Scooter won't go past 6000 RPM when riding By t84a (Read 13,901 times)

[JoeyBee]

The member's library under air, fuel carb. A very good guide. The library has a bunch of very good information. I can spend hours reading stuff in it.

scooterdoc.proboards.com/thread/7678/2ts-carb-tuning

[JoeyBee]

Jan 16, 2015 7:07:43 GMT -6 t84a said:

Jan 16, 2015 6:56:58 GMT -6 JoeyBee said:

It is going to be a combination of both the carburetor and variator weight. At stock my 150cc wouldn't pass 6000RPMs. No matter what.

But first after installing a tunable carburetor, rejetting, and following Alley's guide it raised to 7000RPMs. Next I changed my weights from 13grams to 12grams, I top out just below 8000RPMs. I am very happy with the results and how she runs.

Well, I'm not just looking to raise the RPMs. I need more top speed. It accelerates fine. I upgraded to a better carb so I'm not sure what rks is implying. 

Where is this "Alley's guide"? 

And in a very simplified way, higher RPMs will help with a higher top speed. But the increase in RPMs has to be balanced with the gears. For my 150cc 8000RPMs seems to be the tipping point of optimum performance and power loss. That's why my tuning goal was to reach just below 8000RPMs.

Below are dyno results for a Honda CBF150, but is a very good illustration of the principle.

[dmartin95]

Jan 16, 2015 7:07:43 GMT -6 t84a said:

Jan 16, 2015 6:56:58 GMT -6 JoeyBee said:

I upgraded to a better carb so I'm not sure what rks is implying. 

Did you swap the carb out with the same size carb? Did you change any jets? 

When you swap out carbs, you can change the air/fuel ratios if you didn't stay in the same size. And, just because it's "new" doesn't mean it's tuned for your scooter.... 

If you increase the fuel, it should go without saying you should also improve the breathing.... As we inhale, we must exhale so of course you need less restrictive exhaust to take advantage of your upgrade...

Then again, you could've just stayed the same size and by "better" you mean name brand vrs generic??

Putting a carb on that is the wrong size or improperly tuned will stop you from hitting hi RPM's because it's being flooded with too much gas Because it's pumping too much gas in your cylinder.  Because your getting nice RPM's on the stand, and low RPM's under load it could very well be your carb and not your drivetrain. 

[t84a]

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.

[Bashan]

Maybe I missed it but if there's some question about the CVT working right did you pull the CVT cover, put it on the center stand, and make sure it's operating correctly? Is the front inner pulley advancing all the way? Is the torque spring allowing the ratios to advance? Get a vid of the CVT in action so we can see what it's doing. The fact that it will crank 8K on the stand may rule out ignition but not fuel. It might do 8K no load at one fuel delivery but under load would need more fuel.

[t84a]

[Alleyoop]

Weights are to heavy notice how high the belt travels with very low rpms then when it gets to about 3/8 from the top is when it picks up some rpms.
Alleyoop

[t84a]

Thanks. I'll take it apart tomorrow and weigh them.

[Alleyoop]

You probably would want anywhere from 10-12 gram weights in there. It probably has 13 or 14 gram weights in there. But 150s run good with anywhere from 10-12 gram weights all depends on your motor and also how you like to ride and the rpms you want to run at.

[dmartin95]

I'm not a scooter mechanic, but I've watched a few belts climb before and his seems to be running the ramp just fine and I see nothing in that video that would indicate his RPM's are going to take a hit under load....

Also, it sucks that I have to add a disclaimer like this, but sometimes people can take a question as if it's a challenge to their answer/post... But I'm on here to learn.

t84a's drive train vid shows me nothing that would indicate he's going to take a hit on his RPM's under load. Can someone please explain it to me (again)?

[Bashan]

Discussion around here can be abrupt but I don't think anybody is being argumentative. I'd like to see some weights on these rollers but at this point I gotta agree with Alley that it looks a little hinky. Let's hold off with the fireworks until we get some data. Nobody is getting contentious at this point and we will not go there regardless. Everybody on board with that? Great. Rich

[Guitarman]

How much do you weigh? You DO know that any bike will not develop the full power on the road that it does on the table right....?

[dmartin95]

Jan 16, 2015 21:18:04 GMT -6 Bashan said:

Discussion around here can be abrupt but I don't think anybody is being argumentative. 

Yeah, my post may have came off the wrong way.... I'm not saying alley's arguing, I'm saying I hope he doesn't feel like I'm trying argue with him.... What he is saying doesn't make sense to me I would like a further explanation, .... 

[Bashan]

Understood, it's all good and we're all friends. Now where the hell is Alley!?

[Alleyoop]

Hard to explain Martian you also have to know how a motor sounds and how the rpms rise and fall on a properly setup motor. So watching his video and listening to the motor and the rpms it is making at any one point and watching where the belt is at tells me IMO that his weights are to heavy.

When the weights are to heavy the variator will push the belt into the high ratio part of the variator to soon and not allow the motor to build rpms. Its like a manual stick car put it in 2nd or 3rd gear and step on the gas and it will be slow. Most people would watch the video and say the same thing, I see nothing wrong the variator is moving in and out and the belt moving up and down. But they are not familiar with how a motors rpms should rise and fall, they are just happy the motor starts and runs. Actually I can tell you whether a motor is running a little rich or little lean just by the sound the muffler makes. You have to have been around motors to know some of this stuff and there is no book that explains it you have to have experienced it.

RICH, you got to let folks know what they call me, SCOOTER GOD, CARB WIZARD and THE BOMB.

You can call me anything you want just don't call me SUE or LATE FOR LUNCH..
Alleyoop