Heavy Load performance

[jhanlon110]

Hello everyone!

I am new to the forums, and basically came to ask a few newbie questions. I know very little about mechanics (I can change my own oil, and take a great deal of pride in that) and I'm not all that interested in learning. I do, however, know a really good small engine guy.

I have a 2010 Qingqi 50cc scooter. I weigh 400 pounds.

Right now I'm getting 25-30 MPH in good conditions on a level plane, and 10-15 uphill depending on the incline. I run with throttle open at all times to achieve this.

I have purchased a big bore conversion kit (specifically the one found here: enviromoto.ecrater.com/p/3956695/enviromoto-72cc-power-pack-gy6-50 ). I came to this forum to because enviromoto recommended it as a resource to give to my small engine guy if he encountered any issues. (He's been working on scooters, but I wanted to be safe.) I've reviewed chunks of your newbie resources and I'm really impressed. It's mostly above my head (though the 'how an engine works' descriptions were great) but it sure looks thorough!

My end goal is to have a scooter that can accelerate quickly carrying my weight, and can reach 35-40 MPH. (Closer to 35 is fine with me- less chance of being pulled over.) My other large concern is reliability. I'd like to slowly swap out parts as they need replacement with stuff that's not going to wear down as fast, and generally fine tune the scooter to carry heavy loads. Also, I bought my scooter new and I've driven it as a sole source of transportation for a year. It has 10,000 Kilometers on it. Outside of belts and front side clutch replacements, I haven't done much to it. I've had the oil changed regularly (including gear oil twice) and get someone to give it a general check over for loose bolts/fasteners every 2-3 thousand Kilometers.

So when the big bore kit arrives, I intend to have my mechanic give the scooter as thorough a maintenance checkover as I can convince him to do. From my review of the boards, it seems like I need to make up a checklist consisting of pretty much the entirety of this post: 49ccscoot.proboards.com/index.cgi?board=basicstuff&action=display&thread=344

With all of that said...

1. The guys at enviromoto are going to contact me to ask if I want 6, 7, or 8 G rollers with my kit. I want acceleration over top speed, so I'm inclined to ask for 6 G. Do heavy loads affect this decision? Should I ask for a 7 G considering my weight?

2. The parts listed in the above kit are the *only* things I'm adding at the moment. Are there some low cost (totaling $50-$60) additions that I should make, since I'm upgrading the engine bore?

3. Is there anything else I can do to the scooter that would maximize performance for heavy loads? Including any expensive purchases I should keep in mind for later? (The obvious answer is "buy a 125-150cc," but that's out of my price range for the foreseeable future.)

4. I understand from my reading that one of the things I'll need is a kevlar belt. Is there a brand that you'd recommend? I couldn't find one on the enviromoto website.

5. Given that the scooter has been driven for 10,000 kilometers, is there anything that immediately comes to mind that will require maintenance or replacement?

6. Is there anything else I'm obviously missing?

I'd really appreciate any advice or feedback. I think this is a wonderful community and will certainly recommend it to the scooter owners that I know and will meet in the future. Thank you all for your time.

-Jason

[inuyasha]

Hi Jason
Pleased to meet you
Welcome aboard
You may want to look into a slightly larger carburetor , if not and you keep the old one you will probably have to change the jets when you install the bbk
I recommend a gates powerlink belt
www.scootersgeorgia.com/gapocvtdrbe.html
And why not try a roller tuning kit, then you can find the exact weight you would need to accomplish your performance goals
www.scooterworks.com/Prima-Roller-Weight-Tuning-Kit--16x13-P10348C516.aspx
Once you find an optimal weight i would then recommend you go up one gram and go with sliders, so if a 6 gram roller is perfect go with a 7 gram slider
www.monsterscooterparts.com/16x13-sliding-roller-weights.html
Take care and ride safely
Yours Hank

[Deleted]

The crank bearings have 10,000km on them already? its not going to last long with the load you are going to apply and a big bore IMO. If I were you I would build a motor up from scratch using a Naraku HD crank and 50mm bore.

