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37mm valves/porting with only a RS2, bigbore & FCR?

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Hi Folks,

First time poster here but ive been lurking for a while. I just bought a brand new DRZ400SM and already got under 1500miles on it. These little thumper are in fact a lot of fun! Ive already done the 3x3 mod, FCR-MX & RS2 and its just awesome. But, just like many peoples, im never completly satisfied and im constantly on a quest for more. Ive been looking to get the Athena BB plus some head works like 37mm IN valves and a good porting. Might get the 41mm FCR as well if necessary. Will the OS valves and porting be useless with this setup? Im not ready for the stroker as i dont want to open the crankcase yet. Will a 450cc 12:1 ratio with maybe a 41mm carb will be enough to get the advantage of 37mm valves & porting?

thank you!

Jonathan

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Not money well spent.

To make use of a big valve ported head, it needs to be stroked, it must have a FCR 41 and it really needs the flow ability of the Yosh Ti.

To put a ported big valve head on your current setup with a big bore would see no gains.

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ok I went back to read your furst post

you have the FCR carb with good pipe but your runing stock SM cams

I would say to get a set of hot cams ( easy to install ) to see how you would like that

have you priced out a head worked over from RHC ( the price may help you decide to not upgrade to bigger valves )

ON MY SM I plan ( need money furst ) to stick with the stock crank too but will be adding the BBkit 435cc , hot cams . RHC stock size valves and other goodys he offers , with 39mm FCR

if I'm not happy with that than I need a hypermoto lol

I'm happy with the stok cc's with E cams

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Last year, I sent two heads to RHC. One to get the RHC valves, springs and retainers done. The other head was ported with the big valves, Ron's neato valve seats. I have a big bore stroker engine. I have the Yosh Ti I have teh RHC 187 cams. I did not install the ported head with the big valves. Nothing to gain from it until I have a carb appropriately sized.

Think of it this way. You have only an Ipod to listen to MP3's on. Would you buy $20,000 speakers to connect to it?

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your talking a $1200 (valves,springs,the correct cams and porting labor) cylinder head if you supply the head.

is this a street bike?

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your talking a $1200 (valves,springs,the correct cams and porting labor) cylinder head if you supply the head.

is this a street bike?

Yup SM. I already ordered the valves and got stage 1 Hotcam IN & EX. Ill be doing the porting and valves job by a drag bike shop near my area. They have the Dynojet dyno and are a well known machine shop. 500$ of parts and 350$ of labour. If its going to up the power by 3 or 4 hp in the end, i think it well worth it! :)

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hotcams wont get it done.

its not gonna make 3-4hp more.

you have to understand that in that thread you referenced we are talking about the 470cc big bore and stroke motors.completely different than what you have.

good luck.

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Ive just reread the entire thread...

jparacing made a list of all the mods he currently have and and you gave him an 3-4hp estimated gain with the head works... http://www.thumpertalk.com/forum/showthread.php?p=6690282#post6690282 :) im kinda confused as how it wont add anything to a big bore / not stroked engine. If i swap the hotcam for the ones that RHC made, will it be enough?

thank you!

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i have made 55hp on a stock cylinder head.

the stock head flows fine for your motor set up.if the head flow is already sufficient making it better wont really help.make sense?

it is very very hard to make a drz head better.

it not like doing a "drag bike" head.

if they go in and just start hogging it out it will most definately be worse.

the stock drz ex port especially is already too big.

just trying to help you not waste your money.i have a feeling though that you will just go ahead any way,so im not going to waste to much time on it.

if you are going to use the hotcams and or a 39mm fcr you are wasting your time.

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well, i think you just convinced me to keep stock sizing valves. will save the 37mm for later. will stage 1 cams be good for a 450cc or there just garbage? should i switch the 39FCR for a 41mm?

jonathan

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the 39mm fcr,hotcams and a 94mm big bore kit (no steel sleeves) is a very good package that can make 50hp with a yosh ti pipe and open muffler.

i build that package for alot people and they are always happy.

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Eddie would you upgrade the stock valves / springs / retaners whin runing the HOTcams ??? even thow your still runing stock sized valves ???

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no,thats not what i said.

i said "i have made 55hp on a stock head".took some special stuff to do it but the head was stock.

my point was the stock head is fully capable of supporting a big bore only motor.

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