High-altitude suggestions for stock KZ440 engine?

Hi, folks. I've got a KZ440 LTD with stock pretty much everything engine-wise, other than swapping in a beefier ignition coil with better spark cables. I recently moved to Santa Fe, at 7,000 ft, and the bike runs pretty decently once it's warm, but there's a very narrow window when starting it cold between not enough choke to fire up and too much choke, making it flood. Since I'm at high altitude, it's obviously running rich. If I could get it to start with no choke I'd be fine, but that doesn't quite work. It's a tricky art at this altitude.

The idle mixture is factory sealed. In principle, I could unseal it and adjust the mixture - but is that advised? I can live with how it is, it's just inconvenient to have to bump start it sometimes.

The various ways employed to stop you adjusting air/fuel screws were put there for emissions reasons, inflicted by the EPA, in case you adjust one a 1/4 turn richer and destroy the whole planet. There's no good reason not to get access to these for fine tuning, the restriction was not put there so the bike would run perfectly with how they were set in all circumstances and even fuel will have changed since the bike was built. Assuming everything else is set correctly on you bike and the carbs are clean, you could start off by looking at one size down on your pilot jets, but adjusting your air/fuel screws can give you an idea about that because if the pilot jets are too big or too small, this will effect what you can achieve by adjusting those screws, the mixture needs to be somewhere near for them to work in the 1-2 turns out range which is normal for carbs. If the pilot circuit is way off sometimes you'll find turning the screws appears to have little effect. What year is the bike? and I'm assuming they would be CV carbs on a 440. A little more detail would make it easier to make some suggestions, How doe the bike ride at altitude other than your cold start issue? I've found at altitude the idle is effected most, at higher speeds I think the motor sucks the thinner air in more effectively or something because I've not had to fiddle too much with main jet sizes. Bare in mind a lot of 80's bikes were set to run pretty lean from the factory because of increasing emissions regulation, so may be jetted close, when stock, to what you want at altitude other than possibly just the mixture screw adjustment. With air cooled motors it's best to err on the slightly richer side to help keep engine temps down.

Thanks, redhawk4, good stuff. It's an '83 KZ440 D5 LTD Belt. Original Keihin CV carbs, and everything on 'em. When warm, it runs well, seems to need to idle a little higher, but not a major issue. The main thing is starting, especially when it's cold. I do fuel it with pure non-ethanol gas, so the fuel should be fairly close to what it had in '83. It's always been a bit tricky to start, but at 7,000 feet it's even trickier. A lot harder to find that sweet spot on the choke where it kicks in. A beefier (lithium ion?) battery would probably make a difference as well, to get more cranks before it tires out.

I'd try adjusting the mixture screws and idle adjustment to get a good idle at the correct speed, and then go from there. The other thing on the idle circuit is to make sure your jets and passageways are meticulously clean, draw some copper wire through all the openings to make sure there is not a surface layer that's not being removed with just carb cleaner etc.

I've found if the pilot jet is too rich for altitude the motor bogs in the lower mid range and then clears as the revs go higher, if it's running OK once warm and in normal riding, then you definitely want to focus on getting a good idle before doing any thing else, you don't want to compound problems by changing anything else at this stage.

+1 on using non ethanol fuel, I use that in all my bikes and any motor that isn't running pretty much every day. It may cost a bit more and not always be convenient, but it certainly eliminates a whole host of other issues that can occur with ethanol eating rubber components and the water separation issues. I still think you'll find even ethanol free fuel though is not quite the same stuff we had in the 1980's.

Where was the bike originally sold?
Steve

swest wrote: Where was the bike originally sold?
Steve

It, and I, are from Wisconsin. We just moved to Santa Fe a couple months ago. So I've got plenty of experience with the bike at near sea level. My BMW has the little plug/switch that tells the ECU to use high-altitude settings, so that starts up great, although it idles a bit low once warm, which is obviously easy to fix. The Kawi is mainly really hard to get started on the battery. And I enjoy futzing with it.

redhawk4 wrote: I'd try adjusting the mixture screws and idle adjustment to get a good idle at the correct speed, and then go from there. The other thing on the idle circuit is to make sure your jets and passageways are meticulously clean, draw some copper wire through all the openings to make sure there is not a surface layer that's not being removed with just carb cleaner etc.

I've found if the pilot jet is too rich for altitude the motor bogs in the lower mid range and then clears as the revs go higher, if it's running OK once warm and in normal riding, then you definitely want to focus on getting a good idle before doing any thing else, you don't want to compound problems by changing anything else at this stage.

+1 on using non ethanol fuel, I use that in all my bikes and any motor that isn't running pretty much every day. It may cost a bit more and not always be convenient, but it certainly eliminates a whole host of other issues that can occur with ethanol eating rubber components and the water separation issues. I still think you'll find even ethanol free fuel though is not quite the same stuff we had in the 1980's.

Thanks, redhawk4! Great tips! I'll check into all that stuff!

Yeah, I'm so in need of E0 fuel for my BMW (rubber fuel line, etc.) that I created the website pure-gas.org which has done really well, and stations themselves are now posting up to it, which is cool. There's exactly one source of E0 in Santa Fe - a terminal by the airport with 90 octane (a bit low for the Beemer, but oh well). It's a long enough haul that yesterday I bought a 14-gallon "Flo'n'Go" gas can on wheels, with hose, from Pep Boys - now I can get almost three full BMW fills, or numerous Kawi fills in my garage!!

I assume you have CV carbs. First take the plugs off the low speed adjusters and try to adjust them for best idle. The Mikuni book says 1/4- 1/8 out after that. What do your plugs look like? If black, one or two jet sizes down would be called for. I'd go one in case you ride down hill from time to time. The good news is CV carbs compensate for elevation changes on their own so a pilot adjustment may be all you need. My bike runs like a dog at my daughter's place (4500') but like a scalded cat at mine.(sea level) VM 33's I don't live there so I'm not changing them. :whistle:
Steve

Oh, I should have said you should expect 10% or more less power at high elevation anyway.
Steve

swest wrote: I assume you have CV carbs....
Steve

Yup, stock Keihin CV carbs. I can happily say the bike does NOT run like a dog up here at 7,000 ft. It just starts like a ... mule. Although I haven't had it out on highway yet. But it seems fine once warm on the 40MPH boulevards and still seems to have that 3000 RPM sweet spot that is so terribly nice.

An interesting mistake I made was to leave the choke on a bit and head out. The bike had NO power. I was confused thinking that it just wasn't warm enough, firing on one cylinder, and finally pulled over and realized there was a bit of choke on. Pulled it off and VROOOM. Was an interesting discovery. So it must be running on the verge of too-rich even with the choke off in the current state. I'll report back when I get the carbs tuned to perfection.

What Octane gas are you running?

These old Kaws are meant to run on 87, when I went to Colorado and rode in high elevations I went with the 85 octane because it was available and the bike ran great!
Higher octane doesn't mean better gas, it is added to retard pre ignition in high compression / performance engines, " knock "
Around here elevation aprox. 650 feet I run 87 octane in my stock 78 1000 unless it gets above 90 deg. then I start to hear a little knocking and may go with an 89 octane.

I don't think that the alcohol has as much to do with your hard starting and loss of power as does the octane level.
If you ride the bike a lot I don't think that you have to worry about gas separating, what it does to the modern rubber bits? I don't know but I usually change gas line hoses around every other year, around 18.000 miles because they are hard and replaced the carb and petcock O- rings around 30,000 miles.
Petcock rubber like the one that has all the holes in it for the shut off valve usually start leaking around 12,000 miles but is cheap and easy to replace

What Octane are you running? is 85 available to you? at 7000 bet I bet it is .
Give it a try even if it has a little alcohol in it I think it will help.
www.nicoclub.com/archives/gasoline-octane-myths.html

JD

Good point. I start here, (sea level) and get up there, (4500') and the bike runs like SHT. I have to fill up when I get there, I use to go to Arco but now it's 76 and the bike runs a little better. They sell different gas at high elevations than they do down here.
Steve