Ducati Monster Forum

I own a 2006 Monster 620 Dark. Mods I have done so far is 14 tooth front sprocket, K& N air filter, Dan moto slip ons, i riidium plugs.I have not reflashed my ECU yet , because I hear that you can bump up displacement by swapping out 800 cylinders from a 2006 monster and slipping in  feracci pistons.Any opinions on this?

695/750/800 cylinders are all 88mm bore.
Basically the same though the dowel pin location on the base changed in ~'01-'02, so you'll have to watch that.

With your 620 crank (61.5mm stroke) that will get you 748cc.

Your cams are a little bit better than what was in the 750's.
So it'll then run a little better than a hi-comp 750.

That's not particularly spectacular, but it's better than what you have now.
Perhaps 6-8 HP more across the range.

Considering the cost of parts and labor, it may be more effective to slide in an 800 motor.
That would get you 10-15 HP more across the range, and a 6-speed trans as well.
Depends how much of it you're doing yourself.

'06 620 is already a 6-speed BTW Mr. Speeddog...  [thumbsup]

When my beloved 2005 Monster 620 engine gets to a point where some major engine work is required to keep it running this is what I'm-A gonna do!!

Hmmm... I guess I had the way-back machine set to 2004.  [laugh]

'05 too . . . unless it was the Dark single disc . . . ;D

Are there any considerations re combustion chamber shape and piston choice when doing this big bore upgrade to a 620? Are 620 and 750 combustion chambers shaped differently influencing choice of hi comp pistons?

620 is has better flowing heads . . . you can get more if a pro is doing the work, but, reliability will/might become an issue if you go full HC . . .

Has the 620 a tighter chamber? If so you think 11:1 pistons rather than 12:1 pistons to avoid piston to valve and piston to head clearance issues?

just regular day to day use . . the 12:1 are just too hot for city riding if PO is gonna do lots of canyon riding and track time, then, yes, HC and some head work . . .

my M620 ran great until it didn't . . . with 10.5:1 OEM . . . faster than a few 750 locally

O.K. So what year cylinders, and off what size engine will I have to purchase to do this Monster 620 conversion ?

Be watching this with interest.
I was wondering about this (have a customer with an '06 620 Dark). Assuming the post 02 88mm cylinders are the same it looks like 03+ 88mm cylinders are ok from what Speeddog posted. I guess buying used cylinders in your part of the world is cheaper than boring and replating 620 cylinders? I don't even know if the 620 cylinders have enough material to do that, i.e. if they are small bore versions of 88mm cylinders. Sounds too like you need 10:1 -11:1 pistons with the 620 chamber rather than 12:1 for the 750 chamber which I assume is more open.
These guys will have to confirm.
 [popcorn]

If you go with a hi comp 750 conversion, PCV and an open airbox, should be a decent performance gain. Iirc Darkmonster is looking at doing this so he might have some good info for you.

IF and ONLY IF those cylinders fit the 620 crankcase I would then try to procure myself a set of said cylinders in order to install my 11:1 FBF pistons . . I would NOT have to redo my ECU, since, it would be able to handle it, sure, a reflash and dyno tune would be the best option but, in my side of the world, I don't have access to a bike dyno or tuning software . . . Since Ducati sells the cylinders with pistons  . . . I wanted the 750 cylinders

edit:
or, just get a set of 800 cylinders/piston and reflash ECU

I guess I missed the quick blast of posts last October.



I don't know if there are any differences in the chambers between 620 and 750.
I suspect they're the same, as the valve part numbers are the same when comparing last year of 750 and first year of 620 ('02).
Cams are in the same spot, as are rockers, etc.
620 has slightly more lift on the cam, so they may have moved the valve seats.....
I wouldn't have moved the seats if I were in their shoes, so perhaps they did.  :-\

I've got FBF 750 hi-comps and Mahle 91mm (makes a 750 into an 800) hi-comps, and neither dome is a particularly close fit in a 695/800 chamber.
And the fit of the squish areas aren't so flash either.
Which really annoys me, as they could have done it properly with a relatively tiny effort.
Mahle fits better, but still not as it should.
Perhaps they fit a 750 head better, but I'd be surprised.

