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Post by kaczor on Sept 14, 2007 11:22:06 GMT -5
I've been busy with various modifications of my scooter.  Here's what I have learned over the last couple of months: 1) There seem to be a correlation between the size of the head valves and the optimum sizes of the intake/exhaust. 2) The stock 19mm carb and the stock 20mm exhaust are well matched for the stock head with 17mm intake/exhaust valves - regardless of the engine size (50cc,72cc,82cc) 3) The stock 150cc 24mm carb is a good match for the aftermarket head that has 21mm intake/17mm exhaust valves. Here are various combinations that worked well for me: | engine kit | head | carb | intake | top speed | | 50cc | stock | 19mm,85main,35pilot | stock restricted | 34mph | | 50cc | stock | 19mm,88main,35pilot | stock derestricted or free flow (no difference) | 37mph | | 72cc | stock | 19mm,88main,38pilot | stock derestricted or free flow (no difference) | 42mph | | 82cc | large | 19mm,92main,38pilot | stock derestricted or free flow (no difference) | 47mph | | 82cc | large | 24mm,95main,38pilot | free flow | 51mph |
Things that did not work well for me: - 24mm carb on 72cc kit and stock head - most likely due to the too small intake valve
- after market exhaust on any kit - most likely due to the too small exhaust valve on both stock and larger heads
- derestricted stock intake on 24mm carb - the 24mm carb definitively likes the free flow filter better.
- MRP 28mm intake manifold - too large even for the larger head/carb combo
- Any sort of tubing between the 24mm carb and intake filter. You have to have the aftermarket filter connected directly to the carb. The additional tubing unfortunately slows down the velocity of the incoming air too much and the vacuum developped goes to pieces. With any tubbing I had to use a 200!!! main jet just to get it to run without hiccups, and there were still some.
Final parts list and where I got them from: - 82cc kit with larger head and cam $260 with shipping - ebay store Autotech355 Performance Parts
- 24mm GY6 carb $50 with shipping - ebay store gy6partsoutlet
- 24mm parts to fit the carb: GY6 Stock Type Intake Manifold, GY6 Intake Manifold Gasket, GY6 Intake Manifold Insulator, MRP Low Restriction Air Filter 48mm, Replacement Throttle Cable - $60 including shipping from Oregon Vintage
- 95main, 38pilot jets - $20 (less if you use aftermarket versions) including shipping from motorcyclecarbs.com
So for a grand total of $390 50mph is achievable. Learn from my mistakes don't buy anything else that will not work. I did recuperate some money back by re-selling the 72cc kit and the aftermarket exhaust, mrp intake etc, but I still lost money on those. Also I live near sea level, so those jets work well for me. I can't guarantee they will work for you, but those are a good starting point. The stock 24mm (150cc OEM) carb comes with 107main and 35pilot, neither worked for me BTW. Also I had to lower the needle (to deliver less fuel) by one notch. |
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Post by hillbilly on Sept 14, 2007 12:17:15 GMT -5
Really nice post. How do you like the acceleration and throttle response of your current configuration? Any idea what rpm you are achieving? |
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Post by kaczor on Sept 14, 2007 15:36:15 GMT -5
Really nice post. How do you like the acceleration and throttle response of your current configuration? Any idea what rpm you are achieving? This is with 5g weights 0-30 in no time - I can probably out-accelerate a lot of cars 30-45 - I can keep up with most cars on the road 45-50 - a long time. ;D tach shows ~8000 until about 45, creeps up to 9000 at 50 - this is the build-in Chinese tach, so I can't guarantee it's accuracy unlike the GPS measured speed. |
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Post by Enviromoto on Sept 16, 2007 23:35:54 GMT -5
Very nice post, karma for you. ;D
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Post by Enviromoto on Sept 20, 2007 18:32:41 GMT -5
Did you happen to change the rollers or clutch springs?
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Post by Daniel Wyatt on Sept 23, 2007 16:57:07 GMT -5
Thanks for this post! Karma for you.
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Post by Admin on Sept 23, 2007 17:06:16 GMT -5
Great post.
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Post by 90GTVert on Sept 24, 2007 8:16:34 GMT -5
Good post. Should be very helpful for 4T 50cc owners. Kinda sad though, my 2 stroke 50cc did about 52mph top speed bone stock.
