Robin-Subaru... better airflow

[graucho]

graucho

If you wonder I'm so gruff with people, it is simple. I have put 10 years of R&D into mini four strokes, I have sold a few engines along the way.
Recently I stopped building them for others partly due to issues with owners blindly following advice they got from forums which lead to the destruction of 2 engines.
One was trying to increase compression and against my advice installed after market rings and if my old puter was working I could show pics of a completely destroyed cylinder.
The second was not even run before a couple of "mechanics" convinced him I screwed up on the exhaust port and after hogging it out it made less power than stock.
Both cases wasn't my fault, but I get the blame.

I guess I really don't care why ANYONE here is gruff. Every single person here has problems in their lives. Each of us has stories about misfortune and trials in their life. There are other forums for discussing those issues. Like I said before...

"This is a teaching place"

 

[Old Bob]

Most of the time it looks like Honda bashing place and for sale forum from where I sit.

I can see that you don't appreciate the effort I've made to share info or "teach", its ingrateful people such as yourself that me think twice about trying to help anyone.
When someone goes out of their way to help you, you generally say thank you.

 

[Happy Valley]

Well I'll say thank you for the effort, Bob!

And though I haven't seen him around in a while I'm also reminded of something MBc member uncle_punk13 used to say: "Sometimes it is better to be kind than right."

 

[graucho]

Most of the time it looks like Honda bashing place and for sale forum from where I sit.

I can see that you don't appreciate the effort I've made to share info or "teach", its ingrateful people such as yourself that me think twice about trying to help anyone.
When someone goes out of their way to help you, you generally say thank you.

Exactly my point... "When ANYONE (not just you) goes out of their way to help you generally say thank you"
I've listed over 1500 posts helping people without telling anyone to "shut up". It's this disrespect towards others that I have a problem with. The other Old Bob that i've often read about and respected... I have no problem with that guy. Out of respect for moped-dan's thread I'll let it get back on track.

 

[Old Bob]

Its not disrespect, its preventing people from misleading others into ruining their engines.I don't have patience for ignorant people professing "knowledge" that is based on heresay and myth.Post counts are meaningless.

If someone said their motor was having a breathing problem he instantly went to the exhaust side, slightly ported the exhaust and 9 times out of 10 gave it back to them with a smile. I guess i'm just passing on one of my family's flow solutions.

This is a major problem with teaching. There are people out their whose heads are filled with lore and myths and when presented with facts just don't listen.Its a fruitless effort to try to educate people on these forums because they listen to high post people thinking they may be knowledgable.
Anyone who comes along with facts is questioned and the lore continues.
Recommending starting with the exhaust side is a recipe for disaster.

 

[darwin]

Old bob knows his stuff. It seems to me that putting a K&N type air filter would increase performance somewhat. Instead of 50 deg of surface area to breathe you have 360 deg. Barring a k&n type filter just punching a couple of round holes in the plastic breather cover cant hurt it. If increased airflow doesnt help performance then turbos and k&n are just scams.

 

[moped-dan]

Well, Ive put about 200 miles on the bike with the holes drilled in the cover and the engine is running great. I think I'll stop while I'm ahead and leave it alone now. Thank you to both groucho and Old Bob for the information.

I'm happy to report I can comfortably cruise at 25mph with a 1.25" spindle, before I drilled the holes I averaged 22mph. It feels to me like it fights headwinds and hills better too.

 

[G-Superior]

Dont Agree With Something Here

Like someone said in this thread that does engines can be improved but you wont make it a monster i really dont agree with that
look at those rc model! their tiny engines scream and sometimes make over 8 HP and 18000 rpm with only 35cc
LOTS of time and probably money are needed to make one of those engines monsters but the problem is that it is worth for what its used
you will never use a 8 hp engine at its maximun in a bicycle, 4 hp is enought to bent metal like as if it was cheap plastic.
BUT i would love to have one of those in my BIKE!(SEE PIC)

 

[Old Bob]

Its true a 35cc Quick Draw puts 8+ hp out of the box and the four cylinder is a beast, but they are 2 strokes operating in an rpm range that you wouldn't want to run on a MB.AND they are pure race engine.

This discussion is about 4 strokes that start life as a lowly lawn tool engine that has limited ability to be modified at all.
Modifying a stock block four stroke will make more power when modified, but you won't get more than 3 hp out it at a very high rpm, much less make more than 2 hp at the rpm range the stock engine runs.

A normally aspirated full race billet four stroke in 35cc class is good for a little over 5 hp @ 15,000 rpm.

 

[G-Superior]

is all about reliability

and they dont last long at all if you keep cruising all day 18.000 rpm and it would be useless on the mid and botton end:-/
But it would be fun
G-Superior