High Altitude Carb Re-Jetting By trancebear (Read 2,002 times)

[trancebear]

OK, so I finally found out my stock main jet size, it is a 105. The 2 big mods that I feel I need to re-jet my carb for is the Uni air filter and the exhaust. I tend to bog down until I get to speed and my spark plug is showing running lean. I bought a 107.5 and a 110 main jet. Will this be enough? What would you start with?

[Alleyoop]

Stock go with the 110, with a uni and exhaust 112.
Alleyoop

[trancebear]

Thanks for the info bud.

So as it stands I have 2 people saying it is something else wrong, 3 people say go even bigger than 110 and 1 person says go to 100. I belong to too many scooter forums. I need a consensus!

[trancebear]

I am going to go with the 110 jet and hope for the best. Damn high altitude complications. Now to figure out this whole sliders/weights and so on.

[sprocket]

Alley is the go-to guy for sliders and weights... he wrote the book on it or very close to it!

[Alleyoop]

Thanks Sprocket,

Trancebear,
Here is something I put together a while back so you have a better idea how weights and springs and gears will effect your scoot and how:
Alleyoop
CVT WEIGHTS:



The engines have pretty good torque have descent power as long as you do not go overboard.

Check your Variator first and see if Both Pulleys are the Same Size.
If the Variator itself is smaller than the Outside Pulley you can get what they call a PERFORMANCE Variator that is the same size as the Outside Pulley.
Belts will only climb as high as the Smallest Pulley.
So by having Equal Size Pulleys the belt now can be made to climb higher for more TOP END SPEED.
Also weights play a major roll on making the Belt climb higher.

Heavier weights Require Less RPMs to push the Belt up the Variator.
Lighter weights Require Higher RPMS to push the Belt up the Variator.

Roller Weights - Will Change your RPMS by 500-600 for every gram up or down.
Slider Weights - Will Change your RPMS by 200-350 for every gram up or down.

What I did is experiment with different Gram Rollers first they are cheap.
When I found the weights that I liked and at the RPMS I liked I then put in Dr. Pulley Sliders and went ONE gram Heavier on the Sliders So my Rpms would be almost the same as with the Gram Rollers I liked. So I gained just a little more top end with the Sliders due to Fact they are 1 Gram heavier than the Rollers and still the same RPMS.

Heavier weights will push the Variator out and squeeze the Belt more so it climbs higher for more top end. BUT to heavy of weights will make your takeoff and Mid-range sluggish.
Also Heavier weights will cause your RPMS to drop so you also have to watch out for that.
You want to run at or Near the RPMS the engine makes its MAX Horsepower. If it revs much higher than that the engine is Not producing any more horsepower and in many causes will loose horsepower due to floating valves etc.

Lighter weights take MORE RPMS to throw out the weights to Push Variator out to push the belt up the Variator. To Light and it will not push the belt as high as possible and you will loose top end but you will have a quicker takeoff and Mid-Range because the belt is staying in the lower gearing of the Variator longer.



TALLER GEARS IN THE TRANNY:

Changing the gears behind the Clutch to taller gears for more top end speed:

If you Change the Small Shaft that the Clutch turns by 1 more Tooth AND the Big Gear that the Small Shaft Turns by 1 Less Tooth that Drives the Output Shaft that turns the Wheel or (Sprocket with a Chain) you will gain about 4-5 mph more. For every number of teeth changed you can expect about 4-5mph more Top End Speed.

CONTRA and CLUTCH PAD SPRINGS.

Stiffer Contra Springs effects the RPMS required to OPEN THE CLUTCH PULLEY. The Stiffer the Contra Spring the HIGHER RPMS is required to open the Clutch Pulley so the Belt gets pulled down by the Variator as it climbs up Variator. So if you want your scoot to stay in the lower part of the Variator longer you put in a Stronger Contra Spring.

Stiffer Clutch Springs Require Higher Rpms to get the Pads to come out and grab the Bell to Turn Your wheel.
Stiffer Clutch Springs Also means that you have to keep the RPMS up to keep the Clutch from Disengaging. Cruising around town at 25-30 your rpms will be high at those speeds you always have to keep on the throttle otherwise the Pads will disengage from the bell.

I personally would rather have Clutch Springs that get thrown out sooner so that the Pads are grabbing the bell say around 2500-3000 rpms. And control the RPMS with just the Contra Spring and Weights.

The way a CVT should be setup is when climbing a hill say at 6000 rpms, THE RPMS should STAY at 6000 going up the hill ONLY your speed goes down. Once you get it to that point you cannot get it any better, unless of course you add more Ponies to the motor.

[trancebear]

Thanks Alley. I have read everything there is to be read about the subject (I think) but with that information I still cannot figure what size or weight of them to get. I ask for advice and get 4 or 5 vastly different suggestions based on what I am looking for (higher top speed) or based on the size of my scooter. Being a disabled Veteran I cannot spend all weekend playing with sizes and weights of these little buggers. My body just can't handle it. I have concluded that I just have to hand it over to a pro and have them tune the CVT for me. I hate that I have to let someone else do it but I have no choice, I just cannot grasp the science behind it. It is going to be extremely expensive also having someone else do all that labor. Not looking for a pity party, just stating the facts.

[Alleyoop]

I am also a disabled Nam Vet, just take you time. You will go broke if you take it to a PRO. And believe when I say this, THERE ARE no pros out there that you can take it to that know how to tune a CVT. Most of the scooter mechanics all they know how to do is Charge you 1 hr labor to replace a part. They do not KNOW HOW TO DIAGNOSE a problem let alone tune a CVT.

The first thing you have to do is Take the Variator out and WEIGH the weights that are in there. If you do not have a small Digitial scale in GRAMS take one to your post office and have them weigh it for you.

