98bansheetwin Posted May 6, 2014 Report Share Posted May 6, 2014 I'm looking into getting custom cut domes for my banshee. It has a brand new top end. Its a hjr dune play port. I was wondering what the benifits are when going from a .035 milled head to 20cc custom cut domes by hjr. Considering it is a pump gas bolt on bike. Thanks Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted May 6, 2014 Report Share Posted May 6, 2014 Well there are a few benefits. First off, the milled head doesn't have a very effective squish band when compared to an aftermarket dome or expecially a custom cut dome. Next, if your engine comes apart and damages the dome(s), you only have to pay for a dome(s) rather than a new head or the cost to repair a head. With custom domes, they generally run $60-$110. General PD domes run around $40-60 new on ebay. Also, the cooling capacity of the head that the domes will go in is generally much better than the stocker and they tend to reduce cold spots. Furthermore, they generally come with o-rings instead of gaskets (huge plus). I got the Chariot head with 21cc PD domes and could notice a bt more bottom end and midrange. Also, keep in mind that with a more efficient head design AND a smaller dome, your timing advance requirement is reduced. +4 timing is a rule of thumb, but if you actually put a group of banshees into a dyno session, the ones that have modified/aftermarket domes will require less timing to make optimal power than the ones with stock or modified stock heads. Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted May 6, 2014 Report Share Posted May 6, 2014 20cc is about the limit for pump gas. Make sure you pull that head back off and look for det-pits after you ride the hell out of it for a good 15 minutes or so. If I was getting custom domes, I'd request 20.5, but that's for my elevation. I've seen guys pit the domes with 20s and +4 timing around here, but mine is fine with 21s and +4. I'm not sure what size domes everyone says you need to weld the crank for, but I think it's 19cc and lower. What is your elevation, btw? In the end, the butt dyno likely won't pick up on the difference between 21s and 20s, but 21s are safer from detonation. That should make it an easy choice. Quote Link to comment Share on other sites More sharing options...
Deadbeat Posted May 6, 2014 Report Share Posted May 6, 2014 20cc is about the limit for pump gas. Make sure you pull that head back off and look for det-pits after you ride the hell out of it for a good 15 minutes or so. If I was getting custom domes, I'd request 20.5, but that's for my elevation. I've seen guys pit the domes with 20s and +4 timing around here, but mine is fine with 21s and +4. I'm not sure what size domes everyone says you need to weld the crank for, but I think it's 19cc and lower. What is your elevation, btw? In the end, the butt dyno likely won't pick up on the difference between 21s and 20s, but 21s are safer from detonation. That should make it an easy choice. umm..wot? you should prolly look around this place before you start giving other new guys advice Quote Link to comment Share on other sites More sharing options...
98bansheetwin Posted May 6, 2014 Author Report Share Posted May 6, 2014 So all the information above is false? Sent from my PantechP8000 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
98bansheetwin Posted May 6, 2014 Author Report Share Posted May 6, 2014 I wanted to stick with hjr because he knows exactly what his porting is and could perfect fit the domes to the motor. Do you guys think someone else would be able to make a set of domes for hjrs porting Quote Link to comment Share on other sites More sharing options...
tfaith08 Posted May 6, 2014 Report Share Posted May 6, 2014 umm..wot? you should prolly look around this place before you start giving other new guys advice What is there to look around at? If you start bumping the compression too much, the crank needs to be welded. As I stated above, I don't know how high the compression needs to be before that happens, but I believe that it's around 19cc. I'm new here, not new to Banshees. Quote Link to comment Share on other sites More sharing options...
Deadbeat Posted May 6, 2014 Report Share Posted May 6, 2014 What is there to look around at? If you start bumping the compression too much, the crank needs to be welded. As I stated above, I don't know how high the compression needs to be before that happens, but I believe that it's around 19cc. I'm new here, not new to Banshees. ok Quote Link to comment Share on other sites More sharing options...
98bansheetwin Posted May 6, 2014 Author Report Share Posted May 6, 2014 Ok thanks. I emailed him about a day ago and am waiting on a reply. I appreciate all the help guys. At first I wasn't sure if the custom domes would be worth it. Just reading around here and talking to a few builders, I was introduced to the concept of custom cut domes Sent from my PantechP8000 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
98bansheetwin Posted May 6, 2014 Author Report Share Posted May 6, 2014 It has a new hot rods crank that's welded. Its pretty much a brand new motor Sent from my PantechP8000 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.