I'm having horsepower issues with my Maddog

[jayb]

Hello everyone,

I purchased a 2022 Ice Bear Maddog Gen 1 with a 50cc motor. The engine is a 1P39QMB.
Since I've had it I replaced a couple items.

* Installed a PE19mm Nibbi Carburetor with the
open air filter attachment.
* Changed the stock CDI box out with the Red AC
CDI box - non-restriction rev limiter
* Installed new throttle cable (to fit with the
Nibbi carb)
* Replace the fuel hoses with better quality clear
hoses
* Removed the center portion of the exhaust pipe
so it is now open straight through.
* Changed the oil with new oil.
* Replaced the spark plug.

I am only pushing 30mph on flat road. It feels like something is holding it back from going faster.

So for the odd part. We put it on a lift in order to lift up the back tire and started it. I wanted to see what it would do. We were shocked! The no rev limiter works as the rpms kept on climbing and that back tire was flying. It was doing and sounding like what it should have been doing on the ground. It can't be my 6' self at 210 pounds that drops this from being a beast to a turtle.

What would be stopping it while it is on the ground from pushing out the horsepower and speed that it got on the lift? I am thinking it has something to do with the CVT assembly. There is no restrictor on the variator as we checked it already. But to me it's pointing to something in there. If it's a belt, variator or clutch I do not know.

Any help would be greatly appreciated.

[FrankenMech]

50cc + 210lbs + wind resistance = turtle

[sinfull]

Actually it is a combination of all. 1st generation maddog have the wide 12inch rim, that is already like running a geared up qmb. Does not have the horse power to make the revs needed. Can probably guess full throttle is below 9k rpm. To get a big wide tire with your weight to actually rev up is going to be the challenge. Band aid fixes won't work since you are actually going to end up slower.

Big bore kit is really only option to get some speed. And don't believe the hype or the crazy internet either. Doing a variator won't help either lol. Forums are full of just do a polini variator and you will be flying. Stock variator is 87 or 89mm so going to the 95mm polini is worth nothing but slower. If you can't get the belt to the top of Stock variator adding a bigger variator is absolutely useless and will act just the opposite and act like a taller gear witch is what you don't want. Roller weights are already pretty light so going to say 4 gram is just going to give you more grunt down low, as soon as it tries to upshift 4 grams are not enough to get the belt to the top and lug the car tire. Not enough power.

Seen it done it failed miserably. Put the skinny 10 inch scooter rim on the maddog and laugh. 12 inch car tire barely 8800 rpm and no power, 10 inch skinny tire and have to back off at 10k + rpm.

Also why Gen 4 maddog are the fastest smallest rear tire but considered the ugliest because of the rear tire

Look cool or go fast, most maddog owners choose to look cool going slow

[jayb]

I was afraid of that. What's odd is when I first got the bike it hit 40mph pretty easily. Then the CDI box went out the next ride so the dealer sent me a new one. After I put that on I could only do 30mph.

The bigger carburetor and no rev limiter CDI box I installed should be giving me more but it is still only 30mph.

The bike on the lift I can easily hit high rpms but not on the ground.

Is a big bore kit worth it though? I don't want to end up destroying the engine by slapping one of those on.

[sinfull]

Qmb can run the big bore kits just fine, again internet full of it will destroy the crank, paper thin crank Yada Yada. You can search all day and never find even a picture of a destroyed qmb crank, atleast I have never found one and have never destroyed one and most of my bikes are bbk from day one.

[jayb]

Is there certain ones I should look to get of the big bore kits? Of course Amazon has a million different kinds that rang in different prices.What do you recommend?

[sinfull]

I am currently running a Amazon 72cc with a stock head. If you want the bigger valve head try search for 20 23 head. Taida make a nice kit more expensive, rolling wrench uses Taida in his pro build kits that is basically just rebranding Taida. Ncy has been around for ever and they make a nice bbk again more money. Just depends on what you want to spend and your comfort level. Ebay may have some as well. I have ran a Taida and the ncy both are nice kits, but here is the funny thing, the Amazon kit I got while rougher finish and no nice packaging runs same speed as the other kits, may not be as same quality but it is only a cylinder and a piston, easy to change if I have a failure down the road. 20cc is 20cc no matter where it comes from.

[jayb]

Thank you Sinfull. I will start looking for a bbk.

[jayb]

I found a full kit on Amazon. It's a Glixal 80cc bbk 47mm with the 47mm cylinder head and a A9 camshaft. Do you think that would be ok to get?

I don't need any special tools to install this right? Besides getting feeler guages for the valves.

Then after it is installed, I assume that I will have adjust the carburetor again? That part is not fun. It took me a lot of trial and error to dial in that PE19mm Nibbi carburetor.

Any other tricks or advice if I go this route?

[sinfull]

A torque wrench is helpful for the head and cam bolts. Rest is basic hand tools and pretty simple. You tube some videos and see what is involved. Search mini me 50cc videos, he is pretty detailed and has a good 50cc bbk install video. Plus he has a Gen 1 maddog.

[jayb]

I knew I was forgetting something, the torque wrench. I ended up ordering that bbk from Amazon. Even though it says 80cc I believe it's really a 72cc. So many deceiving products on Amazon.

I'm looking forward to installing this. I haven't had the bike for long but I've spent more time tinkering with it than riding..lol It's a lot of fun though spending time messing around with this and learning a number of things.

I appreciate your comments and helping me out with this.

[jayb]

Oh shoot! I just noticed this kit doesn't come with new rocket arms. Is that going to be an issue?
I don't know why they didn't cone with it.
It has the 47mm bbk with the 47mm valves but not rocket arms.
Don't I need new ones to fit this kit?? WTH I can't use the original ones on my bike now can I?

[jayb]

Just order the rocker arms. The valve head is 69mm so I ordered the 69mm rocker arms.
Man, I hope all of this fits together correctly. I'm freaking myself out a bit since I completely missed the rocker arms when I originally ordered these. Ugh

[sinfull]

It is okay, everything will be OK 👍

You may have 69mm valve, easy way to find out is 69mm are above the head and are on raised valve spring seats, 64mm valve are flat in the head. Look up Brent from 49cc. Com 64mm vs 69mm heads, he goes in detail. Also can probably find it in the tech library on the forum menu

[sinfull]

Yep, look in the 49cc scoot library on the menu page, 4 stroke engine tech and you will find it on the 1st page, 64 vs 69mm valve