Oversize Hi-comp pistons

I have access to custom made CP high compression pistons for the SD.
These are available in 101, 102.2 and 103mm (1050cc) sizes.
Unfortunately the minimum order is for 4 and as I have neither the funds nor the inclination to buy a spare pair i was wondering if there are any takers out there who want to go into this as well?
Ash spoke to Bob Farnham and he will do has flow and skim for about £350 on the heads and I have spoken to him and he is happy to do the rebore and nickasil the bores for the oversize pistons.
Compression is raised to 13:1
Cost for the pistons will be £486 inc VAT but with P&P on top.

Good work guys! If I was minted, which I'm not, I'd be all over that for the sheer fun of it.

So £486 plus £350 for the head work plus £??? for the rebored cylinders. Then a couple of hundred for a new map so you're looking at over £1000 to get a new 1050 engine.

But any idea of the expected gains? Anyone got any idea at all of a new BHP figure and torque predictions? Anyone actually done this before? And what about reliability? Don't you need to be thinking about some new rods as well maybe?

Ash....what you expecting to get from the Bob Farnham tune up, (without the new pistons)? Has he made any claims?

We were expecting to get 135+ rwbhp (+6% on a dynojet or 143+) on Kev's dyno with the 101mm hi comp pistons; maybe 140 or so with the 103mm.
No need for new rods as the motor is 'safe' to 150+.
Yes, overall a grand for that set of engine work.
No real point in doing it without a decent full system or sdr headers and a motohooligan or dna airbox. More power is to be had by fitting larger injector bodies apparently.
cheaper than fitting flat bars to an rc8r though!

as long as the pistons arnt much if any heavier or the compresion isnt raised to high I would,nt think there was need for new rods 350 for the heads gas flowed, I take it thats the heads deliverd to him and not the whole engine

Why not just buy a Ducati street fighter 150hp for what,,two clicks quicker at track day makes no sense to me,,,

why not just get an r1 then

Nothing wrong with wanting to hog out the motor to the max,,,but as stated the rods are good to what 150 hp,,,that my friend is what I call the "edge",, the max,,close to going "boom",,,when you do pistons you will open up a bag of worms that will trickle down to much more than just pistons,,,by the time your done everything will not go untouched,,,everything,,, and if not ,,there will be problems that will rear their ugly head,,,sure it can be done , but when doing so it's trial and error fer sur,,and not just the motor,,,everything right down to ,brakes , suspension, chains and sprockets,,,,,,don't get me wrong,,, punching it up like you say , may work,,,who know's then again there's a new 1200 SD on the horizon,,,,,,,,,,,,

I really don't want to turn this into a debate about whether this is a wise course of action or not: obviously I've got my view on the matter!
Having said that: KTM designed the motor for 150 bhp it doesn't mean the whole motor turns into spaghetti at 152. There are a number of SD motors making over 160 bhp in grass track racing on stock (welded) cranks and rods. The chief problem for these motors is heat dissipation, apparently.

Still if I build it and it goes pop! You'll be able to say I told you so.

To return to the original purpose of the thread:
This is just an enquiry as to whether anyone wants to go in with me to buy a pair of pistons.
any takers?
£1000 for 15-20bhp that's potentially as little as £50 per pony!

Good work guys. Mod to the max

Hi comp pistons now ordered

Nice! Who's taking the second set?

No-one. They said they'd let me take the 101mm hi comps as a pair. It turns out they're cheaper as well at £183+VAT each.
6 weeks delivery time.
Apparently they are made in the US and shipped to Germany where they do a machine finish and then ship them to Belgium to be plated and then back to Germany for a final finishing.
Price includes new gudgeon pins, retainers and piston rings.
Apparently I have to leave a minimum of 1mm of squish which is quite a lot of metal to loose so I might skim the top barrel face as well.
i shall also have to invest in one of those solid state high output batteries as the motor is going to be quite reluctant to turn over!

Sounds good!
Price isn't too bad either. Looking forward to seeing updates here. Good luck with the build!

