Scooter won't go past 6000 RPM when riding By t84a (Read 14,983 times)

[jerryscript]

Alleyoop would you say there's a golden ratio? For instance, should the RPMs be reaching around 4k at halfway up the variator, 5-6k at 3/4, and 7-9k up to the top?

I've tuned my 50cc by feel, and have yet to do a variator travel test with a marker like I should have long ago. My new 150cc, I'm going to be ordering sliders for soon, and want to do the marker test first to see which way I should go. From there, I would like to fine tune it as you are suggesting, and after that I can adjust to my preferred feel as before, but this time know a proper base to be working from. BTW- the 150cc is staying between 3-5k on the below 45mph rides I've taken it on so far. What I'll be tuning for is a bit more low-mid range response to tide me over till I decide if I need a BBK, not worried about top end.

[rks]

Jan 16, 2015 9:51:45 GMT -6 t84a said:

Thanks. I understand that. Your dyno has nothing to do with speed (mph). I have 2 motorcycles so I'm on board with that. The engine revs to 8k+ under no load so that should rule out fueling and ignition. Its either the driveline or simply doesn't have sufficient power. I'm going to pull the CVT apart this weekend. Thanks for the replies.

I believe your assumption is wrong. If you can reach 8000 rpm on the center stand, that would eliminate an ignition component (speed limiter and such), but doesn't mean your carburetor is right. The amount of fuel being used to attain that rpm with no load, is probably 1/4 (or less) of the amount needed when there is a load on the engine.

Your problem may be in the variator.....but you can't rule the carb out, or any of the other fuel delivery pieces, just because it will rev up with no load.

[cyborg]

No more $20 words ok good doctor? you're confusing the rabble,,,otherwise i'll turn the hose on ya

[t84a]

The rollers weighed in at 12.8 and 12.9g. I'm curious from those in the fueling camp what they think is out of whack. I'm on my second (upgrqded adjustable) carb and the scooter starts, idles, accelerates, and runs fine. I'm going to try to fit my pod filter today but need to find some hose and some pipe. I'll call a local scooter shop to see if they have any rollers.

Edited: after some thought and familiarizing myself with the cvt, I'm going to ride it for a while before I do anything to the variator. It seems that in order to gain top speed, I really have to change gearing, which rollers won't accomplish. Rollers just change the speed of expansion. Hopefully I can improve things a bit with the pod filter and carb adjustments. 

Thanks again for the replies    

[Alleyoop]

Just like I said your weights were probably 13s or 14s grams. Those are 13 gram weights in there you will do much better with 11s or 11.5 or 12s. Remember for every gram up or down you will change the rpms by 500-600. So knowing that you can go to 11s and gain approxomate 1000 more rpms WHICH by the way will put you in the POWER BAND where the motor makes it's most horsepower which is around 7500 rpms.
Alleyoop

[tvnacman]

Ken I'm with Alley on most of what he posted , in post #29 the last two lines I'll call him late for brunch . If the carb you changed is the one you got from me it is slightly lean on a 150cc . Your larger displacement=larger jetting . Alley nailed your variator weights , your belt rises quick and steady lighter weights will require more RPM to close the variator , more rpm to make the belt rise=more tork .

Have you done a valve adjustment , your cam markings are different then a 50 or 150cc .

I think we all missed something here (I may have asked you on the phone) what do you weight that effects a lot .
the pod filter will lean the a/f mix even more .

John

[t84a]

Why would you knowingly sell me an incompatible carb? We spoke on the phone before I ordered it. So I need to re-jet? To what size? The valves were and are fine. How will lighter rollers translate to a higher top speed? The local scooter shop told me to not expect more than 55 and said the whole roller weight thing was more for the 50cc bikes because they lacked torque. I weigh 170.

Thanks for the replies.  I think we're chasing two different objectives though. 

[rks]

Someone in an earlier post tried to send you in this direction. I second the motion.......please, please, please read this.

www.scooterfocus.com/scooter_carburetor_rejetting.html

[t84a]

I'll have to wait for John to tell me what jet came in his carb.

[Alleyoop]

What size carb did you buy?
150cc motors come with a 24mm carb or 26mm carb mostly 24mm. The Jets are usually 35 for the pilot jet and anywhere from 103-107 for the main jet.

Upjetting a carb is a trial and error process, you have to match fuel and air which depends on what type of air filter you have on there and how much air it allows in so just about every motor and scoot is different, What might work on one may not work on another.

A good rule of thumb for jetting a carb is as follows:
If you add a free flow Filter you go up on the MAIN JET by 2 sizes.
If you add a free flow Muffler you go up on the MAIN JET by 2 sizes.
So if your stock main is say 105 then stick a 110 main jet. Now this is just a good starting point depending on the motor and how things are setup a 110 may be to much fuel or on the other hand it can handle a little more so maybe a 112 will perform better some will even take up to a 115. It all depends on the motor how much compression it is making and the ignition system.
Alleyoop

[rks]

I didn't ask you to buy something.....just to read something, and gain a little understanding of how a carb works.

[t84a]

I just pulled the bowl off the stock carb since it was just sitting in a box. It has a 108 main. Both the stock and new carbs are 24mm. I'm curious to find out what jet the new one has.

[t84a]

Jan 17, 2015 15:58:00 GMT -6 rks said:

I didn't ask you to buy something.....just to read something, and gain a little understanding of how a carb works.

Lol. Who are you talking to? 

[Alleyoop]

T84A,
150s top end speeds are good for 50mph or a little better. If it does near 55mph stock your lucky.

So what top end speed are you looking for and WHAT IS YOUR CURRENT TOP SPEED or at least what does the CHINO SPEEDO says. Now the CHNIO speedos usually register on the high side compared to the REAL MPH .

Also what size tires are on your scoot.

[Alleyoop]

108 main is a nice size for a stock motor that is on the high size for a stock 150.