That bike has medium length case for 12" wheels but is geared the same as the short case 10" wheeled ones. I have that drivetrain in my 'project yellow fever' bike and the takeoff is slower because of the bigger wheel and same gearing so for rollers you will want 5g maximum probably even lower...again...this is given the load you are applying and the gearing of that bike with that wheel.

The best way to tune the transmission is do like hank said and get several sizes. Get a 'tiny tach' and change roller combinations to get the one that keep you in the max torque range of 6500rpm all the way through to top speed.

Honestly these little 139qmb variators dont handle this much of a load well and i predict you will end up breaking lots of them...and belts. Max load is 220 lbs in that bike i think....and you are applying nearly double that. Also the main enemy of these motors is heat because they are air cooled. More load means more heat....and I dont think its going to last long.

[90GTVert]

:welcome2:

Definitely get someone to go over the things on that maintenance checklist.

If you are reasonably pleased with it now, I do think you'll like the BBK. I share the same concern as 1FAST though regarding reliability. With over 6,000 miles on it now I do wonder how long it will hold up with a big bore. Might be fine for a long time, might not. I will say just don't be surprised if you have a crank failure at some point. Perhaps save that mod money up and just keep it for a bit in case something happens like that.

At 300lbs I managed to squeeze out 50MPH from one of these motors with a 50mm big bore kit, cam, head, CVT work, etc... It lasted a few miles over 2,000 with a brand new stock crank installed along with it. Mine revved a lot higher than I hear most saying, so that's more stress than you'll have. I also used a larger bore, again more stress, but you'll be putting more load on the engine. I'm not trying to worry you and say it will fail soon, but I do think you should be prepared for the possibility just in case.

[jhanlon110]

I really appreciate all the helpful advice.

I'm definitely going to get the gates powerlink belt. The link you made has a gasket as well for half off. Is this gasket of higher quality than the OEM? I would think so but am wondering if it's worth buying.

I will try the roller weight set for fine tuning. it sounds like something both myself and my roommate (who also rides a scooter) would find helpful. Once we find the right weight, I'm definitely going with the sliders. After reading a couple reviews, I'm quite excited about them.

Even with my mechanical ignorance, I can tell that crank failure sounds like a Really Bad Thing. Would that be a really expensive repair, or simply trash the bike entirely? Just want to know what I'm risking before I start making changes. (Also, does the mileage and load mean that I'm looking at a crank failure in the future regardless?)

1FAST, I'm interested in your alternative. Could you elaborate? From what you said, I'm guessing you mean I should buy something like this crank shaft ( www.superscooterparts.com/SPD/nk100-81--800048D9-1317238954.jsp ) (first google hit I found, if there's a better store please let me know), this bore kit ( enviromoto.ecrater.com/p/6362855/ncy-80cc-50mm-big-bore ), and this cylander head ( enviromoto.ecrater.com/p/6362872/ncy-50mm-high-performance-cylinder ). Do I have that right?

If that's true so far, what other associated items should I get? For example, the 72cc BBK that I listed in my first post comes with additional items. This setup would not. I presume I'd have to get them independently. So what all would I need?

If I've understood the alternate proposal, just the three items I've referenced above would be in the $400 range combined, before we add other stuff and labor. That's certainly above where I'm currently shopping, but if it will give me a brand new scooter (as far as the engine) and the reliability that would come with it, I'm going to seriously consider it. I'm just trying to fully understand the options.

[Deleted]

Apr 23, 2012 18:26:27 GMT -5 jhanlon110 said:

1FAST, I'm interested in your alternative. Could you elaborate? From what you said, I'm guessing you mean I should buy something like this crank shaft ( www.superscooterparts.com/SPD/nk100-81--800048D9-1317238954.jsp ) (first google hit I found, if there's a better store please let me know), this bore kit ( enviromoto.ecrater.com/p/6362855/ncy-80cc-50mm-big-bore ), and this cylander head ( enviromoto.ecrater.com/p/6362872/ncy-50mm-high-performance-cylinder ). Do I have that right?

