Baja bike question.

[Jameshotjr]

PLEASE HELP ME!! Urgent question.

Hi guys great forum here. I'm giving my nephews Baja bike a overhaul for Xmas (motor is blown). I've pulled everything off and repainted the bike the clutch on it is smoked also. Here is my question, I thing we are going with tav instead of clutch. I think we are going with a 30 series. And I'd like to order parts today. New motor is a 212cc (6.5) predator rated at 3800 rpm. The driven unit is a 6" pulley it will have a ten tooth gear on the drive pulley for 40/41 chain and rear sprocket is a 50 bike has 18 inch tires I believe. Will that be Ok or will It smoke belts? I don't know how to calculate gear ratio with the tav. Any input is appreciated. I just don't want him to ride it on Xmas morning and smoke a belt. Thanks Alot, James

 

[Denny]

You are right it will smoke belts but not because of the gear ratio (which is fine by the way). The Chinese tavs come with crappy belts. Replace it with a genuine Comet and it will be good to go. The sprockets on mine are 10 tooth drive 40 tooth driven (wheel) in #40 chain and works great for me or the kids I'm around 300lbs.



Denny

 

[bob58o]

I don't know how to calculate gear ratio with the tav.

Number of teeth on Rear Sprocket / Number of teeth on front sprocket

In your case... 50 / 10 = 5
So your sprocket ratio is 5 :1.

30 series TC with 6" driven is 2.68 :1 in low and 0.90 :1 in high.

So in Lowest gear, you will be at 5 x 2.68 = 13.4 :1
In highest gear, you will be at 5 x 0.90 = 4.5 :1

With 18" tires and turning 3800 RPM you should be traveling around 45mph.

(3800 / 4.5) * 4.71 * 60 / 5,280 = 45mph

3800 = Engine RPM
4.5 = Gear Reduction in Highest Gear
4.71 = Tire circumference in feet
60 = Minutes per Hour
5280 = Feet per Mile


BTW, The Predator engine will not come with a lamp coil to power the head light.

 

[J.S.@SMS]

Actually the tires are 19". However that isn't enough to smoke belts from what I've seen. And you can completely remove the throttle limiting screw, and get about 4200rpm from the engine (free hp and rpm increase, without pulling the engine apart).

PS: Do a mock up of the engine in the farthest back position and mark the frame under the rear oil drain bolt, then move the engine all the way forward and mark the frame. Drill about a 3/8" hole on each mark (use a punch to keep the drill from moving around) then cut out the space between the two holes. This gives you a hole in the mounting plate to drain the oil from the engine without making a mess.

 

[Bwdeaton]

I have the same setup on one of mine, and haven't had belt issues on that one (212 predator, all stock and an ebay 30 series with 10t sprocket).

I did smoke a belt on my other one but it was the cheap belt that came with the ebay kit and it had 50+ hours on it. It shredded when i got stuck in some deep mud. That bike has the factory motor with no governor, ebay 30 series and a 9 tooth front sprocket.

 

[Jameshotjr]

You guys are awesome I'll order a comet belt. Do you guys know the part # ? Can I find a lamp coil on eBay and hook it up to fix the light? The wiring and bulb are gone as well so I have to try to find that as well.

 

[bob58o]

Well you need to have a flywheel that has the magnets that work with the lamp coil.
Problem is that Predator crankshafts have a different flywheel taper than the Honda's or clones do. The original engine on the bike was most likely a Honda Clone.

If you have a Hemi style Predator, then you need a Kohler flywheel, which has the same taper. If you have a Non-Hemi style Predator, then there is no known flywheel with magnets that has the exact same taper. However, many have claimed success using a clone flywheel on a Non-hemi Predator crankshaft. They are not exact, but are close. I wouldn't recommend it, but some have done it. Many others have ended up spinning the flywheel on the crankshaft because the taper is not the exact same.

I have an electric start/charging Hemi Predator. I used a mixture of Kohler and Honda/clone parts to make it happen, but it cost a bit and isn't really worth it.

On another build, I used a low wattage led head lamp and a battery pack like this.
https://www.ebay.com/itm/2X-27W-Flo...-Offroad-SUV-Boat-Truck-ATV-Car-/251988934210
https://www.amazon.com/dp/B00MF70BPU/ref=emc_b_5_t

COMET Belt # is 203589A. But those are triple the price of cheap belts and don't last three times as long. So up to you. Cheap belts are probably more cost effective in the long run, but will require maintenance (replacing the belt) more often. If you don't ride that often, get the Comet and should last you years.

 

[J.S.@SMS]

The original engine was a cheap 196 Honda clone built by the Changzhou Globe LTD. And these engines aren't that well built. The one that came on my warrior started smoking after about 20-30 hours of use. And during disassembly I discovered that the rings weren't in the correct order (the top ring was in the middle groove and the middle ring was upside down and in the top groove). And the head gasket was bent when I pulled the head off. I ended up completely rebuilding the engine and have just finished breaking it in.

I installed a predator 212 non-hemi in my warrior while I was waiting to rebuild the 196. And I just removed the lighting system since I rarely do any night riding and when I do its on my 95' Yamaha Warrior. I would have to say that, despite the fact that the predator has no charging system, it is a far superior engine that pulls much harder than the original.

 

[Jameshotjr]

Thanks guys. I think I'll scrap the light and just let the kid ride. I think I'll order a 3 pack of eBay belts for backups, the belts are easy. I'll post pics when I'm done this weekend, it's a shame they lost the tank, but that does make it easy to work on lol

 

[Jameshotjr]

Here she is. Thanks for your input guys.

 

[Jameshotjr]

What do you guys think?

 

[landuse]

What do you guys think?

Very nice!!! Although that chain looks a little rusty

 

[bob58o]

You'll have to let me know how hard it pulls off the line.
Can you give it full throttle without standing it straight up?
Does it wheelie a little, a lot, or not at all?

 

[Jameshotjr]

Yea the chain is a little rusty, it sat outside for about a year after it blew up. A little oil and she'll be fine. I'm Imma do the 3 hour break in and I'll let you know if she wheelies lol

 

[J.S.@SMS]

It probably will pop a wheelie. Be careful, I used a 9t sprocket on the TC for my warrior and half throttle stands the bike up.

PS: It might be a good thing that it doesn't have a tank as it makes it extremely difficult to fill up the engines tank.

 

[Denny]

The tires are dirty, I don't like them! Be glad the tank is gone, they look crappy without them but it sure makes putting gas in them a lot easier. I ended up taking the one off the girls MB II.


Denny

 

[2SlickNick]

It will do fine... I prefer the 9T sprocket for a little more low end grunt.