I picked up a used Trailmaster XRS 150 that is in great shape. It has a GY6 150cc 4-stroke, air cooled engine.

Soooo...let's mess with it!

I was looking into replacing the stock air intake/box (which seems very restrictive) with something like this. I'd likely also have to replace the carb jets with slightly larger ones. However, the main question I have concerns the two small hoses also attached to the stock air intake filter box. One goes to the cylinder head; the other to the CVT.

Since the new intake doesn't have hose barbs, what do I do with these two vent/air hoses?

The next change may be exhaust...

I can’t help you at all, but after reading this thread and some googling, now I want an off-road go-kart. Damnit!

Red Beard's Garage on youtube does a lot of minibike mods. He works on Predator (Harbor Freight) engines a lot, but it may give you some ideas on your engine.

quote:

Originally posted by Outnumbered:
I can’t help you at all, but after reading this thread and some googling, now I want an off-road go-kart. Damnit!

I saw a pair of these Trailmasters at an auction; we were considering getting something similar for the kiddos. I almost got both, but it went a bit higher than I wanted to go. I know it's going to be a rabbit hole...

quote:

Originally posted by Some Shot:
Valve Cover Breathers

Ah ha! I was wondering about something like this. Of course, this assumes that neither the cylinder head nor the one on the CVT require a pressure differential that the intake provides. I'd also have to find smaller ones. The barbs are ~6mm and ~10mm.

Is that the case? What's the point in either of these? For the cylinder head, is it similar to a PCV? Or does it just keep pressure from building up in otherwise sealed areas when the engine gets hot?

Sounds like fun project.

As far as jet, you might want to go smaller because of your altitude.

quote:

Originally posted by Greymann:
Sounds like fun project.

As far as jet, you might want to go smaller because of your altitude.

That makes sense. Of course, I'll have to measure the currently installed jet size to see what I'm working with. Google tells me that the stock jet size on these is #112 or #114. Some sources are saying that the jet doesn't need to be changed above 5000ft.

I may just order a jet kit to tweak it once I have the intake installed.

quote:

Ah ha! I was wondering about something like this. Of course, this assumes that neither the cylinder head nor the one on the CVT require a pressure differential that the intake provides. I'd also have to find smaller ones. The barbs are ~6mm and ~10mm.

Is that the case? What's the point in either of these? For the cylinder head, is it similar to a PCV? Or does it just keep pressure from building up in otherwise sealed areas when the engine gets hot?

Before we had smog, crankcases were just vented to the outside and worked fine. (That's how old I am.)

I keep pieces of various diameter hoses to shim-out mismatched fittings. It's a lot easier than finding the right size.

Got it to crank after installing a fresh battery. The existing one was toast; my NOCO charger gave it a hard NO. The starter works great! It took me a while to figure out why I couldn't even get it to crank; you need to have the brake pedal pressed (derp). The Chinese-translated manual for this thing BLOWS.

It wouldn't turn over, so I pulled the carb. I got some lovely green gas to dump out. That plus the gas in the tank looking like post-asparagus piss let me know that it had sit too long with ethanol gas in it. I ordered a new carb ($30! ) because this one wasn't rebuildable. I also emptied the gas tank, cleaned it out, and replaced the diaphragm pump. The new carb should come in today!

I also replaced the crankcase fluid and the oil. Both actually looked pretty good, but why not? Each was <1qt. The suspension has multiple grease zerks, so I also hit up all of them.

I want to hit the trails and am getting ancy. I already got a pair of black motor cross helmets so that I feel cool.

43 MPH! I would be so unalive by the end of the first day.

Plotting...

quote:

Originally posted by ArtieS:
43 MPH! I would be so unalive by the end of the first day.

Plotting...

I saw that, too. I’m a bit skeptical. I’m betting they got that speed with a 13-year-old driving and no passenger. Still, it’s going to be really fun.

I’ll try to remember to post some photos tonight.