I spoke to bob yesterday about just sending the heads as I thought it was a little strange because when skimming the head or the block it is better to have the whole lot to get your mesurements right, as not every motor will be the same there also might need to be a little cam phasing when the head block is skimmed to get the timming right he quoted me 700 for the engine in strip and rebuild,

Watching with interest....will it still run on pump petrol?

it dawned on me while thinking how nice 150hp would be... that the current radiator would not be enough; working on a 25% thermal efficiency (very rough)... and with an extra 25hp (most bikes are able to make 125hp) you would producing 75hp just in heat.

you may be able to get away with adding an oil cooler on the return oil line (mount in front of the oil tank but with the same curve radius) and an extra fan on the right hand side of the bike (been done on here before).

you might just get away with it... heck while going all at it add a methanol injection fogger in the intake for cooler intake and valve temps

i was under the impression that a squish band running over .75mm fails to work properly and leaves unburnt fuel in the squish area instead of squeezing it into the center of the combustion chamber..most mass produced engines fall into this category with just the odd engine which gets the components at the right end of the tolerances scale to mate up tight enough to give a smaller clearance and then you get your flyer...reckon i dropped on with my superduke ...05 black and runs like its been blueprinted .....ahhh i get it forged pistons grow more when they heat and those are large pistons so 1 mm may be the figure....get a full explination from your engine builder you want that squish band working ...when you look at the pistons after they have run awhile the squish should have no carbon formed on it if its actually doing its job.....good luck with it , what a great project

To eliminate the heat problem you could get a custom radiator fab done with a thicker core and perhaps more surface area,,,to cool it down,,,,,,
http://www.aaronradiator.co.uk/index.php?p=home

What company didi you buy the Pistons off mate?
Do they do other upgrades, I like to look and dream a little

With the heat..being another issue..Squish area etc..Does building it bigger change the balance of the motor..?? I'm guessing it will all be evaluated completely..I'm watching this thread too..Quietly.. No sense for me at this point..My engine is too new to change this drastically...but if I sucked a piston..I'd probably seriously take the jump...It's only money and we ALL are spending good bucks doing our mods..I don't know too many Superdukers with completely stock bikes..

Keep a good charged battery with the new hi-compression pistons. My Ducati ST4S has the big slugs and now has a new sprage starter clutch no thanks to a new battery that was too slow turning over the big twin. A couple of back fires and the starter clutch gernaded. $400+ in parts. I have to keep the trikler battery charger on the red beast and ride it in the warm summer days. So much for a daily rider....but oh what a ride. Big Boomer.....

Ktmtwins.com has an ignition torque limiter that might help?

http://www.ktmtwins.com/ktm-990-super-d ... ng-mod-kit

I bought the pistons off Sean Wilson Racing Limited (they do Speedway bike preparation)
They are the sole uk importer for Tornado who are a German company specialising in speedway and grass track racing.
KTM SD motors are very popular in Europe for grass track.
http://www.gw-racing-parts.de/index2.ph ... 009&lan=en

I will seek advice on the heat issue, thanks guys.

Update:
The CP pistons have been made and shipped on Friday from the US to Germany where they will be refinished and plated before being shipped out to me.
By the looks of things i should have them in my sweaty paws by a week on Friday.

i'll be keepin an eye on this too - Mine's only got 19 k miles on it but someday if i keep it long enough i'll be needing to rebuild er and maybe then gettin more ponies would be cool. Otherwise / probably by the above there'll be some of the new 1200's available for sale and hopefully they already have more HP - and hopefully by then i'll have the money - LOL too many hopes !!!

john

Pistons arrived in the UK today.
Feel like Christmas has arrived early.
They should be with me tomorrow or Thursday.
As soon as they are in I shall send Bash's heads with my barrels, pistons, heads and high lift cams off to Bob Farnham to work his magic.
Once the motor is back in its bodywork and running gear rebuild time.

OK the pistons have arrived:





As you can see the new pistons are obviously hi comp compared to the original and quite lovely IMO.
What is bothering me, however, is the weight: the original piston weighs in at 329g whilst the new one is a portly 376g.
I was already planning to reduce the rev limit but can anyone give me some advice on what this weight increase really means?
Thanx

My basic opinion..
Higher compression has more dome material on top of the piston..Makes it thicker and a bit heavier..Also..isn't it a larger dia. piston that you will be boring from the cylinder sleeves ...and a forged piston.??
They sure are purdy!!

Sweet

Heavier pistons would mean a small drop in max rpm wouldn't it?

The heavier pistons will lower the balance factor. Sweet spot will move in the RPM range. There will be more stress on the rods/crank.

