| Author | Message | ||
     Tdshepard |
Get some modeling clay and place a layer of it on top of the piston. Assemble engine with used head gaskets and torque to specs. Rotate engine to get valve impressions in the clay. Disassemble and measure the thickness of the clay. Bon-ami should never be in a motor shop!! | ||
| Aaron |
Ben, it can certainly be done by hand with a file. It's a fair bit of work and somewhat tedious to get it right, but it can be done. Be careful not to slip and scratch up the deck. There's a better way, though ...  An XB head getting it's chamber cut for angled dome pistons  An XL1200R head that's been cut on the CNC machine for Thunderstorms. The XL1200R head is the same as an XB head excepted it's black with polished fins. The machine does a nice job. | ||
| Benm2 |
Thanks. The bon-ami will NOT go near the assembled bottom end, I was going to pull the cylinder and do that match work on the couch. I think I'll use the modeling clay thing to verify the squish on final assembly. Do I need to use used gaskets? The "standard" gasket sets come with 0.040 head and 0.020 base gaskets, but I wanted to use the thinner ones. I expect that I'll have to buy these in addition to the kit, so my limited pool of money will get smaller. Can I use the new ones with nothing on them, and use some smaller, nominal head torque to verify the clearances? Aaron, at this point I've memorized alot of the Nallin price list. If I won the lottery, the heads would be off to you tomorrow, for more work than I've mentioned above! As it is, money spent on the motor reduces capital available for track days in the coming season. So, I look wistfully at the nice pictures you post, but I'll have enough trouble scraping together enough for the valve job. The cost of the gasket set has already shot my plan for larger valves. Nuther question, though. Will I be able to re-use the stock pushrods? | ||
| Tdshepard |
I only use my gaskets one time so I mock up with used gaskets to save money. If you know the compressed thickness of all gaskets just do the math. The compression ratio is already very high for a street bike (at least for here in hot Arizona) so be careful what you wish for. Improving the squish is great but not at the price of making the bike un streetable. | ||
| Aaron |
Ben, I understand completely. And I've done what you're talking about doing, by hand, and you can do it and get acceptable results, it's just tedious is all. If you wanted to send me the heads unassembled, I could give you a break off the normal $130 charge for decking & cutting squish bands on a pair of heads. But by all means, you can tackle it yourself with a file. Here's another pointer: after you bolt the head and cylinder together, reach up inside the cylinder and scribe a circle around the perimeter of the chamber as defined by the cylinder, and use this as a guide during your filing. The chambers are rarely well centered from the factory. I highly recommend using solder as the measurement media for your mock assemblies, as opposed to clay. Clay is difficult to work with and measure, it likes to change sizes as you peel it off and then your calipers will compress it entirely too easily. I generally place 6 small strips of .060 diameter solder across the dome angles, 3 on each side (front, middle, back) and hold'em in place with a dab of grease. Roll the motor through TDC once, pull the head, and measure the solder thickness. It gives you a good idea of the variation in the squish around the chamber. I've found I can run the squish tighter if I install and ream new wrist pin bushings and put'em on the tight side of the spec. I've run under .020 without contact problems. Likewise, I've seen motors with loose wrist pin bushings that were banging the head at .035. It doesn't really matter what head gasket you use for the mock assemblies, as long as you know it's thickness. I highly recommend the Cometic EST's for final assembly though. EST's are highly reusable too. As far as CR goes, Td has a good point. Generally we have to take around .030 off a T-storm head in order to be able to do the squish band properly. Even though the overhang will be around .020 in many places, you have to mill to remove the worst place. Then you're talking another .030 or more of thinner gaskets (I often don't even use a base gasket, and then end up with a .025 or .030 head gasket). So you can easily end up with .060 or more of total drop. And that'll raise your CR significantly ... I'll withhold the math for now, but trust me. So some chamber relief may be needed, and that means making volume measurements and doing calculations and sneaking up on it (don't want to overshoot). On the flip side, a more effective squish has detonation reducing effects, so it'll tolerate a little more CR. Much depends on your cams, too. And yes, at that much drop you've gotta be thinking about pushrods as well as piston to valve clearance. Best of luck. | ||
