HS 142 "Giant Boulder 4" build.

Pete Lawrence

New Member
Local time
1:09 PM
Joined
Jan 1, 2013
Messages
8
This is my just recently finished 4 stroke build, my first, may i add. (Id had previous experience building 2 strokes, but this was an entirely different beast) And i have a couple of questions for you more advanced motorbicyclists. Whilst the HS 142 seems to pack plenty of low end power, it seems to die out a bit towards the higher end, it sure screams, but i dont feel the power. Are there any reasons for this, or is it just how the HS/4 strokes in general work? Also, how often do the connecting rods on these things actually break? It feels pretty solid to me, but then again, i dont even know if there is a way to tell what RPM the engine is running at other than listening to it. Long story short, have you got any tips?

Also, Pics of my new build:
image-3.jpg
image.jpg
image-2.jpg
image-1.jpg
 
There are battery operated rev counters you can get from kart or motorcycle race suppliers.

I've seen pictures of snapped rods as well with these engines, so max rpm may well be above max safe rpm. Any higher speed will probably require a gearing change. I would think most of your questions are answered on the 4 stroke engines section anyway.
 
Cool. We don't see many mountain bikes with thumpers mounted in the frame.
 
Really? Is there a reason for this? I would have thought theyd be pretty common, since being shaken up and beat around is what mountain bikes are made for, and thats pretty much what the engine does...
 
I think there's a style/cultural thing that leads people to use the clasic American frames. Having said that, the ally frames might fail from vibration fatigue after a while.
 
Thats the same kit I got! Had lots of torque because of the rear sprocket size(50 or 52?) The real problem is that gearbox. The tiny sprocket inside starts to wear down immediately, and you'll start to feel slippage, and then a constant chatter/****. Better start looking for something like a belt drive. The old sprocket came in handy as a shim for my new setup though. I did eventually open up the exhaust a little at a time until the engine seemed to flow open through different operating ranges.
 
You are already screwed......Replace the "Hoot" gearbox before it leaves you side of the road......
 
It doesnt matter now, turns out the piston ring is wrecked and the engines lost compression. The gearbox had nothing to do with its eventual demise...
 
Back
Top