not sure what pipes to use on a 421 stroker

[gmctruck1976]

I am sure ill get a few different answers here but i need to ask any how. I am looking for a set up to run on my shee. I am running fmf now had them on the mainly stock setup and loved them with my single carb. had the the power where i wanted it. I just got the shee back together after after putting a stoker crank and big bore cylinders on her she runs good but hits in a wierd way now. and top end dies. what i mean by that is at around three quarter throttle theres like nothing. not sure if its the pipes or carb. Im not wanting to give up the single carb. yea ive got a set of 34s t0 put on it if need be but just not wanting to lose the bottom end ive got now its nice for where i ride. I am looking for something to exstend the power top end. the fatties just are not suited for the job. I know are some diffrent pipes on the market. im kinda looking for a coustum set for how i ride and what im looking for. any help would be nice

[rdzbangshee]

I am sure ill get a few different answers here but i need to ask any how. I am looking for a set up to run on my shee. I am running fmf now had them on the mainly stock setup and loved them with my single carb. had the the power where i wanted it. I just got the shee back together after after putting a stoker crank and big bore cylinders on her she runs good but hits in a wierd way now. and top end dies. what i mean by that is at around three quarter throttle theres like nothing. not sure if its the pipes or carb. Im not wanting to give up the single carb. yea ive got a set of 34s t0 put on it if need be but just not wanting to lose the bottom end ive got now its nice for where i ride. I am looking for something to exstend the power top end. the fatties just are not suited for the job. I know are some diffrent pipes on the market. im kinda looking for a coustum set for how i ride and what im looking for. any help would be nice

[GNR101]

ditch the single carb... on a 421.. thats just dumb

 

try the 34s.. if they dont have the bottom u want. go pwk28s?

[captainhowdie]

Is this a cub or vito's cylinder or what? I run 39pwk's on a 421 cub with inframe shearers.

[gmctruck1976]

It is the vito,s,big bores I have an update with this post. I actually got out on it for a good little ride today. I have just been breaking it in intill to today. Finally got a chance to really get on to the pipe. sure pulls like hell but its got a wierd kick to it. maybe you all can help with this. when it comes on to the pipe its sounds. damb near like its detonating. It starts pulling like hell and keeps pulling but sounds like its missing. im not sure what it is. cant tell if its timing, jetting or the pipe. Hell it may just be me not use to this setup. im just worried it is going to exsplode under me.

[J-Madd]

Check your plugs for signs of detonation (plugs backing out, burned strap, metal flakes on plug). Make sure the jetting is not lean. If those aren't the problems, it may just be revving past the limits of the pipe. Those pipes will restrict the rpms at which that motor can make power. Try some CPIs, Shearer's, or Vito's Fat Bastard pipes.

[MacRacer1]

cpi in or out of frame big bores

[papa_smurf49319]

Shearers!

[gmctruck1976]

thanks guys ill give the plugs a check. i thought the pipes may be a issue to they ran good on the stock engine didnt think about it on the stroker.

[firebanshee]

Fat Bastards, i loved mine.

[misterww225]

At greater than 3/4 throttle you are using the main jets. With a bigger engine, it will suck harder on that single carb and make it run rich (it will missfire and "burble"). At full power when an engine is under-carbureted it will tend to run rich, whereas an over-carbureted engine will tend to run lean. I would put on the 34's and "dial it in". Sure it's twice the work, but with the top-end power gain you will see it will be worth it.