Friday 1 March 2013

Engine stuff

Starts to get interesting here.
Continues to get more expensive here.

Problem attitude - Gone this far might as well put some good parts inside.

Whats this re-phase thing all about???? K Google helped me find my answer. Now my 40 lb crank has been shipped as far away from here as you can get, without falling into an ocean, crank is in Florida at Falicon. Whats it doing there you ask? Well children, it is getting re-phased to 276.923 degrees. Click the link if you don't get it.

Rephased

Shiny new!


So Falicon is replacing the rods, bearings and pins for us while they have it apart. They are going to weld it together re-phased then dynamically balance it for my new pistons and other reciprocating parts. These guys know what they're doing.


Some people cut apart the cam shaft and weld it back together for the re-phase. Megacycle will not cut it in half. They will grind it, weld it, then regrind it with bigger lumps in all the appropriate places.They'll even set me up with a slotted sprocket. Now the slotted sprocket is only for the 447 engines, but if you ask nicely and offer cash, they'll do it on the 256 sprockets as well. If you elect to not go with the slotted sprocket, the cam needs to be degreed by pressing the sprocket on and off the camshaft. Not a good plan at all.





Perfect work.



 Anyways now I have a beautiful new 250-30 cam to match my funny crank. Of course you need sparks to happen at the right time in this engine. So we acquired a Pamco ignition kit. obviously, the dual coil re-phased one.

Of course the cam needs something to lift. I was happy with the 1mm larger than stock valves and the 103Y spring kit with aluminum tops... but then someone mentioned 7mm valves... damn! WTF I need to stop listening. Anyways found a guy who would custom make me 7mm valve stemmed 2mm bigger diameter than stock intakes and 7mm valve stemmed stock diameter exhausts. He'd also make me new guides to fit the skinny stems, get us some kick ass springs and top it off with some cool titanium tops. He'd even throw in some seals and we'd be good to go. Soooooo.... after mulling it around and falling back on that previously mentioned adage, we've gone this far might as well ...


Mmmmmmmmmm Ti


Okay, following along here? So we now have 80mm pistons attached through new NOS rods and bearings on our re-phased dynamically balanced crank inside our 750cc cylinders. This is breathing through the 7mm stemmed, lighter, (wayyyy lighter), than stock valves, being lifted .440" up into the air by the re-phased cam pushing the new NOS rockers, sucking air and fuel through a beautiful set of RS Mikunis being lit by a kickass ignition... good right? Well good enough for some.




... But wait, the ports suck in these heads, and I mean suck. in a bad way, not the good way. The exhaust ports are way to big and horribly shaped with really bad core shift. Intakes are just about as bad and are horribly shaped. So I showed them to my friend Roger :). This is always a good idea. He can't stand crap, even less than I can. I shared with him some of the documentation I had dug up on XS flows and showed him the inserts available for "fixing" the exhaust ports. I gave him my new valves and guides and asked him to keep the bill reasonable. Well he ignored my request and fixed it his way. There is a lot of welding in those ports. The engineers over at Yamaha wouldn't recognize their own f--k'd up ports ever!

Roughed intake, no guide yet.


Welded and roughed exhaust, no guide here yet either.

Shrouding removed, seats roughed out.
Wish I had a picture of stock to show.


F--king nice ehh? Roger is impeccable as/usual.

So any guesses on what the little 650 turned 750 engine costs now? Don't forget the new clutch hub, plates, friction discs and springs. Don't forget the new transmission bearings. Don't forget the labour to bead blast all the cases and refinish them all with high temperature coatings. Don't forget the new timing chain and tensioners. Don't forget the $300 for the permanent magnet alternator so I can have some spark at low rpm when I kick it. You can forget the extensive welding, porting and valve seat/guide fitting work, Roger's paying for that :).

So how much?... 4k ish in the engine lets not add it up accurately K. Tracy has a computer and I don't think she really wants to know. One thing I'm leaving out of this so far is the freight. So far there is well over 2k of UPS/FedEx/USPS/Canada Post/Hong Kong Post/Royal Mail charges. Being on the west coast of Canada, and having to bring it all here, sometimes there then here a la crank and cam, adds up, big time.


New rockers good to go. Have to take care of those pretty cam lobes.


1 comment:

  1. I would have to think that the tall domes could cost some power, are the 256 rods longer than the 443s , I think the 533s ((Europe only and have bigger journals). Would allow a shorter dome. Mixture motion and around 9.5 to 10:1 would be good. Are you using an XS2 case? The stock cam is a very good cam. The EPA made Yamaha change the cam for 73 and it essentially neutered the cam. I had an XS2 and it would run away from any other 650 . I wish I had it now. I would love to rephase an XS2, clean up the ports like I did on my 83 which is quite similar to what you did 7mm stems 1.78 intakes and 1.5 exhausts with a squish band to push mixture into the plug crevice. So much fun, but I wish I could have had an XS2 cam.

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