They look sweet

Here's the math/s using: http://www.wallaceracing.com/Calculate- ... Piston.php

Values Used:
RPM: 9000
Stroke (Inch): 2.46
Rod Length (Inch): 4.92

Piston Weight (Gms): 329
Inertia Force is 2,052.71 pounds.
Effect of Rod/Stroke on TDC and BDC inertia force:
Upward Inertia Force at TDC is 2,565.88 pounds.
Downward Inertia Force at BDC is 1,539.53 pounds.

Piston Weight (Gms): 376
Inertia Force is 2,345.9 pounds.
Effect of Rod/Stroke on TDC and BDC inertia force:
Upward Inertia Force at TDC is 2,932.44 pounds.
Downward Inertia Force at BDC is 1,759.46 pounds.

By that calculator,
Reducing the limiter to 8.5k gives you just over the same inertial forces.

I asked for some help and I got it!
That's really excellent, thanks.
As I understand it raising the rev limit on the stock pistons severely limits their life which, of course, I found out to my cost!
The new pistons are forged so they should withstand these forces better but we are running a 20% increase in compression ratio plus they are 14% heavier.
BTW: the pistons are 101mm i.e. stock size - I'm having the bores replated and then cut back to exactly match the new slugs.

Clearly I don't want to reduce the rev limit too far but neither do i want to spend a significant amount of money producing an Austrian grenade!
What rev limits would our panel of experts recommend?

[DNA Stage 3 Airbox,
Tornado Hi lift cams
CP 12.5:1 pistons
Bob Farnham gas flow
Akrapovic Evo system]

Not planning to go for larger valves right now. The cost was huge in comparison with the rest of the work.
So we will have a motor that opens the valves further, longer and with increased overlap but not more surface area.
The gas flow will increase the gas flow by a significant amount. When you take the valves out there is a lot of metal overlapping the valve seats. Just removing that metal increases the motor's ability to pump gas by over 10% I believe.

would just leave the limiter at 9500 or 9600 rpm.. its the bottom end, gudeon pins and rods that are taking the extra strain... the pistons themselves willl be fine.

if you wanted to be safe you could lower it to 9200 or 9300 but probably not necessary. The guys who a raising their limiters to 10300rpm are doing way more damage than what you will be running

On my last big bore motor I went up in piston size by + 5mm & compression from 10:1 to 12.5:1 & it vibrated quite alot, learning from my experance when I do it again I will balance the piston rod & crank before assembly, the small end sized up after a few thousand kms & will be fitting a new bushed conrod soon & will get it all balanced up before assembly.

The bigger the vibration the bigger the chance of bearing failure.

I have done a few big bores over the years & found for each compression point I got 1 HP & for eack mm bigger in bore size I got 0.75HP.

Need an underwear change. Those are pretty. What did they set you back?

They cost £440 inc VAT.
Which i recon is a pretty good price, don't you?

Should be ok at the Std SD rev limit, the higher compression cushions the forces on the crank/rods at TDC, the extra load at BDC will less of a problem, the balance factor would be my main concern, the higher load at BDC and being out of balance together will put extra load on the big end bearing...
Run the best fully synthetic oil you can and change more often will be a little help,
Extra heat should not be a problem aren,t the SD and SDR rads the same

Have you checked the weight of the pistons are exactly the same

Balancing the pistons if they are not will help a little

Oh and avoid banging into the limiter or missing a gear, a soft limiter would be a good idea

Looks like its coming together nicely mate!

Sorry I didn't get back to you mate - had a twat of a week!!

Bell you tommorow when I should be local!

Did you have a chance to see how close the pistons weight to each other? That helps to balance / smooth the engine down.I would spend time with the rods also. Had a chance to ride a big bore 500 single 2 smoker dirt bike (Husky) from the mid 80's. The vibration was so bad you could not sit on the seat. My 430 Husky (82) was a dream compared to the 500.

have you considered starter motors? will the standard still crank it over

We think the starter motor will be ok.
If its not I shall junk it and the alternator and use a starter at the track (I already have one for starting classic race bikes)
What won't be OK is the battery. I've been running with one out of an RVF400 which is ok - ish provided its charged and maintained properly. Can't see it coping with a 25% increase in resistance.
If the starter motor is ok turning the motor over I will invest in a solid state battery.

The Shorai battery I use has 270 cca 18A, standard is 220 cca 14A

How's this all coming along Tripod?
I'm watching this space with avid interest!

Barrels, Heads and new cams are with Bob Farnham at the moment.
I'm expecting them back early in the New Year.
The plan is to get the motor back together for the end of January.
Kev has taken the forks and shock out - I'm picking them up tomorrow to take to K-Tech
All very exciting!

