Carbs

[traveller]

sorry about the confusion on the venturi thing, I should have said what size carb should be used on an engine with these mods. And it's an 88 ci. carb mods is a yost power tube, 200 size main jet, plastic slide drilled out, 45 slow jet.

 

[Jack Klarich]

You can polish the throat and radius the bottom of the slide for better flow, in the early days the CV carb was dismissed as a piece of junk, now they are much sought after and very tuneable

 

[dolt]

sorry about the confusion on the venturi thing, I should have said what size carb should be used on an engine with these mods. And it's an 88 ci. carb mods is a yost power tube, 200 size main jet, plastic slide drilled out, 45 slow jet.

Your OP indicated that your current carb is a 42mm CV? If that is correct, you don't need any more carburetor. IMHO, the motor work that has been done will really come to life with more displacement and a good set of ported heads. The 42mm CV will accommodate more displacement and head work.

I got fast fingers in my previous post wherein I stated a 42mm CV would accommodate displacement up to 110"; should have been 44mm. IMHO, when displacement exceeds 103", it's time to go to a 44mm CV which might be a bit more than is required at 103" but a 42mm might be marginal. That is assuming cams, exhaust, heads, compression, etc. have all been upgraded for performance as well.

You are holding back the performance you have on tap with 88" and heads that don't flow. Also not sure of the benefit of the Yost carb stuff. I am running Yost needle and emulsion tube in a 44mm CV in my all bore 107" motor right now (120TQ/105HP; pipes are hurting my HP) and I will revert to the OEM emulsion tube and needle and put her back on a dyno this Saturday for a back to back comparison of the Yost components vs the OEM components. I think the OEM components will make the same power that the Yost components make but with better fuel economy; we shall see.:s

Bore to 95"/98" and get those heads ported and it will be a different bike. The rest of the build looks good; it's just being strangled by small displacement and heads that don't flow.:hii

 

[Bodeen]

Your OP indicated that your current carb is a 42mm CV? If that is correct, you don't need any more carburetor. IMHO, the motor work that has been done will really come to life with more displacement and a good set of ported heads. The 42mm CV will accommodate more displacement and head work.

I got fast fingers in my previous post wherein I stated a 42mm CV would accommodate displacement up to 110"; should have been 44mm. IMHO, when displacement exceeds 103", it's time to go to a 44mm CV which might be a bit more than is required at 103" but a 42mm might be marginal. That is assuming cams, exhaust, heads, compression, etc. have all been upgraded for performance as well.

You are holding back the performance you have on tap with 88" and heads that don't flow. Also not sure of the benefit of the Yost carb stuff. I am running Yost needle and emulsion tube in a 44mm CV in my all bore 107" motor right now (120TQ/105HP; pipes are hurting my HP) and I will revert to the OEM emulsion tube and needle and put her back on a dyno this Saturday for a back to back comparison of the Yost components vs the OEM components. I think the OEM components will make the same power that the Yost components make but with better fuel economy; we shall see.:s

Bore to 95"/98" and get those heads ported and it will be a different bike. The rest of the build looks good; it's just being strangled by small displacement and heads that don't flow.:hii

Post the difference between the Yost and stock emulsion tubes, please!

 

[dolt]

Post the difference between the Yost and stock emulsion tubes, please!

I will. Plan to do it this weekend but it looks like rain and I want the comparisons to be similar and high vs low humidity will make a difference. I will get it done and post the difference when I do; just not sure if this weekend will be when I do it.:hii