Now knowing the current gram of the WEIGHTS and the RPMS and the TOP SPEED your running at. I can help you decide which gram weights to get. I can tell you what rpms you will be running with the different gram weights and if it will be strong in the mid-range and good top end.
How does that sound my friend
Alleyoop

[trancebear]

Oct 12, 2011 21:34:27 GMT -6 Alleyoop said:

I am also a disabled Nam Vet, just take you time. You will go broke if you take it to a PRO. And believe when I say this, THERE ARE no pros out there that you can take it to that know how to tune a CVT. Most of the scooter mechanics all they know how to do is Charge you 1 hr labor to replace a part. They do not KNOW HOW TO DIAGNOSE a problem let alone tune a CVT.

The first thing you have to do is Take the Variator out and WEIGH the weights that are in there. If you do not have a small Digitial scale in GRAMS take one to your post office and have them weigh it for you.

Now knowing the current gram of the WEIGHTS and the RPMS and the TOP SPEED your running at. I can help you decide which gram weights to get. I can tell you what rpms you will be running with the different gram weights and if it will be strong in the mid-range and good top end.
How does that sound my friend
Alleyoop

That is the one thing I am going to do is find out the weight of my rollers/sliders (are they the same?) I have a digital scale that I bought awhile ago thinking I was going on a diet..lol. I have an impact wrench to get the big nut off (right or left hand threads?) and I have downloaded a video off YouTube that takes you through it step by step. I plan to replace the clutch and possibly the springs once I have everything open. I am lucky to have a racing scooter shop that has everything I need in stock. Although they hate giving free advice. Of course I would love to go all Dr Pulley and stuff with the parts but that won't work right now, my diesel truck I race needed a bigger intercooler this month. I am afraid I must just replace the parts with mostly stock for now until I can free up some funds. i am willing to give this a try and see if I can mange it. I really appreciate you helping me with what you can. Tomorrow will be installing new main jets in the carb and hopefully pull the CVT apart and see how many miles my scooter really has on it. The odometer quit working a long time ago. When I accelerate it vibrates slightly and I think some parts are really worn down. Well enough rambling for now. I must find me some time to eat. Cheers bud.

[trancebear]

Oh, the next drama with this scooter is consuming more oil than fuel. I empty the engine of oil roughly every 50 miles. Blue smoke from the tailpipe tells me oil is making into the combustion chamber but I have to find out how.

[Alleyoop]

Great you have an Impact wrench that is all you need. I have one to, I have taken my Variator and clutch of so many times I can chanage weights in 10 minutes.

Ok the Variator Nut As well as the Clutch nut or LEFTY LOOSEY, RIGHTY TIGHTY.

BAD NEWS on the oil consumption and bluw smoke out the Tail pipe, looks like your rings are shot and maybe your valve stems. You are probably looseing a lot of compression and power.
I would not spend a lot of money on a Variator right now Just maybe weights and springs to try and get your rpms up. But your going to have to get your motor sealed up first with new rings and valves. So In your case I would just wait and put on that BBK you mentioned then work on your CVT. Otherwise you may spend 50 or so bucks now and then have to spend about the same with after the BBK is in. Reason being with the BBK that will change your powerband and you will probably have to change your weights again.
Alleyoop

[Alleyoop]

You have the same engine I have 157QMJ. Before Stock I could get my rpms up to 8200 if I wanted to just by changeing the weights. I coud also get them all the way down to 6800 and any where inbetween 8200 and 6800 with weight changes.

But I was limited on the top end speed due to the GEARING I ran out of gearing on mine.
Now after I had the BBK and Stroker Crank put in I have not had it up to 6800-6900 rpms and that was with 11gram weights. I am currently running with 11.5 Dr. Pulley Sliders and at WIDE OPEN THROTTLE the MAX RPMS are 6500, but it will do 65mph.
It has a lot of Torque and gets up to speed really quick, cars behind me do not have to wait for me to get up to the speed limit.
So with a BBK you will gain a lot of torque and low end power and it will not REV UP AS high.
Alleyoop

[trancebear]

Oct 12, 2011 22:10:23 GMT -6 Alleyoop said:

Great you have an Impact wrench that is all you need. I have one to, I have taken my Variator and clutch of so many times I can chanage weights in 10 minutes.

Ok the Variator Nut As well as the Clutch nut or LEFTY LOOSEY, RIGHTY TIGHTY.

BAD NEWS on the oil consumption and bluw smoke out the Tail pipe, looks like your rings are shot and maybe your valve stems. You are probably looseing a lot of compression and power.
I would not spend a lot of money on a Variator right now Just maybe weights and springs to try and get your rpms up. But your going to have to get your motor sealed up first with new rings and valves. So In your case I would just wait and put on that BBK you mentioned then work on your CVT. Otherwise you may spend 50 or so bucks now and then have to spend about the same with after the BBK is in. Reason being with the BBK that will change your powerband and you will probably have to change your weights again.
Alleyoop

I have a hail mary pass i am going to try and my scooter needs it any way. I have heard that if your crankcase is not vented right it can also cause blue smoke so I got me an oil catch can with a real PCV valve. Right now I just have a mini-uni filter on the end of that hose tied above my engine. we'll see.

[sprocket]

Don't use a PVC valve... stick a fuel filter on the end of the hose and check the air flow through the fuel fiter every oil change...

The valve cover vent must be open and not restricted.. otherwise the pressure builds in the engine and your gaskets could fail...

What the roll weight changes do is to move the POWER BAND up and down on the RPMs. So it is really trial and error to get it to a sweet spot that is right for YOU. Weights are like big steps and sliders are half steps...

No need to change the Contra spring for street riding...