Big Bore and Gas Flowed Head Project
 

Ok, after my Stage 3 DNA Airbox mod (with a Power Commander and cans), I am looking at doing further modifications now to compliment the DNA Airbox.

What is so good about the DNA Airbox, you don't lose any power or torque anywhere, and the improvements are in a very wide area of revs, right from just above tickover to the rev limiter. This makes it a cracking mod in my books.

(With some mods, you lose power at one end, and gain on the other end; normally the top end of revs).

So, I am looking at a Big Bore, which should give me gains through the rev range, and a Gas Flowed Head.

This should give me a nice and smooth power boost, and I am hoping for a total gain, with my existing mods, of around 10-12hp over a Standard bike.

I have just started this project, it will probably grow and change a bit, and have sourced a second hand barrel, but I am looking for a spare cylinder head. If anyone has one, please pm me, thanks.

You will need these.

http://cgi.ebay.co.uk/GENUINE-YAMAHA-CYLINDER-BASE-GASKET-XT660X-XT660R-/380239567677?pt=UK_Motorcycle_Parts

http://cgi.ebay.com/ebaymotors/Yamaha-Raptor-Grizzly-700-EST-Top-End-Gasket-Set-103mm-_W0QQcmdZViewItemQQitemZ220636955493QQptZMotorsQ5f ATVQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/COMETIC-EST-TOP-END-KIT-103MM-YAMAHA-RAPTOR-700R-06-_W0QQcmdZViewItemQQitemZ380260180414QQptZMotorcycl esQ5fPartsQ5fAccessories

I would use this piston if I did it again. The difference between a 102mm 11.5:1 & a 103mm 11:1 piston would be less than 1 HP difference.

http://www.tqsatv.com/proddetail.php?prod=RAPTOR-700-TECH-PISTON

Kev...thank you for those links!! Top Geezer!! I was wondering.........

Firstly....I didn't realise the bore needed plating, however I have found someone who does Nikasil ...so no problem with that. Would the bore wear out quickly without it? Is it an alloy bore, coated as standard?

Secondly,

...on the Carillo site , the CR pistons are either 11:1, 12:1 or 12.5:1?? Not 11.5:1 ?????
Is the CR piston forged, and the others not? Is that why its dearer/better?

I have found a JE 103mm piston kit 11:1 (item no. 360083541989 on ebay.com) , he will send it carriage free to the UK at $171.99, and a top end gasket set for $68, about �155........I'm think I'm going to go for that..........

Thirdly, do you think a gain of 10-12 hp is on with this, over Standard, with my mods?

being just up the road from you, I'd be interested to see the results of your conversion

You will need head work & a +2mm throttle body to get that HP with a standard cam.

All the research has been done on these conversion have a read on what HP you get from what mod in the mod section.

Have a look at my dyno runs with just the big bore with a 11:1 102mm piston it got an extra 2.5 HP gain so I would expect the 103mm to have around 3 to 3.5HP gain. You would have less vibration from the motor with a 102mm piston unless you get the motor balanced.

CP do make a 11.5:1 is has been around for a while now, I have seen good results with this piston with dyno runs. The link I gave you is a valid.

Thank you Schoemrich for the barrel ! I collected it last night....you have a nice bike project XT there mate, I am looking forward to seeing that coming together in the New Year!!

CP have returned my email and confirmed a 686cc 102mm 11.5:1 CR piston.
Kev is pointing me towards this, thank you for your input mate, but I would like a 700cc conversion...

So, I'm going to go with the JE piston kit, a 700cc 103mm 11:1 CR piston. (a Standard bike has 10:1 CR, so this is still a good compression boost.)

I have now ordered it today, and will wait for it to arrive from the USA, so that I can take the new piston and the barrel to the machine shop to get a match.

I am hoping to see gains on my bike of around 10hp..this is my estimate..

My Standard Bike with PC111 44.50HP
With DNA St.3 airbox and CCC 50.00HP (49.01 so far -not been fine tuned)
With JE 700cc Piston 11:1 53.00HP
With a gas-flowed Head 55.00HP

I am hoping that the standard throttle body can chuck in enough air/fuel to make it work properly.

Torque wise, I am looking a similar gain of a total 10ft/lbs.
Torque gains in the low to mid range - is the really important part of the Project for me...

Money-wise for just the 700cc conversion, my estimate,
Spare barrel �60
Machine/ plating �130
Piston kit �115
Top end gasket �37
Bottom gasket �10
Oil sundries �20

Total �372


Now, I am turning my attention to the cylinder head. I am thinking of keeping the standard valves, in order to keep the torque gains to the maximum, at lower revs. I am keeping the Standard Camshaft. Or would bigger valves still give as much gain in low revs?
So, I am looking for a cylinder head.....anyone??

