5hp Robin/Subaru Engine Mods

[super8isgreat]

I though I would post photos and share what I did to modify my 69 Rupp. I know how much i relied on photos when i was building this thing (hell, I still am).

-New fuel line and B&S performance filter.
-Fancy Breather (auto zone)
-Air Filter (OldMiniBikes Warehouse)
-Air Filter Adapter (OldMiniBikes Warehouse)
-18lb Valve Springs (OldMiniBikes Warehouse)
-Custom Header w/ B&S Lawn Mower Muffler
-Zip Tie Governor Bypass
-Tiny Tach (knock off brand)
-Drilled Main Jet to roughly an 80.

This thing is great! I'm loving it and wouldn't mind going faster haha I've been testing it out lately and reach about 34-35mph max speed. The tach says im getting up to about 5200rpm, and thats about when i back it down...dont want to do any damage.

The header sounds badass! Turns that little boy into a man. I used a b&s mower muffler and drilled out the plug that was in there to give it better flow...sounds great. It's loud, but much more quiet than just the header. Haven;t had the cops called on me yet! :001_tt2:

The zip tie trick works wonderfully for bypassing the governor. I understand the risks involved if over-revved. I've been really cautious and even bought the tach to regulate it.

Any feedback is appreciated! I'm always learning more and more every day.

ps. big thanks to Steven Durham for the rear turbine wheel! that thing was in perfect condition when I received it :thumbsup:

 

[george3]

Is the hot dog welded on? why? whats the zip tie for? The gov. is adjustable.

 

[Strigoi]

http://www.oldminibikes.com/forum/h...nor-your-engine-OldMiniBikes-please-read.html

:facepalm:

 

[super8isgreat]

Is the hot dog welded on? why? whats the zip tie for? The gov. is adjustable.

hot dog isnt welded...its clamped. i welded a piece of metal around the threads so it could easily be removed if need be.

the zip tie trick prevents the governor arm from retracting and slowing your engine down. i found several threads on here that explain it in detail. also, just curious...how can i adjust it? if it does what the zip tie does, then i might just do it.

 

[george3]

hot dog isnt welded...its clamped. i welded a piece of metal around the threads so it could easily be removed if need be.

the zip tie trick prevents the governor arm from retracting and slowing your engine down. i found several threads on here that explain it in detail. also, just curious...how can i adjust it? if it does what the zip tie does, then i might just do it.

I read the zip tie thing a long time ago. If it works Just use it but its prob.not governed at all. Its not too smart to have it screaming between your legs. I just re-adjusted the gov. on another members bike it functions but doesn't come on so quick. it could be deadly eliminated being stock rod and flywheel. the arm has a bolt on it that tightens on the gov shaft loosen the bolt and turn the shaft just a hair, re-tighten. make sure it still funtions but a bit less. much safer than than zip tie. you will prob. have to add a spring on that arm to return it to idle.

 

[Strigoi]

the zip tie trick prevents the governor arm from retracting and slowing your engine down. i found several threads on here that explain it in detail. also, just curious...how can i adjust it? if it does what the zip tie does, then i might just do it.

http://www.oldminibikes.com/forum/h...nor-your-engine-OldMiniBikes-please-read.html

:facepalm:

since you can't be bothered to read links, you can get banned for talking about modifying the governor.

 

[graygoose420]

Nice rupp super . Good little build. I have one myself.
Mine goes 77mph in the 1/4 .
If you want to go faster I suggest a clone . A lot of aftermarket parts .

 

[super8isgreat]

since you can't be bothered to read links, you can get banned for talking about modifying the governor.

no problem. i edited my posts. and just so you know....it's not that i was ignoring your link -- for some reason i only get about half of the email notifications for thread replies...i would have read the link earlier if i knew about it.

Nice rupp super . Good little build. I have one myself.
Mine goes 77mph in the 1/4 .
If you want to go faster I suggest a clone . A lot of aftermarket parts .

thanks man! i know, this subaru engine is a pain in the ass. it's a real hassle to make things fit and purchase aftermarket stuff for it (it came with my bike when i bought it used). 77mph?!? i would piss my pants if i ran 77.

 

[super8isgreat]

since you can't be bothered to read links, you can get banned for talking about modifying the governor.

actually....it won't even let me edit it out.

 

[doodlebug6.5]

What was the stock valve spring pressure?

 

[cxbra]

It would be SOO cool if those Robin/Subaru engines had the same boxer rumble as the Subaru WRX! Ahh.. Of course it cant happen, the boxer sounds like that because its a multi-cylinder, but you can still dream.