| Author | Message | ||
     Rockbiter1 |
Anyone know which heads will fit the Blast? I heard rumors of XB heads, but i think i can find sportster heads cheaper, if they will fit. I'm getting close to taking off the top end for other maintenance, and thought this would be a good time to throw on some bolt-on heads. Of course, i COULD send the current head to Nallin, but i don't really want my wife to find out  | ||
| Ezblast |
The XB heads would require a E series cam simular to the XB or above due to valvespring tension, and modifying your motor mount, but would be a great base for further mods down the line - before the XB heads where considered the Best, they where using aftermarket Sportster/Buell heads and getting good results. Really though NHRS is the ticket, but then the full kits just a bit more, and so it goes - those little darkside wispers - lol Got Thump?! Just Blasting on the Dark side! EZ  | ||
| Blake |
"The XB heads would require a E series cam similar to the XB or above due to valve spring tension" I don't follow that. Why would you "need" to change cams? Don't forget Cycle-Rama, the King of high power V-Twins. | ||
| Ezblast |
The stock cams lift is pretty mild and made for lighter springs. GT - JBOTDS! EZ | ||
| Blake |
Ed, You done got yer thinking backwards. The springs are chosen to work with the cams, not vice versa. So you might say that "the stock cam lift is pretty mild and does not require the heavier XB springs." The heavier springs of the XB heads will work just fine with the stock Blast cams. No problem whatsoever. But if you want, go ahead and put comparable lighter springs into the XB heads. Not sure if Blast springs would slip right in or not. Probably would. Heavier springs... good, lighter springs... big problems. If valve springs are not stiff enough, the valves will begin to bounce or float at high rpm. If the valve springs are a bit stiffer, they simply have a higher margin of safety before the onset of valve float. Of course the the valvtrain will be subjected to mildly higher loads, but not anything to worry about. Zat make sense? Or do I need to sketch a picture? The usual fallback for us engineering types when we fail at normal means of communication.  | ||
| Blake |
One other thing, just to be real picky... Valve springs are never in tension. They are always in compression. Well to be perfectly accurate the little cross section of the coil spring itself is in torsion, but that is for another discussion entirely. As a whole the spring is always in compression. | ||
| Ezblast |
OK - but wouldn't the heavier spring - or what I'm really saying - will the stock cams be able to handle the extra pressure those springs would apply, and wouldn't the opening and closing events be sped up by the extra tension applied by the springs? - Thus not getting the fuller burn? GT - JBOTDS! EZ | ||
| Aaron |
The XB springs aren't really any heavier than the standard springs. They both measure about 135 on the seat at 1.850", and fall to the 120 range after a few miles. They have more travel however, and the stock XB head has more retainer to guide seal clearance. Hence their ability to handle more lift. They're not interchangeable, as the retainer & lock setup for the XB springs is made for a 7mm stem, versus 5/16 for the stock Blast spring. You can't move those retainers between the two springs, either, as the XB spring is a single beehive and has a small diameter on top. The springs that came on the Blast are the same spring that came on every Harley and Buell (except the V-Rod) since 1983, until the 7mm stuff came along. Twin Cam, Sportster, Buell Thunderstorm, etc, doesn't matter, all the same part number for the springs. Something to keep in mind, though ... as has been explained to me, part of the reason HD can get 7500rpm safely out of the XB9 valvetrain is the exceptionally gentle dynamics of the "E" grind cams. I'd be very wary of twisting that hardware that high with a more aggressive lobe profile. Of course, all of the new Sportsters now come with that hardware stock (smaller valves in the XL883 heads though). The new 883's still come with the old "D" cams (i.e. used in all S2's, domestic M2s, and 91-03 Evo Sportsters except the 1200S). The new 1200 Sportsters come with "W" cams (used in the 1200S and Blast). So they're pairing the old grinds with the new hardware. But they also aren't twisting them 7500 rpm. Blake's comments on valve float and seat bounce are right on the money. I'd add that it tears the hell out of things, too. Overly heavy springs are hard on things as well. It's important to spring the head properly for the cam and intended rpm. | ||
| Newblaster |
So... In other words... To get the best out of the XB head, you should use the "E" grind cams? | ||
| Gearheaderiko |
This is why I come to Badweb.Thanks Blake and Aaron. (and, of course, thanks to all who bring these questions up) PS to EZ: there seems to be way too many subtopics lately. I know you're working now so that may be why or maybe its just me? | ||
| Rockbiter1 |
Ok, saw some Sportster valve springs listed in 05 HD catalog. Rated to 7000 rpm behive springs, (designed for pre- 05 models). Those will drop in the Blast then? Would I need to change valves or other expensive work? I'm going to use the pro-series cams, so no, I'm not going very radical, but i will eventually be going to a new ignition so I can nudge the rev limiter up a few notches. Since i will have the engine apart now, and not then, it pays to plan ahead. | ||
| Blake |
Thanks Aaron. You still know too much. Ed, wouldn't the opening and closing events be sped up by the extra tension applied by the springs? - Thus not getting the fuller burn?" The springs just keep the valvtrain together, in contact as one contiguous mechanism. They cannot change the rate at which the valves open or close. That's the sole purview of the cams. Cam bearings would experience accelerated wear with more aggressive cams or higher rate springs or both. But I bet that the cam bearings in your Blast are the same as those in the XB. No matter. Aaron cleared up the whole issue, so it is a moot point no? You can put the XB head assembly onto a Blast and still use the stock cams with no fear. But the XB cams will work much better. | ||
| Gearheaderiko |
