| Author | Message | ||
     Hugie03flhr |
I've built many engines over the years and I was thinking we have 93 octane here in Jersey so I should pull my heads off my 02 M2 and have it decked for a bump in compression alone with a mild port job. OR should I swap out the stock head gasket for a thinner one??? I would like to hear from anyone who has experience doing this to their bike!!! If it made a difference in power or did it turn into a heat soaked ping monster? | ||
| Phelan |
If you're bumping compression and porting, I'd recommend getting forged pistons to bump the CR. Stronger and more workable. | ||
| Sloppy |
I run 92 octane on a stock compression engine and it pings on hot afternoons... I'd be REAL careful about bumping compression. I'd focus more on gearing and port flow. But most importantly, ask yourself, "WHY do I want higher compression?" Don't forget Rob Muzzy's 10 Commandments (I have this posted in my shop): Analyze the work to be done -- reliability first, performance second. Work on jobs that pay off quickly. Don't pin down talented people on low-yield projects. Keep away from the dyno and the flowbench unless you know what you want and why you need it. Run combinations that work together. An engine is a system, not a parts list. In a system of parts that must work together, choose the cheap parts to complement the expensive ones. If there are two good ways to do a job, one simple, the other complicated, use the simple way. Use everything you know in your work, even if it seems irrelevant. Do everything you can in your own shop. Have enough of the things you know you'll need. Big numbers on the dyno are no substitute for races won. (Message edited by sloppy on April 30, 2010) | ||
| Phelan |
I like extra compression because it's louder, especially with a Force exhaust  . My S2 is still stock 9:1 though. For how I ride daily, the Force is dumb because the motor is stock and I lost a little midrange, but every once in a while, I romp on it, and it makes me smile . When I get around to building my motor this summer, the megaphone will make more sense. | ||
| Buellistic |
ECONO HOP-UP(works where you ride every day on a stock engine) !!!: Adjust your Drive Belt and Primary Chaln correctly ... Install 1.75 to 1 rocker arms ... Exhaust Wrap my header ... Open up the right rear of my OEM Muffle ... BLAST rocker arm cover PVC Valves and a timing plug PVC Valve ... ECONO FORCE Air Cleaner system: Plug the holes in the OEM Snorkel and put on a K&N(RC-3680 Tapered Filter) Air Filter(it fits inside my OEM Air Box) ... Set your timing to where the timing mark is just coming into the timing plug hole and run HIGH TEST GAS ... Jet your carburetor correctly("i" use a FUEL/AIR GAUGE), radius the slide, remove the accelerator pump, and do not drill slide(keeps gas mileage) ... ###This is my PLAN when and if the heads come off my 1997 S3T: Just a little bit more performance, 0.030 thousands head gaskets and no base gaskets(adjust timing accordingly) ... Put in aftermarket XB valves and springs, "BUT" leave the ports OEM size(have LIGHTING HEADS which have small ports) so the engine preforms best for me whee "i" ride(RPMs) ... | ||
| Texastechx1 |
10.1:1 is enough for me. some have gone to 10.5 with strictly premium only but i wouldn't want to that. (Message edited by texastechx1 on April 30, 2010) | ||
| Sportyeric |
If you deck the heads to get a tighter squish area, that will allow you to increase the compression ratio, as I understand the process. Deck the heads to get the squish set at 30 thou then adjust the CR to 10.5:1 and it should be fine. (the decking will probably give you too much CR and the adjusting will be a matter of enlarging the combustion chmaber a tad.) Raising the CR without getting the squish tight enough and you'll have to back off the timing to avoid pinging, which defeats the purpose. That's my understanding of the concept. I've done one engine each way. (The second by bad planning more than design.) (Message edited by Sportyeric on April 30, 2010) | ||
| Hugie03flhr |
Thanks guys! I did an EVO engine with 10.5 to 1 with very good results. This bike has 1.75 roller rockers and the upgraded oil pump/bronze gear I installed. Now I was thinking a cheap head gasket and port would get this bike ripping!!! I understand I need to clay the pistons but I wonder how much time Buell spent if any setting the squish/quench. If it's tight from the factory than this will be a waste of time... | ||
| Sportyeric |
They don't spend any time setting quench. They cast parts to ensure that there is adequate clearance in a worst case match up. The 15 degree shelf in the head that matches the angle of the piston dome would have to begin at zero at the edge of the bore to give you 40 thou clearance with a stock head gasket. (Which is still 10 thou too much to be effective.) On the Thunderstorm heads I put onto the S2, that shelf began with a 30 thou step, meaning I had 70 thou clearance to start with. That said, the shelf is just sand cast and so isn't consistent around the perimeter. I don't want to talk about what I did with mine, but in hindsight, on a budget, I would take turn the head upside down, put the cylinder in place, then drop a piston with maybe lapping compound or something to find out where the highest point of the shelf is, then clean it all up and measure from there. Alternatively, on a better budget, mill the head to get that shelf starting even with the bore then machine the shelf to be exact at 15 degrees. Then ccc the chamber to get your CR back down. | ||
