| Author | Message | ||
     M1combat  |
For those of you who have built engines... Specifically stroked engines... What changes need to be made to the timing? | ||
| Fullpower  |
zero. only concern is cranking pressure. ignition advance of around 28 to 30 degrees is a reasonable ballpark for our air cooled twins. stroke on sporty is 4-5/16" cranking pressure is 205 psi. runs well with 28 degrees spark advance, on gasoline. could run a few more degrees on methanol. | ||
| M1combat |
So... If a person were to place a 12 crank/rods in a 9... They could still use the nine ECM if they found a way to adjust the fuel delivery? Anyone know what the difference in cranking pressure between a nine and twelve is? They both run 10:1 compression yes? | ||
| Hobanbrothers  |
12 rods in a 9? It would result in a low compression unless you would cut cylinders considerably. Do not take this the wrong way, but what are trying to achieve? | ||
| Hobanbrothers |
I am sorry, now that I look I see 12 crank and rods... Nevermind... | ||
| M1combat |
I'm trying to figure out as much as I can before I put a nine ECM in my 12... I've talked to someone who has put a twelve ECM in a nine (I can't tell you who) and they said it worked just fine, but obviously was a bit rich. I'm looking to go the other way for no REAL reason... I rarely get above 5500 before I shift anyway, but I figure a few more R's could be useful coming out of corners and that sort of thing. I suppose it would be useful on the salt as well... Maybe even on a road course... It'll be a while before I do it, but I do intend to try. | ||
| Slaughter  |
I'm trying to figure out as much as I can before I put a nine ECM in my 12... Remember, the 9 has the higher redline so if you are used to hitting the rev limiter, you'll also have to get used to rebuilding your motor! You can get more fuel with a Techlusion to feed your bigger motor though. If you put all the components in it for a faster-spinning engine - springs, lifters, pushrods, roller rockers, valves and guides - you might just be able to make it work but WATCH THOSE REVS! (Message edited by slaughter on February 17, 2005) | ||
| M1combat |
"If you put all the components in it for a faster-spinning engine - " They're already there... I have the same valvetrain as a nine... Same heads even... AND... "I rarely get above 5500 before I shift anyway, but I figure a few more R's could be useful coming out of corners and that sort of thing. I suppose it would be useful on the salt as well... Maybe even on a road course..." "You can get more fuel with a Techlusion to feed your bigger motor though. " This is exactly what I was thinking. | ||
| Slaughter |
I'd bet it'd work just fine once you get the techlusion dialled in. Run it on a dyno with a sniffer just to make ding-dang-doggone sure you're not lean anywhere. Spitting aluminum out the tailpipe is never a good thing! That higher redline together with a longer fuel shot from the Techlusion might pretty well mimic the race settings with the higher redline. Just keep in mind the redline of the XB12 and stay away unless you really "need to" go there. Those high revs are really hard on the bottom end. (Message edited by slaughter on February 17, 2005) | ||
| M1combat |
Agreed... I talked to Nallin Racing and Aaron (if I remember correctly) said that he's had very few problems running the old tube frame 1200's up to those RPM's... I know the XB cases use roller bearings instead of Temkin bearings though. One of the techs at NRHS mentioned that you can get about 115-120lbs of torque out of them before they spit out the side of the case. I don't think I'll get to that level though... They're working with someone to get some cases machined for use with Temkin bearings from what I remember. YMMV, I could be wrong etc... | ||
| Stealthxb  |
hard on the bottom end | ||
| Blake |
Torque produces stresses on the bottom end. So does engine speed. Stress on the bottom end due to reciprocating parts goes up along with engine speed squared. So going from 6,800 to 7,500 rpm will increase reciprocation induced stresses by almost 22%. But if I were racing, I'd probably give it a go. ![: ]](http://www.badweatherbikers.com/buell/clipart/proud.gif) | ||
| M1combat |
I don't want to go past 6800... I really just want a little more option coming out of a corner. I've been leaned over just about touching the sides of my feet in third coming out of a corner, realize I should really be in fourth and have to level off the throttle input because I can't put my foot under the lever. I'll still treat the 6800 RPM redline as the redline, but if I need to creep into it before I can shift I want to be able to. I'll still run lower RPM's for 99.99% of my riding, I just want options is all. That said... I may convert to a GP shift pattern as well anyway. Probably not though. | ||
| Fullpower |
ran points on a stroker sportster for a while, saw the tach go way past 7000 rpm many times. dont really know how high i revved the poor thing up, but it is still alive. | ||
| M1combat |
How much power was it making? What type of crank bearing? | ||
| Hobanbrothers |
We will be running to 7,800 RPM with expectations of 8,000 in the draft at Daytona, that is hard on equipment though. We do our own XB's with Timken conversions. I do not believe it is the RPMs that effects the Ina bearing as much as stress from higher torque and HP. In a stock application I have not seen one fail yet. We also set up our lower ends for the higher RPMs, some special bearings from Buell race department seem to help. Once in a while bouncing off the rev limiter is a lot different then planning on living there for a race weekend. | ||
| M1combat |
Thanks for the info  . Bought a nine ECM today... | ||
| Rigga  |
and i plan on converting my 9 to a 12 or bigger and keeping my 9 ecm/tfi set up....keep us informed | ||
| M1combat |
Are you going stroke length or bore dia to get to 1200 or greater? | ||
| Rigga |
plan on fitting 12 crank /rod set and poss bore the cylinders..was advised before purchasing the 9 that it gave a better base for tuning,but as far as i know its only the crank/rods that are different? | ||
| M1combat |
I would keep the nine stroke if it's a race bike, but go with the twelve stroke if it's a race bike. Also, I know there are places to get light XB cranks w/ whatever stroke you want. | ||
| Reepicheep  |
The FX racers are getting the best power and reliability from keeping the 9 stroke with a really oversquare piston, a trick Aaron recommended here ages ago. Go for a 1050 or 1200 kit that keeps the stock 9 stroke and keep the rev's up. | ||
| Rigga |
well im after an increase in torque and low end power which the displacment increase will give me...i was just going to replace the 9 ower end with the 12 version and then poss overbore the cylinders whilst is was all strippped,but the idea to keep the 9 crank and just hog out the cylinder has got me thinking..... pros and cons over the two ways of getting the 1200 capacity would be appreciated guys | ||
| M1combat |
Well, stroke would be better for the street, bore is better for the track. when you stroke an engine, you increase piston speed. This generates more heat and greater forces acting just about everywhere. When you go oversquare, you retain your RPM capability and gain displacement. It's not that there's NO more stress anywhere, but it's not the same as stroking. Most race engines are VERY over square because they want torque high up so they can take advantage of torque multiplication through the gearbox. It's rare to see a long stroke race engine, but they work well on the street. Aaron told me once that he believes the 12 punched out to 88" would be pretty close to the perfect street bike. MUCHO torque down low, and the ONLY thing RPM really gives you is outright speed. We don't need that on the street. | ||
| Kowpow225 |
Balance, baby, balance. I'm interested in hearing how this turns out. Please keep us informed! | ||
| Steveshakeshaft |
Rigga, when you pull the cylinders and look at the liner thickness (thin) I think you might change your mind about "boring the cylinders". If you want a significantly bigger bore you need to buy the Axtell, Millenium (or other) cylinders and bore the case mouths to suit. HTH. Steve. steve_s@ukbeg.com www.ukbeg.com | ||
| M1combat |
Of course... that's why it makes sense to go as big as the largest un-bored cylinder you can get the first time you do it. |
