open carbs versus airbox ??/

Twangled your powervalve grommit in your woodruff key? ask someone how to fix it here
Post Reply
pauliboy
Smoker
Posts: 65
Joined: Fri Feb 13, 2015 7:35 pm

open carbs versus airbox ??/

Post by pauliboy »

Hi, anyone done back to back tests running open carbs versus with an airbox ?
I am currently running PWK 35mm carbs with v force reeds into an airbox with a ram air tube feeding from below the headstock (above the radiator) into the airbox. I know open carbs = less engine life etc but thats how we always ran TZ350's and wondered what people's opinion's on this are ?
User avatar
JanBros
Avgas Sniffer
Posts: 3306
Joined: Wed Jul 26, 2006 11:50 pm
Location: the land of Francorchamps

Re: open carbs versus airbox ??/

Post by JanBros »

always better with airbox, but I wouldn't bother presurising it. if yours is built that way I'd drill some holes in the back to bleed of the presure.
why is it better ? most important is to get cool air in that's not heated by the engine, also less turbulent air.
My ultimate goal is to die young as late as possible !
Luders
Avgas Sniffer
Posts: 3926
Joined: Fri Jun 18, 2010 11:29 am
Location: Oxfordshire

Re: open carbs versus airbox ??/

Post by Luders »

The reason why TZ350's didn't run airboxes back in the day, is because people didn't know better back then. Even airboxes designed in the early 90 are considered crude by modern standards. So much more R&D went into designing airboxes to improve performance.

Just to echo what Jan has suggested, the key to a good setup is cool still air.
pauliboy
Smoker
Posts: 65
Joined: Fri Feb 13, 2015 7:35 pm

Re: open carbs versus airbox ??/

Post by pauliboy »

I won't argue with people who have superior knowledge to me on this subject but I like a healthy debate :)
Myself, my brother and a few others ran highly tuned YPVS's with the crmc a few seasons back and they also ran 'open' carbs (upgraded to 34mm or 38mm), they ran superb and generally gave around 68bhp at the rear wheel with a good spread of power. Some guy's even locked the power valves wide open arguing that they were only needed for road rider's and when racing these YPVS's the rev counter should never be below 7,500 rpm anyway, in other words ridden like a piston port TZ. What's people's opinions on this ?
Luders
Avgas Sniffer
Posts: 3926
Joined: Fri Jun 18, 2010 11:29 am
Location: Oxfordshire

Re: open carbs versus airbox ??/

Post by Luders »

Hmmm I suggest trying that out on a dyno is all I'm going to say.
User avatar
JanBros
Avgas Sniffer
Posts: 3306
Joined: Wed Jul 26, 2006 11:50 pm
Location: the land of Francorchamps

Re: open carbs versus airbox ??/

Post by JanBros »

they are correct. on track in the powerband, exhaust valves are unemployed.
My ultimate goal is to die young as late as possible !
Post Reply