Yes x3

and.......

www.racingplanetusa.com/camshaft-naraku-touring-139qmbqma-5080cc-p-5722-1.html?sessID=8e80225fa8e06f1f312e8b04aea442c8

[jhanlon110]

As I continue to read different forum posts, I think I'm slowly beginning to catch on.

I found an old BBK discussion thread that was extremely helpful. It seems that crank failure isn't the "buy a new bike" disaster I thought, though it's pretty pricy when you're not doing your own work.

If I'm understanding my reading right, higher RPMs mean more heat. Smaller rollers get the engine to engage at a higher RPM. It seems like a choice of "acceleration over top speed" also means shorter life span. Does that mean small rollers mean shorter lifespan while larger rollers mean longer lifespan?

1FAST, I can that I'm going to have to replace the crankshaft soon regardless- I can either replace it in the upgrade or break something and have to replace it then. Is there a reason that a 50mm bore is better than the smaller bore 72cc kit for someone with my weight? Would it be a bad idea to go with the Naraku crankshaft and the smaller BBK?

[Deleted]

the smaller 72cc bore and Naraku HD crank might be better for longevity.

I can either replace it in the upgrade or break something and have to replace it then.

That means having to do the top end twice.....personally i would rather do it all once..and do it right with a good crank.

higher RPMs mean more heat.

but at high rps the fan spins faster too. low speed heavy load pulling with the fan spinning slow means even MORE heat.

Smaller rollers get the engine to engage at a higher RPM.

Thats stiffer clutch springs. heavy rollers: the engine 'changes gears' sooner and takeoff is slower...but they will ensure top gear.... lighter rollers: the bike changes gear later making a quicker takeoff but top speed will suffer if you go too light.

trans tuning is very important. you want the weight that gives you the best acceleration but still gives you top gear.

A 'tiny tach' hooked up you want 6500 rpm (max torque range) all the way through to top gear then (hopefully) you will have enough horsepower to push you faster.

I think for your application you are going to want as much low end grunt as you can get. this to me would mean some tighter clutch springs and the lightest rollers that put you in the 6500 rpm range right from a dead stop.

if it were me i would get a full set of clutch springs:
www.ebay.com/itm/CLUTCH-SPRINGS-PERFORMANCE-SET-3-GY6-50cc-Baja-Honda-DIO-Jonway-Tank-/150737578540?pt=Other_Vehicle_Parts&vxp=mtr&hash=item2318a8ea2c

and a set of torque converter springs
www.ebay.com/itm/TORQUE-SPRING-CLUTCH-PERFORMANCE-GY6-50-Baja-JMstar-Jonway-Roketa-Sunl-/150737618712?pt=Other_Vehicle_Parts&vxp=mtr&hash=item2318a98718#ht_500wt_994

a tighter torque converter spring will give you a greater range of options on roller tuning given the load you are working with.

Building this motor is not going to be cheap if you want the best possible performance.

You could even go with a stroker crank. this would give you much greater low end grunt....but we are still exploring the variator options that hold up the best even with a 250 lbs load..the stock ones dont cut it at all:
49ccscoot.proboards.com/index.cgi?board=4perfrom&action=display&thread=2608

[jhanlon110]

I can see why transmission tuning it so important. It looks like one of those things that is going to involve a lot of labor and pain, but simply has to be done.

Since heat is such a concern, and summer is coming on, is there anything I can do to help cool the engine?

[Deleted]

not really. some cvt cooling will help your belts...and that will help engine temps a little. but the engine cooling system is what it is.

[Deleted]

its fun to build up a scoot motor
If i were you I would build up a 150 instead.