Realistic HP numbers, I do not see why you would not get 55HP with the ported head. Marcel got 55HP + an extra 12 HP with a cam & throttle body using the same piston, his cylinder was also decked, he ran at 11.3:1.

Don't forget to add dyno time to the price.

Thats what I was thinking, I could skim the cylinder head to "up" the CR.

Kev., I wll look into throttle bodies !

The dyno will add �150 to this project. But if I can source the head soon, I can get it all done for free, as the Dyno "owe me" another 3hrs......

I'm still looking for a cylinder head tho......!hint! ..... anyone?

I can't see a Big Valve advantage, as I am retaining the Standard Camshaft, so I will just go for a nicely ported flowed head. There is someone not too far away who can do that for me.

would a raptor head Fit?

apparantly the Raptor head wont fit.....I am ringing round Breakers, but they will only sell a whole lump. And I don't want a whole lump, well not another to go with my tuned ZZR x2, ford X-FLOW x3.........I'll be stubbing my toes on it.

By the way..i've had 192bhp out of a ford x-flow (Mk1/11 Escort)...i couldn't keep it in a straight line even with a LSD .....

Doesn't the Capt have some spare bits?

No, not any more.....Someone must have a cylinder head.....

I'm looking at possibly adding a +2mm Throttle Body...but I need to understand how it will help my Conversion...I'm not convinced at the moment, as it has been only used on the "big power/ hot cam" conversions.
Has anyone tried one with a standard camshaft?

Well, a larger throttle body allows more flow basically.

When you get all these mods (stage 3, big bore, ported head etc) the only other intermediatary between the outside world and the inside of your engine is the throttle body.

The larger that is, the more that can flow through it.
I've read on here that people get some positive gains from a larger TB.

Oh, and the cams... they come in different shapes offering different 'degrees' of angle.
The shape of the cam determines when the valves open/close and for how long they are open for.
Say for example, on the intake stroke, you want the exhaust valves to close pretty much top dead centre, and the inlet to open at top dead centre.
Obviously, the exhaust must be closed before the intake opens otherwise you'll get blow back through throttle body and I've stood next to car carbs when they've backfired through them.
Trust... I thought I needed a change of underware after that!

So how the cam is ground and shaped changes all of this. There is no 'Ideal' either as it depends on what you're looking for, whether you want top end power or low end grunt.

I honestly couldn't tell you how the shape of the cam affects the power though

I meant that I didn't think the +2 throttle body would be as beneficial on my conversion, than on ones with hot cams. I would like to know if it would benefit me tho.....or if no information on that, I may just have to try it Daz!

personally, I'd have both throttle body bored and a hot cam, simply because I love revving the tits out of the engine and thats where the most power is made with that setup.

For yourself, someone who doesn't rev the nuts of the bike, a hot cam would be detrimental as you'd rarely be in the band where most the power is produced.

as far as I know... a bored throttle body would be beneficial regardless of the cam.

Ok, opinions are valued, thanks.

I think the standard cam has a really nice map curve, and is so useable at low throttle openings.......I can't see a reason to change it! Good design in my books! Very easy and drivable. Now, IF there was a cam below the Mudplugger/Stage 1, I would be very interested, but at the moment, that is a standard cam.

If I was racing it, maybe stage 2 (really hot cams are difficult to get the best out of...you need Close Ratio gears, you'd be upping the rev limiter, etc etc. ) But you would still want "pull" from say 3500 revs. And it will need a bit more attention....

As it is, I think I will be happy with the outcome.

Hey, I have just seen the OTR +4MM headers...oh no!

I wonder if they are "matched" to the head, or if they are the standard size bore, going out to 4mm.....hmmm...only trouble is, I don't really want to deal with OTR. I have had three exhausts made up on other projects, so I could just go for custom headers.

I could get my head matched up to some bigger bore headers.......and link pipes....

You need to read the other big bore threads, all the mods you are talking about have all been done with dyno results.

I think I'll have to pull my finger, and join the Supporters Club!

Alot of the information on this site is only available to Supporters, and apparantly its all the juicy bits.

Well worth a tenner methinks..........

About bloody time :toothy3:

Ok, getting my Supporters organised....

Now, does anyone have a spare throttle body?
Or a cylinder head?

I don't want to use my standard parts, as I won't be able to put it back to standard when I, eventually, sell it.
Plus my bike is virtually new....so I really want to keep my standard bits.

If I can't find a Cylinder Head for reasonable money, fairly soon, I will just do the big bore conversion. (and throttle body, if I can get a spare).....There is a head on Ebay Germany, a breaker has one..280 Euro...too expensive.....but I have made an offer on it.....have to await the outcome

I haven't measured it yet but looked at the barrel, there is not much "meat" on it. I am going from 660cc to 700cc, plus 3mm. Its been done before, so it should be ok. The piston kit is on its way from the U.S.

