Which Carb to use on modded bike?

[golfandcars]

Hello Gentlemen its been a long time since I posted on here but anyways planning a big ride in a few weeks and trying to get my bike in tip top shape.

I have a dilemma on my hands however with a couple choices in Carbs. First off let me give you my current set up. My bike was mostly stock but last year I purchased my brothers bike with alot of interesting parts and put all the good stuff on my bike.

My current set up:

-Open air box
-Gas mixed 32:1
-Graydon Pipe (i think, it is a right bend of some kind and came with a graydon silencer so im assuming they match)
-Standard bore with Wiseco piston and some light porting I think. When by brother bought the bike the motor was in pieces and the jug had been bored to the max. So he sent the Jug to Ken and had a new sleeve pressed in and bored/honed. While Ken had the jug he said he cleaned up some of the porting and said it looked fine but I dont think its any kind of crazy port job just some cleaning up of the casting marks and such.

Now on to my real question:

I am currently running the 38mm (i think) Keihin PWK that came off my brothers bike. He had it setup well and the stock carb cap from my bike was stripped so I just opted to use it instead of mine and never really thought anything of it.

After some reading around I am not sure that my motor has enough done to it (porting, head mod) to require such a large carb and Im wondering if I might be better served to go back to the stock carb.

Currently the thing runs very well, but as you can probably imagine it is very happy on the top end and lacks in the lower end. I dont particularly mind this but i would like to have a bit more linear power.

From wat I have read and seen on here, unless the port work is more extensive than I am giving it credit for, I might lose a tiny bit in the top but could possibly achieve more power down low.

Id like to hear some input from some of the experts on this site whether Im thinking in the right direction or whether i should just leave this thing alone and ride the hell out of it. Also I just ordered the TORS eliminator kit for the Stock carb and i have a large assortment of jets for both carbs. So getting either one set up is not an issue. I just wanna know what you guys think about switching carbs and the effect on performance it could have?

Thanks in advance for any advice this forum has taught me so much. It has really been a huge help.

 

[motoman159]

It all depends on what kind of riding you do. I run a heavily ported stock stroke with a head mod and I run a 30mm. Over all power is great. You can set them up alot of ways. Stock airbox, smallerish carb, heavy porting, top end power pipe = hard pull all the way through.

 

[98blaster]

I have a stock stroke stock bore engine with heavy porting an head work, vf 4 reeds, an Toomey pipe an silencer, im running one of the original cpw oko 30mm carbs an its perfect, but ive heard the oko carbs have went down hill on quality, if i was doing it all again now,id be buying a pwk 28mm, an maybe have it opened to 30, after all the oko 30 starts life as a pwk 28 clone an the bore it to 30, you can see the marks from them boring it in the carb

 

[Wifesblaster]

A stock carb will be fine for your set up. I would not go any bigger than a 28mm. I run a 38mm carb, but I have a lot of motor work. If the carb is an air striker I am interested in buying it. Let me know.

 

[woodrow wilson]

I'd jet the stock carb for your mods!! Your pwk38 is it an airstriker or just pwk?

 

[jus_me]

If you don't mind spending the $ on buying a new carb you could go down a bit to gain some bottom end.. But you will most likely lose some top end. Have you tried a reed spacer?

 

[golfandcars]

The PWK is not an Airstriker just a standard PWK. All of your responses are basically wat I had in my head already. I think I will try the stock carb and see how it does. Hopefully it wont kill the top end to much cuz when it comes on the pipe it is freakin wicked. Also on the reed spacer question I have not tried that but it isnt really my goal to move the powerband as I like it Peaky its just i think i could benefit from a smaller carb as my engine isnt creating enough air velocity to utilize the PWK in the low end and im not even sure its fully utilizing it in the top end but i could be wrong there.

 

[Blaaster]

With the stock 26mm carb your motor will be very, very happy, you should loose nothing.

You will however regain the bottom end, large bore carbs are good fo engines that draw a lot of air, but poor for the stock setup.

 

[golfandcars]

Ya im gonna give it a try I already ordered the TORS delete kit anyway so its worth a shot. Now I just gotta hope that my assortment of jets is large enough I ordered a bunch of them but I dont remember which ones. I also gotta test for air leaks I hadnt done it in a while its due for it.

 

[Blaaster]

Leak testing should be done at least twice a season.