve as the majority of the flow during "pseudo static" flow passes on the short side on the SR intake.

Also beware to check on the rockerbox axle bores as they like to wear out oval!

Kind regards and keep us informed :)

Christian
 

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Hi Christian

I worked for Carl Morrow in Sana Fe springs tuning Harleys in 1994, Megacycle were in CA too, so no bother, but now, with no email, no PayPal, and very expensive, especially when i can get a cam reground in the UK for E100.

The cams we get done, are either new EN40B billets, or reground stock cast iron, all are computer designed, over the years we mapped every Megacycle profile on an Andrews products cam machine.
We have access to the same cam grinder that Andrews use, a British made Landis 3L
That is what Newman cams bring to the table for us !

The SR500 cam is an adaptation of one of the profiles Newman cams and i designed over ten years ago for the XS650
inlet 0.460 lift ( 11.67mm) 258 degrees @ 1mm lift
exhaust 0.420 lift ( 10.65 mm ) 254 degrees
its a bit like a MC 140 but with very fast ( computer generated ramps, I am running beehive springs and a top collar that weights 7grams ( see pic) i wont run it over 7000rpm, i want good part throttle response, not interested in anything over 7000rpm, just plenty of torque
I have a 152mm diameter crankshaft for more inertia, i dont like the lightweight XT500 crank at all, we shrunk steel bands around the stock crank, and machined the scraper ledge and cases for 152mm diameter

Inlet valve closing will be around 55 degree ABDC @ 1mm lift

The rocker box pin bores wear oval just like the XS650 ones did, i have an XS1 we had to sleeve the pin bore on

thanks for the advice

Howard
 

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Shoo so also in the xs they wear out/ovalize.
Crap, i was in hope with their bigger diameter and more of a press fit at least on the xs they were of sound design, oh well.
Thanks for your advice too.

For the crank diameter i would have to check but I seem to remember that the very first years used bigger diameter cranks.

Kind greetings Christian
 
Yes. the pin bores do wear on the XS650, but in the hundreds of XS engines i have seen, it is VERY rare. The XS1 I have, sat for a long while before i bought it, the rocker had stuck to the pin, and the pin moved in the bore.

the 1978 and 1979 SR500 had a flywheel diameter of 148.5mm, in 1980 it went to 141.5mm. The earlier crank is much nicer, i like the inertia effect, so we shrunk seamless steel sleeves around the crank to make it larger still, up to 152mm. The inertia is more than the 148.5mm crank, by around 5%.

We will do the same to the XS650 cranks, it is possible to shrink bands around the flywheels to take them to 138mm diameter

H
 
@howardsmed

Good day Howard,

Sorry for the delay didn't mean to be inpolite.
Thank you very much for the insight on Newman cams as i wanted to call David or his son already for a while regarding some pre war AJS cams (i own an AJS M1 and oxymoronicly a berco RAC mini clone but barely any time on hand) and some other assorted cam questions (helicoidal Speedo drive etc)
I knew they had just like Megacycle landis grinders but didn't know that Landis is an English company (very cool indeed, in particular since berco closed its doors).
Thanks again and kind greetings from Italy

Christian
 
I went to see John Andrews years ago at Andrews cams in the USA, he was particular about what machinery he used and he had Landis.
Ken Newman has two, one they recently bought from Mercedes.

He has been making the cams that i designed for Smedspeed for around ten years, they are the only ones i have seen that are new steel billets

the megacycle profiles in the main are fairly antiquated pre computer designed 3 arc profiles, they sacrifice low speed driveability as the ramps are so long, i shortened the duration of a 25-130 by eight degrees , as it had more duration than the cam in my 115hp Buell

The exhaust on my SR500 i cam going too start at 38mm Internal then go to 40mm internal and then maybe just before the muffler up to 42 internal

An AJS M1 is nice what year ?

Howard
 
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