Ray or Spooky(Eric) or ?: What did you do to the Blast front cylinder head/isolator mount to use the XB head with the Blast frame? Did you elongate the holes or just one of them or make a new mount? Thanks for your help! (Message edited by gearheaderiko on November 29, 2004) | ||
| Spooky  |
I just elongated the hole thats toward the outside. That was the only hole that was moved on the head beside the rear mount. I just left the rear mount off. | ||
| Gearheaderiko |
Thanks! | ||
| Ezblast  |
Erik - are you using the stock XB piston or going with 11.1 compression type? GT - JBOTDS! EZ | ||
| Gearheaderiko |
10.5:1 XB piston. (I do not know if thats a stock compression.) | ||
| Ezblast |
A thought from another board - Note this will work with our stock cams - the 1.75 to 1 rockers from Crane Cams give good low end torque with out having to increase RPMs to stay on the cam - workable on a stock HD cams - would this work with the Pro-series/B50/Sportster 883 cam(pre-04) - being a stock type profile? GT - JBOTDS! EZ (Message edited by ezblast on August 19, 2006) | ||
| Swampy |
Back in the old days, That was one of the things we used to do was increase rocker arm ratio. Then we used to have to try a bunch of different length pushrods to get everything in the correct position. Yeah, it would work.just as long as the valves didn't hit the piston which probably isn't going to happen. | ||
| Gearheaderiko |
Besides checking the valve to piston clearance you need to know at what point spring/coil bind occurs. That will affect what cams/lift you can use. Hi lift rockers will also lower the rpm at which valve float occurs. The valve has to travel a longer distance in the same amount of time, which means it has to travel faster, which is the same as increasing rpms. Its a great idea, but there is gonna be some math involved to do it right or reliably. It would also be kind of silly to throw in the ratio rockers with a cam and find out its now the same specs as a different cam. Double the work-same result (be there, done that)! | ||
| Ezblast |
Here are the ifs - Here are the IF's: You must have 0.060 thousands MIN. clearance before the valve springs coil bind ... You must have 0.040 thousands MIN. clearance piston valve pockets ... In BLASTing LaFayette Thank you LaFayette - So where does that leave us and would it work with the B50/Pro-series? GT - JBOTDS! EZ | ||
| Ezblast |
More from the Motorcycle Dr. - yesterday i read some things posted on 1.75 rockers.i think some things need to be cleared up on the subject.1.75s r fine with stock engines.more power through the rpm range.u will also have a loss in fuel mileage,as with any performance mod.these rockers can be used with performance cams.I don't recommend anyone tring to install after market cams and valve train parts. Everything has to be setup to match.I offer the rockers in some of my performance packages and one does include Andrews B50s.You can go with a higher lift cam, but as i said before, everything has to be clearanced for the lift. Even bolt in mods have to be checked when it comes to the valve train.if u want to try the rockers I suggest having a professional install them.If u dont have anyone close feel free to contact me,I'd be glad to help anyone out.I do offer heads set up for any cam,valve,piston and rocker combination You want.The main thing i want to stress,is just because its in a catalog, doesn't mean you can bolt it on and everything is fine. Same as with what you read in this Blast group. All have good intentions,but there is a lack of in-depth knowledge. If you want more hp and torque while maintaining reliability,ask a professional.In the long run,its a lot cheaper and beats the hell out of tearing up your ride. So surely someone here knows those numbers and can do the math - or is this clay time - lol GT - JBOTDS! EZ | ||
| Gearheaderiko |
Isnt that what I wrote only mine was simpler? | ||
| Ezblast |
Yes - but I'm curious to find out if I would have to change anything else out to use these with the B50 cam - thats what my question becomes. GT - JBOTDS! EZ | ||
| Gearheaderiko |
My guess (without doing the math) would be that if the B50's are the max lift with stock heads, adding hi lift rockers to it would not be a good idea.Its the same as throwing in a hotter cam. I'd also bet that a Chevy Performance book would have the math formula for determining lift with ratio rockers (and maybe including reduced valve float rpm). Clay time??? | ||
| Sarodude |
I think that another significant factor would be valvetrain geometry. I remember Aaron mentioning that sometimes just bolting in higher ratio rockers will not only not buy you extra lift - but may actually reduce lift. Besides the little / nothing potential, I'd imagine the tweaked geometry wouldn't be good for your components. -Saro | ||
| Ezblast |
I've seen these run on stock vw bugs with no problems and plenty of miles put on the motors and seen/felt the gains, now I learned of a kit that includes these and the B50 for the Blast - so I'm trying to break it down to what is actually needed and not - its only tweeked if it is harmfull or does not work - lol - otherwise we may be onto something here for performance and stock longevity - always my goal for the red bike - we are talking 1.75 as has been used in vw's forever not the radical racing 2.25 puppies - lol - lol - I know this is old school, however, I also know that there are plenty of gray hairs amongst us;0) GT - JBOTDS! EZ | ||
| Ezblast |
Clay time - is when you use clay to check head tollerances - so if you have to experiment with a head - its time to play with clay - was the old phrase or clay time. Juice to be passed out after naps;0) GT - JBOTDS! EZ | ||
| Mygirlspurplethumper |
Thought I'd run something by you guys to see how many different problems might be involved in this project. I was thinking of an upgrade to a rear cylinder XB head. You have the performance gaines. The Intake Port, Carb and air filter are moved forward into oncoming air, wich is good right? I realize there's some fuel delivery issues but that's just longer lines as I see it. The Exhaust port exits the rear and would entail some custom fab. headers, but if you brought the header around to the front and down under like the current replacement full systems, you'd have more distance for the gas to cool down. In theory the cans would last longer, or maybe not wear out at all. So what am I not thinking about? | ||
| Jprovo |
How would the front isolator mount to the cylinder head? |
