On Sat, Jan 2, 2016 at 10:38 AM, RobertWichert robert@... [DSN_KLR650] DSN_KLR650@yahoogroups.com> wrote:
OK, Martin, I'm jumping into this fray...
Lipstick on a pig, yes; but everybody wants an edge. Nobody wants a fair race. So we look for little tweeks and big ones if we have the money.
Theoretically, a 685 will get you a 5% increase in power and torque. Slightly less than than in practice, of course. A 700 nets just under 8% increase. In my engineer's world, anything less than 10% is not worth chasing, but then again, if it's top speed you seek, and you believe the cube root of power is proportional to speed, that's almost two MPH on the 685 and two and a half MPH on the 700; assuming a 100 MPH 650, which might be a stretch. If you can't get to 100 MPH on a stock 650 and you can on a 685 or 700, well, that's enough justification by itself!
But wait! There are cheaper and still significant improvements to be had... I have "heard" that the exhaust cam one-tooth-change is noticeable, so I am saying it must be at least a five percent improvement. And compression is king, so a thinner base gasket will improve things too. Some say the thinner base gasket gives more than the displacement on the 685. That might be true, depending on how thin is thin, I guess.
Putting all those together on a 685 or a 700 should be better than 10%, I'm guessing.
Head work? Sure, head work is the cure-all of four stroke engines and makes the power of today's bikes and cars what it is: better than any muscle car of the 60's ever hoped for. Plus Turbo-charging, of course. So yes, head work can improve things dramatically for a four stroke engine. But do you have the ability to take advantage of that? Can you straighten the passages enough, or at all? Can you add carburetor, tuned to the new ports? Can you tune the airbox? The exhaust? Do you need a different piston to actually take advantage of that internal head work? Will internal head work actually do anything, without a new piston-top configuration?
There are too many questions in that last paragraph for me. If somebody has a scienced-out head replacement that shows significant dyno gains for sale, let's see it. I'm a doubter.
So, yes, I would increase displacement if I could do that with a proven kit (and a lighter piston is available too, I'm told) if I needed to rebuild the top end anyway. I have always increased the bore as much as possible, within reason, on automotive engine rebuilds. I would not boldly go where few have gone before though. The 700 sounds like a rare change and the 15 cc are, let's say, pretty small potatoes.
If I don't need to rebuild the engine, I would still do the exhaust cam switch, if I can remember which way to move it. Why haven't I done it? Laziness and fear, I suppose.
Congrats on the new Triumph, Martin. It sounds like a sweet ride!
Robert Wichert P.Eng. LEED AP BD&C HERS I/II CEPE CEA BPI CERTIFIED SF/MF GREEN POINT RATER +1 916 966 9060 FAX +1 916 966 9068 =============================================== On 1/1/2016 4:52 PM, Martin Earl mjearl4@... [DSN_KLR650] wrote:
http://www.eaglemike.com/
You pose an interesting question; 685 vs 700 vs xyz.
I did mine because the oil rings failed at 55K (upgrade at 57K) and figured I was buying my bike back for $650 total cost, to include some carb up grades, gaskets. It was a good investment.
Just my opinion, IRT to head upgrades-- Putting a lot of extra money in the head is like adding lipstick to a pig. If you really want more power, change bikes. Personal budget/disposable income will of course, drive a lot of what we do. But of course, if it is just a fun project, that 'justifies' the means. yawn. guilty as charged.
I did exactly that. cough. I wanted more power and did it the easier way; I started stuffing Franklins down the HP rabbit-hole. I recently bought (Aug 2015, logging ~5k miles in 3months) a new to me Tiger 800XC. It is purported to be an 'adventure bike'. hmmm. My thumb-nail eval is that it is a 'sport-bike' for geezers. It appears to me, they have taken a 800cc engine and pressed it into many different genres. + Roadie, sport bike, adventure bike. It does not need lipstick; however, it needs plenty of armor (all ready installed) to keep the delicate parts protected if you are going to ride it as an adventure bike.
Motorbikes have replaced flying machines for various reasons; most of which is 'cost'. (I refuse to say I am to old, cough.) My ongoing personal evaluation of the (English Princess) aka Tiger vs KLR650 (Japanese Doll), is conducted much like I did when I was still flying, especially while performing post-maintenance test flights = evaluating an aircrafts performance at its current state of readiness. That evaluation also comes in baby steps slowly learning the balance of the bike over the past 4 months.