| Hugie03flhr |
So it sounds like I have a lot of room for improvement??? | ||
| Rick_a |
There's always room for improvement. The factory CR is a great match for the stock components. Do the port job and skip the higher compression unless you're willing to mess with more. Higher compression is easier to achieve with less ill effects using a cam with a later closing intake lobe. Keep in mind that even then, more power will also mean more engine heat which will make slow/stop and go traffic and high ambient temps more of a hassle. | ||
| Buellistic |
That is why "i" have always run an OIL COOLER and FAN ... | ||
| Hugie03flhr |
It's funny you said that! I just finished putting together a fan and oil cooler set up. I'm waiting on some fancy oil line from summit racing. OK, from what you guys are saying a deck and port job can work but I get the feeling the stock pistons aren't machined very well and my question is.....(.030) is the tightest I can go or is that a give or take (.005)all around the piston to head clearance??? Thanks | ||
| Brinnutz |
I am going with xb heads, jugs, xb9 pistons, and .536 cams...But, only if it passes the squish test to within tolerances. Should put compression about 11.7-11.8:1. If it doesn't pass, I'll be going with the Nik a sil 1250 kit from Revolution as a backup. | ||
| The4ork |
im running 11:1 on some modified xb9 pistons and stg3 xb heads, and im worried for the summer time. its already up to 85 degrees here and its already started to ping. time for a timing adjustment, and i may need to either get an aftermarket cdi to tune the curve, or drop the oompression | ||
| Hugie03flhr |
I would love the 1250 kit but the funds aren't there yet. I'm really into big torque that tops out around 6500 rpms. I took my friends xb12 out and what a nice revver but I think my M2 has a little more grunt in the low end!!! | ||
| Sloppy |
Long stroke, air cooled engines running 11:1 compression; you are far braver, or richer  than I. | ||
| Pkforbes87 |
My X1 is running 10.5:1 compression after installing a 1250 kit including aftermarket cylinders with THICK iron sleeves and quality forged pistons. I initially set the timing mark in the middle of the window and the bike would ping at high RPMs on a hot day. Now it's set on the right side of the window and runs like a champ. I've also got a leaking front head gasket after only 7000 miles on the rebuilt engine. Temperature has never been an issue with the higher compression pistons. I check cylinder temps every once in a while with ECMSpy imediately following a ride, and they've consistently been around 310* My thermostat dipstick reads around 200* after a ride. I've heard from a lot of people that nikasil-coated cylinders are preferred because iron sleeves insulate more heat and can cause issues when expanding/contracting at a different rate than the rest of the aluminum cylinder. That hasn't been my experience at all - I'm thrilled with the iron sleeves. btw, the pinging I was experiencing was with 91 octane - the highest octane commonly available fuel in my area. Not everyone has this state of mind, but I love riding the X1 because it's rude, the torque in first gear still scares me, and it begs to be ridden hard. At the same time, I realize that riding a 10.5:1 engine hard means I have maintenance to look forward to on a regular basis. Luckily I enjoy working on the bike almost as much as riding it. For anyone who wants a perfectly reliable bike that doesn't require much maintenance, leaving things stock and only upgrading the few known weak points is probably a better route to take. ie: Cometic gaskets everywhere, bronze oil pump drive gear, replace spring plate with two steel plates and 1 friction plate, XB rocker covers, make sure your primary chain adjuster is the thick version. That's all I can think of for now.. there may be more. | ||
| Hugie03flhr |
Thanks PK for a good break down of your experience! I feel I have all the week links covered except for the clutch. At the moment it doesn't slip at all with 10k on it. Do you think if you could run 93 octane your bike would be perfect or do you think the timing would still need to be back off? | ||
| Texastechx1 |
octane in relative to elevation. here in lubbock (3300ft above sea level) we get 90 and 91... but thats equivilent to 93 in Dallas | ||
| Phelan |
I didn't realize that Tech. That explains a bit. | ||
| Hugie03flhr |
I was still hoping someone could tell me about the .030 quench/squish. If I clay the piston and if I find inconsistencies in some spots under .030 but the majority is at .030 if that is OK? OR should I make sure everything is .030 +.... I want it as close as possible but I do not want too take a chance on a piston rocking or flexing and making contact. | ||
| Blake |
Did this actually happen, or are you theorizing? I'd not be comfortable with much less than 0.030". | ||
| Hugie03flhr |
Just trying to avoid surprises..LOL Thanks for the answer I was looking for!!! | ||
| Pkforbes87 |
Hugie..after retarding the timing and seeing what a massive difference it made, I don't think the difference between 91 and 93 octane would have effectively fixed my pinging. | ||
| Hugie03flhr |
Thanks PK!!! |