| Benm2 |
Aaron: Thanks again for the detailed info! Based on your input, I guess the only things I'll be able to swing are the Cometic gaskets and some new pushrods. By rights, I'll get them from Nallin, as the advice is worth more than the parts. The bike is NOT a streetbike. I've cut the kickstand mount off (with the passenger peg mounts), its got no lights, and I'm probably setting up for total-loss this winter. The cams are N4's, so I don't expect too many clearance-related issues. But, I'll check as bent valves are expensive. Compression ratio? Hmm, didn't think of that. Thought it might go up some, but how much? My guess: Compression ratio = starting vol / finished vol Starting volume = finished vol + cylinder displacement CR = (FV + DISP) / FV or FV = DISP / (CR-1) I get FV to be 66.8cc's, with a 10:1 guess at factory compression ratio. Cutting a slice 0.060 x 3.5" dia out gets me to 11.8:1. If the factory CR is 9:1, then I get 10.2:1. Assuming I did my math right, 11.8:1 is a little higher than I'd like. But, I thought I saw here that the stock CR was closer to 9:1, in which case the new CR is okay. Am I close? Ben | ||
| Aaron |
Your formulas are right ... but I get a slightly different number ... perhaps just rounding error. Going with your 66.8cc Fv, 10:1 is 601cc displacement. .060 of gasket at 3.5" is 9.46cc ... making your new Fv 57.34cc ... and that works out to 11.48:1 at 601cc displacement on my calculator. But yeah, that's right. If you buy those pushrods and gaskets, you'll get the best pieces available  TIA. | ||
| Sarodude |
Aaron- I'm trying to understand what is / isn't affected by the centering of the combustion chamber. With that in mind, does the position of the valves move relative to the bore also or are the valves' positions gonna vary relative to the CC surface? I'm just trying to understand if the valve guides & seats are installed / machined relative to the combustion chamber or something else - like the cylinder studs. FYI, I've written off Loli's sportster and am working on getting myself another Blast so I can start playing. That's why no mods from me yet. Can't Frankenstein Loli's only running, available, real bike. -Saro | ||
| Aaron |
Saro, I haven't seen the process, but I'm assuming they pull the raw castings out of the molds and then pick a spot where all the machining is referenced from, that's how it's generally done. So things that are machined are reasonably accurately placed relative to each other, but where you get lots of variation is in the placement of the machined areas relative to things left as-cast. That would be chambers and ports primarily. So while I've never made the measurements, my bet is that the placement of the valves stays pretty constant with respect to the other machined areas. This variation is often referred to as "core shift" but I think it'd actually be more accurate to call it "machining shift". You see it in virtually any cast part that then gets machined on. Every Chevy hot rodder knows to look at the placement of the cam hole relative to it's boss for a quick view of a block's core shift. Some heads have it worse than others for sure. I've seen heads that we had to take down .040 to get the chamber to square up. Some may only take .020. They average about .030 though. We also see variations in port flow, and we certainly see variations in performance on stock pieces from this shift. And it seems to have gotten worse over the years. The T-storm head you can buy today is not the same as the T-storm you could buy in 1998. The XB's look pretty good, though. It's almost like the molds wear out or something. | ||
| Rattler |
Aaron advises: <<And yes, at that much drop you've gotta be thinking about pushrods as well as piston to valve clearance. >> Don't forget, you will probably have to file off the intake port flanges some on the intake manifold after a .060" drop..the stock manifold will now be slightly to long due to the drop in the heads....the "V" is closer together. Dale A. | ||
| Benm2 |