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Post by Daniel Wyatt on Sept 26, 2007 0:09:57 GMT -5
I think this should be sticky really.
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Post by riker140 on Oct 7, 2007 17:16:49 GMT -5
excellent presentation and a very good work. I wish I could have done so well in presenting my information. a karma for you.
Dave riker140
P>S> to those who can't understand why we take small cc engines and make them do more than anyone else. Let's just look at the guy's with riding lawn mowers; they race them now and the guy's with small garden tractors they have tractor pulls. So you just stay with your 125cc or 150cc or 250cc and shake your head at us guy's that love a challenge. "Take something small and make it bigger than any thing it's size or you size too!"
I smoke a 250cc stop light to stop light. with a 72cc
Again you did a very nice service to all the members of the forum.
Dave Riker140
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Post by Enviromoto on Oct 7, 2007 18:15:49 GMT -5
Not to mention we dont need a special licence or insurance.
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Post by Aaron on Oct 7, 2007 19:48:48 GMT -5
Great post and as such I stickied it. May find a better place for it in the future. kaczor great work and please keep contributing.
Aaron
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Post by 90GTVert on Oct 8, 2007 11:12:30 GMT -5
P>S> to those who can't understand why we take small cc engines and make them do more than anyone else. Let's just look at the guy's with riding lawn mowers; they race them now and the guy's with small garden tractors they have tractor pulls. So you just stay with your 125cc or 150cc or 250cc and shake your head at us guy's that love a challenge. "Take something small and make it bigger than any thing it's size or you size too!" To be fair, the 150s are kinda in the same boat as us 50s. They aren't exactly over-powered either. In my state at least, they are meant to be motorcycles, not scooters like the 50s. They need some help to be able to drive like a motorcycle without getting run over. I get what you are saying though, I enjoy small engines for the fact that I can tinker without spending TONS of money. A cheap 70cc cylinder on my 50, that's hardly more than the cost of an oil change on my Mustang. Kinda cool to have fun without breaking the bank... unless you really wanna, and that options out there too. I smoke a 250cc stop light to stop light. with a 72cc As long as those stop lights aren't too far apart.  |
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Post by riker140 on Oct 8, 2007 17:14:32 GMT -5
No that 150 had me for about 1/2 the way but when I hit 10,200RPM
it' over
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Post by Daniel Wyatt on Oct 21, 2007 19:53:50 GMT -5
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Post by Enviromoto on Oct 24, 2007 19:16:38 GMT -5
I would go for Baotain because its a complete kit and comes with everything you need no B.S. However I'm not real shure about the conversion rate so you tell me which one is cheaper but the baotian would get my $.
As far as the intake and 150cc you will have to jet the 150cc carb way down and for the money I would just upjet my stocker to a #90 and run a UNI intake. Then you can make your scooter quicker by ajusting the transmision and tune in other areas like a performance CDI and Coil.
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Post by Daniel Wyatt on Oct 25, 2007 13:22:45 GMT -5
Thanks for your input! The baotian would cost about $238. The one from partsforscooters (including the seperate head) would be about $230 + S&H. So there's really not much price difference. But the baotian comes with the cam, the other doesn't. I think i'm gonna be goin with the baotian. Thank you!
Hmmm. Yes I see. I already have a UNI filter. So I guess I could just rejet the stock carb. I think I will.
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Post by keith4scoot on Oct 25, 2007 17:23:44 GMT -5
Thanks so much for this write up. I bought a vespa looking "retro" scooter from a guy who said it was a "50cc with special valves". It's gone 50mph since I got it. I just learned it has the 150cc carb on it. I wonder if it also has been converted to 82cc...
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Post by daddyeby on Oct 25, 2007 21:59:14 GMT -5
I would say its a least a 72cc if not a 82cc I don't the the info on the carb is correct but I could be wrong.
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Post by 2Down on Nov 5, 2007 3:49:25 GMT -5
This weekend I was able to improve my EVO Roadrunner Classic 50cc from a top speed of 32 to a top speed of 46 on the level confirmed with a gps. All I did was to remove 3 of the 6 rollers in the clutch. The engine whines out a little more at low speeds, but doesn't seem to complain too much at top speed. Now, it's a comfortable ride anywhere in our city. At 34mph it was too slow for many of the roads and I had cars lining up behind. Now it hangs with traffic nicely, and since it has the same front disk brakes as the 150cc model, it stops well too. I have another 50cc scooter with drums front and back, and it's inability to stop quickly is a bit unnerving. I'll be checking the mileage over the next few weeks.
