Case of the missing shroud...
- Thread starter silverbear
- Start date
What about the shroud on the HF ? anyone take one off and put it back on successfully...just asking because I want to paint or remove mine but another guy had the pull start come apart upon removal.
Cheers
Cheers
I'd planned on using a Trail Tech temp gauge in cylinder head temp mode, and removing the shrouds after break-in. I had a turbo Corvair that occasionally saw 500 degrees cylinder head temps when it was really being abused, and the airplane I fly is redlined at 400 and I try to lean it out so it cruises at 385. You really don't want an airplane engine to stick up 'cause you can't pull over to the side of the road very easy. I remember some old Harly flatheads with gauges and they went to 500 and the guys didn't get nervous until they were above 475.
Many old Briggs motors spent most of their lives pushing scooters and bikes without the shrouds. Even when they were still and idling, they weren't under load so they didn't get hot very fast. A stationary engine working hard needs the air moving accross it. I don't know how fast the air is moving, but it won't push your hand very hard.
When you put a coffee can shroud around the flywheel, and it fits tight and reduces the airflow, it also reduces the power loss. Putting you hand over either the input or output of your shopvac will show you what happens. There will be less energy loss because the fan isnt doing any work. It no longer has to pull air in, creating a vacumm, or push it out, pressure. It just moves the same air round and round at the same speed.
Many old Briggs motors spent most of their lives pushing scooters and bikes without the shrouds. Even when they were still and idling, they weren't under load so they didn't get hot very fast. A stationary engine working hard needs the air moving accross it. I don't know how fast the air is moving, but it won't push your hand very hard.
When you put a coffee can shroud around the flywheel, and it fits tight and reduces the airflow, it also reduces the power loss. Putting you hand over either the input or output of your shopvac will show you what happens. There will be less energy loss because the fan isnt doing any work. It no longer has to pull air in, creating a vacumm, or push it out, pressure. It just moves the same air round and round at the same speed.
I don't mind the shroud on the HF so painted mine. It being metal makes a difference, I guess. I removed mine to paint it and don't see how that should affect the pull start. Just leave the pull start alone... no need to remove it in order to paint.
SB
Greybeard,
I found your comments of great interest. I had not considered there might be a difference in power with the coffee can shroud in place of the stock one. I noticed no problems with the engine heating up last summer and I did pay close attention, having no desire to wreck an engine. I don't have a gauge, but you know when an engine is hot. It sure does look better and made me want to find a way to do something about the plastic transmission cover, too. I've been thinking about it since and this winter my friend Tinsmith (Dan) made a nice prototype out of electroplate tin which I'm looking forward to putting on the bike when I get back to Minnesota. It even matches the coffee can. Ha!
SB
Back when very young, my uncle had converted a bicycle to a four stroke engine he had taken off a lawn mower. Drove the wheel with a belt that you had to apply tension with a foot lever. Case is, this engine had to be started with a rope and had no cooling shrouds at all. I rode that thing to **** and back and was still going when I left. Just a thought.
Interesting concept. Do you recall your uncle's bike having pedals, or was the foot lever in place of the pedals?
Cannot really remember first thought is no pedals. Picture a rod shaped like a wide "V" with a 90 degree bend in front, pivot at the bottom and a roller on the rear that tightened a belt that was on a regular belt pulley on the engine etc. Worked great. No one around to talk to now. But bike ran like a deer. Got in trouble plenty times. Fuel from a round can like a coffee can that hung from the upper cross bar. Neat bike. and no covers at all fins in the breeze. lol
Hey, why not put a large louver in the tomato can, aimed at the cylinder . Would be just like a Solex shroud. They have no cylinder tin, and the shroud vent on them blows air at the cylinder when the bike is not moving.
Some of the new Harley cruisers with all the fairings, have electric fans to help cool the rear cylinder. Some Buells too.
Some of the new Harley cruisers with all the fairings, have electric fans to help cool the rear cylinder. Some Buells too.
Wayne,
That's a good idea, especially for the guys riding in a hot climate. Sorry for posting late. I just saw this.
SB
The new Harleys' electronically shut down the rear cylinder while at idle, removing the heat generated by the firing of the spark etc. Most riders I have talked to that have this feature say they cannot tell the difference at all with the exception of the reduced heat of course. The engine restarts firing the rear cylinder after a prescribed speed is reached. Riders in parades really like it because it removes the heat under their butt while in a slow or stopped portion on the parade. gpil
Mr Z, that is a very good idea. I was talking with SB just last week about removing the rest of the plastic from the HS motor. If we do it I'll try to incorporate your idea if you don't mind. I'm sure SB will document and post the attempt if we ask real nice. Dan
Hi guys, Long time lurker and rarely post. I have been a huge fan of the the little HS142F Honda clone for a couple of years. Just found this thread and thought I might add something to it. I have been running several HS142's without cooling tin or shroud for over two years without a single problem. Climbing the hills and several thousand miles. Three motors, zero problems. Again, no cooling tin or shroud.
Stationary it might be an issue, but on a bike it doesn't appear to be so. Looks a whole better and gets a whole lot more looks ;-)
Stationary it might be an issue, but on a bike it doesn't appear to be so. Looks a whole better and gets a whole lot more looks ;-)
That's good to hear. It's a good bit warmer in your part of the world than in mine. I keep running my H.S. and also have had no problems with overheating or anything else, actually. It is a fine little motor and you are right: it does look a whole lot better without the plastic shroud.
SB