Pro design cool head question

[Ducman]

FYI, if you mesure the dome with the syringe, use rubbing alchohol. Water has more surface tension so you will get a miniscus (dome) of water and your measure will be as much as 1cc too much. If you measure your squish with the domes installed in the head on the motor and then with the domes out of the head this will tell you if you need to add or subtract cc's from you measure due to the piston going into the dome (positive or negative deck height). You can calculate this small volume like you would calc the volume of a cylinder. These were directions given to me by David Noss for determining the dome volume and I got very close to what he got when I sent the domes and squish measurements to him. If you dont take these differences into account you can be off by more than one cc on a regular motor or several on a stroker/longrod. Even an off the shelf dome marked 20cc could measure 19cc on one motor and 21 on another with the slight inaccuracies of the measurement method and differences in base gasket thicknesses, ect. This is probably why one guy blows his motor up on pump gas with 20cc domes and another guy runs it hard for years.

 

I highly reccomend measureing your squish with the domes on the motor, send the domes and that measure to Noss with what size dome/octane you want to run at what elevation and empasis on low/mid/ or top end power and he will make you a dome that is as perfect as you can get for your application and current engine configuration.

[FireHead]

FYI, if you mesure the dome with the syringe, use rubbing alchohol. Water has more surface tension so you will get a miniscus (dome) of water and your measure will be as much as 1cc too much. If you measure your squish with the domes installed in the head on the motor and then with the domes out of the head this will tell you if you need to add or subtract cc's from you measure due to the piston going into the dome (positive or negative deck height). You can calculate this small volume like you would calc the volume of a cylinder. These were directions given to me by David Noss for determining the dome volume and I got very close to what he got when I sent the domes and squish measurements to him. If you dont take these differences into account you can be off by more than one cc on a regular motor or several on a stroker/longrod. Even an off the shelf dome marked 20cc could measure 19cc on one motor and 21 on another with the slight inaccuracies of the measurement method and differences in base gasket thicknesses, ect. This is probably why one guy blows his motor up on pump gas with 20cc domes and another guy runs it hard for years.

 

I highly reccomend measureing your squish with the domes on the motor, send the domes and that measure to Noss with what size dome/octane you want to run at what elevation and empasis on low/mid/ or top end power and he will make you a dome that is as perfect as you can get for your application and current engine configuration.

 

That's good advice. :thumbsup:

 

I didn't want to be the guy that offered the serious and complicated solution for once I suppose.

[96_banshee_96]

Holy shit I dint know this was going to be so complicated :: . I will take in consideration sending the domes in but I think for now I will run my stock head and just get some VF3's or something. Which one will be the most noticeable gain? The motor has a true and welded hot rod crank, ricky stator with adjustible timing plate I have some cheap ass pipes that came with the bike that I have never even herd of before they are LRD's if you guys have ever herd of them before and thats about it. The cool head is off another motor I have and what Ducman said about blowing a motor made me have second thoughts about slaping on the cool head.

Edited February 24, 2007 by 96_banshee_96

[FireHead]

Holy shit I dint know this was going to be so complicated :: . I will take in consideration sending the domes in but I think for now I will run my stock head and just get some VF3's or something. Which one will be the most noticeable gain? The motor has a true and welded hot rod crank, ricky stator with adjustible timing plate I have some cheap ass pipes that came with the bike that I have never even herd of before they are LRD's if you guys have ever herd of them before and thats about it. The cool head is off another motor I have and what Ducman said about blowing a motor made me have second thoughts about slaping on the cool head.

 

You will see a a definite performance gain with the head. The reeds will just give you better throttle response and porbably not muchy else with your combo. I am not a fan of the LRD pipes if they are the adjustable type. If they aren't the adjustable type then I do not have any experience with them. :thumbsup:

[96_banshee_96]

You will see a a definite performance gain with the head. The reeds will just give you better throttle response and porbably not muchy else with your combo. I am not a fan of the LRD pipes if they are the adjustable type. If they aren't the adjustable type then I do not have any experience with them. :thumbsup:

 

Yes they are the adjustible type. Thanks for all the help.

[FireHead]

Yes they are the adjustible type. Thanks for all the help.

 

From my experience, the adjustable LRD pipes will leak at the adjustment point no matter what you do. Depending on what type of riding you do(not sure what pipe may be best for you), you might be able to sell them on eBay and buy a different set of pipes without losing any money. :thumbsup: