I have a 05 hh150 I have had for probably 10 years or so. It has 12g sliders and a white 1500 rpm main spring. I need more torque. I want to spin the tires off the line. I do not want to do an engine swap for a different power plant.

I’m thinking big bore kit etc. but I really want to keep reliability and I want to have something I am not going to have cuss with every time I get it out of the garage.

Anyone have any luck with the big bore or stroker kits? What is the best dealer to get these parts from?

All of these will require rejetting the carburetor, but this is a list in the order I would do them:

Cold air intake
Port and polished head
Torque cam
Big bore kit
26mm carburetor

Cold air intake? Are we talking a uni filter?

Remove the airbox filter system and replace with a 6-8" intake runner and UNI on the end.

Gotcha. That’s what I thought you were talking about.

I have heard alot of good things about the A12 cam as well.
Big bore kit you will have to have your case cut to fit the bigger jug and get the head that matches. Also check your exhaust pipe and clean up the flange most have some large casting flaws that can be smoothed out with a dremmel for a little better flow. These are 150 motors so every little bit helps.
PGHs list is spot on for the things that you will notice the biggest improvement from

Its a snow ball effect. If you gonna open the case for a bbk you might as well put a stroker crank in. Head work or 4 valve head ,stroker, bbk ,carb,and exhaust will make that buggy a real fun machine!😁

just make sure you have good seat belts because the buggy will become a whole new animal. these ar little buggies add speed and power and you get more roll overs. Minehas the following
155 cc kit
cold air intake
head not ported but casting flaws all cleaned up ports matched and exhaust runner polished.
rejetted carb

It has been rolled a couple of times now and the spped increase was only about 8 MPH but more power off the line

Havent touched rollers yet and need to get the bigger carb but like i said each thing you do gives you a little bit more to work with. Just dont forget with power comes dangers

Great advice guys.
I am really considering a stroker with a big bore etc. I do not want to give up the reliability though.

The seat belts broke a couple years ago so have already been upgraded to a better belt.

You will want to contact SycArms or Jersey Devil for case boring and crank clearancing for a project like that. They will be be able give advice on what is needed to build out a reliable engine.

A modded 150 buggy is gonna break more because you are gonna take on alot more challenges!😁

Thanks for the direction.
I am trying to get my kids excited about working on it. They need to learn some mechanics. We rode the tires off it last weekend and got them reintroduced to it. It has been setting for a bit. Busy with life, a new house, starting a business (that was about 8 years ago) etc. We have rode it a bit in the last 8 years but not as much as I had hoped. Now that the weather is starting to cool off a bit and things are slowing to a normal pace I’m hoping to get them more engaged with it and get them wanting to work on it.

This is true! As long as the motor holds up I can deal with the rest.