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Post by daddyeby on Nov 13, 2007 22:10:49 GMT -5
2Down I can give you a tip on your drum brakes that may help you out. If you take the wheel off and look at the cam that pushes the shoes apart you may find that you are toward the end of the useful travel of the cam even with new shoes. You can make a shim to wrap around the locator pin at the bottom of the shoes out of steel that it will take up most of the slack. I used a band on a drive in cement anchor. It improved the braking on my scoot greatly. Before the shoes had been only contacting the drum on the very top.
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Post by jstr on Dec 21, 2007 14:25:47 GMT -5
This weekend I was able to improve my EVO Roadrunner Classic 50cc from a top speed of 32 to a top speed of 46 on the level confirmed with a gps. All I did was to remove 3 of the 6 rollers in the clutch. The engine whines out a little more at low speeds, but doesn't seem to complain too much at top speed. Now, it's a comfortable ride anywhere in our city. At 34mph it was too slow for many of the roads and I had cars lining up behind. Now it hangs with traffic nicely, and since it has the same front disk brakes as the 150cc model, it stops well too. I have another 50cc scooter with drums front and back, and it's inability to stop quickly is a bit unnerving. I'll be checking the mileage over the next few weeks. I was wondering how the 3 roller setup was holding up. I thought about trying this also ... |
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Post by indy50 on Dec 22, 2007 10:46:01 GMT -5
Im workin on it. 48mph without a bore kit. Heres what works for my lil roketa: 88 main jet, uni freeflow filter,gutted stock pipe,Dr pulley 5.5sliders,Bando hi output coil&no rev limit CDI,Iridium plug, valves set at .002intake&.003exhaust. It is a project in the works ;D BTW: I weigh 170
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Post by riker140 on Feb 24, 2008 21:33:06 GMT -5
Hay! any one who has done an upgrade to the 82cc or 80cc did the rejet and the free intake--Tell me how your scoot has done? Pleasae
I want to do it.
Dave Riker140 the real old fART --YEH MY 72CC DID A LOT TILL I BURNT IT UP SO i WANT TO TRY 82CC/80CC OK
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Post by motomech on Feb 25, 2008 19:19:40 GMT -5
Why not a two-stroke. Like duh.
But a very cool post, I would give him a Karma, but I think he is getting too big-headed.
Motomech in Costa Rica
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Post by 2Down on Mar 16, 2008 0:19:52 GMT -5
Sorry it's been a while since I've been on the forum. I've been ridingmy Kymco 250 all winter, but didn't take my 3-roller-modified 50cc out until gas hit $3.30/gal. Last weekend I took my 50cc, and gps and went for a ride all over Eugene, Oregon. I rode over 70 miles and had average mileage of 72 MPG. Not nearly the 100+ it's supposedly rates at, but it does run at about 45mph. It really winds up from a stop and doesn't accelerate as fast as it did with all 6 rollers, but soon evens out at high speed.
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Post by ireland2004 on Apr 22, 2008 12:35:24 GMT -5
Sounds good, a cheap mod with results... Although I'm kinda in the boat of wanting good acceleration myself.
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Post by fastasssr20 on Apr 23, 2008 22:15:58 GMT -5
where was this post when I was playin with my 50cc. great post +1 for you sir.
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Post by motomech on Apr 23, 2008 23:45:07 GMT -5
Yeah, it's a great post that I refer folks to on a regular basis
Unfortunately, this was Kaczor's last post and he has not been back since.
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Post by kaczor on May 2, 2008 15:42:20 GMT -5
Ok, have no fear, I'm back after a long winter break and about 600 additional miles. Changed the oil and my scooter is still driving strong. It's still fairly cold and I put in a 100 main jet. I also moved the needle to the top most position (highest fuel) to get rid of hickups in cold weather.
One long term observation - I seem to be going through rolling weights like there was no tomorrow. The average lifespan of my weights is about 250-300 miles. It looks like this much power does put a strain on the transmission. The belt of all things is lasting longer - about 500 miles or so.
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Here's what I have learned over the last couple of months:
