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Should I Upgrade?

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I have the Yoshi 450 Big Bore and Stroker "kit" which includes their cams and trc exhaust. I kept the stock carb and jetted it and it runs great. I really like the torque in the mid range. It really pulls out of corners. I do 20 minutes of highway commuting a day and the rest is spirited backroad twisties.

Would a frc39 keep that torque but give more top end too? A 41 would just be for more top end or more displacement? I don't really want the mid range to change too much. Im not sure about dropping more cash on it unless it is really recommended.

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I have the Yoshi 450 Big Bore and Stroker "kit" which includes their cams and trc exhaust. I kept the stock carb and jetted it and it runs great. I really like the torque in the mid range. It really pulls out of corners. I do 20 minutes of highway commuting a day and the rest is spirited backroad twisties.

Would a frc39 keep that torque but give more top end too? A 41 would just be for more top end or more displacement? I don't really want the mid range to change too much. Im not sure about dropping more cash on it unless it is really recommended.

 

Trust me, just drop the cash.  I recently purchased a FCR39 coming from the BSR36, 175mj - blue # 5 - 25pj - stock fuel screw - 2.875 turns out.  My mods on my 2002 DRZ400S are.....Stock piston - 11.3 to 1 compression - FMF Powre Bomb & Powre Core 4 (un corked) - Stage 1 Hot Cams - 3x3 - Twin Air.

 

And the Grand Finally winner is the FCR39 Slant.

 

160mj

200maj

100paj

EMM #3

45pj

Stock fuel screw

2 turns out

 

Improved power everywhere, it was the missing link to all my other mods.  More bottom-end, monster mid-range & impressive top-end (revs to the moon).  Off road is almost comparable to my CR500 (excellent).  And on the hi-way it's excellent too, it's not choppy like I've heard some people say.  Totaled about 2 hours of hi-way time yesterday and it was smooth as hell.  At times it was up hill & against the wind and it was barely noticable.  My concerns about buying this carb were similar to yours, bottom-end was my main concern but it turns out I couldn't ask for more bottom-end !

 

I hope this helps you spend your money.  :devil:

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So I guess the question really is 39 or 41? For the $30 difference is there a big difference? Is the jetting that come with it okay?

Edited by RyanSupermoto
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So I guess the question really is 39 or 41? For the $30 difference is there a big difference? Is the jetting that come with it okay?

 I know nothing about the 41.

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I would go for the 39 with the Yosh kit.

You will probably loose a lot of bottom/mid range and gain a small bit on top with the 41mm

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Are you running a stock head. Or +1 intake, port job?.

Stock head 39fcr would be my choice I'm considering going back to a 39mmfcr since I have being riding more off road.

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If you don't plan on porting the head and stroking the motor then go with a 39. If you do a search you see a dynograph with the two different sized carbs

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Trust me, just drop the cash.  I recently purchased a FCR39 coming from the BSR36, 175mj - blue # 5 - 25pj - stock fuel screw - 2.875 turns out.  My mods on my 2002 DRZ400S are.....Stock piston - 11.3 to 1 compression - FMF Powre Bomb & Powre Core 4 (un corked) - Stage 1 Hot Cams - 3x3 - Twin Air.

 

And the Grand Finally winner is the FCR39 Slant.

 

160mj

200maj

100paj

EMM #3

45pj

Stock fuel screw

2 turns out

 

Improved power everywhere, it was the missing link to all my other mods.  More bottom-end, monster mid-range & impressive top-end (revs to the moon).  Off road is almost comparable to my CR500 (excellent).  And on the hi-way it's excellent too, it's not choppy like I've heard some people say.  Totaled about 2 hours of hi-way time yesterday and it was smooth as hell.  At times it was up hill & against the wind and it was barely noticable.  My concerns about buying this carb were similar to yours, bottom-end was my main concern but it turns out I couldn't ask for more bottom-end !

 

I hope this helps you spend your money.  :devil:

Yeah .. I like what you are saying but ... " almost comparable " to a CR500® ??

I will say my CR500® will Destroy my DRZ , the 500 has me shaking and Trembling when I get off.

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The Yosh 450 kit is a +5 mm stroker crank and +2 mm bore.....

The yosh cams are very mild and are nothing to get excited about...

Depending on the type of riding your are doing I would be leaning towards a 41 fcr for mostly road use

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Yeah .. I like what you are saying but ... " almost comparable " to a CR500® ??

I will say my CR500® will Destroy my DRZ , the 500 has me shaking and Trembling when I get off.

 

Yup.....Thats why I said " almost comparable " I should have ellaberated a little more.  I meant from a torque prespective,  HP...No way.  And yeah, my hands used to tingle for like 10 minutes after riding my CR500.

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Long live the CR500R

+1 My last motard build was a CR500R, 87 engine in a late model 97 steel chassis, road legal, 115kg missile, 15/38 on 17" wheels with big brakes. Mine was smooth - very smooth, had better and smoother low down than most any new 4T motard, The CR5 engine has genuine GP heritage and can be lightening fast, the 87 engines were supposed to be 67.5hp, mine was bored 90mm had a new well sorted crank and sorted head/squish/compression etc with most of the rest of the engine in new condition as well, PWK carb and PC pipe, nothing special there but should have been ~75+ or - few hp, had similar suspension wheels and braking to my 08 SM, the DRZ is a way better long distance bike but not to be confused with the CR500 2T which really is more similar in capability to a 1000cc twin 4T yet lighter than them as well - yes indeed long live the CR500R ! but for longer distance road/back road the DRZ is very cool and mods only make it better !

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The FCR is worth the money,  it pulls much harder and faster with it. 

 

 

Yup, best mod I ever did. It made the throttle and the rear wheel feel directly connected.

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The yosh cams are very mild and are nothing to get excited about...

 

 What is the profile of the Yoshi cams? 

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 What is the profile of the Yoshi cams? 

 

Yoshi..... IN.. 9mm lift 236 dur...... EX ...9.3mm lift 242 dur

Edited by Craigo 485sm

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