A few things come to mind on immediate impressions-- The XC (currently on street oriented tires =90/10) has 3x the hp, but oddly enough does not go through the turns and better than my KLR650 on sport bike tires. That may change when I install a 50/50 tire on the XC in the spring. Admittedly, I am not the most accomplished of riders, yet, the max mph/lean angles I push a KLR through a turn is about the same on both bikes. Probably a riders limitation, as I personally don't like the smell of grinding flesh in the mornings. But that is just me. Seems like every time you add 100lbs to the mix, you get a bigger pig to wrestle. wink. You have to relearn grin-muscles as you touch the throttle and find your self accelerating along canyons of pine trees and deer scat. Or perhaps pushing a smile into quadrants-unknown when you discover yourself in predictable, two wheel drift while pushing through wide, canyon sweepers.
What the XC really does well, it wails out of the turns (like a sport bike should) and rapidly consumes the pavement between turns. It is a good thing that the English princess has really good, ABS brakes; and the new rider beware because the closure rate is a lot higher than before. Yet, I am extremely reluctant to take it down rock strewn trails, where I would my KLR until I get better at handling a heavier bike. Several have document the TAT and the GDR on the Tiger, though those are not for me just yet. It will come, through small steps, and short rides, it will come.
It is a daily, fun project to explore the design limits of a machine; any machine, but especially on a motorbike and especially since you can do it for about $4/hr for fuel. That price point, $4/hr, is a huge difference between what you can rent a Cessna 172/182, and then feed it $40-50/hr for fuel. Well, it was a daily fun project till it started snowing. sigh. now, it is just keyboard-dreams, sharing with those who 'read' the list wisdom. blessing to you all, during 2016. revmaaatin.
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On Fri, Jan 1, 2016 at 3:59 PM, christopher.eckert@... [DSN_KLR650] DSN_KLR650@yahoogroups.com> wrote:
OK, The engine is out and I have a desision to make. 685 or 700 cc. I hear good things about the 685 kit but havent heard much about hte 700. I like the idea of porting the head and going with bigger valves which kinda leans me towards go big or go home. Has anybody heard good or bad about the 700 cc kit.
Also I understand Eagle Mike has the 685 kit but I dont have his contact info. I've been off list and off line a lot this year. What is his contact info
Chris
Here are some important points I may have left out.
I am doing this because I siezed my engine at the Pine Barrens 500. When your engine starts to burn oil you should not ride trails hard for a solid day straight! Just saying. If I am taking off the top end to replace parts then there is no reason not to go 685. It is cheaper than restoring back to 650 and the stock piston is too heavy anyways.
Porting a head does not always involve grinding the cavity larger. The most gain is by smoothing out the casting to allow smoother/faster airflow through the head. Not going bigger, just cleaning off the bumps. This will always help some and I have felt its affects before in 4 cyl engines. If nothing else it helps an engine breath beter. I tis more important at the top end but smoother flow helps mid range power a lot too. In the case of the KLR head it is more dramatic though. The problem with the KLR head is that is doesnt allow the engine to breath anywhere but the lowest end. The head option is to open the ports up to allow the bigger vlaves to be of use. Then you have much more flow. I have done this to a few of the 4 cyl engines I have built and you get a really noticable impact.
What I want to know before I go to bigger valves is the affect at low end. If you look at the dyno charts on the mtech site you will see huge improvements in both HP and Torque. What you might notice though is that at low low end, below 2600rpm, it drops way off.Bigger valves mean a bigger hole for the air fuel mixture to go through. At low ends this means the air and fuel are not forced into the caos needed to mix them well. Granted most riding is done above 2600rpm but I would like to see the Dyno charts for the 685 or 705 kits with the head stock, then with the head ported but with stock valves. If you like to lunk the engine around 2k a lot then I suspect that would show a beter sweet spot. Me, I ride hard and rarely am below 2600 so the head makes sense.
Now for reality. I may go 685 and the new pipe plus port the head but leave the valves as are, then do the bigger valves next year to get those dyno turns of the two independently. My bike has a long hard ride to make this summer before being relegated to commuter and general travel duty.
Option 1 - 685cc and refresh seats & head. for $891.95
In this option I include the 685cc kit plus bore and $100 for valve seat grinding which may be high. This adds 35cc and gets the head back in shape but does nothing for the crappy head design or flow.
Option 2 - 685cc and upgrade head. for $1,535
In this option I include the 685cc kit plus as well as rebuilding/porting the head with bigger valves and new seats/guides.
Option 3 - 705cc and upgrade head. for $1,935
In this option I include the 705cc kit plus as well as rebuilding the head with bigger valves and new seats/guides.