Painting engine?

[Deleted]

I have my engine on the bench getting ready for a BBK install, 50cc GY6, and I'm wondering about the cooling shrouds. I can see where they'd be neccessary in conjunction with the fan with it being hidden behind the fairings etc, but since I'm going with a naked frame design, the engine will be well exposed and I'm thinking it would be a neat detail to either paint the entire engine or at least the edges of the cooling fins on the cylinder. Any thoughts?

[spaz12]

I did it. If it's air cooled then maybe not the fins or the head?

[niz76]

Wouldn't suggest running without cooling shrouds if that's what you're getting at, but many here have painted their engines and may even be some beneficial heat loss with painting the cylinder and/or head flat black.

[gsx600racer]

So are you saying that your scooter is going to be a naked build, you want to eliminate the shrouds so the engine has a naked look too ?. Unless you plan on running it a couple minutes at a time with cool down periods in between, I suggest leaving them on.

[dexameth]

After I installed my BBK I had left my shrouds off because I somewhat cracked them removing them for the install. I ran it for a week or so, until I noticed one thing: the direction of the cooling fins. They are positioned for the direction of airflow from the fan, not from direct front-on airflow.

This would make my newborn heat up way too fast... so I had to put her clothes back on. The crack in the shroud wasn't as bad as I thought; when it was reinstalled back on the engine everything fit in place like it should. There's one little hole on the left side of the engine shroud, and every time I rev it up at a stop I can feel the airflow on my leg. I know now, having the shroud is a GOOD THING.

[jeff84]

if you have an air colled engine, you HAVE TO run the cooling shrouds, no if ansd or buts

[iwannascoot]

Aug 21, 2016 22:53:00 GMT -5 jeff84 said:

if you have an air colled engine, you HAVE TO run the cooling shrouds, no if ansd or buts

Perhaps you need to qualify that statement. Motorcycles have had air cooled engines without shrouds for decades.

Billy

[wutno]

I think we can all agree you need them on-on these cheapo bikes. The chinesium just can't handle the heat.

[iwannascoot]

I agree totally that we need shrouds on our scoots just not all air cooled engines.

[dan50]

Air cooled motorcycle engines are designed for cooling without shrouds. Scooter engines are designed for the shrouds to be intact. It's all in how they are engineered and designed.

[ThaiGyro]

Ha! I just re-ran across this thread. I friend was asking why some scoots and bikes have shrouds and some do not. He has a few scooters and one race bike, but had not thought of what and why.

In the above responses, it appears that many are making assumptions, when they are covering the answer like fly's on pasture brownies.

Air cooled engines require AIR to cool. Simple? OK, maybe not! The engineers look for answers that fit the style, design and overall appearance. Usually that requires a fan to induce draft from one location and move air to another. This is done with the shrouds, because under-bone frames block too much air.

In my view it is all simple. Get enough air, no problem. My '98 Ducati was the worst version of air cooling I have experienced. Get caught in traffic on a 90+ degree F. day...the lower cylinder would overheat and engine would die. No air movement. Why? the lower cylinder has the head facing the windward direction. When no motion, not enough air movement.

You can get rid of unsightly shrouding without hurting anything! Just find...or engineer an air source. BTW...same issue with water buffaloes. They need air too! Ducting works with a bit of speed or natural wind. Fans can be super simple electric...look at your PC or Mac! The fans are all 12 volt. Low volume, though. Good for lower speeds.

My friend has a 70cc Gyro canopy with a monster pipe and much hp. He has no shroud, nor goofy plastic crank fan. He does have a thermostatic controlled 12V 6 inch fan mounted in front. (Front in a Canopy means you must find an air source from ??) Comes on at 135deg. C, I think. He was trying to get my Koso unit...it controls two...one at 120C. and one at 200+C. or something, all programmable. We did make a nice eductor. Kind of like a rear diffuser on a road race car, but designed for simple air flow, not ground effect. (HIs is mounted behind the cylinder...above the cases. He rarely gets a CHT over 215, he claims. Oh...the nice part is that his exhaust is in the middle tunnel. (Of three) That heat behind, helps DRAW air from the cylinder out the back. Cold to hot...low to high...sound familiar?

The question of paint? Honda and nearly all others have done it for longer than most of your lives. I am doing a red cylinder soon and head, with polished fin-ends.

If you take the time to install a cylinder head temperature sensor or a water temp. sensor...what is to be concerned about? Shrouds, no shrouds, fans or none. It is all about how your engine performs and at what temperature. The real questions: How much air is enough and where does it come from? (You can over cool too, robbing power)

[Raizer]

Many of the Japanese Gyro builds I see are run without any shrouds.
From what I can pick up through translate is they run them a bit rich at low throttle.


On the subject of painting engines, I used vht paint on my Suzuki, has held up very well over the last couple years, little bit of fading where I've repeatedly spilt petrol while changing jets.

My Gyro engine I had powder coated, would guess it's going to hold up really well.