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Post by meniscus on Oct 16, 2019 7:48:55 GMT -5
So, I've been helping a friend who has one-eye and had to get a moped for transportation to work. Here's the setup:
Icebear Maddog 49cc Gen1
High flow air filter, right on carb (no tubing, just a 45 degree angle to clear throttle cable)
Casoli CDI NGK 7544 Iridium Spark Plug
Stock 19mm carb (what an absolute pain to replace ground off bolts to get to the jets and remove cap/replace fuel mixture screw with one with a spring in order to tune) Adjustable needle Stock exhaust with catalytic converter. Have not checked for restrictions.
260 lbs. rider Current tune: 94 main jet, 35 pilot jet, middle clip on needle [lowering one clip (raising the needle) causes bogging at top speed and some through the middle throttle range]
Environment: Sea Level, flat terrain Currently at 600 miles on the odometer (calculated from km)
We finally got the engine tuned well. No bogging or hesitation throughout entire power range and feels strong. Runs very close to the same on colder or hotter days in both lower humidity and high humidity.
Current performance: No hesitation starting, doing 32 mph top speed. Runs the same on the stock CDI and the Casoli.
Previous performance: On stock after break-in, it was most certainly running lean on stock jets and cap over fuel mixture screw. However, he was seeing 36-37mph top speed.
I am confused about what roller weights to start with to help him with power and top speed. It seems like after the tuning and running just a hair on the rich side, it seems to run a little slower and the rpm is clearly lower at WOT than it was running stock after break-in. I'm guessing that he is making a little more power after the tune, but I remain confused about what roller weights to choose considering he is a heavy rider at 260 lbs.
Caveat: I know that he would be best served with a BBK, but money is very tight for him and it is not in the cards for the immediate future. We will likely go to 72cc later, for reliability purposes rather than an even larger BBK, but for now, he is sticking with the current setup.
We have not opened the variator to look at the roller weights yet. However, when we buy a kit to try others, I need to make certain he has enough range to tune the variator for the current setup and also when he goes to 72cc. I don't know how to choose the right rollers considering he is a heavier rider. I'm guessing we need to optimize the rollers so that the final RPM is a little higher. I have a tachometer, but it doesn't seem to give us realistic RPM despite trying two turns around the wire or 4 turns around the cap where it mates to the spark plug.
Any help is greatly appreciated!
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Post by meniscus on Oct 16, 2019 7:59:33 GMT -5
Another question: Is there a chance that the valve clearances have tightened and need to be adjusted at just 600 miles on the odometer? Could that be our issue for the loss of top speed?
Also, what dimension rollers do we need for this GY6 4-stroke engine? I see lots of different sizes and this creates some confusion.
Most of the kits I see say for temporary use only, for tuning. Is this really the case?
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claydoh
Scoot Enthusiast
Posts: 172
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Post by claydoh on Oct 16, 2019 9:37:29 GMT -5
You probably want to purchase a roller tuning kit, which has a range of weights to help you decide which weight works best, something like this set then purchase a set of 'good' weights once you have determined what works best. I am a fat dude, down to 280 at the moment, and a 72cc kit will make huge difference down the road. My scoot is a crusty used 2014 Tao Tao that runs like a top but looks like junk, but it gets me well over 40mph. It ran slightly faster when it was running lean, so be careful, as it looks like you have been. As to which weight, that really needs to be tested to find what works best. Lighter weights mean more RPM, and better acceleration but likely lower top speed, with heavier weights giving slower acceleration, lower RPM and likely higher top speed. So you have to find the spot which the rider likes things the best, as it will be a trade off. As you have not looked at the CVT, you should be able to de-restrict it, which alone should give a little boost, give you that little extra top end as the pulleys will have more range to work with.
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claydoh
Scoot Enthusiast
Posts: 172
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Post by claydoh on Oct 16, 2019 9:42:13 GMT -5
Also, sometimes these high flow air filters make it difficult to tune the carb. I got rid of mine, and went back to the stock, but de-restricted airbox, though mostly because of the noise. There was no difference in performance I could tell.
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Post by meniscus on Oct 16, 2019 9:44:40 GMT -5
Thank you. I wasn't clear if the icebear maddog had a shim that restricts the variator. Obviously, I can use a marker to see how far up the belt rides. What I don't know is how to avoid having the belt go too far or ride too high where it will come off. Any idea how to avoid this or what precautions should be taken to make certain it doesn't go too far? I've read just about everything I can find and watched most of the videos related to this, but haven't seen an answer to this question. An additional question, how do you determine what are 'good' or high quality weights and should we stick with rollers verses the other designs that slide?
