Opinion: Biggest contributing factor(s) to VMax performance loss over time?

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Shuriken

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Location
Southwest USA, 5700ft Elevation
All of the bikes I have owned over the years basically started as piles of junk. I'd buy them for cheap and bring them back to life. See my VMax saga here: http://www.vmaxforum.net/showthread.php?t=3410

While my repairs have gotten them all back on the road, none of the bikes I have brought back to life seem to have the factory pep in them. I think a lot of it is the altitude (5700ft) but I also think a lot of it is just many little things wearing down over time that eventually rob power. I haven't rebuilt the engines (pistons, rings, valves, etc.) on any of my bikes (except 2 dirt bikes).

My question is, what do you guys think are the highest contributing factors to performance loss over time on these older bikes (meaning 1980-2000)?

For example, do you think it's the carbs wearing out / getting misadjusted over time? Or is it overall piston/rings wear, or misadjusted valves? Obviously, all of it causes loss, but what do you think causes the most loss?

I'd like to hear from some of you wrench-heads who have been working on bikes for awhile or who have been into enough bike engines through the years to know.

I'm going to guess elevation, then piston/ring wear, then carb issues?

One of my old XS11 bikes measured as low as 90psi on one cylinder and the rest were like 110 cold. That bike smoked and it had obvious top-end wear. The next XS I got measured like 130psi compression (and it was faster) and this Max I have is maybe 150ish with a bit of oil? (have to dig up the numbers...)

So it seems most of the bikes I get have top end wear. Combine that with elevation issues (carb / jetting) and I'd guess I lose at the least %25 percent performance vs. what you guys are getting out of your bikes. Yeah my bike is fast and powerful but it isn't nasty. I've managed to pop a small (6") wheelie in 1st with a good launch at an intersection and I can burn the tire as well but there is no worry that this bike will loop it in 2nd when boost kicks in... On my XL500r dirt bike, I rejetted a bunch leaner and it will stand up easy in 1st with throttle and in 2nd throttle only with a good yank.

So it's always bothered me to hear people riding a Max at sea level and all the sudden the 145 ponies are lofting the tire in 2nd with ease. I want that kind of performance but I wonder how much of it is really to be had on an '85 Max with ~40k miles at my elevation? If I were to buy the newest Gen1 I could find, would it "put the caffeine in the coffee," or would I still be at a loss at this elevation?
 
lol I think you have been reading to much hype latley. I think the loss of power on some older bikes is a little of everything you mentioned. My bike is still pretty new. The only time it wheelies in second is when I **** into gear under hard acceleration. One a few times I have had to roll out of the gass because the front end was still climbing. Now your elevation is a big factor. I live at 600 feet but with in a 1/2 hour in 3 directions from my house I am close to or above 4000 feet. within a hour going east at 5000 feet or up to 8000 feet. The Vmax still runs good at higher elevations buy not nearly as strong. It is very noticeable. I noticed this more on my bikes than in my cars. I think the higher reving 4 cyl bike with multi carbs run much better at lower elevations . Good luck
 
If you don't " **** " into gear it wheelies better............lol

Sorry I had to someone got me on kinkage the other day.
 
I have always been shocked by how just the smallest adjustments of the carbs (like shims) can make the bike run good or bad.

With all the **** I have been through on mine I would say Carbs are #1 and electronics #2. My bike being an 85 means all the electric **** on it is 24 years old.
 
All kinds of different things can contribute to power loss on an older bike.....1st off would be how many miles are on it?.... 2nd, how long and where did it "sit" before being brought back to life? Piston wear, along with brittle rubber valve seals/ weakened valve springs, gas that has turned to god knows what in the carbs, can all have a factor on how an older bike performs. Your high altitude does not help anything either, but I would think with the correct jetting changes, you should be able to overcome it.
 
So, regarding the other thread I posted here http://www.vmaxforum.net/showthread.php?t=8337, I'd have to go again with elevation....

The thing is, my bike would not wheelie when I first got it. It had the end caps removed and drilled baffles and stock jets. I capped off the baffles and rejetted leaner. Now the bike will wheelie in the right conditions.

Elevation didn't change but changing fuel/air mixture did, which is a compensation for elevation. So carbs / elevation, IMO only, have to be up at the top of the list. I very much agree with HDKILA.
 

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