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General => Technical | How To => Topic started by: TBR125 on April 05, 2020, 02:05:26 AM
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Generic Disclaimer:
Conditions apply. If you experience the following symptoms, speed obsession, random vehicular disassembly, or wrecking please see your psychiatrist for assistance and rehab.
Hi,
I own an Agility 125 scooter for transportation. I have always worked toward increasing performance as much as possible considering my limited budget. The following posts will outline the mods I have completed that can be done by almost anyone for free or very little cost (I am assuming time is free which for many it is not).
Current scooter.
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Soon after I acquired the scooter I began having occasional start problems and started running non ethanol fuel. On warm days the bike would die after a few seconds and then would not restart until it had sat for an hour. After research and diagnostics I found the problem was the expanding wax auto enricher. The bike ran rich from the factory and the auto enricher always gave the equivalent of full choke.
Solution: Manual Choke
$28 at the time of purchase.
https://hammerheadperformance.com/manual-choke-for-150cc?matchtype=&network=g&device=c&adposition=&keyword=&gclid=EAIaIQobChMIpb_a55rQ6AIVC5SzCh1mjgsHEAYYAyABEgKt4_D_BwE
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I was having valve float problems going down hills and needed to check rpm with a Tachometer.
I mounted it under the mirror screwed on a scrap doorbell striker bar.
Tachometer:
11$ at time of purchase.
https://www.amazon.com/Maintenance-Tachometer-Replaceable-Motorcycle-Paramotors/dp/B07PMJH7QV/ref=sr_1_5?dchild=1&keywords=tachometer&link_code=qs&qid=1586052983&sourceid=Mozilla-search&sr=8-5 (https://www.amazon.com/Maintenance-Tachometer-Replaceable-Motorcycle-Paramotors/dp/B07PMJH7QV/ref=sr_1_5?dchild=1&keywords=tachometer&link_code=qs&qid=1586052983&sourceid=Mozilla-search&sr=8-5)
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I wore flat spots in the 14g roller weights from riding on the highway with the variator fully extended for long periods. I replaced them with 12g Dr. Pulley sliders.
The valve float was from unwittingly hitting 11500rpm at 78mph:) Tachometer proved useful.
Sliders:
25$ at time of purchase.
https://www.amazon.com/Dr-Pulley-Sliding-Roller-Weights/dp/B00VUXF8W6/ref=sr_1_3?dchild=1&keywords=dr+pulley&link_code=qs&qid=1586053462&sourceid=Mozilla-search&sr=8-3 (https://www.amazon.com/Dr-Pulley-Sliding-Roller-Weights/dp/B00VUXF8W6/ref=sr_1_3?dchild=1&keywords=dr+pulley&link_code=qs&qid=1586053462&sourceid=Mozilla-search&sr=8-3)
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The Dr. Pulley slider completely changed the power band and massively increased mid range pull. I realized with the tach that the bike had sufficient power but was running out of variator range to stay at max power at 7500rpm. The drive belt was running within 1/2 an inch from the outer edge of the pulley sheaves. The hindrance to utilizing the full pulley face and effectively increasing the pulley diameter was the sheaves contacting each other at the shaft on the drive boss.
The solution was to remove material from the pulley sheave cone until the belt could reach the full diameter. The belt was 20mm and the pulley groove when compressed was 23mm. Leaving 1mm for safety I removed 1mm of material from each pulley face. I then shortened the drive boss by 2mm.
Cost: Free+4 hours sanding
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With the variator tuned the bike cruises at 7500rpm at 74.6mph. With the extra variator range power was the limit. My stock exhaust was crunched and highly restrictive. I purchased a hi flow exhaust unit because it was cheaper than I could build a baffled pipe for.
Performance Exhaust:
$24 at time of purchase.
https://www.ebay.com/c/22009506411 (https://www.ebay.com/c/22009506411)
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Here is the exhaust.
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With unlimited exhaust capabilities I am increasing air intake by installing a large UNI foam filter to the carb. The carb in the pic is not the one from the bike.
