Hi everyone!
First off I'd like to say that I've been lurking on these forums for many moons, and finally went around and made an account. I've spent the last 2 months gathering parts slowly for a complex build, and now she's finally all put together. I've had to improvise and customize a lot of stuff on this build, and everything has (for the most part) come out better than expected, but now I seem to have hit a wall
I've got a 4-stroke HS 142f engine, purchased in a kit off eBay from an outfit called PetrolScooter. They had the best price on what seemed to be an identical kit to the dozen or so other sites I looked at. It's a 49cc, looks identical to the other HS 4-stroke engines in the various YouTube videos and posts here on these forums. Kit was purchased at the end of 2013. Engine had a very faint smell of fuel and/or oil when I inspected it, but did not appear to ever have been fired up. I have not made any adjustments to the valves.
Carb is stock. It DOES have the brass mixture adjustment screw, which some models made in 2012 seemed to either not have or have a blob of metal obstructing the screw.
The major issue I ran into was with the air filter - the bike frame I had didn't have enough room for the stock air filter - it bumped into the seat post, and because of the position of the down tube and the size of my mounting plate (with the SBP jackshaft kit), the engine wouldn't fit in the frame unless the filter came off. I bought an aftermarket air filter and used a couple of manifolds, a copper elbow joint, a couple of lengths of heavy duty rubber tubing and some hose clamps to build a 90-degree angle adapter to mount the air filter off to the side, so it didn't hit the seat post.
To further save space, I also removed the plastic "insert" plate that was clamped in between the carb and the engine and replaced it with a thicker gasket.
Here's where I'm having trouble:
What gives? Am I totally blowing it here, or could this be a simple fix? Do think my engine is running too rich/lean? Any advice would be greatly appreciated!
First off I'd like to say that I've been lurking on these forums for many moons, and finally went around and made an account. I've spent the last 2 months gathering parts slowly for a complex build, and now she's finally all put together. I've had to improvise and customize a lot of stuff on this build, and everything has (for the most part) come out better than expected, but now I seem to have hit a wall
I've got a 4-stroke HS 142f engine, purchased in a kit off eBay from an outfit called PetrolScooter. They had the best price on what seemed to be an identical kit to the dozen or so other sites I looked at. It's a 49cc, looks identical to the other HS 4-stroke engines in the various YouTube videos and posts here on these forums. Kit was purchased at the end of 2013. Engine had a very faint smell of fuel and/or oil when I inspected it, but did not appear to ever have been fired up. I have not made any adjustments to the valves.
Carb is stock. It DOES have the brass mixture adjustment screw, which some models made in 2012 seemed to either not have or have a blob of metal obstructing the screw.
The major issue I ran into was with the air filter - the bike frame I had didn't have enough room for the stock air filter - it bumped into the seat post, and because of the position of the down tube and the size of my mounting plate (with the SBP jackshaft kit), the engine wouldn't fit in the frame unless the filter came off. I bought an aftermarket air filter and used a couple of manifolds, a copper elbow joint, a couple of lengths of heavy duty rubber tubing and some hose clamps to build a 90-degree angle adapter to mount the air filter off to the side, so it didn't hit the seat post.
To further save space, I also removed the plastic "insert" plate that was clamped in between the carb and the engine and replaced it with a thicker gasket.
Here's where I'm having trouble:
- Engine starts up, but revs high - idle adjust screw is barely touching the throttle mechanism. Test performed with and without throttle cable connected, same results.
- Carb adjustment screw is 3 turns out (that is, I tightened it until it bottomed out slightly, then cranked it back out counter-clock 3 turns).
- When the engine starts, it seems to sit right around the 2k RPM mark (as per the tach on the handlebars).
- When I twist the throttle, the RPMs go down and the engine sounds like it's going to stall - this is the behavior through most of the throttle range - opening up all the way doesn't get me past 2500 RPM, and the engine doesn't seem to like it. Only left it there for a few seconds.
- Engine will only run with the choke ON. If I even so much as nudge the choke lever, the engine will sputter and stall. This is mystifying - when I had the carb disassembled, I could see what the choke was doing and the fact that so little movement is having such a large impact makes no sense.
What gives? Am I totally blowing it here, or could this be a simple fix? Do think my engine is running too rich/lean? Any advice would be greatly appreciated!
