Created with Sketch. Created with Sketch.
Mini Bike Parts

Mini Bike Parts

Jan 5th 2021

I have a Comet TAV2 that I lost the face plate /cover to. The Bolt was not tightened enough and it all came off in the woods. I lost just the black cover. Any chance I might buy just that part from you?

I have a hopped up BT minibike and was wondering if a set of different springs might add a little more get up to my machine? What color springs would you say is best for a Tillotson 212 stage 1 with a mikuni? I do a lot of trail ridding and weigh 210.

Any need to upgrade that driven spring?

My 212 engine has stock internals, gov delete and 18lbs or 22 lbs springs intake and exhaust. I am running a 36 jet right now might step up to the 37 on the stock carb for now. Is the Mikuni 22mm carb a smart way to get more power/revs out of the motor? Or should I dive into the motor first with billet goodies?

Here is the outside drum for the 3/4" Comet units. Please make sure that you inspect the art springs that go around the zinc weights. Those can get stretched out when you lose the drum! We have replacements springs here.

I prefer the stock engagement spring on the driver clutch. Let the engine work! If you went with a higher engagement spring that can cause the bike to be too jumpy and unpredictable as you have to get into the throttle before anything starts to happen. I would focus on the driven spring. There is a hub on the driven with 3 holes. Your spring is in the center hole. Move that center hole around until it is straight up in the 12 o'clock position. If you move that spring to the 11 o'clock position, it will provide more tension in the driven and allow for a later opening. This keeps the torque converter in a lower "gear" if you will and will help you get into the rpms and power before it opens up all the way. I think the stock spring and the driven tension will be better for trail riding. I typically only suggest a later engagement on the driver with built engines...more cam, more compression, and the right billet parts! 

We have a stronger spring for the driven unit but I don't know if that will be any better for you. That spring is VERY stiff! Brings friends when installing, it is not easy! I would rather you try the spring you have now and evaluate the results. The yellow spring I use for modified engines with bigger cams, more compression, and making more power than what you have. I don't we need to go there yet! You can also drop down a tooth on the torque converter. This will help the bike launch harder and get into the power.

Here is my take on governors and this is how I feel and not just for company liability. I will not throw my leg over an ungoverned engine in a minibike. My private parts are important to me...even with 2 grown children! The stock, cast aluminum connecting rods will typically starve for oil at less than 6000 rpms. This is when the rod overheats, sheds aluminum onto the crank and the "experts" will pull the side cover and say out loud "that rod still looks is tight on the crank". Reassemble the engine and let 'er rip. That is when the rod overheats, fatigues, breaks in half, and exits the case! The oil at 325 degrees is like a deep fryer for your legs. 

The stock flywheel is not designed for high rpm use. I don't see many flywheel explosions...we see more of the magnet flying off, ripping the coil from the block and breaking the case...that is if you are lucky! EVERY engine I build starts with a billet rod and flywheel! ...and no...I don't get all my parts for free!

A Mikuni carb is a performance carb. A performance carb should be on a performance engine. I see too many people try and build an engine from the outside in...when we really should start from the inside out. The Mikuni carbs consume most of my day with too many people not knowing how to install and tune them. There is no way to govern a Mikuni carb. See the attached pics from a stock engine with a Mikuni carb. A Mikuni carb is a great addition to an engine with billet parts, a bigger cam, heavier valve springs, and more compression. Trying to tune a Mikuni on a stock engine is a bit trickier. The stock cam cannot keep up.

Jetting. If the engine runs good with a 36 jet, why fix it? A larger jet does not necessarily make more power. Most of my stock carbed engines will use a 36 or 37 main. If the mixture is too rich with a 37 main, that will cool the head too much with the additional fuel and you will lose power. 90% of the customers I deal with over-jet their carbs! Lean is mean! Keep the heat in the head. A built engine with a bigger cam may want a 37 or 38 jet, but I have never seen a need for anything bigger than that.