Looking forward to seeing this beast in the flesh at some point.

I think i'd get off on just hearing it crank over.

Sounds pretty cool to give that motor some more hp.I would love to do it but where I live I don't know anywhere to go.I have an RC8 I love the power.
I love my dukes riding position.I would love to have close to RC8 power on a duke.I work out a lot and my weight with all my gear on could really use the help.On the RC8 my weight is not a problem. If I had someone that knew what they were doing I would spend the cash I just spent a bundle to get the RC8 dialed in new FMF pipe and it will be remapped this week end going for a canyon blast in Calif this Sunday if weather permits. I really want to see what it can do with all the weight off.Stock exhausts must weigh 40lbs.
Can't wait to hear how the build up performs. After all the RC8 is more or less a punched out 990 motor that 200 cc makes a ton of differance.
If KTM really does a 1200 duke It will interesting to see if they can keep the fun factor of the 990.
When aprilia went to the 1200 dd it changed the whole bike.The 750 was so much fun and the 1200 gained a lot of weight plus the changed the steering and more.I hope KTM does not do the same thing.

All innuendo aside there is a massive amount of metal to take out of those heads.
Even with them in my hands it took a few minutes to realise that there is metal inside the valve seats making the inlet and exhaust ports smaller than the valves themselves.
Apparently this leaving excess metal in the heads is a KTM thing. They are well known for it in the off road bike world and the power increases that can be had just from removing the excess up to the valve seats is huge, apparently.

I've had a baseline dyno done on my SDR so I'm keen to see how much a port and polish will increase... Even without the new stacks.

So has this thng been buttoned up with the new pistons and ported heads?

Fired up yet?

Ya whats the deal man? Im excited to see what this thing does.

Hope this isn't hi-jacking Tripod Dave... If it is , let me know and I'll start another.
I'm getting my SDR ported and polished and have just had some photos sent through.
I thought this would be the most relevant place to post it as this is where people are looking to, to see this sort of thing.







These are unfinished as yet but I hope to get it in Oz before the 20th of Jan.
Much thanks to Danny Boyd for the work, I'll post up results as soon as I get them.

Looking good Linga!

Where are you getting the porting done?

I'm really looking forward to seeing the two results side by side.
Don't forget to take as many photos as possible of all the angles you can once the porting is complete so we can compare back to back.
I'm expecting the valve guides to be completely flush with the reprofiled port once done: are you expecting the same?

In answer to the other question: I'm expecting to have the motor run up for the first time last week in Jan/first week in Feb.

I'm using the stock valves for 2 reasons:
cost and revs.
The cost of buying a set of even SDR valves and fitting them would have changed the cost of the engine build dramatically - if memory serves the valves would have added about £500 on their own.
I'm not sure i need them at this stage: the problem the SD has is breathing that's true but that could be fixed just by removing the horrific amount of excess metal out of the heads. Plus the additional valve size isn't going to be as important as I'm planning to run a lower rev limit - perhaps down to 9,500.

What's your plan?

Have you waisted the valve stems? They look thinner!

I'm not sure on most of your questions...
I'll drop an email and ask Danny.
The guy doing my work is Danny Boyd from Tri-Valley but he is doing this job in his spare time for me.
I'm leaving it all up to him, he is going for increased volume ( not so much velocity) He also said that the cast marks and lumps on my SDR were horrendous and he's very excited to see what the results are. I had the option to up the compression but didn't want to run any special fuel.
I'll get as many photos as possible off him.
He also said that my next major hurdle is going to be to get enough air into her. I'm hoping MrZ32's stacks will be half of the equation. The other half will be a custom airbox similar to GoGo's it I'm hoping to get even bigger ducts by using an 06 tank and filling in the top of the spoilers.
I'll let you know the answers to your questions as soon as I get them.
P.S. I was watching your thread with interest Dave but ran out of time to see the results... I hope I haven't made a mistake by pussying out of the high comp!

In general 10% higher compression means 10% more torque and therefor 10% more power.

I thought Tri-valley was in the US so was wondering (you being in Aus) how you hooked up with them and how much it's costing you to send stuff back and forth.

Well Danny has nearly finished with the heads!!
I sent him an email but he only had a few photos for me but a full reply to all questions.
This is his first set of SDR heads but has done SD and many European bike before.
He said that the SDR's heads were a better design but the casting was worse than that of the normal SD eg, casting marks and bumps.
I'm glad he has done so much work for me as he has been so excited about the project that he has gone well past a stage 2 port and polish.