Question of the day: The counterbores in the heads that match the locating studs on the cylinders look like they might be an issue. If I just increase the countersink depth, will that be adequate for milling the head (to allow the studs to move further into the head)? Or, do the holes need to be remachined entireley (re-bored & re-countersunk)? I am almost done with the "porting". Maybe I'll post pictures for everyone's amusement. Ben | ||
| Benm2 |
 Intake port. Can't see detail too well, but I cut down the boss around the valve guide. It's tight to the guide, and has a lead in I "borrowed" from looking at edelbrock CNC'd intake ports. There's a ridge down the center as a splitter. Its the only "reshaping" I did, I left the port floor alone. Exhaust was similar, but no splitter. Kept the shape of the taper away from the exhaust valve guide, jut moved it closer to the guide (cut away the boss). Next, moving on to the combustion chambers, once I get to mill the heads & do the blend valve job. | ||
| Benm2 |
 Intake port. Can't see detail too well, but I cut down the boss around the valve guide. It's tight to the guide, and has a lead in I "borrowed" from looking at edelbrock CNC'd intake ports. There's a ridge down the center as a splitter. Its the only "reshaping" I did, I left the port floor alone. Exhaust was similar, but no splitter. Kept the shape of the taper away from the exhaust valve guide, jut moved it closer to the guide (cut away the boss). Next, moving on to the combustion chambers, once I get to mill the heads & do the blend valve job. | ||
| Lee |
Who here's put their Buell on the bottle? | ||
| Vr1203 |
Lee, I did a Duc, an aircooled Monster. It was fun. | ||
| Lee |
Cool! I'm just trying to get some scoop on whether or not to do it. No one seems to want to touch it though.....that's OK I'm used to it. Lee | ||
| Turnagain |
Lee, I believe Eisanmann (who's busy shootin' sheet over on the More pictures please! thread) said he did it once to his bike. If I remember properly, something blew up.  | ||
| Lee |
Ouch! Yeah Steve..that's the type of stuff I'm trying to find out! | ||
| Firemanjim |
The Nallin boys have shot nitrous in everyhting with wheels on it,get aholda them for pointers.I have a good site tucked away on building your own--let me dig it up. | ||
| Firemanjim |
Found it,good reading. http://www.diy-nitrous.fsnet.co.uk/ | ||
| Vr1203 |
NOS,www.nosnitrous.com. has all the info you need, they sell the stuff. Nothing blows up if everything works right  The idea is simple but the execution is a little more difficult. Conservative jetting is pretty safe . Big gains will be more risky and fun! | ||
| Snowdave |
Here's the question: if no support parts needed to be changed out, what would the cost difference be in building a 1250 vs. a 1424? I already have most of the parts to support either, but I am debating which way to go. Any insight? | ||
| Jon6516 |
I am buying a 2001 X1, I want to stroke it. I also want to keep the stock cases. How long a trough or stroke will my stock cases accept. Also if I use S&S’s 5” crank it will increase the engine height 1.1”, will this cause interference with the frame? | ||
| Blake |
I've never heard of anyone stroking a Buell. I don't think it is possible with stock cases. Surely not to 5". Why are you wanting to stroke a Buell? | ||
| Jon6516 |
Well then let me inform you that the cases can take a 5" stroke. Also a 3.8125 bore, that’s 114 cubic inches. But being the engine also gets taller by 1.1" or .5" for the 98", my question is. Is there enough clearance? Can I get an engine that is taller than stock in the frame? Or do I have to take it to the frame guy. As to why. Why not? Add a tall gear, you have allot of bottom end tork. White knuckle riding < | ||
| Vr1203 |
Theres a different front cylinder to frame bracket available to install taller engines in Buell tubers | ||
| Jon6516 |
Do you know who makes the bracket? I tried S&S, Zippers, and a few others. | ||
| Vr1203 |
I know I've seen it, give me some time and I'll see if I can remember. | ||
| Firemanjim |
Jon,see if you can get Aaron to chime in as he put the 100" motor in the S-2 frame.Cannot remember the details. | ||
| Jon6516 |
Jim if it was an S&S 100 it would be a whole different setup. I am trying to keep the stock cases (numbers matching, and stock appearance ). That limits me to the 3.8125" bore and tall cylinders. The S&S has a 4" bore and shorter cylinder & rod length (A BIG S&S ON THE CASES). edited by jon6516 on April 05, 2004 |