800 and 900 valves are the same part numbers, at least for 8mm stem 800's.

I've compared a couple years of '02 and later 620/695/750/800 crankcase part numbers, and each individual year they're the same part numbers.
Can't compare cylinder part numbers, as OEM they come with pistons, which are different due to the different strokes.
From that, I'd say all '02 and later 620/695/750/800 cylinders will swap without issue.

You'll need to get the proper piston deck height to match whatever crank you run.
620 and 750 are same stroke, so that makes it a lot easier.
800 pistons are ~2.25mm shorter deck height than 620/750.

I will be riding my 620/750 SS tomorrow at the track. I built it this winter to replace the 97 750 motors that keep cracking cases. It is a simple conversion with off the shelf parts but a few pitfalls and a few things that should be taken care of if you plan to keep it more 620 than 750.

The smaller bore does mean the angle cut on the pistons to heads do not match well. You could either machine the 620 heads or just bolt on a set of 750 heads. I was trying to just get back to 750 at this time so I simply set squish after finding the high points and will re-visit the heads this fall as I have a set of ported 750 heads if I decide I want "more"

I would have the heads re-cut as it should be a easy job for a machinist and then it is done. Cams are higher lift on the 620 but less duration so it may not be much better. I hope to swap to 750 cams just to find out at some point. The stock 750 pistons do NOT have room for any more lift unless you sink the valves in the heads.

You can find 750 heads that will bolt up but keep in mind you are also changing pistons weight which means you may change balance so keep that in mind as well. Sometimes for the better sometimes worse, you could always re-balance and be better than oem.

Interested to see the results of your 620/750 cam comparison down the track.

Me too, I am wondering if the bike will prefer high lift short duration vs low lift long duration. Sort of old school thought vs new.

The balance of the motor with the 750 pistons is not great as the motor is not as smooth as I would like. I would tear it down for a balance job if I did not have plans for different pistons at some point. Maybe I need to build another bike to play with and just balance this one to be my 60hp rain/training bike.

The soft motor rain bike ;D.

Old school Vs new school cam comparison thread would be a beauty. [thumbsup]

I have wondered how cams with 750 cam duration and carbed 900V cam lift would work in a hot 750 motor. So reground 750 cams for more lift. Alas I dont know who could grind that down here. I wish I knew who did Vee Two's cams.

I "heard" someone once say "a 750 with 620 heads is better than a 620 with 750 heads". . . this was referring to EFI models . . . koko, have no idea how the 750 with 900 cams will react

If I get my hands on a set of stock 750 heads I will let you know.................. wait I might just have a set.

next up 750 cams in the 620 heads
or
750 stock heads
then
750 heads with 620 cams
750 heads with 900 carby cams
750 heads with 900ie cams
750 ported heads w/ 900 carby cams

620 heads and the 2 sets of 750 heads are different and it is a SS so i have to take the frame off everytime I do a head swap so I am not sure how quickly I will get this done as it is bike season here and I need to get to work.

This experiment should only take 4 or 5 seasons. [evil]

cause what I want to do is the 750 FBF 11.1 conversion but keep my 620 heads . .  and "some magic tot he bottom end". ..  looking for "efficient/dependable"
  [laugh] [laugh]

Just swap horizontal heads, and double whatever gains or losses show up on the dyno.

[popcorn]

 :D

You know Nick I just might try that, hey the harley 883 racers used to cheat by putting a 1200 piston and cylinder in the rear as tech never checked there. you know the vibrations cannot get worse.

Shifty brilliance that. [laugh]

I reckon 750 cams with about 2mm more lift for inlet and exhaust would be interesting.

