| Author |
Message |
    
Sportyeric
| | Posted on Tuesday, July 05, 2005 - 12:46 am: | 
|
So here's the theory: "The Sportster Performance Handbook" claimed, (in the early 90s) that an 883 converted to a 1200 using dished pistons will outperform a naturally born 1200 up to 5500 rpm because the smaller ports and valves create a higher velocity charge, therefore better mixing. After 5500, the smaller ports and valves can't flow enough to continue making power. Bob Johnson, of Johnson Engine Technologies (JET) was featured in Thunder Alley and Hot XL propounding the use of 883 exhaust valves in his (very expensive) re-worked heads and he claimed 90rwhp with stock cams. (Pass the salt.)
Now, I consider the matter of S1 Lightning heads (which I have on the Sportster) compared to Thunderstorms. The T-Storm heads have bigger valves again than the S1 heads, which are the same size as earlier stock 1200s. You would then expect that the T-storms would be lagging in the mid-range, as the old 1200s did cf. the 883/1200s. But they don't. And the reason they don't, I think, is because of the squish area that the domed piston of the T-storm combo creates. This provides the turbulence that is provided by velocity in the S1 heads. But those S1 heads still give up some turbulence cf. the 883/1200. The larger valves of the S1 are a necessary evil to make power above 5500rpm. All this suggests to me that there is some gain to be found in the mid-range (<5500 rpm) by combining the moderate size of the valves of the S1 Lightning heads with the squish provided by the T-Storm pistons.
To this end, I have sent my heads in to a local shop to have the 10 degree shelf of the Lightning heads machined to 15 degrees, to match a set of T-Storm pistons. Once they're done, I'll be taking the dremel to the combustion chambers to return the compression ratio to a proper figure. I'll have to remove 3cc's, so I get to re-shape the chambers into a shape that is pleasing to me. Somewhat bath-tub shaped, I think, although I haven't really got a good grasp of how much play room I have to reclaim the required 3 cc's.
I ran this notion past the gathered intellects here a year or so ago. Aaron Wilson granted me a page long PM to point out the things to watch out for, for which I thank/thanked him. Others wondered why to bother. Cost is one issue. Smokin' mid-range (hopefully) is the other. (While not giving up to much to 6200.) And, of course, the joy of DIYS.
Progress is slow. I still need to pull the engine and get the bottom end in for a re-build after I strip it down. Re-assembly before winter is unlikely, given time and budget constraints. In the hopefully unlikely event that the S2 throws a rocker cover gasket or some other excuse to remove it from service for repairs, I would install this set-up on it. But I don't want to mess with a running bike mid-season. I'll be posting pics as things progress. I only started the thread today because I needed a location to hang a question for the pros: Are stock 1200 valves the same PN as S1 valves. I know the diameter is the same. Is the length? |
Buellistic
| | Posted on Tuesday, July 05, 2005 - 01:46 am: |
|
Sportyeric:
"i" do not rev my 97S3T over 6K RPM if "i" can keep from it ... Below 6K RPM is where my engine
lives ...
My engine has LIGHNING HEADs and "i" plan to put
in XB valves and springs leaveing the ports basicly as they they came ...
After all the "GRUNT" that "i" can get to 6K RPM !!!
In BUELLing
LaFayette |
Tripp
| | Posted on Tuesday, July 05, 2005 - 10:55 am: |
|
what are you doing about matching components for the results you seek? i bet properly matching components will have a lot to do with your final product. if you choose cams with a beefy middle along with a big breathing intake and exhaust you might be able to get the results you're looking without the guess work. i do admire your resourcefulness and i'm sure you have a plan for the whole package as i've read your posts on this site for years. i'll be interested to see how it works out for you. i wish i had the knowledge to contribute but i'm sure others will chime in. |
Buellistic
| | Posted on Tuesday, July 05, 2005 - 03:48 pm: |
|
Tripp:
"i" have a plan, "BUT" will not take engine apart
until it has to be taken apart ...
What "i" have done so far are PERIPHERAL:
1)Different ratio rocker arms which make the stock cams work better(the stock cams are are
Good enought for my purpose) ...
2)Put exhaust rap on my header ...
3)Put a stcck 1999 muffler on the 1997 header
with a reversion chamber ...
