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gregjet

Weisco hi comp pistons

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gregjet
Didn't know where to post this as we don't have an engine section and it doesn't seem to fit the tech categories.
Discovered Wiseco is making stock hi comp pistons for the Fz/MT 07. For Aussies IF the cyl can be bored out to the full size MT we finally have an affordable way of making our little ones the proper size.
12.5:1 comp ratio.
Straight dropin for racers if you are allowed to swap to hi comps.
 
 http://www.wiseco.com/PDFs/YamahaFZ07-4.pdf
 
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rowdy
Interesting... I wonder what other mods would be required to make that work. ECU flash? PCV?

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gregjet
To optimize the change would almost certainly need a reflash. Suspect ignition timing for a start. Possibly fuel maps would be different especially at bottom an top of rev range.
The Aussie LAMS 655cc one would need a substantial redo ( lower comp ratio , displacement and air flow as stock). I still haven't found out from anybody if our pistons and/or bores are coated. If the bores are coated I can rule out boring my 655cc one.

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markstertt
Indeed the bores are plated, these are probably the pistons Hord uses in his 88 hp fz-07. You have to pull the engine, split the cases and remove the crank to get these installed, plus run a diamond hone or perhaps ball hone thru the bores for the new rings. Hordpower has his own PVC map that is designed to still run 87 oct. with this set up, I believe this is the map that he has available for those running his airbox/filter kit & Yoshimura exhaust. He is also running a hotter intake cam to compliment the other mods.
 
If you're not in a big hurry, you might want to wait for a big bore kit since so much of the same work is involved as in just swapping the pistons, except of course for the boring and plating.
 
 

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markstertt
Hordpower is a vendor, you should check out his site, store and facebook for what's going on..if you haven't already. He also offers head work to go along with the pistons/cams etc. and is a really good guy to deal with.

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twotone
Indeed boring and plating the 655 is a big and expensive undertaking in OZ.
@gregjet contact weisco they can custom make a set of pistons for you @ ~$450 with higher crown etc, after which the 33cc disadvantage will hardly be noticeable.

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markstertt
Indeed boring and plating the 655 is a big and expensive undertaking in OZ. @gregjet contact weisco they can custom make a set of pistons for you @ ~$450 with higher crown etc, after which the 33cc disadvantage will hardly be noticeable.
Probably true but what about 90cc more  at around 742cc with 12.5-1? The  downside is the cost of the boring and replating once you've pulled the engine down or depending on where you live, where it has to be sent for this work. If cost was doable, I think what would worry me is having my top case half getting lost or damaged in shipping, now that would really suck. I'm looking forward to reading about some big bore FZ-07's, some dirt trackers must be into this already don't you think? 

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markstertt
Ok so I'm a little behind the power curve on these pistons, since first responding I decided to look a little further. First thing is you can go 3mm over to get 742cc according to what I found on spearsenterprises.com site. I found no mention of cost on boring/plating but you're going to have to be pretty serious to go big I think.

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gregjet
I would be a bit circumspect about boring the stock cyls on the 688 as it doesn't look like a lot of meat there. Really would need new cyl if it's a thin as it looks( like the kit made for DRZ's, cyls, pistons etc. unbolt/bolt up).
For me the easiest would be to get stock Yammy cyl ( the 688 instead of the Ausssie 655) and the Weisco pistons) and bolt it up to everyone elses' specs. That would be enough for me.
HOWEVER is the tracer 07 comes to Australia AND it is the full version , not the childrens' LAMS 655cc version, I may just go to it. Maybe my current )& won't be my last bike after all. 17litre tank is a big draw card. And most of my mods will go straight on to it.

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markstertt
There are no separate cylinders to replace (top case and cylinders are one pc., good for rigidity but poor for those who like to modify) and the bores are siamesed with no gaps between bores so you can only go so big, it looks like 742cc is about it and would probably be pretty nice boost with the increased compression. I haven't heard anyone comment on a stroker crank yet but that's always a possibility too.
 
Still, if you'd be happy with the 689 engine then that's all you need and with an airbox and ecu/pvc and exhaust it's pretty darn entertaining.
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norcal616
The stock airbox can go in favor of a HordPower airbox... It's a worthy bolt on performance in my opinion before I would start looking at bigger bore sizes and hi-comp slugs if I had the LAM edition FZ-07..I could feel the weight difference between the 2 airboxes with the HordPower airbox being way lighter... The intake tubes in the stock airbox are like using a crazy straw to draw air into motor ?

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gregjet
Norcal,
No fair! I was fine without a Hordpower airbox until you mentioned it was lighter. The weakpoint of a weight weinie.
Actually a stroker crank on this motor wouldn't appear to be such a bad thing, as the motor currently revs way higher than it's power peak and has a biggish dropoff, which is an effect of the cams. A stroker should give more power (torque) well within the current cam timing. Might just drop off a little faster. 5.4mm extra stroke would give 744cc but the comp ratio would end up a 12.3:1. That's is pretty much what the Weisco's would give. Not sure how the current valves would cope with the flow but I am guessing with the longer stroke they should be fine.
Pf you wanted to maintain std comp ratio you would have to remove about 2.5cc. Not a lot of meat on the piston to play with to drop the comp to stock, if you wanted to to.
 
I forgot the cyls were part of the case. Did know it , just forgot ( I am getting old). I hate it when they do that, but guess reasonable with a motor as a proper stressed member.

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stickshift
The Aussie LAMS 655cc one would need a substantial redo ( lower comp ratio , displacement and air flow as stock). I still haven't found out from anybody if our pistons and/or bores are coated. If the bores are coated I can rule out boring my 655cc one.
The LAMS version also uses a different camshaft to 689 cc version. 
There are quite a few used 689 models for sale around Aus, would make far more economical sense to sell yours (return it to stock first) and pay a little/no more and start with a full power model. Transferring all your good bits to it of course.
 
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gregjet
Not that desperate for more power, now I have it piped, inlet tubes, filter and reflash done. It's only a road bike so no real need for big power ( It only takes about 11HP to do 100kph).
But the new Tracer model, IF we get the proper one and not the stupid LAMS one, has other upgrades worth, having like a tank that you can actually get to the next city with, so I could go that way.

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norcal616
I went with the Hordpower airbox as the stock airbox hinders the mid up to red line rpms...we already put an aftermarket exhaust on, why not let it breathe in air better?
 
The Hordpower airbox is more noticeable if you spend majority of the time riding in the mid-upper rpms to redline in my opinion, it still feels like in using stock airbox in the lower rpms with no performance loss which is what Hordpower wanted to achieve... this is my fun bike to take to the drag strip or rip around on a nice warm Friday night...next year I will have to take a short 3hr ride to Hordpowers shop for a dyno session...
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norcal616
Look at what APmoto arts has for an intake system if you really wanna lose some weight ?...

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