I reckon that all 750 cams should be recycled for their steel...

If it were my motor, I'd put a set of 695 heads on it, some 11:1 (or 12:1) pistons in it and ride the piss out of it.

I wonder if people would feel the same way about these cams if they had about 2mm more lift. Seems to be more wrong with 750 heads than just the cams.

Swapping heads sounds like a great way to go.

Stu and I did a 695 heads + 11:1's on a customer's 750 carbie.

When I lit it off, Stu ran into the shop like his hair was on fire.  ;D

Customer really dug it too.

Yup.  Sounded mean and ran awesome too...  It was a carbed '01 BTW.  We did not have to change the jetting much either.

Okay I will add the 695 heads to the mix
695 heads with 695 cams
695 heads with 900ie cams

I need to find a set of ST2 cams, I have been building 800's (695 heads) and getting good hp

How much does the larger chamber of the 695/800 head effect the compression? I have a set of 695 cylinders & heads in my garage that I plan on putting on my 04 620. I just need to decide on what pistons.

Ok, so, I need to get:

695 heads or S2R800

750 FBF 11.1

750 cylinders or ???

MY 620 bottom end

Some $$$

New ECU to reflash/dyno tune

Right? Something else?

Gotcha . . .

THANKS

Checking FBF website, I copy/pasted the following statement:

"PISTON KIT - 88mm 11:1 750 Ducatis

This fit the following model: This piston when used with the Big Bore application for a Ducati Monster/Multistrada/Hypermotard 620 will give a 12.0:1 compression."

Is this because of the 620 heads?

Combustion chamber size I guess. Havent seen inside one so the other blokes will know.

Just a heads up.

I finally got a 620 on my dyno. It is a 620 monster all stock but for a set of sil slip on megaphones and a light flywheel.
55hp and 37ftlbs torque

I compared my 620 to 750ss motor and the HP was only up about 5hp, not impressed with that but I think it is due to the differences in the head to piston shape match.
On the up side the torque of the 620/750 was just about 50 for about a 12ftlb gain. The SS runs the 750 mikuni carbs and long manifolds and is a pretty good match for the other 750's I have run, nothing special for a similar stock 750.  The torque gain from the 620 was huge though, most everywhere a good gain. It would be good to see what a injected short manifold 620/750 might do as the 620 made most of its power up high where the carby was done by 8000

Interesting.

 :o

I guess more capacity and long manifolds gave the grunt.

I would say yes it was displacement that boosted torque, I would like to see my carby rev out like the 620 did as the 620 made its power a good 1000 rpm further up. I have no plans on flat slides for this bike as it is not supposed to become a parts whore, simple and cheap mods are the goal. I hope to try pod filters in place of the airbox as I ran a 900 with hi comps and pods and it mimicked the short manifold bikes power curve. If it is possible to not use split single carbs it would be better for most.

This one 620 is not a trend so I do want to run a few more on my dyno to make sure this one is as standard as possible. Next I will need to build another 750/620 to make sure it was not just my 750.

Maybe open up the inlet manifolds cross section, so a bigger bore on the alloy manifold tapering down to the port? So trying to get the manifold closer to the 38mm diameter of the carb with a late taper. The IE manifolds aren't exactly short, just fat. What's your opinion?
I've been trying this to see if the bikes hold their power more from an inlet port/cylinder volume perspective, but don't have back to back data. I have the opinion (which I cant back up yet ;D) that the carby manifolds are not just too long for top end torque but too narrow. It may not be their length, just too skinny. I got thinking about port to cylinder volume ratio and the resonance stuff due to a Lofgren article and talking to a race car tuner buddy.
I don't know, I'm trying to get a grasp of this stuff.

Just a quick tape measurement has the long manifold being double the length of the injected manifolds (5" vs 2.5") The long manifolds also do have a pretty good bend in them to transition from the downdraft carbs so on the vertical cylinder the charge has a good bend and then 5" to the head before the bend into the combustion chamber.

