2012 Super 8 - Powerband and carb tune

[netlag]

Since doing the exhaust, and air box / snorkel removal mods thought to start fine tuning the carb to squeeze what I can out of the current setup.
Also, installed a micro tach to help evaluate any adjustments.

Observations:

Idle RPM is 1850 to 2200 (when warm)
Idle RPM is 2200 to 3k+ (when cold and on center stand)

0-15 mph WOT 3800 +/- RPM
15-25 mph WOT 7200 +/- RPM
25-29 mph WOT 6800 +/- RPM
29-32 mph WOT 7400 +/- RPM
32-36 mph WOT 7600 +/- RPM
36-38 mph WOT 7800 + RPM

Max RPM is 8670

Imagine that the powerband is around 7k after seeing those numbers; does 7k sound right for a 50cc, or KF10AA motor?

Am planning to up-jet ... especially hearing how much air is being sucked into the airbox now. But, then again...
       
          Do I want to be instantly powerbanding at 0-15 mph (3.8k RPM ) on a daily driver?

          Would the lower rev at 25-29 mph (6.8k RPM) be increased if I did?

Lastly, is it consistent to say that for low end powerband entry I am going to need a roller / clutch adjustment?

[netlag]

bump

[netlag]

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[mclark999]

What exhaust mod did you do?  If you opened the airbox, you need to put in a larger main jet or risk blowing up your scooter.

[netlag]

What exhaust mod did you do?  If you opened the airbox, you need to put in a larger main jet or risk blowing up your scooter.

Down pipe / EGR on stock.

Only removed the snorkel out of the airbox; seemed removing it did nothing...except make more sucking sound. Got tire of hearing it, so put it back in.

As to main jet ... Is it consistent to say that if the scooter was experiencing a lean condition that would brick the engine... the carb's air-mix screw would be nearly screwed loose at this point to compensate at lower then WOT?

[mclark999]

Down pipe / EGR on stock.

Only removed the snorkel out of the airbox; seemed removing it did nothing...except make more sucking sound. Got tire of hearing it, so put it back in.

As to main jet ... Is it consistent to say that if the scooter was experiencing a lean condition that would brick the engine... the carb's air-mix screw would be nearly screwed loose at this point to compensate at lower then WOT?

The air screw really only affects the idle and up to a quarter throttle. It sounds like your issues are when you go past quarter throttle. That's your main jet and circuit. If you put the snorkel back in, your meeting should be fine. It may just need another can cleaning

Sent from my VS988 using Tapatalk

[netlag]

The air screw really only affects the idle and up to a quarter throttle. It sounds like your issues are when you go past quarter throttle. That's your main jet and circuit. If you put the snorkel back in, your meeting should be fine. It may just need another can cleaning

Sent from my VS988 using Tapatalk

Thanks for the reply.

This is more of a question vs issue.

Thanks for the confirmation... read before that the main-jet kicks in past 1/4 throttle.

With that, wouldn't it be consistent to say that a deficient main-jet would cause a problem past 1/4 throttle and all the way through the powerband?

Again, here is example of rev and mph at WOT:

0-15 mph WOT 3800 +/- RPM
15-25 mph WOT 7200 +/- RPM
25-29 mph WOT 6800 +/- RPM    <<<<<<<<<<<
29-32 mph WOT 7400 +/- RPM
32-36 mph WOT 7600 +/- RPM
36-38 mph WOT 7800 + RPM

Anyways... would a main-jet, or circuit issue cause a dip in revs, but still allow rev increase as noted?

Or is this possibly a BOSS, variator, clutch deficency?

[mclark999]

You are on the right track thinking it's a variator issue. Except for the low rpm from 0-15 mph, the rest seems okay.

So when you are first taking off, your scooter is really bogging down? How is it on a steep hill?

[Chris0381]

He did an airbox mod including removal of the snorkel. I can testify the air box is not very but ultra sensitive to opening it up to allow more air in. I think this could be an issue that the holes made in the airbox are just a bit too big..

[netlag]

You are on the right track thinking it's a variator issue. Except for the low rpm from 0-15 mph, the rest seems okay.

So when you are first taking off, your scooter is really bogging down? How is it on a steep hill?

Not really bogging, but just not that responsive. Limited to 4k rev until after 14 mph.

Yes, same situation where roadway-upgrade is a concern. Lacking trig skills ... I estimate the bridge ascents around here at 15-20 degrees max for 50 feet, or so.

Surmised that performance is just a limitation of a 50cc motor's hp/torque when increased angle was introduced. Figured that even if top-end speeds on upward roadway angles are normally limited to 28mph, but still reaching max rpms (7.8-8.6k) ... there is no issue.

So, suppose I just need to put some different weights in to get a little better bottom-end responsiveness?

[netlag]

He did an airbox mod including removal of the snorkel. I can testify the air box is not very but ultra sensitive to opening it up to allow more air in. I think this could be an issue that the holes made in the airbox are just a bit too big..

Snorkel removal vs drilling MOD.

Tuned to what I could with the OEM jet. Figured I was going to have too much air to compensate for by drilling, or cone filtering.

Noticed that I had almost two more turns on the air screw before it would be "wiggly" loose. Thus under-jetted.

Have since put the snorkel back in and re-tuned the carb.

Did seem to getting from one to three mph more top-speed with the snorkel out, and the carb tuned with OEM jet.

[Chris0381]

Opened up my box also and it would initially bog big time then speed up. I closed the box back up ever so slightly and its was smooth again. Running a 90+  jet, I don't remember which exact jet I'm running

[netlag]

Opened up my box also and it would initially bog big time then speed up. I closed the box back up ever so slightly and its was smooth again. Running a 90+  jet, I don't remember which exact jet I'm running

Ah, okay. For me it seems that I can still use the OEM jet ((99101-116-0700)#70)) with the exhaust mod,  and could also use it after snorkel mod with some fine tuning (gain of 1-2 mph).

Will keep 90+ jet in mind if drilling, or moving to a cone.