28 or 32 carbs

[roboz]

I am ready to purchase some new carbs for my shee, i have dune port,coolhead 18cc,vforce reeds, no airbox. +4 timing,stock bore and pro circuit pipes. What size would you recommend? i am leaning towards the 30mm ones that are on ebay occasionaly. or would i be better off going to say a 32 mm or down to the keihen 28's.

Edited January 26, 2009 by roboz

[elwilliams13]

I got the 30's and they work great for me. Most people will tell you to use 35's with a dune port. 32 will be in the middle. 28 is not much over stock and are used when you want to keep some bottom end, Those pro circuit put out some good bottom end also. Some CPI or shearer pipes will also really wake up that dune ported motor.

[locogato11283]

do you plan on upgrading to a 4mm at some point? if so, i would go with 33mm pwk.

 

no real sense in going from 26mm stock carbs to 28mm.. waste of money really. i would go for the bigger carbs if youre planning on doing a stroker on down the road..

 

otherwise, the 30's would be your best bet.

[roboz]

I have been thinking about a 4mil but not sure if i can afford it right now.i would have to send it back in a get porting for the 4mil if possible on my already ported motor. If i do go to a 32 or 33 carb how will that effect the bottom end? I do dunes 95% of the time and the occasianal drag racing. Sounds like i might want the 33 just in case i do the 4mil. So confusing....Thanks guys for the responses.

[Snopczynski]

if your going to continue to run those pipes I would go with the 28mm carbs. Redline on those pipes is not up where you could fully utilize a carb much bigger than that.

[roboz]

Thanks, i have been doing a little research on here and it sounds like i may want to try some CPI pipes and maybe do the 4mil later in the year. So i may go with a little bigger carb like the 32mm.

[elwilliams13]

Yeah the CPI and the big carbs with a 4mil would work well if you ride mostly dunes.

[roboz]

Does anyone know anything about the mikuni flatsides in 32mm, found a pretty good deal on a set of those. or the pj34 i believe they are a round slide.

Thanks again

[blaster2006]

Does anyone know anything about the mikuni flatsides in 32mm, found a pretty good deal on a set of those. or the pj34 i believe they are a round slide.

Thanks again

 

hmm. my really old mate of mine, had a banshee, with the normal ol pipe, reeds, filter mods. He ran 30mm carbs and it was fine he told me, he couldnt compare it with 26mm, as he put them on with the mods, but he said it ran great no problems.

 

go with 32s id say . if you can get 30s, then why not. but between 28mm and 32, fo sho get 32's, and those pro circuit pipes of yours will compensate for the bottom end loss

 

32s sound perfect to me, for later if you plan on getting a stroker like others said.

 

thats just my opinion tho

[Snopczynski]

hmm. my really old mate of mine, had a banshee, with the normal ol pipe, reeds, filter mods. He ran 30mm carbs and it was fine he told me, he couldnt compare it with 26mm, as he put them on with the mods, but he said it ran great no problems.

 

go with 32s id say . if you can get 30s, then why not. but between 28mm and 32, fo sho get 32's, and those pro circuit pipes of yours will compensate for the bottom end loss

 

32s sound perfect to me, for later if you plan on getting a stroker like others said.

 

thats just my opinion tho

 

the pro circuits will not compensate for a bottom end loss. Your intake velocity will be reduced, which will reduce the amount of bottom end the motor makes. The biggest thing is, you usually use a bigger carb, the higher the motor revs. If your redline remains low, like 9,000 rpm (pro circuits), then your motor will not fully utilize a big set of carbs. So not only have you reduce the low end power, you have not fully utilized the carb to its full potential. He stated he was going to change the pipes, so that will warrant the use of bigger carbs. However, the power curve a set of cpi pipes makes is ALOT different than the pro circuits. So be prepared for that.

 

Which mikuni carbs? Flatslides, rounds? TM, VM, TMX?

 

I run a set of Mikuni TM 28mm carbs, but I also like the Lectrons.

[shanYE west]

I think the 28 pwks are the best all around carb for the smaller builds IMO.. Carry the higher RPM well and still keep velocity up to maintain the bottom end. I always like them on my dune/trail motors.

[deckheight]

With your mods I would be looking at 33mm PWK's :biggrin: So far they have been pretty user friendly on 350's with 100 octane and above type compressions. Plenty of signal, all circuits dial right in and meter fuel consistently through out the rpm range. They also seem to hold their tune real well under moderate RAD changes. Have not tried them yet with lower compressions, not sure how that would work out... Might not???

That would be my next move with your set-up anyway... For what it's worth.

[roboz]

the pro circuits will not compensate for a bottom end loss. Your intake velocity will be reduced, which will reduce the amount of bottom end the motor makes. The biggest thing is, you usually use a bigger carb, the higher the motor revs. If your redline remains low, like 9,000 rpm (pro circuits), then your motor will not fully utilize a big set of carbs. So not only have you reduce the low end power, you have not fully utilized the carb to its full potential. He stated he was going to change the pipes, so that will warrant the use of bigger carbs. However, the power curve a set of cpi pipes makes is ALOT different than the pro circuits. So be prepared for that.

 

Which mikuni carbs? Flatslides, rounds? TM, VM, TMX?

 

I run a set of Mikuni TM 28mm carbs, but I also like the Lectrons.

 

 

Not sure which ones they are heres a link.

http://www.bansheedepot.com/proddetail.asp?prod=22%2D5728

[Snopczynski]

Not sure which ones they are heres a link.

http://www.bansheedepot.com/proddetail.asp?prod=22%2D5728

 

Its a TM. You have to make sure they have the correct slide cutout, needles, pilots, needle/seat, siphon tube, and your gonna have to get the mains close of course.

[roboz]

Thanks for all the info Snopczynski.