4)Modified the 1999 muffler to bypass i/2 of the baffles which which is like the XB12 with out the "VALVE" ...
5)Have tweaked the stock Keihin carb a bit which
serves my purpose well ...
6)Have a economy FORCE in a box, ie: pluged the
holes in the snorke added a K&N air filter on the end of the snorkle and put the air box cover
back on ...
7)Up-dated the head breathers to the BLAST/XB type ...
Have 82,212.6 miles as of last ride and when "i"
get a 100K on it it will be time to take it apart and look in side ...
In BUELLing
LaFayette |
Sportyeric
| | Posted on Wednesday, July 06, 2005 - 02:16 am: |
|
And me, just growin' where I'm planted. The Sporty has been running a 3" K&N, a Branch intake (1/2" longer than stock) (and doesn't fit on the Buell), S1 cams, some home-done porting, Vance and Hines SSR2 two into one exhaust. I've liked the results so far so see no reason to change. But its been missing a proper squish area and will have that now.
Added to the budget attractiveness of the project, Firemanjim has provided a slightly used set of T-Storm pistons 5 thou over at no charge. Although I would have gone this route regardless since an overbore and new(er) pistons were required anyway. (85,000 hard miles on the Sporty mill). And, I've just scored some BRAND NEW valves off eBay. (Rare that I've put anything new on the thing.)
A successful project may lead to a repeat with another set of S1 heads, maybe matched to a slightly used set of 30 degree domed pistons, for the Buell.
Buellistic's plan seems contrary to mine. The XB springs are to allow the engine to rev higher without valve float. If you don't often go over 6000, I see no point. I think the XB valves are as large as T-Storms, with the resultant decrease in mid-rpm intake charge velocity. |
Buellistic
| | Posted on Wednesday, July 06, 2005 - 08:06 am: |
|
Sportyeric:
By the looks of your sportster in your profile you have done good ...
BRANCH INTAKE: If this is the BRANCH that does the PORT FLOWING, that is an indication the intake lenght is too short ... WELL IT IS ...
Have the stuff to lengthen my intake track to the correct tuned length but have not got around to doing it yet ...
Your choice of a two into one gives you more bottom end "GRUNT" ...
VALVE SPRINGS: "i" think the XB springs are the
better stock springs ...
XB VALVES: A lighter valve train is always better ...
Just so you know, "i" am not into hoping up the engine ... "BUT" to do product inprovements to
make it run better(low end GRUNT) and last longer ...
In BUELLing
LaFayette |
Tripp
| | Posted on Wednesday, July 06, 2005 - 02:39 pm: |
|
i am a big fan of low end grunt!! i have kept my stock sporty cams even though the lightning cams seem to be a very popular mod for a cyclone. i will probably go with the se536 cams if and when i get some headwork done. so far however i am very happy with the amount of power and where it is with my current setup, i have done all of the work on my bike except for the 1250 kit install. doing the headwork seems a little out of my league but i'm not afraid to take the heads off and send them out, though i may never do it. i keep my rpms under 6000 and have plenty of power for my purposes. thank you for the info gentlemen i'll be very interested to see your progress with however you make your motors motor!! |
Sportyeric
| | Posted on Saturday, July 09, 2005 - 11:29 am: |
|
Shorter sparkplugs. How can I find them? What is the meaning of the codes of plugs? I think my best course of action for re-shaping the combustion chamber requires removing some meat from the plug area. I could just work around it but it would be nice to just shorten the plug by a thread width or two. |
Tripp
| | Posted on Saturday, July 09, 2005 - 12:04 pm: |
|
maybe this will help, the info is a little old but alot of it is still good.
http://www.strappe.com/plugs.html |
Tripp
| | Posted on Saturday, July 09, 2005 - 12:07 pm: |
|
here's another
http://www.nightrider.com/biketech/spkplghnbook.htm |
Jackbequick
| | Posted on Saturday, July 09, 2005 - 02:09 pm: |
|
Sportyeric - Try stacking copper spark plug washers if you can find some. When you reuse copper washers, use a propane torch to heat them to a dull red in a dim room and drop them into cool water. That anneals them and also usually leaves them cleaner. They work harden in use, airplane mechs used to anneal them to soften them and get a better seal when re-used.
