Jetting for altitude, shop said no big deal...

mhardgrove · Post by **mhardgrove** » Wed Aug 31, 2011 3:53 pm

Popped into Sportique in Englewood, CO yesterday and asked about jetting for altitude, as my buddy is from sea level.

Clerk told me they send the scooters from the factory with jetting set to one standard, and they don't need to be re jetted for the altitude differences.

So, was the clerk correct? I don't really know much about carbs, but I do know we have close to 20% less oxygen a mile up. I guess I can read the plug to see if I'm running to rich or lean and go from there.

Legitimate Mustard · Post by **Legitimate Mustard** » Wed Aug 31, 2011 4:38 pm

The clerk was not totally wrong, but also not right. Your scooter will run without rejetting, but it could run better.

Tocsik · Post by **Tocsik** » Wed Aug 31, 2011 4:42 pm

I go to Sportique in Denver and what they told me is that the stock jetting is just a little bit rich.
so, when I added the Prima pipe, they said I didn't need to re-jet.
My spark plug visual inspection tends to agree.

jijifer · Post by **jijifer** » Wed Aug 31, 2011 6:26 pm

my buddy runs slower over 4K ft and is ridiculous at 7K or higher. See how it runs compared to what you were used to.

At 4K ft I see about a 5mph drop in WOT. At 7kft I start to get the coughs and hiccups and WOT drops to about 45mph. When I hit 8K to 11K, my WOT from 30mph to 20mph and you couldn't even hear my pipe. If it wasn't for my scooter moving forward, I probably would have thought it died.

In Denver you're already over 5k. Do you see you buddy running different?

Silver Streak · Post by **Silver Streak** » Wed Aug 31, 2011 7:17 pm

Even if the jetting were optimized for whatever altitude you're dealing with, your scooter will still be down on power compared to sea level, and it gets worse the higher you go. There is simply less energy in each charge of the cylinder, even if the mixture is perfect.

PeteH · Post by **PeteH** » Wed Aug 31, 2011 7:45 pm

Yet somehow, piston driven aircraft managed to Jump the Hump in the Himalayas in WWII.

I would contend that a less-restrictive air side (filter, box, etc., a scoop maybe??) would be needed for prolonged high-altitude operation, but far more 'energy' comes from the fuel rather than the air. High-altitude aircraft had superchargers to blow in more air, increasing the amount of compressed air trapped in the cylinder after the intake valve closed to ensure enough for proper combustion rather than conventional (scooter) engines that can only one cylinder volume (say, 150cc or so) at ambient barometric pressure.

So yeah, there's a high limit for our engines at altitude, but there are measures like derestricting the airflow that might help.

Syd · Post by **Syd** » Wed Aug 31, 2011 8:01 pm

viney266 · Post by **viney266** » Wed Aug 31, 2011 9:55 pm

PeteH wrote:Yet somehow, piston driven aircraft managed to Jump the Hump in the Himalayas in WWII.

I would contend that a less-restrictive air side (filter, box, etc., a scoop maybe??) would be needed for prolonged high-altitude operation, but far more 'energy' comes from the fuel rather than the air. High-altitude aircraft had superchargers to blow in more air, increasing the amount of compressed air trapped in the cylinder after the intake valve closed to ensure enough for proper combustion rather than conventional (scooter) engines that can only one cylinder volume (say, 150cc or so) at ambient barometric pressure.

So yeah, there's a high limit for our engines at altitude, but there are measures like derestricting the airflow that might help.

^^^^ So you "re with me? Its time to supercharge a scooter!!!...Now where to find a blower small enough LOL...

jrsjr · Post by **jrsjr** » Wed Aug 31, 2011 10:20 pm

viney266 wrote:So you "re with me? Its time to supercharge a scooter!!!...Now where to find a blower small enough LOL...

It's not rocket science. There's already a production blown scooter. Meet the Peugeot Jet Force 125.

mhardgrove · Post by **mhardgrove** » Wed Aug 31, 2011 10:44 pm

Actually haven't started the scooter yet, hooking up the fuel lines shortly and will see how it's runs. I will just keep an eye on the plug and adjust the jetting if needed. It would be funny to see a supercharger on a Buddy.

HowHH · Post by **HowHH** » Thu Sep 01, 2011 1:42 am

jrsjr wrote:It's not rocket science. There's already a production blown scooter. Meet the Peugeot Jet Force 125.

Peugeot seems to make a really nice scooter. I come across them on youtube and online every once in a while and they come across as well designed machines. We'll probably never see them here however.

PeteH · Post by **PeteH** » Thu Sep 01, 2011 2:46 am

Well, you know what they say on Car Talk: "Once you own a French car, nothing worse in life can happen to you."

I wonder if that applies to French bikes.

<<<<-------- former owner of three Renaults.

HowHH · Post by **HowHH** » Thu Sep 01, 2011 1:59 pm

PeteH wrote:Well, you know what they say on Car Talk: "Once you own a French car, nothing worse in life can happen to you."

I wonder if that applies to French bikes.

<<<<-------- former owner of three Renaults.

Years back, when they still sold French autos here, some of my friends had French cars. The Peugot was funky looking for the time, had controls in unexpected places, but ran well and seemed to be reliable. The Le Car, however, almost seemed to rust away overnight.

PeteH · Post by **PeteH** » Thu Sep 01, 2011 2:11 pm

Heheh - we had a Le Car, which my wife just loved, a Fuego which was my beast, then an Alliance convertible, probably one of the last ones on the road. They were everywhere, then seemed to disappear all at once.

Th17kit · Post by **Th17kit** » Sat Jun 15, 2013 4:50 pm

This is an old thread but I was looking into altitude adjustments for my Buddy 150 which I bought and Sportique in Denver. I assumed they prepped it for altitude but I've never checked. Some folks here say the 90 stock jet will run a bit rich here but I don't know/have never looked to see for myself. However I have always gotten about 60-65 mpg which seems really low so I wonder if that's due to the jetting being rich.

I've taken the scooter up to Echo Lake Lodge on Mt. Evans numerous times, and over Loveland Pass (Continental Divide!) twice and I've never even noticed a difference in performance. With all the altitude talk I'm finding on here I feel fortunate that my Buddy seems to do fine with whatever high altitude situation I throw at it.

I have a Prima pipe arriving soon and from what I gather I don't need to change any jetting with that either - maybe it will even improve my mileage if it makes the engine run leaner. I had no idea living at altitude was so great for the Buddy

avonpirate · Post by **avonpirate** » Sat Jun 15, 2013 11:05 pm

I live at 7,000 el work at 8050 el. I have a 1.5 mile uphill climb with a 1500 el gain. I have nothing to compare with. I get up to 65mph on Hgwy 6. On my final climb to work I average 40mph and it is a steep category climb. I am averaging 105 mpgal.

And that's all she wrote.....

Modern Buddy

Jetting for altitude, shop said no big deal...

Jetting for altitude, shop said no big deal...

High altitude experience