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Post by djeeper on Nov 10, 2010 18:59:10 GMT -5
I had this in my other thread, but i feel like it was being overlooked as the title was for a different issue....so here it is again (old post deleted of course) ok, so i just saw on Scrappy's site, that he has a gear set for sale on the cheap (40 bux).  it has a tooth count of 49/17. what is this going to do to my RPM's at a set speed? say at 35mph my rpm's are 6000. with these gears, at 35 (assuming full cycle of variator has taken place) what will my rpm be with the new gears? i tried to figure out where these gears went... but i couldnt, so i cant calculate the ratio difference. any help? |
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Post by D-cat on Nov 11, 2010 10:51:13 GMT -5
These are secondary reduction gears (the primary stays the same). It didn't make sense to me at first either, so I asked Rick. What it is the sub gear in the final transmission can be separated with a hydraulic press or a punch and hammer. The large gear replaces the one on the final drive shaft and the small one replaces the inside of the sub gear.
The stock gearing is first step 3.21:1 and second step 52/15=3.47:1 for a total of 11.12:1.
For comparison, the Naraku set is 52/14 secondary which is 3.71:1 for a total of 11.92:1 reduction. Why doesn't that make sense? Increasing the reduction would improve acceleration and lower your potential top speed, which is opposite the advertisement. Anybody see what I'm doing wrong? Alright, moving on...
Scrappy's is 49/17 = 2.88 secondary reduction = 9.25 final ratio. This will make a noticeable reduction in acceleration but with the power of a BBK you will have a higher top speed, up to 20%.
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Post by buiditright on Nov 11, 2010 11:49:00 GMT -5
kat, if you can tell me which set of gears would be better to get Srappys or eviromoto naraku
set in your humble opinion.
Bill
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Post by D-cat on Nov 11, 2010 13:03:00 GMT -5
I think it depends on what you have for power. If you have a mostly stock setup and you aren't reaching your full speed potential, the Naraku set might actually help speed you up. If however you have so much power you are regularly redlining your scooter, go with the Scrappy gears.
I remember reading that 90GTVert made a comment that when he put on the Naraku gears, his top speed actually went down, and we know how much he likes to pack in the power. My numbers support his result. I'm starting to think now that the Naraku gears are meant to speed people up who don't have enough power to overcome the forces transferred by the stock gears, and not the BBK crowd. This is devastating for me, I feel like Galileo finding out the Earth is not the center of the solar system, never mind the universe, and having to tell the church...
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Post by buiditright on Nov 11, 2010 13:26:34 GMT -5
SO guess I will go with Scrappy since I do have the power and always redlined. That is just about the only thing that I have not done is gears.
Thanks for the help.
Bill
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Post by Eat Sleep Scooters on Nov 11, 2010 15:45:19 GMT -5
Im glad somebody explained the difference between the 2 sets of gears. Not a bad price for them on scrappy's end.
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Post by 90GTVert on Nov 11, 2010 17:20:48 GMT -5
These are secondary reduction gears (the primary stays the same). It didn't make sense to me at first either, so I asked Rick. What it is the sub gear in the final transmission can be separated with a hydraulic press or a punch and hammer. The large gear replaces the one on the final drive shaft and the small one replaces the inside of the sub gear. The stock gearing is first step 3.21:1 and second step 52/15=3.47:1 for a total of 11.12:1. For comparison, the Naraku set is 52/14 secondary which is 3.71:1 for a total of 11.92:1 reduction. Why doesn't that make sense? Increasing the reduction would improve acceleration and lower your potential top speed, which is opposite the advertisement. Anybody see what I'm doing wrong? Alright, moving on... Scrappy's is 49/17 = 2.88 secondary reduction = 9.25 final ratio. This will make a noticeable reduction in acceleration but with the power of a BBK you will have a higher top speed, up to 20%. You are right. I knew the ratios were wrong for increased top speed when I ordered my Naraku gears, but at the time they were all I could find. So many people said they went faster with them that I thought it was worth seeing for myself. I also went through a denial phase when I did the math and then saw the real world results, wondering what was up with me or my scooter that I was the only person that could see that the Naraku gears are not meant for increased top speed. They might increase speed on a scooter that lacks power and heavy riders. I could definitely cruise at a higher average speed with the Naraku gears, but top speed was reduced by 5MPH or so from what the stockers are capable of in my scoot. Just a note to anyone considering Scrappy's gears... Those are gonna be a pretty significant change. I would suspect that only 70cc and larger scooters will see much benefit. If you are a heavy rider, think about this one a bit before you buy. If you can't manage a genuine (gps, radar) 45-50MPH now, you probably don't have enough power to make good use of these gears. The stock final drive transmission is capable of those speeds. |
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Post by djeeper on Nov 11, 2010 19:57:12 GMT -5
these sound like a good investment then, for someone with a BBK...
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Post by junbug on Apr 18, 2012 13:01:14 GMT -5
im all stock will the scrappy gears help me? WOT im 45 at 6500-6700rpm. cruising i do 40 at 6000-6200.
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