Project 100hp rephased 880

£6500 that's about $10K USD. An enormous amount of machining work, and parts, and six years of racing knowledge.

In a trick lightweight frame and suitable suspension, the bike might be 350-370lbs, with 90 ( reliable) hp, that would be a fun bike for something near £10K
 
Ha ha ha! I stand corrected!

Back in the spring I spoke with Steve a little about this engine, he shared some information with me in regards to the modified intake angle.
I’m fascinated by the work being done here and excited to see more!

Will you be sharing your porting work or is it to secret/classified?

Daniel.
Hi Dan

i have just done a raised port inlet and exhaust on an SR500, the port is +6mm higher, which straightens the port pout no end. i cant go any higher the port walls are only 2mm thick now ( at the top that is)

and I welded the chamber up to give much more compression ( with a nearly flat top 90mm piston) and to decrease the flame travel distance

this is where i am currently, i need to mill the gasket face back and bit, ( angle mill) and surface grind the head, then cut the seats properly. I am running a Mikuni TMR36 which was Husqvarna OEM fitment for awhile, they are the absolute best Mikuni made,

and just planning a stroker for the XS650, either shorter or longer depe3rneing on what peeps want
short stroke around 66mm, or long stroke around 85mm

just got to juggle rod lengths, piston speeds, rod to stoke ratios blah blah
 

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Hi Howard,

Love this work!

I’ve recently joined a great group on Facebook dedicated to porting and I’m trying to be like a sponge and absorb all I can as this topic fascinates me!

I did enquire with Steve about him reproducing a replica of his head but alas he’s too busy for the time being.

Daniel.
 
Steve Mann recently sold the 880 engine, as the size puts him into the 1000cc bracket, and although the engine is 90hp, the BMW1000 airhead engines are over 100hp

he got £6500 for it, for a guy who is going to put it in a road bike

I would of bloody loved this engine!

Daniel.
 
i have asked Steve for the dyno sheet on the race 750 we did with 76hp, i will post it if he can find it.
The 880 was a real surprise, i did the cam with Ken based on the flow figures, and when Steve called me to tell me what the result of the dyno run was , i expected around 83-85hp rear wheel, he got 90 at the stock redline, and when they revved it a bit higher it got 92hp.
This engine was valve limited !! We would have fitted 44.5mm inlet valves which would have given more top end, but the larger seat ID reduces the low speed port velocity so some response and torque is lost

i am just trying to work out a long stoke ( or short stroke crank for racing) using stock parts modified

i know i can build an 80 x 84mm engine ( 844 cc) and i know we can add the 880 bore and amke this a 1000cc ( basically two sr500 specs) BUT the ports and cylinder wont cope with 47mm inlet valves which is what an sr500 has, so the top end would be limited to what the biggest valves will flow which is around 95hp

for a road bike a "stroker " is the best, i built Harley stroker engines for years, here and in the USA.

the trick isn't the building at all, it is telling the engine builder very accurately what you expect, and what you realistically use the bike for

i maybe be able to replicate the raised port work on the SR500 on an XS650, i have a top class welder here, so that part is sorted at least

When i worked for carls Morrow speed shop in the USA, their cylinder head porting guy who had worked for Russ Collins, Vance and Hines and few others, told me what to do on an 80 inch Harley i had done some work on before, that Harley produced 80 hp rear wheel, i did what he suggested and got 90 rear wheel ( same dyno, just six months apart) all we did was 5 angle inlet and a full radius exhaust valve seat cut, took the rough edges off the ports and did nothing else at all, he said all the power is 1/2 either side of the valve seat !!!!

i have emulated this mantra on almost every engine since that time, and the XS650 i built and other engines are testimony to his words

one thing is for sure the ports on ALL 2 valve Yamaha engines are too big

Howard
 
The bathtub combustion chamber shape is very similar to what HD has done in recent years with the Twin Cam engines
 
half a lifetime ago i worked for a HD tuning shop here in the UK, i had a set of Branch heads on my 80, and then STD modified bathtubs on my 98 and 103 both done by Doug Coffey in Canada

The bath--tubbed heads always worked very well for me, so started copying the method, welding has changed a lot in 30+ years, it is now easy to find the right filler rod, and Argon TIG welding is superb

I have been welding up heads for as long as i can remember, i recently did a BMW R80ST as well

the chamber shape on my Buell was bathtub, it was a Buell XB head from 2008 but then the head was spun on a face plate and a 30 degree angle cut on the flat squish, the SR head i will cut an 11 degree which is what the low compression 90mm Wiseco is.

we always wanted to weld the XS heads but the cast in skull, is a real problem, we adapted the chamber by building an 880 which gives the best of a bad job, the piston is almost flat, still with high compression
 
Our XS880 has 92hp rear wheel hp, ( from TTS one of the most reputable performance shops in the UK) when someone shows me an XS650/880 dyno sheet that is better than that, i will see what we do next.

