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sprocket suggestions? 480 BB...

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hey new to TT, I bought a 2005 SM with a cylinder works 480 big bore and a full FMF power core 4... I did the 3x3 .. gave it a 30 pilot jet (from 22.5) and a 148 main ( from a 134.5).. anyway i wanna change the gearing i get about 95 on the speedo (aka the dream meter).. its effortless to get there, im sure there is more to the little monster than that it has the stock geraing witha 15 tooth on the front and a 41 tooth on the rear. I am new to this so am unsure how to select a good set up for the sprocket size.. if anyone has any input it will be greatly appriciated!

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hey new to TT, I bought a 2005 SM with a cylinder works 480 big bore and a full FMF power core 4... I did the 3x3 .. gave it a 30 pilot jet (from 22.5) and a 148 main ( from a 134.5).. anyway i wanna change the gearing i get about 95 on the speedo (aka the dream meter).. its effortless to get there, im sure there is more to the little monster than that it has the stock geraing witha 15 tooth on the front and a 41 tooth on the rear. I am new to this so am unsure how to select a good set up for the sprocket size.. if anyone has any input it will be greatly appriciated!

Cylinder Works 480 big bore??? you sure ??... maybe it's a 434 big bore or 480 stroker/big bore....???

Try a 38 or 39T rear if its feeling short in the gearing...

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Cylinder Works does not make a 480cc bigbore, in cylinder alone.

Though Hot Cams / Hot Rods / Cylinder Works (all the same parent company) do make a 4mm stroker crank and 94mm Bigbore… Is that the combo you have?

Huge difference in power available to drive a given gear ration between just the 94mm BB and the 94mm BB and 4mm Stroker crank combo.

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If that is a stroker and your feeding it with the stock paperweight....there is a potential for some big power gains....

I am interested to know your setup ...i.e. What carb, cams, valves ,altitude ,etc...

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yes its also a stroked... forgot that.... 4mm hot rod stroker crank i believe.. with a 93.5mm bore.

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If that is a stroker and your feeding it with the stock paperweight....there is a potential for some big power gains....

I am interested to know your setup ...i.e. What carb, cams, valves ,altitude ,etc...

thanks for the replys everyone!

yes i have the stock mikuni, as for the paper weight? i dont get the term...

heres the set up i have, craigodrz400sm, stock sprockets... 480 stroker/bb and its a 94mm not 93.5mm bore, sorry, the altitude i am in in between 750ft and 1100ft above sea level most the time i ride, stock factory cams, and valve size, rear tire 150/60/zr17, 3x3 mod. and i checked the main jet today its a 145... stock plug...

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4mm stroker crank plus 4mm overbore to 94mm gives a displacement of 462cc,not 480,if you are running standard cams and the cv carb the increase in engine size is a waste,as you will never get any real power out if it,and indeed may have reliability issues regarding head gasket life .... you really need some suitable cams and a better carb,fcr41 being the ideal choice

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thanks for the replys everyone!

yes i have the stock mikuni, as for the paper weight? i dont get the term...

the Mikuni BSR36 carb is what they are referring to. With is smaller throat (36mm) and the choke butterfly in the ari stream, they flow less then optimum for a Big bore stroker. Add in the slower throttle response of the vacuum operated slide,, and you have a carb that can work, but not as well, nor will it produce as much HP as a properly set up FCR 39 or 41 carb.

480 stroker/bb and its a 94mm not 93.5mm bore,

66.6 stroke (92.6 OEM plus 4mm stroker) x 94mm bore (90mm OEM plus 4mm larger bore) = 462.4cc

sorry, the altitude i am in in between 750ft and 1100ft above sea level most the time i ride, stock factory cams, and valve size, rear tire 150/60/zr17, 3x3 mod. and i checked the main jet today its a 145... stock plug...

With the BSR carb and OEM cams,, Im going to say, 15/38 is about all your going to be able to pull in 5th gear reasonable. You could go 16/38.. but it's going to be sluggish in 5th gear.. if it pulls at all to red line.

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Hmmm... i was told by the shop that put the BB/Stroker in that it was a 480 is there any way to tell what it is for sure?

i bought the bike with a blown head gasket when i bought it is the smaller carb the issue for that? because i couldnt find a reason for it being bad,

i have the 2005 sm.. do i need the frc with the tps, or hot start? there is an electrical plug on the mikuni now...? thanks!

Edited by pntfrk
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the Mikuni BSR36 carb is what they are referring to. With is smaller throat (36mm) and the choke butterfly in the ari stream, they flow less then optimum for a Big bore stroker. Add in the slower throttle response of the vacuum operated slide,, and you have a carb that can work, but not as well, nor will it produce as much HP as a properly set up FCR 39 or 41 carb.

66.6 stroke (92.6 OEM plus 4mm stroker) x 94mm bore (90mm OEM plus 4mm larger bore) = 462.4cc

With the BSR carb and OEM cams,, Im going to say, 15/38 is about all your going to be able to pull in 5th gear reasonable. You could go 16/38.. but it's going to be sluggish in 5th gear.. if it pulls at all to red line.

and if i get the fcr 41? with i was thinking hotcam intake and E cam exhaust?

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Without stripping and measuring the bore and stroke exactly your not going to know,for sure what's in there,won't be a 480 as to my knowledge no kit was ever around to get to that size,if there is a thin spacer plate below the barrel you may have a 470 kit,but more than likely its the previously described 462cc kit,the note that you got the bike with a blown head gasket is very telling,and if indeed it does have the stock drz cams fitted then that's the source of that issue,and no hotcams and E spec cams won't cure it either,the carb will only cause low power problems you really need a fcr41 and a very free breathing exhaust to maximize the displacement increase ...... if its fitted that is.

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Its possible to get around the hotcams problem with pushing gaskets by lowering your compression and increasing the torque specs, if not RHC all the way.

good luck.

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thanks for the replys everyone!

yes i have the stock mikuni, as for the paper weight? i dont get the term...

heres the set up i have, craigodrz400sm, stock sprockets... 480 stroker/bb and its a 94mm not 93.5mm bore, sorry, the altitude i am in in between 750ft and 1100ft above sea level most the time i ride, stock factory cams, and valve size, rear tire 150/60/zr17, 3x3 mod. and i checked the main jet today its a 145... stock plug...

There is no way it's a 480cc with 93.5mm bore and 66.6mm stroke..Try 457cc...

Stock Carb,Cams and Valves??...You need the following if you want it to really go... a 41fcr, rhc 187 cams with rhc stage 2 valve spring kit and +1mm valves...

And an SSW/MRD..The FMF will run reasonable in the mid range but will limit your top end power,as with the stock valves..

So howzit run...It must be set up with low compression , other wise it would be pushing head gaskets......Got a jet kit in the mikuni?..

Edited by CraigoDRZ400sm

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.It must be set up with low compression , other wise it would be pushing head gaskets......

That would seem to be an issue......

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sorry it took so long to reply to this guys... just figured out how to use the web site :bonk: but it rus awsome! tons of torq she'll get to around 90mph then start breathing hard... im pretty sure its hight copression seeing as how its a flat top piston... im just an amature mecanic learing most of what i know from the clymer book and from u guys.... 😏

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im pretty sure its hight copression seeing as how its a flat top piston

Your doing fine, everybody started someplace..

"flat top piston" No such animal… for this motor.

A flat top piston for this motor would be LOWER compression.. the piston for this bike has valve relieves, so the deck height can be HIGHER,,more stroke, more compression.. a “Flat Top” piston would be the opposite of all of that… and, to my knowledge one has never been made or used in a DRZ motor.

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