Anything that helps flow will benefit at higher revs, most porting gains are really felt up top where the oem drops off.  Thing to be careful of is opening up the port too much as it can cause a drop in Velocity and kill flow as well. We used to see heads from a well known tuner that were just bored to such a size on the bike they did not flow enough as the velocity was not there, they looked nice though.

I did have the test bike carry on high rpm with no porting but pods so there might be something there. I just need time to play which I do not have this time of year. Maybe come August things slow a little.

Yeah  I was looking at increasing inlet tract volume and trying to create a more tapered effect. Note how the ie manifolds are tapered and some even have a bulge to increase volume. I think if you include the alloy casting protrusion it adds to total inlet tract length. I havent measured from butterfly to valve. Pity I cant discuss this over a beer. :D

found this listed

http://www.ebay.com/itm/Ducati-Performance-Camshafts-racing-cams-1000ss-DS-SportClassic-Paul-Smart-/222180427711?hash=item33bafc47bf:g:xQgAAOSweWVXf6Wm&vxp=mtr (http://www.ebay.com/itm/Ducati-Performance-Camshafts-racing-cams-1000ss-DS-SportClassic-Paul-Smart-/222180427711?hash=item33bafc47bf:g:xQgAAOSweWVXf6Wm&vxp=mtr)

Snap 'em somebody.

Not bad, worth having if you have a 1000/1100.

1100 cams identical to 1000 or shim adjustment needed for shaft length? I think they're a smidge hotter than evo cams with a little more lift and duration, but close.

I clicked this thread expecting to see the 620 owner scoffed at for wanting to mod an entry level bike instead of just selling it and buying up.

But this is way, way better.  [thumbsup]

Syscrush
I have always looked at it this way ...........

If you cannot build you buy
If you cannot buy you build
If you cannot stop yourself from building become a mechanic and build other peoples stuff with their money.

true . . .unless, locally some of the tools or processes are NOT available

eric, sent you a pm

I went to option 3 ;D.

I started with #!
switched to #2
went fully nutz and got to #3

this was my route too . . but, I must let someone else do it if I don't have ALL the tools or processes

Well . . found a possible 800 donor engine but, I would use my 620 cases to keep engine # and not have to re-register a new engine . . . Also going for ECU  . . .

would have an 800 mild hc engine under the cloack of 620 cases . . .  [evil]

 ;D

 [evil]

 ;D

I don't know what register means in this context, but I advise you to make sure your insurance company knows what you've done, or you're likely to invalidate your policy.

not where I live...not USA

Well . . found a donor engine/ecu for internals so that I can still use my cases to keep my engine legit here . . .some work will be done to said internals . . .

updates as they happen

 [thumbsup] [popcorn] Cool. Looking forward to hearing how she goes.

while I wait for engine tool to remobe engine and have mobility . . . I will study "how to" tune the ECU with different softwares and "butt-dyno" . . .

Into that subject, any if the techs in this thread could recommend a "good NOT expensivo" dyno with pros and cons . . . it would be a great help, maybe I could become "that guy" and get more business by attracting other shops and maybe purchase a tunning software or 2

Maybe a used dynojet dyno?

I'm looking . . . remember, is just NOT the price of the equipment but, the shipping and import duties

Check with the vet on used Dyno Jet equipment. He's experienced.

wished I could send him my bike . . .

How's it going mate?

Swapping the 800 in place of the 620 was the single best hp gain I got. I spent less than $1/cc for it. Took a day to swap in. And I've put almost 80k on it since.

What compression ratio would I attain if I used the FBF 12:1 750 pistons with 800 cylinders and  620 heads ? The reason I ask is FBF are currently out of 88mm 11:1 pistons that would give me 12:1 in a 620.

I'm not capable of giving you that number, but it will likely be high enough that you'd need race gas.

If this is a track only bike that's fine, but are you going to carry 5 gallon pails of fuel?