I am not a clever man, i just use the mathematics that i learnt obtaining my B/Eng ( Hons) in Mechanical Engineering, it seems to be working so far

I like to see proof positive of these theories, ALL the chat in the world about cams, and head work and trick chamber design is all OK, BUT we have proof of our work, and i have posted the sheet/s !

A tutto gas

Howard
 
Why so angry?
I just wanted to tell ya that one can TIG-braze the cast chambers and you being in England have the best connection for filler materials by SIF-bronze or Ampco.
I allow myself to give hints and tips on welding as Ex G6/HL045 Tig weldor and IWE (besides i never mentioned that I'm a very smart person either, just had the great luck to have met smart people in my life and tried to learn from then)

Kind greetings
Christian
 
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I am not angry, sorry if it sounded so, email can be misconstrued easily, i am very grateful for your advice, i have seen your work, and its inspirational, one of the main reasons i welded my SR500 head up, was seeing your work. It is TIG welded, the guy who does it can weld tin foil !

On the XS880 race bike we considered many options before we did anything, i have learnt the more things you do, in the end you dont know which one created torque, so went with simple and it worked well. The compression with nearly flat top piston from Jerry, is 10.7:1 ( volume checked)
we wanted minimum surface area to volume ratio. that is achieved in this instance by having a flat bottom to the chordal chamber, it gives us good compression with no shrouding, the inlet was raised up ( welding in tubes) so much it broke into the spring pocket

The cam in the 92hp bike is very mild, 265 degrees and 12.8mm lift, it is a road race sidecar bike, so big torque is so important

what power and torque do you expect from my mildly tuned SR535 ?

you have all the experience, i have none in this area ( except i have owned six )

Howard
 
@howardsmed

Thanks for the cudos, the guy who welds all that aluminum is actually me.
So basically I'm sportimg now a big friggin smile :).
And yes the guy used to weld on occasions coke cans without cheating (thus filling em up with water) haha

Depending on how far you go on porting I'd reckon a honest 42-44ish, for everything beyond that one needs either the 130 or 180 grind.


Kind regards and happy weekend
christian

Ps: one of my buddy's used to have a halco kneeler with various wild engines (i think one was gears and 270 1000 or even 1100 with sp370 pistons but memory might trick me now)

PPs: i just noticed we were almost at the same period of time on the west coast (me from 89-92), times were still glorious back then concerning Ic-engines.
 

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I have used SP370 pistons,( 85mm) i built a bike for martin Guilford, who was a professional sidecar moto-crosser, ( his father Mike was the workshop manager at WASP) using them, it is an 840cc, with an 84mm stoke ( same as SR500) it is a 999cc

above 900cc, the heads strangle the engine, up to that point they are quite good.

if i get 42hp, i would be really happy, i am using a Mikuni TMR36 i bought for £50

thanks for your advice

good to talk to you

Howard
 
@howardsmed

Braze em Xs chambers up with bronze, worked fine for me :)

Kind regards

Christian
Back when I was experimenting with the XS head, decades ago,I was mig welding the cast chambers to a bathtub,slow process but it can be done without distorting the head or cap. Never occurred to me to braze em up:thumbsup:
 
all conjecture without a dyno sheet too prove it

lots of peeps on this forum saying " do this and do that" but without proof positive its just fresh air
 
all conjecture without a dyno sheet too prove it

lots of peeps on this forum saying " do this and do that" but without proof positive its just fresh air
And a dyno sheet to prove what exactly? No peeps on my end, I've proved my point years ago , do you think you're the only one who's digested the XS 650 head for extra flow that yielded positive gains? And besides, I was making a friendly comment to have a conversation with Christian, not you, so why are you being so defensive? This is one of the reasons I left this forum, people like you who get their feathers ruffled by misreading the context of the message. The work you've done is nothing new( but it's pretty porn) as I was doing it decades ago just never pushed it to your extent and went in another direction to achieve my personal goals in reconstructing the intake port and like you I was successful. Christian if you're reading this, glad to see you come back every now and then........Later
 
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Hi Jack,

I just wanted to mention that i enjoy reading from you as i liked reading your posts so far.
I'm sorry to say I'm not quite sure if mig welding was the right approach to the cast chambers skull, as with the rapid heat input there are good chances that brittle ledeburit/permit (i think that was their name would have to look) Crystallic structures that might be a hint sketchy. But if it held up til now I'd reckon it's gonna last :)

So no bad talking on my part!
Best of all with CuSi or CuAl bronze you can, respecting some cautionary steps/rules (no metallic GG-CuSi mixture permitted)TIG braze the chamber without running into dangers.

For the rest even though it's not my thread I'd love if people could be a hint more jovial to others as i know as an example some really capable folks in Germany that do not posses a Dyno but do all their verifications with a stop watch which also seems to work ok. (Obviously not that much in detail as a Dyno sheet but hey after all one would need an acc Dyno as well as a brake Dyno or at least a Dyno with a super heavy wheel i guess)
So happy weekend to everybody (weather is beautiful here today) :)

Christian
 
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