Jack |
Rick_a
| | Posted on Monday, July 11, 2005 - 08:35 am: |
|
The exhaust is supposed to flow a certain percentage of the intake according to most experts...I forget the figure. Anyway, if you go with a bigger intake valve you should go with a bigger exhaust. If you're more interested in midrange grunt the Lighting heads seem great. I was gettin' 82hp and 81 ft-lbs out of my stock motor...more with a velocity stack on. I was getting almost the same power as a few people did with their Thunderstorm bikes. She ran out of steam right at 6200 RPM. |
Sportyeric
| | Posted on Monday, July 11, 2005 - 07:48 pm: |
|
Thanks for the props, Buellistic. And the advice, all. That's quite a bike, Rick. A lot like my main riding bud's.
I'm sticking with the stock valve sizes. I don't like to rev beyond 6000. T-Storm valves seem to be sized to still flow at 6800. I don't go there so I'll take the charge velocity that the S1 valve size gives. This follows the same principal that has Kawsaki putting smaller valves in the ZRX engine than comes in the 1100 Ninja. (And many others.) Better for the mid-range.
I've gotten the heads back from the shop. A bit pricy. The machinist told me that he'd decked the heads one thou at a time for the last five thou. To avoid taking off more than necessary. A total of 17 thou. I'd told him, "As little as possible but no more than twenty thou." I hadn't expected that he'd be so anal about it. But better too precise than too careless. (The milling was required because the 10 degree shelf that they come with starts with a (17 thou) drop off at the outer perimeter. I have to reclaim that chamber volume also with the re-shaping excercise.) Pics coming soon. |
Sportyeric
| | Posted on Monday, August 01, 2005 - 01:22 am: |
|
Hmmm. I didn't do the math about the 17 thou of milling. Times pi r-squared equals a heck of a lot of re-shaping. I've had to find 10cc! And I'm running out of places to get it from. Ending up with a broad oval. And the catalogue for NGK reveals that 12mm plugs come only in 3/4" or 1/2". 10mm plugs have two length choices between those values. So I'll stick with stock length.
Not the pretty bathtub I was anticipating. Next time I'll mill less and put up with imperfections in the shelf area.
But if a stock T-Storm runs 10:1, I think a properly set-up squish would allow 10.5:1, yes? |
Sportyeric
| | Posted on Thursday, November 08, 2007 - 01:45 pm: |
|
Ta da!!!! I can't believe this project is taking so long! Bought a Buell. Bought a house. Got divorced. Bought the house again. And reassembling this to be a screamer is now on the top of the to-do list!!
Re-cap: S1 Lightning heads, with their smaller valves and ports for good velocity, decked 17 thou, with the shelf machined to 15 degrees to accept Thunderstorms pistons, for the squish area, re-shaped the chambers with a dremel to 65 cc to get a 10.7:1 CR., and ports smoothed as seemed right.
(Message edited by Sportyeric on November 08, 2007)
(Message edited by Sportyeric on November 08, 2007) |
Rick_a
| | Posted on Friday, November 09, 2007 - 12:50 pm: |
|
One thing of note between Lightning heads (also the SE dual plug performance heads) compared to all other Sporty/Buell heads is that they have a huge exhaust port opening. The intake ports on the XB and '04-up Sporty's seem to share that smaller is better philosophy and they have a slightly raised and reshaped floor. They went back to a smaller exhaust port after the Lightning heads supposedly so they worked better with the OEM exhaust gasket. I also like that the new heads also have much more streamlined valve guide bosses as well. Big valves don't always hurt low end performance, either. A valve can only flow what the port is capable of. A big valve with too big a port may be a different story.
The early Ducati Monster 900's are an example of this. They supposedly went to heads with smaller valves for more torque but they most likely just needed to get rid of a surplus of old 750 heads. Power suffered on the top end and there was no gain anywhere else.
My new XL heads with a longer duration cam using only moderately more lift made 21hp over the Lightning heads and gained a bit of peak torque (measured on the same dyno). Most surprising to me was that I gained more low end power as well.
I think the Lighting/883 heads were the choice before there was any other alternative. I would get those professionally ported before bolting 'em on. I had Cycle Rama do mine recently, and the intake port floor ended up radically changed. I unfortunately have to wait until I can rebuild my bottom end to see the results.
(Message edited by Rick_a on November 09, 2007) |
|