I'm doing my first offroad escapade (it looks very gentle) this weekend with some guys from the forum. It is mainly gravel roads, in and around Stonehenge.....that will be enormous fun....first time offroad on my XT!

http://cgi.ebay.co.uk/YAMAHA-XT660X-...torcycle_Parts


http://cgi.ebay.co.uk/YAMAHA-XT-660-...torcycle_Parts

couple there matey

Bargain with them, I paid a lot less for the 2 I bought.

thanks Daz for those links....I think they are a little expensive, but useful. It should be easier to source than a cylinder head......

I haven't fully decided on the throttle body yet, and Kev can't convince me either... .....I really can't see me getting a gain worth talking about with a standard camshaft.
All the gains of a +2mm throttle body have been on much higher performance engines than on my project, and the gains are in the last third of the power band. The good thing is, it doesn't rob any low end torque/power though.

IF ONLY someone did a "fast road" cam...then I'd have one.

I just don't want a Stage 1 or 2...too extreme for me.

If you are after torque only, I think the standard cam is your best option. There are still a few more tricks to get more midrange power out of the XT motor.

One thing I have learn't from this XT motor is the more torque you have the more the motor feels like it is on steroids, very twitchy in the mid range when cruising.

I personally would not go with the 103mm piston. Assuming you get a stock raptor barrel, instead of re-coating it, rather stay with the stock 102mm and around 11 to 12:1 in compression. Boring the sleeve out just weakens it, especially if you want the thing to last in a road bike. Also it requires a lot of extra cash one could spend somewhere else on the bike to get a 103 mm barrel set up.

The flatter the top of the piston, the better, so try and avoid buying pistons with domes. If you look around, you might find raptor pistons with a correct desk high feature. The stock raptor piston has a lot of unnecessary deck clearance and the corrected piston sorts that out, without having to skim the barrel down. Again saving you cost, plus giving you a flatter piston.

The stock valves will choke up the 700cc motor. So I have found that +2 on the intake works well for me. Leave the exhaust stock. Note, when you port the head, don't increase the ports size itself. Concentrate on correcting the valve seat diameters and then blending the seats to the ports. PM me the sizes recommended by the guy who will be doing your porting and I will confirm if he is right or not. I don't like stating on a public forum what sizes I use.

Then, I run a +3 mm throttle body. I would love to go larger to around a 50mm, but that means you have to build your own throttle body, which is not that easy.

There are no gains from the exhaust by using larger than 37mm inside diameter headers. Reverse megaphone exhaust designs work great, if you can get them.

On raptor 700's I built and a big bore XT, breaking 55HP with these mods will be easy as pie. A 686cc raptor I built with a stage 3 cam and the mods above easily cracked 70HP, but the XT motor cannot pull the RPM you need to do that. 55HP should be easy to get, but I would say you need to aim for about 60 plus with the mods if you do this right.

Thank you Kev and Freez.

Freez, I have a cylinder wall of 4.5mm.
Rebore 103mm will leave me around 3mm. I HOPE that is enough left on there.......

One cylinder head for you.

http://cgi.ebay.de/Zylinderkopf-Ventile-Yamaha-XT-660-R-X-XT660-XT660R-/370424616095?pt=Motorrad_Kraftradteile

One XT660 camshaft for you.

http://cgi.ebay.de/Nockenwelle-Kipphebel-Yamaha-XT-660-R-X-XT660-XT660R-/370424617113?pt=Motorrad_Kraftradteile

hehe thanks Kev, but already ahead of you.....(a mystery shopper has already made offers on them!).....they are a little expensive....but much appreciated!!

has anyone tried a standard raptor cam....?
and are they all the same for 660 and 686?

Yes I have, as you know I have one for sale, AUD$70 + postage cost..

XT660 & Raptor 686 cams have totaly different profiles.

I've now joined a Raptor forum too! Very informative, just spent a couple of hours on the Raptor 700 modifications, its chocka with info.

(Save bending eveyones ears......!!! lol)

They are absolutely bonkers these guys, all of 'em! You should see what engine mods they do....really impressive stuff.

I have been nudged in the direction of having a look at the Fiftyfifty cam....................
It has bags of low down torque, and a quite alot of power, ....hmmmmm

hmmmmmmm

This could change things...but I have alot to look at, so keep you posted.....

Oh,.. and how does my new Supporters badge look? Like the colour?

Why couldn't yamaha just do all these mods to the bikes in the first place...

imagine, buying a brand new XTX with these mods already done out of the box.

Just think of how big you're smile would be and a massively happy customer!

Well Daz, it's just mind boggling with all these mods on the Raptor forums.

But, these are racing engines....

And I want to build a nice road/greenlaner bike....theres a big difference!
(note: I am not talking about brakes, suspension, how well I ride, getting the most out of your bike,etc...... just tuning the engine).