UNI Air filter:
18$ at time of purchase.
https://www.amazon.com/dp/B001KO6KS6/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B001KO6KS6&pd_rd_w=HdoPO&pf_rd_p=48d372c1-f7e1-4b8b-9d02-4bd86f5158c5&pd_rd_wg=DBnys&pf_rd_r=41ZNGA6CSMJPNC7G5TSB&pd_rd_r=1c1311ad-c03d-42b4-9168-1f21f7355272&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyNFVIRDhaMjRaN0dOJmVuY3J5cHRlZElkPUEwNTMxNTk5MlBGQzNMMURFS0RYViZlbmNyeXB0ZWRBZElkPUEwMTc0OTA3R09OMExSN0VUQkxQJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ== (https://www.amazon.com/dp/B001KO6KS6/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B001KO6KS6&pd_rd_w=HdoPO&pf_rd_p=48d372c1-f7e1-4b8b-9d02-4bd86f5158c5&pd_rd_wg=DBnys&pf_rd_r=41ZNGA6CSMJPNC7G5TSB&pd_rd_r=1c1311ad-c03d-42b4-9168-1f21f7355272&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyNFVIRDhaMjRaN0dOJmVuY3J5cHRlZElkPUEwNTMxNTk5MlBGQzNMMURFS0RYViZlbmNyeXB0ZWRBZElkPUEwMTc0OTA3R09OMExSN0VUQkxQJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==)
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I'm currently re-jetting and tuning the carb. I will update the post with future mods.
Hope some of this was helpful. Let me know if additional info is needed.
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Thanks for sharing. I was thinking about a similar variator mod as well. The only downfall I can think of is that driving belts probably need to be replaced more often - because when the belt becomes worn (narrower) the inner part of the belt might start touching the variator Shafts ?
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Really impressive! Good pictures! The variator mod makes sense. De dee is the first to do something like this on a Downtown 300i and could never understand how he did what.
You rapidly becoming the go to guru!
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Thanks. I understand the mechanical aspects but will need some advise in the future on electrical harnesses.
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Aha! That can be some of the biggest mysteries! Wiring diagrams NOT in the service manuals are very scarce. The ones that are in the service manuals tend to be incomplete monochrome line drawings. This will be fun for all! No, REALLY! Har, har!
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Thanks for sharing. I was thinking about a similar variator mod as well. The only downfall I can think of is that driving belts probably need to be replaced more often - because when the belt becomes worn (narrower) the inner part of the belt might start touching the variator Shafts ?
That was definitely a concern. I accounted for it by controlling the drive boss length which negates the effect of a worn belt.
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Good job! [emoji106][emoji106][emoji106]
Will follow this thread.
Courious to see how the jetting is gonna go!
Sent from my Redmi 4 using Tapatalk
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Hi, to any performance nut.
Has anyone mounted an Airspeed indicator on their scooter for true performance data. Would that even work in turbulent traffic air flow?
Feel free to critique/criticize.
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Does it backfire on deceleration?
Sent from my Redmi 4 using Tapatalk
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That question sounds like experience. The short answer, yes.
My bike currently runs rich and without the catalytic converter if I decel to quickly it does pop a time or two. I'm designing a baffle that should minimize the shock-wave if I can get enough pressure flow data.
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That question sounds like experience. The short answer, yes.
My bike currently runs rich and if I decel to quickly it does pop a time or two. I'm designing a baffle that should minimize the shock-wave if I can get enough pressure flow data.
I'm having the same problem.
I have an Technigas 4scoot exhaust. Bought it because the original one was in bad shape and wanted something that's legal for road use.
The engine breathes easier, but it started backfiring.
The strange thing is it didn't do it from the beginning.
Checked for leaks, couldn't find any, and changed the exhaust gasket ring, but it still backfires on deceleration.
Maybe I need to repack the exhaust...
I thought that by putting on a less restrictive exhaust the engine would tend to run leaner?
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As far as I am aware, any carbureted engine when perfectly tuned momentary runs rich at some place during decel causing backfiring in any exhaust system that doesn't have a catalytic converter. With glass pack mufflers the shorter the chamber the louder the pop. I live in an area where pick-up trucks are straight piped so my scooter exhaust is not comparatively loud.
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Hi, to any performance nut.
Has anyone mounted an Airspeed indicator on their scooter for true performance data. Would that even work in turbulent traffic air flow?
Feel free to critique/criticize.