As it is, 12:1 might be tough with pump gas.

Due to the longer stroke 800 crank, the piston pins are located closer to the tops of the pistons than 750 pistons.  Therefore, if you were to attempt this, you'd have to space up your barrels away from the engine case which may cause the intake manifolds and exhaust header not to fit right.  Even if it did fit right with barrel spacers, I'm w/DP on this one: too much CR yields the need for racing fuel or additives and that's always a pain.

I was gonna say that same thing Duck-Stew

What OEM ducati pistons could I use in place of the Ferraccis

bore is 80mm in the 620 . . . 750/695/969/796 are 88mm . . so you would need to bore and re-nickasil the cylinders . . .

best bet, get an 695/800 engine and ECU or reflash your ECU to 695/800 DP Map . . . as someone said, since these ECUs are Magneti Marelli and most compatible with your actual wiring harness

http://www.ebay.com/itm/Engine-motor-17-k-miles-Ducati-Monster-800-03-F6-/111986593492?hash=item1a12ebced4:g:HCUAAOSw~OVWxmdl&vxp=mtr

http://www.ebay.com/itm/Ducati-Monster-S2R800-06-08-Engine-Motor-Video-Only-1-615-Miles-22521821A-/272275475387?hash=item3f64e20bbb:g:~GMAAOSwvg9XYcXX&vxp=mtr

http://www.ebay.com/itm/07-Ducati-Monster-S2R-800-ENGINE-MOTOR-11K-MILES-VIDEOS-INSIDE-/381221328527?hash=item58c28fd68f:g:UM0AAOSwBahU9f5m&vxp=mtr

http://www.ebay.com/itm/2005-DUCATI-800-DESMODUE-ENGINE-/401023127335?hash=item5d5ed74f27:g:Jx0AAOSw~bFWPADu&vxp=mtr

http://www.ebay.com/itm/06-DUCATI-MONSTER-S2R-800-Motor-Engine-/201653207459?hash=item2ef377c1a3:g:upsAAOSw9NdXvds8&vxp=mtr

That is not the path I want to take. I already own a set of 03 800 cylinders. All I would need is a set of pistons. The FBF 88mm 11:1 sets are suddenly unavailable, so I am looking for the right size Ducati pistons that would work.

if you have the cylinders you would need to "add" a head gasket in order to lower the comp and be streetable . . .

There is also this option, http://www.pistalracing.it/  and check the 796 option . . .

Wait. 

Hold the phone and all that. 

I thought somewhere in this thread you swapped the entire engine for an 800.  Am I wrong?  Do you still have a 620 which will be receiving the 88mm barrels?

If so, then yes.  Ferracci 750 pistons will work for you.  As far as the CR goes, I think the combustion chambers are roughly identical between the 750, 620, 695 and 800.  I could be wrong.  I've never measured.  I did, however, put a set of 11:1 pistons into an '01 M750 and topped it with 695 heads for a customer. 

THAT was a fun bike to ride!  Ran on premium pump fuel w/o issue from what I remember if that's any indication of compression ratio.

Another tid-bit:  The Ferracci 12:1 pistons can be machined into 11:1 pistons by having a shop cut the tops off of them.  I'm not sure if you want to do that or not, just thought I'd throw that into the mix as it were.

And while they are at it they may need to smooth the edges of the valve reliefs. A recent set of 12:1's I handled had very sharp edges on the valve cut outs that could cut your hand (literally). The blade like protrusions could make for great hot spots/glow plugs.

Would I be able to use 800 Ducati pistons that came with the 800 cylinders?

yes and you would have an 800 engine . .  just reflash the ECU to DP map . . .

Now you have me confused. I thought the 800 pistons have the same part # as the 750s. The stroke on a 620 is the same as a 750.

There's a bit of confusion about exactly what Poco has.
My understanding is it's a 620 motor he's starting with.

800 pistons will come up way short if they're used with a 620 crank.

695 pistons are tall.
750 pistons are medium, same height as 620.
800 pistons are short.

695 pistons and 800 pistons could likely be made to work with a 620 crank.
But at a minimum, there's quite a bit of fabrication and/or machine and/or special assembly work that would need to be done.

For example, 695 pistons could be made to fit with a base gasket/shim ~2.25mm thick.
That introduces possible issues with throttle body and exhaust fitment.
Requires re-indexing the cam to provide proper timing.
And may well not work at all due to the length of the cam belt.

Don't 750 and 800s both have the same part number? Therefore how can one piston be medium and the other short?

I personally went the way of getting an 800 engine and reflashing my ECU . . . project on hold since I need some legal documents in order to send the parts of my engine that have the engine # . . . but, indeed I am installing some mild HC pistons . . .

Now, as Speeddog says, could you tell us exactly what you have and what you want ??? This way we could help you better and easiest way is to get the 800 engine and if you want HC pistons then the link I gave you could be your best bet or any of the "Gurus" here might give you pointers of other choices

I own a 06 monster 620. I want to add a big bore kit to poke it out to 750. I so far aquirred a set of 03 800 cylinders of of Ebay, in the hopes I would be able to get FBF pistons item #F27510 11:1s. Therefore I would not have to rebore my stock 620 cylinders and replate. But guess what, Ferracci is all sold out of F27510s. Therefore I was trying to use a replacement ducati pistons as a replacement. I would love to know the piston part number of the ones included with the Ducati factory big bore kit that was intended for the 620.

No I did not swap the engine for an 800. I just purchased the CYLINDERS to an 800 off of ebay, so I would not have to spend more money reboring stock 620 cylinders than replating.

We own the same bike basically . . .   If I find my accesories catalog, I will send you the PN of the kit and a dealer might be able to get the PN you want/need . . .

For your cyls best bet now would be to get 800 heads . . . then down the road get the pistals or other brand hc pistons

I looked at the link you posted Darkmonster, but couldn't see any pistons for the 800, so am I dense, or are there ones from another bike that work? I thought the only hicomps for 800's were the long gone run of Mahle pistons and getting them done custom.

http://www.ducati-kaemna.com/catalog/ducati/88mm-pistal-hc-kolben-piston-796ccm-fuer-for-hyper-monster-scrambler.html

They list this one for 750 also... http://www.ducati-kaemna.com/catalog/ducati/88mm-pistal-hc-kolben-750-ccm-modelle.html

Don't know that it isn't the same set.

ETA...definitely a different piston. Skirt looks longer, and the pin looks like it's further from the piston crown.

Wow, this is dangerous. Thanks.

800 piston would have a shorter deck height, and hopefully larger valve reliefs.

I wrote to piatal and the 796 are a fit for the 803 . . . the 696 are NOT

It was thorn14 that made the swap.

So if Poco has a 620 bottom end, which pistons does he want?

I wanted the FBF item # F27510 88mm 11:1s that in a 620 head would give the bike 12:1, but ferracci has sold out of them,not expecting them maybe in spring. I was thinking of maybe the FBF item #F27511 these are 12:1 already, not knowing what ungodly compression ratio these would give in my 620 engine.So I am not sure that these would work.

I was asking the question regarding the Pistal product.

FBF pistons are J&E.

CCW had a contact for Mahle pistons iirc.

Maybe as a back up plan get the 12:1 FBF pistons and have them machined. The valve pockets will need a tidy up anyway. Having a pro set them up setting squish and machining them for piston to valve clearance is probably a good idea.
Some "drop in " pistons are not quite just a drop in propisition.

           Then in that case I could get away using the stock 750 Ducati pistons in place of the FBF88mm 11:1s ?

FBF or otherwise, you'll need 750cc 2V drop-in high comp pistons to make this work.

Yes, you can use the stock 750 Ducati pistons, and you'll get stock 750 Ducati compression ratio.