Big bore. Yes
Head port and valves. Yes
Throttle body. Ok, if that will help the above, yes
Rally/race camshaft. errrrr, would I like that? I don't know.

The only way to know is to try it. Like you say Daz, I wish I could test drive a bike with one or two of these camshafts in. Every camshaft I have looked at seem very "spikey" , certainly on paper, compared to our lovely standard one.
And the standard one is so nice and driveable and smooth and easy. A camshaft can radically change an engine, especially when doing the above-mentioned mods. EDIT: (I really like the standard camshaft, don't I ? )

And also add-in the factor of (un) reliability.
As my bike is at the moment, it will be no less reliable than a standard bike. (Stage 3 DNA Airbox, Cans, PC111)

Adding a big bore/ higher compression /(ported big-valve head) will compromise reliability and engine life for extra power. And it will be thirstier. Ok , I can go with that. I like big bores.

Adding a rally/race cam will also add-in less reliabilty, and more engine wear. And what about the strength of the gearbox, Clutch, Cam chain, cam gear, camshaft, big-end bearings, con-rod, the uprated valve gear, small end bearings, oil pump, etc.? ...Not sure about that.

So, all these factors really come down to each individual engine build. We have two really helpful and knowledgeable techie-tuners on the Forum, Kev and Freez, (and thank you guys for your input again), but as I say, it all comes down to each individuals wants/needs/budget/, and the trade-off of more power/torque- against - reliability/engine wear.

My list if I do it again.

5050 Raptor cam.
+2mm Inlet valves, get them from Freez or http://www.whiteknuckleracing.com/index1.html
Valve springs & retainers, http://www.whiteknuckleracing.com/index1.html
Ported Head
102mm CP 11.5:1 piston kit.
Re-deck the cylinder.
Stroker crank + 5mm, cost is high to make one ?
+3mm throttle body
Dynojet ignition.
PCV or PCIII
DNA stage 3 airbox
Carbon Cans exhausts.
There you have a + 70HP motor which will pull from low down all the way up.

Below was the build of a Raptor 700, the dyno runs done were with 3 differrent Cams on the same bike on the same Dyno for back to back testing.
11:1 piston, stock valve head, dynatek ignition, pc3, +2 tb, FCI

As you can see the 5050 cam in Green has the best torque & HP by far.

http://i23.photobucket.com/albums/b3...cks/002-20.jpg

Very good post Kev!

(Finished editing this post!!)

It is a fab cam Kev........fab......fab.......!!! I like it!!!!
I looked at this yesterday, and was thinking...IF I go this far (the cam adds alot to budget and complexity)...I would be happier taking it to a better engine builder than myself ! Access to machinery etc...valve pockets may need careful checking etc. .

What were the other runs?...looks like same cam.....?

Didn't the standard valves bounce around like mad? i bet they were doing a Salsa!! i think a spring kit like WKR does is good!

Did you do any bottom end heat treatment, balancing or anything else?

How long or how many k's did you travel with this set up?

Revving the engine that high for "dyno showing" is fine....but by how much, or where, even with upgraded valve gear, would you set the rev limiter?(personally, I won't hold you to anything/liability etc.) about 7500-8000rpm looks sensible, and errs on the "more safe" side.......

Would you recommend a stronger cam gear/chain/.. wouldn't it be great if you could have the cam gear-driven....??

Taking an educated guess...with a plus 3mm piston/bore, do you think that would behave itself? Or is it TOTALLY bonkers? I think I would have to keep the CR sensible and not extreme....11:1-11.5:1 true.

How, or in what way, do you think a big bore would effect the power curve/torque curve? It would make the engine a little tad slower right?

How strong are our wheel spokes???????? and gearboxes??????? lol

You can't use standard valve springs with the 5050 cam the rockers also need to be radiused so the lobs can clear the rockers.

I posted the dyno runs as a compassion between the 3 cams.

5050 cam
Stage 3 Hot Cam
X4 cam

You used the Raptor decompressioner & cam sprocket, the XT's cam chain is fine.

Personally 7500 rpm would be the highest I would set the rev limiter on a XT motor.

Bigger the bore, more torque, more vibration. The motor behaves very twitchy in low revs on light throttle openings.

I'm guessing..that with a the Big bore..

Torque will be similar to what I have now (v.good), up to 5000rpm. But I will be gaining more torque 5000-7000rpm..... so far so good...in fact brill!

Power is good, you have more up top to help push the bike through the air..
It looks like up to 4500 again, very similar to what I have now (v.good).

But that is on paper, as Kev says, twitchy on light throttle...

Eh...this is great!

I'd better get my entry in for the Rakkau Hillclimb!

It's all about money the more you poor in the more HP you get out.

Guessing, with all the parts, machining, and getting a engine builder to do it, fine tuning.... �?