HB Unique Feature

HB , Helmet Burnhard, engines, Made in Germany. Owned by RJL Industries since 1989.

Moderator: SteveM

HB Unique Feature

Postby w6vfo » Mon Feb 13, 2012 1:51 pm

The person I recently acquired a HB 61 from said that by rotating the carburator 90 degrees, the enign could be made to run backwards (i.e., clockwise). I don't see how rotating a carb 90 degrees could work - is there any validity to his statement? Thanks - Bob
w6vfo
 
Posts: 3
Joined: Wed Feb 01, 2012 10:55 am
Location: Fair Oaks, CA

Postby SteveM » Mon Feb 13, 2012 4:38 pm

Are you able to remove the backplate and nose piece and swap them perhaps? Rotating the carb has no effect.
SteveM
 
Posts: 242
Joined: Mon Nov 20, 2006 10:33 am
Location: Ottawa, Ontario, CANADA

Postby ffkiwi » Mon Feb 13, 2012 10:02 pm

This can be done in engines with a separate front housing and symmetrical bolt spacing. Rotating the front 90 degrees to the right (viewed from the rear of the engine) so the intake and carb are horizontal) will allow the engine to run in the reverse clockwise direction.
This is no doubt what the vendor meant, but perhaps didn't explain very well......

ffkiwi
ffkiwi
 
Posts: 91
Joined: Thu Jun 12, 2003 3:59 am
Location: Christchurch, New Zealand

HB Running Backwards

Postby w6vfo » Fri Feb 17, 2012 9:20 am

ffkiwi wrote:This can be done in engines with a separate front housing and symmetrical bolt spacing. Rotating the front 90 degrees to the right (viewed from the rear of the engine) so the intake and carb are horizontal) will allow the engine to run in the reverse clockwise direction.
This is no doubt what the vendor meant, but perhaps didn't explain very well......

ffkiwi


Thanks ffkiwi - I saw several other forums where they talked about rotating the front protion of the housing. However, none mentioned which direction to rotate. I appreciate your response and will give it a try.
Take care.
Bob - W6VFO
w6vfo
 
Posts: 3
Joined: Wed Feb 01, 2012 10:55 am
Location: Fair Oaks, CA

Postby Fabricater » Sat Jan 26, 2013 7:32 pm

Well, You got me thinking Ron... But now, I'm totally confused. I thought, that the intake charge always led the pin. Generally from my experience, the centerline of the crank pin follows the centerline of the port by 20 some odd degrees. By my thinking (could be dangerous) Viewed from the rear... most two strokes intake port opens at 135 degree's of crank and closes at 20 some odd degrees after top dead center.The longer the stroke... the longer the intake charge duration. (wider the port slot in crank)



Again, as viewed from the rear, seems to me... rotating the front casing on an engine CW would tend to align the port timing to make for a reverse running HB61.



With rear intaked engines.. seems the same principle would work as well.

However, great care is needed to ascertain the proper piston skirt to backplate clearance. Sometimes you can cut a radius in the skirt... but it is always best to create the clearance on the backplate if enough stock is present to do so, although the increased crankcase volume created... is a power killer. ie the charge tends to loose it's velocity, making for fuel/air separation. Nothing that some well placed JB weld in the old clearance cut, couldn't fix.

Where do I have it wrong?



Thanks for your time,

Duke
Fabricater
 
Posts: 3
Joined: Fri Jan 25, 2013 12:34 am
Location: Michigan

Postby MECOA » Sat Jan 26, 2013 10:44 pm

here it is for a rear intake engine

http://www.mecoa.com/faq/crankshafts/cr ... rrotor.htm

some more info

http://www.mecoa.com/faq/crankshafts/cr ... /crank.htm

and for a front intake engine looking at the front you must rotate the front housing 90º CCW if it's removable.
MECOA
Site Admin
 
Posts: 1095
Joined: Mon Jun 30, 2003 9:48 pm


Return to HB (German) engines Tech Questions

Who is online

Users browsing this forum: No registered users and 5 guests

cron