On waisting the valves Danny said he tried to take as little off as possible so because little gains are to be made.

On grinding down the valve guides, he is polishing and smoothing but leaving them there, he advised that if I don't want to strip me heads down every few runs that I should leave them (gains to be made but weakens the engine so more costly maintenance)

On Valve angle, he has done a 5 angle and said that that therte was very little lapping to be done as it all fitted sweet.




I hope to have it run up in a week or two and in Oz by the end of the month, I will post full runs US and Aus

Looks good mate.

Looking really good!

Your man's comments on the differences between SD and SDR heads is interesting. Having talked to a number of people who tune KTM MX/Enduro machines its clear that there are significant gains to be made just by tidying up and removing the excess metal. I wonder if its KTM policy to ship their bikes in a form that can be easily tuned and this is carried over into the SD/SDR?

Are you going to raise the compression at all?
I understand that the method of choice is to skim the barrels rather than the heads.

Im not going to bother mate, just thought that there wouldn't be enough gain for my troubles.
If this motor goes well ( and I can ride it) then maybe I might build a better one next year...

Watching this thread i really wish i was getting my heads flowed!!!

Bloody sods law i go to all the trouble of pulling the heads off only for the business to lose 2 big clients, a wacking great tax bill come in and also christmas all in 1 hit

You know I thought of another thing with those pistons(which look really sexy BTW) is that they have sharp edges around the valve reliefs and could cause detonation. "Common problem areas are sharp edges of metal either on the piston or in the combustion chamber. For instance, if the piston has a valve relief cut into it, there is usually a very defined edge that the cutting tool leaves. This sharp edge is greatly prone to super heating and will actually retain enough heat that it will start to glow. If the fuel should hit this glowing edge either prior to the lighting of the spark plug or even after ignition, it is very likely that another flame front will initiate. If this unintended ignition occurs very early in the compression stroke, then the piston will be forced up against the increased pressure of the burning gas and will result in a form of abnormal combustion referred to as preignition. When this happens, the end result, if severe enough, is that the connecting rods bend.Carbon deposits that build up in the combustion chamber or on the piston top will have the same effect, along with the decreased volume at TDC, which in turn raises the compression ratio" Just a thought if anyone esles wants to chime in on this. You should take the sharp edges of of those pistons as not to create heat and detonation.

How do SDR heads differ from SD heads other than just flowing more air stock? Is there the same amount of excess metal in SD heads? From what I'm reading online a port and polish job costs about $800 here in VA and if the gains were good enough I might consider it.

Should have some results this week guys and will be able to confirm in feb at my local Dyno...
I can't wait

Yeah mate.
Danny and I got talking for sometime last year on set ups and the things he is doing with his own business.
And he is doing some amazing stuff that every one should be seeing soon regarding bike builds.
When I told him what I was thinking, he immediately wanted to jump on board and has done the swingarm and heads for me really cheap and in his spare time over the holidays.
I couldn't ask for more from the guy, I can't wait to see the dyno!

First run!!

Got a nice note! Did you stay stock compression? Take some more vids of the swing arm a what not. Keep up the killer work!

Does it sound different to a standard SD?

Heads and re-bored barrels back 1st week in Feb.
Rebuilt Forks and shock should be back at the same time.

yes it is!
Replacement pegs arrived today from SES. An ebay purchase recommendation from Kev @ Projex. They were about £11ea and look top value not to mention being a little bit cheaper than the Rizoma replacements.

Put together a Goodrich - based order for the cam cover breathers yesterday and today with those nice people at Demon Tweeks.
I'll post pictures and a parts list for those who want to do this in the UK / Europe and are struggling (like me) to replicate exactly what our Ozzie cousins did.
My interpretation will use a common catch tank for the heads and crank case which will have a filtered breather - a scaled down version of what they do for some rally cars. Pipe internal diameter will be 8.6mm throughout.

Spoke to Bob Farnham. Bores are done. Heads should be finished this week.
Very excited.
sold my CR today so I can afford it all.

Very cool mate!
I can't wait to see how your bike turns out. I'm already regretting not upping the comp.
The common catch tank sounds like a great idea.

one of the things that scares me a bit about upping the compression is the batterie struggles to start the bike as is, I also thought that after removing metal from inside the squish area, gas flowing that sometimes they skim the head /barrels to get the compression back to oe?