After tuning, the high flow air filter seems to work just fine, just had to adjust a lot of things to get smooth throttle response throughout. It seems happy as a clam now, better than many of the tuned hondas and yamahas I test drove while we were trying to determine which scooter to buy. We ended up with the maddog just because of the reliability and simplicity of the design as-well-as the lower center of gravity/balance since my friend only has one eye.
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Post by meniscus on Oct 16, 2019 10:42:00 GMT -5
Claydoh, did you change the cam when you went to 72cc or did you just use one of the Naraku 47mm drop-in kits?
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claydoh
Scoot Enthusiast
Posts: 172
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Post by claydoh on Oct 16, 2019 13:16:23 GMT -5
Claydoh, did you change the cam when you went to 72cc or did you just use one of the Naraku 47mm drop-in kits? I have no idea, as it was used. I am at least the third owner and it was already installed. I did just swap the cam for a cheap A9, but have not ridden it as I broke a stud changing the exhaust. It has been raining the past few days, and I don't have a dry place to work in it. I'll be pulling the head off as soon as I can, perhaps I can see any branding or markings on the jug when I do that. As to the shims, it should be safe as those are put on for markets that need speed restrictions, and left off for those regions that do not (as I understand it) so it coming off shouldn't be an issue, but I only have actual experience with this particular scooter, and it was already modified. Rollers vs sliders is preference, and a little on cost. Brand names will be better quality than Ebay or Amazon el cheapo selections, which seem to be crappy tuning-quality units. Dr Pulley seem to be the best, and Hoca are what I have bought recently, and seem durable so far. No more Ebay and Amazon parts for me, even if I am broke (which is normal lol).
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Post by meniscus on Oct 16, 2019 13:23:15 GMT -5
Considering that the variator roller kits run about $30, which doesn't seem like a lot of money to me, but is to my friend considering an additional set would need to be ordered once best top speed has been matched to the engine RPM, my more detailed question is as follows:
Considering we are dealing with a GY6 49cc motor with 39mm bore and a 41.5mm stroke, most of us agree that max power is achieved at 7500 RPM. However, max torque is commonly stated at 6500 RPM. It makes sense to me that there are many folks here on the forum who run stock 49cc engines without a BBK. Could someone weigh-in and share what weights they are currently using on their variator, running a 49cc engine?
By the same token, hearing from those who have 72cc without a cam change and what weights they use would also be helpful.
I'm inclined to believe that the output of a 49cc tuned engine, regardless of load, will likely be very similar. The question is what weights are being using by everyone to get close to the 7500 RPM at top speed?
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Post by meniscus on Oct 17, 2019 13:17:49 GMT -5
Anyone?
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Post by milly on Oct 18, 2019 1:02:35 GMT -5
meniscus I have a collection of weights can post over to you for your friend to try. Will get back to you later off to work now.
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Post by christopher on Oct 18, 2019 5:27:07 GMT -5
It might help to fill in your location in the user profile. There maybe someone near you that has weights,
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Post by meniscus on Oct 18, 2019 6:52:22 GMT -5
Thanks guys. We are in Southeast Virginia, near Norfolk, but I regularly drive up towards DC for work. I'll update my profile.
I would just buy the weights myself, but I bought the moped new and he is paying me back as he can. I'm tapped out at present. The good news is that he no longer has to walk nearly 2-hours one-way to get to the rendezvous spot to ride with his other coworkers (before the buses start running).
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Post by aeroxbud on Oct 18, 2019 15:53:30 GMT -5
The thing with roller weights, is it's hard to recommend one weight. What contra spring, clutch, can all effect this. Good luck though.
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Post by christopher on Oct 18, 2019 21:32:53 GMT -5
What size weights does it have? What is the current weight of the rollers? Some us may have spare but need to know what you have.
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Post by meniscus on Oct 21, 2019 6:43:35 GMT -5
Since the bike isn't at my house (friend drives it every day to work), I haven't pulled the variator to see what weights are there or weigh them if they are not marked. Everything in the CVT is stock at present, but can't find any place online that talks about what is stock in the Gen 1 Maddog.
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