Yamaha 660 what mods can be done

[basser23]

Wonk,too much !!!! I'll be working on my carbs this weekend,plan to have a few
brews ..I'll save the cans for future carb mods..
MSW: yep I believe the "gas flowing" is porting...most benefit to those that also
have better intake and exhaust..
Chip

[MSW]

yep I believe the "gas flowing" is porting...most benefit to those that also
have better intake and exhaust..

Ahh... Makes sense. I figured it was the same thing.

Question for the tuners: If you have your head ported/gas flowed, does that change the position of the intake and exhaust ports as well? I.e., would you then need to reposition the carbs/headers? Or is the port/gas flow work all internal? Or am I still misunderstanding the effect of porting/gas flowing?

BTW, I vote this for thread of the year.

[Wonkmeister]

OK...sorry guys (and Bill, just messin!)
Yes gas-flowing is port and polish, sorry bad terminology on my part!
When you P&P a head you create a smoother exit route for the gases to escape to your exhaust,in a simplified explanation. When you increase engine capacity, i.e over-bore 102mm bore gives you +26cc, 686cc, 105 gives +60cc thus 720, longstroke gives you +100cc thus 105LS=760cc. When you increase cubic capacity you are obviously creating more gases and a larger "smoother" escape route helps dissipate heat and gases to the exhaust manifold and out through your end can/s as efficiently as possible. Adding bigger carbs and jets, with a higher rate/load of fuel feed to the cylinder, obviously means the bike will rev harder and faster and in turn is creating more bhp/torque (also why you need a larger air filter to cope with bigger carb). Bigger headers/manifolds will obviously cope with higher gas volumes and help remove gases, as mentioned above. Bigger carbs are needed to help cope with your cc increase capabilities....in a roundabout way. Bill could probably explain it more "technically" than me!

Basically get the right mix and you end up with an engine running at optimal performance through-out the revs. You have to adjust things like the CDI rev limit, etc(remap) to compensate for the motors "improved" rev limit.

I think that's right...i'm no guru mate that's for sure...LMAO!

[basser23]

MSW,
Porting/Gas flow...internal smoothing and shaping to increase flow..no physical
port changes externally...minor port shaping to match intake and exhaust.Usually
done with an intake/exhaust gasket as a stencil to match the manifolds.
Think this is correct...Google cylinder head porting
Chip

[Wonkmeister]

Yeh, what you said! I'm trying, i hope what i said helps...


Sorry i'm a bit hyper today!

[CasterTroy]

BUMP for a kick-ass performance post

[bikeseamus]

VERY HELPFUL

A TDM cdi and some mild jetting is all I have done, and of course I have lost my tach as a result. I have a 2001 Traveller, and I remember years ago it was common knowledge which wire to disconnect when installing the TDM box to retain the electric tach reading.
..... But I have lost the information.
Anyone tell me?

Jimmy Connors (Bikeseamus) It is nice to look at it and have it FUNCTIONAL....though it certainly isn't VITAL for the mild (not WILD) way I drive my old sweetheart...... It is a Slow .....DANCER......

But it sure does DANCE on a sweet and tight two lane road... for hour after hour...

again..... Many Thanks bikeseamus

[alfredoenrique]

Hi bill...I think my wife is going to hate you because im pursuint the TM34-65 for my 2005 mz baghira....you seem to know alot so Ill bother you with the following questions:

1. Can you baby step me all the way in what I need to buy to change ALL my FRONT BRAKING SYSTEM...the stock one sucks ass!!! It has more them once caused me to go change my undies!!! I have ben riding Superbikes and moved to Costa Rica and bought an MZ before I left as it is perfect for here but braking is HORRIBLE!!!...It is the only one it the country and It gets all the looks, speceially since Im running the M4 can on it!!! Tell me what to purchase as I have asked before and no straigh forward response...i.e Caliper brand and size, disk, lines everything...Im not vere crafty in mechanics but I like to push my bike ridding...

2. What headers should I purchase to go with the M4 slip on?? I have the stock but they look crappy with the bike...

3. I want a wheely monster, what sprocket combination and spocket brand fit the baggy ??

Bro I appreciate your input...

thanks from a fellow rider..

fred

[alfredoenrique]

102mm oversize (686cc) - (WISECO or JE)
105mm oversize (720cc) - (JE)
105mm (88os pin) - Longstroke (760cc) - (JE)
Gas-flow head
Carrillo rod
Taller 1st gear and Lower 5th gear
Close ratio gearbox (Mega money but worth it if you can afford it-wheelie mayhem!)
Carb mods...well....BJ recommends budget so get yourself two coke cans, cut the ends out, shove some elastic bands in there-don't forget the cocktail sticks...VERY important, glue to an old biscuit tin, bash it into shape then clamp it onto your engine and you should be sorted! Otherwise choose from Keihins or...er.....yeh Keihins.
Cam-chain conversion
Stainless bolt kit
Oversize headers and a 2into2 system
Downdraught head can also be used on the SKORPION if you use Andy Drivers bodykit and airbox conversion. Fuel tank goes under seat! Tank becomes airbox.
Change rear swingarm too if you so desire, KR1s swingarms are favorable. Ther's also a very good friend of ours in the states that can help you out with a swingarm and a Titanium axel to fit.
R6 fork conversion...means more wheels available, you can also change swingarm to fit R6 or CBR 600 wheels.
Modified CDI (£90 from Slipstream) Allows engine to rev its nuts off...



I WANT THIS...WHERE CAN I BUY THIS..I WANT TO GO UP TO 760CC OR MORE IF POSSIBLE....I WANT TO FLY OF MY BEATCH WHEN I HAMMER IT....RIGHT NOW IT IS WAY FAR FROM THIS!!!

HELP!!! HELP!!! MY KAMIKAZEE SIDE WANTS HELP!!!

[aussiedroptop]

Bill where have you been. You are the answer to my prayers. Here in Australia I cannot find anyone with enough experience to confidently modify my Skorpion Sport Cup (there were only 10 imported to Australia and all were Audi Orange)
I will take your advice about the carbs. I have already modified the exhaust and fitted a Remus Revolution can from a 750 Kawasaki with 54mmid pipe size.
I will change back from a 14T countershaft sprocket and go with a 39 rear. will the ignition box you sugested provide 8000rpm (stock 6800) and work with 98RON unleaded fuel? and will the engine live/survive ? I think leaving the engine standard is the best for my requirements. I bought the bike new in 2002 and it only has 5500klms on it althought it has had 2 services and valve clearence checks.
Regards
Colin

[Bill Jurgenson]

I would definitely go for a larger chainwheel, 41 at least, 43 better. Unless you have gone to etensive tuning, the engine cannot pull the long OEM ratio (15/39) in 5th gear to the top.That means that with a sensible limiter allowing RPM over 8000, th bike is just as fast with 15/43 a it is with 15/39 but of course acceleration is vastly better.
Use a top quality chain like a DID 520 ERV3 or a RK GY520XO. If sensible, use a motorcross chain without seals as it uses even less HP. A runofthemill O- or X-ring chain such as those supplied with chain kits, uses up to 2HP all by itself and that is 2HP you don't have to waste on a cheap chain.


The Ignitech Sparker TCIP4 is fully programmable. You can set the ignition curve a you see fit and the limiter whereever you want.
here is an example of a curve I use:

here is another page from the SW where things like the limiter are set, here to 8400 'cause the owner wanted it that low.

I have mine set at 9000 in the SZR and rev the thing regularly to at least 8500 in the first three gears. The air-cooled 4-valve XT600 engine in my Skorpion doen't rev that high regardless. BOth teh XT600 and SRX had no limiter at all!What for?
This is the page with basic settings. Yamah XT600 is the nearest stored curve and necessary for the basic pckup data but it is otherwise meaningless.

I have no idea if there is an importeur for Ignitech in OZ. I can supply you with one programmed and ready to use plug and play if you want. If so contact me off list (email below, no PNs!)
BTW, Ignitech's rectifier ist worlds better than the DENSO part in the MZ as well. After several Densos and a "universal" (ha!) part, I can testify to the superiority of the czech part.
The SW runs in real time, so you can change settings while the engine is running. RPM are then shown and of course the red bar reading no connection is green.

You are wrong about the Denso box, tho. The limiter is fixed at 7200, regardless of what myths the tach may be telling.

[aussiedroptop]

Thanks for all the tips Bill. I will be in contact about the ignition kit. I've included a pic of my Sport Cup

[Bill Jurgenson]

It should be well known that if you want to remove the deco from the camshaft, you have to plug the end and both plunger holes in the camshaft or there will be less than no oil pressure.


This week I had a "stroke of genius" and can now modify the cam in about 15 minutes. I will do this for anyone for 20€ if they send me the camshaft.

BTW, the gear is that of the XT/SRX.

[Bill Jurgenson]

there were lots of questions and misinformation on the Skorpion forum which also touched on the necessity of other valve springs, so I will post my expanations here, too.
---------

the Kibblewhite retainers look like this



The retainers are very deep instead of flat like the originals to make room for longer springs. Longer springs mean a flatter force curve so the slightly stronger springs actually don't need much more force when completely depressed thant the OEM springs with the larger lift of the tuning cams.
The here discussed Megacycle 280-2 does not necessarily need other springs but cams with more lift do because the OEM springs block.
Die sind wesentlich tiefer als die OEM Teller um Platz fuer laengere Feder



The hole at the end is clear




but the two visible large holes for the deco plunger must also be closed. However the two small lubrication holes in the race at the left and left cam lob must be open.
Just plugging the end is not the trick and putting the deco shaft back in without the plunger does not close both of the large holes, one of which alone is several times larger than the oil pipe to the head.

As far as I know, there are no billet cams on the market for the XTZ/Raptor 660. All good sources (Megacycle, Kent, Grossewaechter) rework OEM cams so the deco thing has to be taken care of properly.
Hotcams may have a billet cam, but I would only use one of theirs for occasional jaunts to the icecream parlor. Definitely not for racing or long travels.

[aussiedroptop]

Why must you do this modification? Do you remove the decompression unit in your engines? Is there a problem with cam bearing lubrication?
Also will increasing the compression to 10.5:1with a new standard bore piston, make enough of an improvement (along with carburettors and cdi module) to warrant the work involved to fit it?
Regards
Colin