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rc
4fiddy Racer
Joined: 11 Jun 2007
Posts: 266
Location: west oz
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 Posted: Wed Oct 15, 2008 8:02 pm Post subject: YFZ 450 Stroker upgrade |
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Hi all just a few questions on yfz stroker cranks etc.
1. Do you have to run stainless valves or stock are fine.
2. Can a High comp piston be used.Heard that stock size only.
3. Will stock cams be okay too.
Plus any other helpfull info on this subject.My yfz 450 07 has done a full season and more and is in need of a freshen up.Just a thought at this stage.
Has anyone done this and what do they think.
Cheers |
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ReD HeaderZ
Roostin Away
Joined: 24 Jul 2006
Posts: 828
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| Posted: Wed Oct 15, 2008 8:22 pm Post subject: Basic info and call the guys who really know ! |
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Hi I have done a stroker kit for my Raptor 660 from a 660 to a 719cc 4mm stroker.
This is a very overall view for normal stroker motors, full race/drag engines can get bigger then these options.
1. Do you have to run stainless valves or stock are fine.
If you upgrade the cam to a stage 2 yes you need better valves from what I have been told in the past.
2. Can a High comp piston be used.Heard that stock size only.
Depending upon the stroker crank you get ? There are lots of options.
3. Will stock cams be okay too.
Stock cam will work but it depends if you want more punch or a longer power curve or more top end power. You can buy stage 1 very punchy down low, stage 2 power in the mid range or stage three cams more power up top end for long straights etc.
I suggest you pm roots racing or explosive racing for more detailed information or go to their websites take a look and call them.
They can make that YFZ as fast as you like rc.
http://explosiveracing.com.au
http://www.rootsracing.com.au |
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Hudson
4fiddy Racer
Joined: 12 Feb 2006
Posts: 287
Location: This Week... Back in Texas
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| Posted: Thu Oct 16, 2008 4:31 am Post subject: |
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All depends on budget. My recommendation for head porting would be Rams Head Service in Windsor NSW. YFZ valves can be very expensive to replace (titanium) and when racing its recommended to change them yearly to prevent having a valve failure and destroying half the engine. I've seen it happen and it ain't pretty. Stainless are a cheaper alternative but also are heavier which will most likely result in the need for a stronger valve spring also.
As for stroker kits there are a few companies that offer anywhere from 470cc all the way to 565cc. I have previously built a 502cc that was more than enough to holeshot most races whether at the moto x, speedway or moving up the grid in super moto.
If the bike is for racing and racing only and you have already got the most out of the right suspension setup and can use the extra power without buzzing the tyres off of it than go the biggest you can afford but know that like the higher stressed the engine and the higher hp its making than the quicker it will wear out.
A few links for US companies that sell complete kits
http://www.maxpower-engines.com/index.php/atvs/yamaha/yfz-450.html
http://www.faliconcranks.com/bbk.html
I'm sure most racers will tell you though that a new set of tyres every race meet is equal to a bunch more power and depending on how many times you race a year can be cheaper too. It doesn't matter what the dyno sheet says if you're not getting traction
_________________
You Can Fix Alot Of Things In This World But...
You Can't Fix Stupid!!! |
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HSR
Blaster class
Joined: 11 Jun 2006
Posts: 122
Location: Melbourne
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| Posted: Thu Oct 16, 2008 6:59 pm Post subject: |
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Last paragraph of Hudsons post is without a doubt the best advice anyone could give to anyone else regarding what REALLY works and what doesn`t well said Hudson.
_________________
we do not stop racing because we grow old
we grow old because we stop racing |
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rc
4fiddy Racer
Joined: 11 Jun 2007
Posts: 266
Location: west oz
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| Posted: Thu Oct 16, 2008 9:45 pm Post subject: |
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thanks heaps guys. Yes have finished my first year of mx in perth and finished 1st in clubman.
i also have all the extras like LT elkas and a-arms axle etc.
But looking to keep the bike for one more year before upgrade.Thought a bit more power would be helpfull.Looking at a 3mm stroker so 470cc i think.
Would stock valves be ok budget is not great but just size up wether to or not.
cheers rick |
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Quad Squad
Blaster class
Joined: 05 Apr 2007
Posts: 193
Location: Melbourne
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| Posted: Fri Oct 17, 2008 5:21 am Post subject: |
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The stock valves will be fine, just make sure they are in servicable condition and have new springs fitted. Bigger valves in a 470cc arent justafiable for the cost.
Also, if you are planning on using the Hotrods +3, be prepared for regular piston replacements as the rod angle is very hard on the piston skirts.
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rc
4fiddy Racer
Joined: 11 Jun 2007
Posts: 266
Location: west oz
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| Posted: Fri Oct 17, 2008 5:54 pm Post subject: |
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| what one do you recomend. If its going to be better for the life of the piston.Do you think this will be a noticeable upgrade. |
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Quad Squad
Blaster class
Joined: 05 Apr 2007
Posts: 193
Location: Melbourne
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| Posted: Sat Oct 18, 2008 10:37 am Post subject: |
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| rc wrote: | | what one do you recomend. If its going to be better for the life of the piston.Do you think this will be a noticeable upgrade. |
There are lots of options for cranks and it comes down to the old saying "you get what you pay for"
Any long rod crank will be better for the life of the piston but you will need a custom piston with a raised pin height or a cylinder spacer. For MX its a bit overkill because the $$$ could be better spent in other areas.
Dont get me wrong, the HR +3 is good bang for buck, but because of the shorter rod it puts more side load on the piston.
At the end of the day you need to weigh up if the extra power is worth the extra work on the bike during the season.
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