I owned a sailboat for 35 years, and therefore have experience with wind speed indicators; in fact, I still have a hand-held model (that's the only kind I can imagine being able to install on a scooter). I would expect that the majority of hand-held units would be made for sailing, and therefore calibrated in "knots"; so, you'd have to do measurement conversions (to MPH or KPH, depending on location). By the way, one knot equals 1.151 MPH, or 1.852 KPH. Also, the range of wind speeds that are anticipated when sailing, are much lower than experienced on a scooter; for example, 50 MPH (over 80 KPH) is in excess of 43 knots. I doubt that a hand-held unit would be designed to measure accurately at speeds approaching that magnitude, since, in my opinion, most sailors wouldn't care about the details of such a blow, because they'd be too busy scrambling to find their life jackets. So, I would conclude that a practically-sized wind speed indicator would not prove useful on a scooter, but I'm quite willing to stand corrected.
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As I don't want a cup anemometer on the handle bars, I agree with the impracticality of a unit intended for general use. I have been using knots as my standard speed unit because of my work with aviation and sailing in the BSA Sea Scout unit.
Thanks for the info Fogie.
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As I don't want a cup anemometer on the handle bars,
Hand-held units don't have cups, but they're still impractical; for example:
https://www.globosurfer.com/best-anemometers/ (https://www.globosurfer.com/best-anemometers/)
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Why not use a GPS?
Sent from my Redmi 4 using Tapatalk
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I have a GPS but air resistance is what limits speed. As in 5kph tailwind =5kph faster. Knowing relative wind speed is more accurate for engine performance check.
I stripped an exhaust stud in the head and am working on it. With the muffler back on I will be ready for jetting. I should have the info from that posted this weekend.
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Hi,
The oiled UNI filter is on.
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Another picture.
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wow, just saw this thread...I seem to miss clicking on the Technical / How To section...
great mods! Your ability to do all this for so little $ is extra impressive. Can't imagine going 78mph on a scoot!
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Patience and hand tools can work wonders. My dream scoot would look like this.
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My carburetor is re-jetted! I swapped the main and pilot out a few times with test rides in between and settled on a 115 main and a .38 pilot. I will take a long ride tomorrow to finalize the tuning.
As a side note, I always expect a job to be harder than first thought, but still, the carb tuning was the most complex thing I've ever done to the bike. I feel a tad bit invincible. I will have performance data tomorrow and will see what the 56 dollars for jets, air intake, and muffler really did.
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When pulling the scooter air box I came across several breathers that I rerouted into a filtering reservoir but one hose leading into the intake baffled me. Come to find out after several hours of searching with various keywords it is a charcoal filter for the fuel vent line. After looking at what it controlled I pulled the unit and routed the vent line through the body panel above the fuel tank. It works fine and pulled 2 pounds off the bike.
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Here's the rerouted vent line.
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My carburetor is re-jetted! I swapped the main and pilot out a few times with test rides in between and settled on a 115 main and a .38 pilot. I will take a long ride tomorrow to finalize the tuning.
As a side note, I always expect a job to be harder than first thought, but still, the carb tuning was the most complex thing I've ever done to the bike. I feel a tad bit invincible. I will have performance data tomorrow and will see what the 56 dollars for jets, air intake, and muffler really did.
The original main is 105?
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Sorry I didn't mention that. The original main is 102 with a 0.35 pilot. Remember I have the agility 125 but not the city. Jets may differ slightly.
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Sorry I didn't mention that. The original main is 102 with a 0.35 pilot. Remember I have the agility 125 but not the city. Jets may differ slightly.
Thanks!
I also changed the pilot from 0.35 to 0.38 hoping that more fuel would eliminate backfires at rapid declaration, but that didn't happen.
It did get a bit easier to ride 2 up.
Fuel consumption went up as well.
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I've got the .38 pilot as well. For me the backfiring disappeared but I don't know what did it. Those jets may not be my final choice until I put some miles on the bike. What baffles me is now the bike idles super rich even with the screw maxed lean. I would think it would idle lean with the larger filter flow.
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Idle screw should be around 2.5 turns out when all stock.
Can't remember at what position mine is now.
I know that I fiddled with it when I changed the exhaust, and somehow during a ride the idle screw fell out! The scooter couldn't idle properly, but would run ok when the revs went up.
Couldn't believe that it fell off [emoji23]
So I put a new one in (luckily I had a spare one at home), and didn't mess with it any more.
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Oh, I was not referring to the idle speed screw but the idle fuel mixture screw. It is located on the engine side of the throttle butterfly valve increasing or decreasing fuel to air ratio at closed throttle. I set the idle speed screw at 1700rpm as is spec.
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Yes, I lost that screw! (https://uploads.tapatalk-cdn.com/20200414/08fb1e6642a9eb7beb6d8ca063280e2d.jpg)
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Ouch.