A A A
Avatar

Please consider registering
Guest

Search

— Forum Scope —






— Match —





— Forum Options —





Minimum search word length is 3 characters - maximum search word length is 84 characters

Register Lost password?
sp_Feed sp_PrintTopic sp_TopicIcon
Head Troubles (mine)
Avatar
Swing42
NSW Australia
Second Gear User
Site Member
Forum Posts: 45
Member Since:
February 5, 2019
sp_UserOfflineSmall Offline
1
November 15, 2020 - 8:31 am
sp_Permalink sp_Print

Just cannot get this bike to run properly .. 1956 D3 ..

We've rebuilt the engine withe new parts,seals etc,fitted a whizz-bang CDI ignition,renewed carburettor parts,timed it correctly,jetted the carb ... everything that a restoration usually entails  ..

It'll now revv like a chainsaw ,if its in neutral,but when riding,it wouldn't pull the skin off a rice custard 🙁 ..

Loosening the 3 screws on the stator plate and rotating it when the engine is running at about 1/4 throttle didn't seem to make any difference. 

So,I'm asking .... will the engine run AT ALL ... with the piston in backwards ? (we're sure we got that right .. or did we ?) 

Thanks all .... 

Avatar
Number6
Lincolnshire
Top Gear User
Club Member
Forum Posts: 575
Member Since:
January 18, 2020
sp_UserOfflineSmall Offline
2
November 16, 2020 - 12:14 am
sp_Permalink sp_Print

If the piston was backwards the ends of the rings would snag in the ports and break off, I think, then you'd know all about it.

Personally I'd forget the CDI for the mo as a "step too far" and try to get it working on points, the old original system. Summat is awry alright. cry

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

Avatar
Number6
Lincolnshire
Top Gear User
Club Member
Forum Posts: 575
Member Since:
January 18, 2020
sp_UserOfflineSmall Offline
3
November 16, 2020 - 12:22 am
sp_Permalink sp_Print

Loosening the 3 screws on the stator plate and rotating it when the engine is running at about 1/4 throttle didn't seem to make any difference.

From memory, it doesn't work quite like that, you ride it to see what it's like, if you want to try tweaking the timing stop, alter the angle a bit, ride it some more, if it behaves better OK, if it behaves worse, stop again, put it back where it was, and like that. Owner's manual says once set right it shouldn't need altering on a regular basis, which makes sense if the contact breaker gap is kept correct.

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3558
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
4
November 16, 2020 - 7:36 am
sp_Permalink sp_Print

Swing42 said
Just cannot get this bike to run properly .. 1956 D3 ...

It'll now revv like a chainsaw ,if its in neutral,but when riding,it wouldn't pull the skin off a rice custard 🙁 ..

... will the engine run AT ALL ... with the piston in backwards ? ...

As No6 says, piston backwards runs the risk of ring breakage, but I don't think it will affect running 'per se'.

If it revs in neutral, is that uncontrolled revs or on the throttle? As for the power, I'm not sure of the consistency of Ozzie rice custard skins, but a D3 is not over endowed with horses anyway - do you mean it bogs down when in gear, or some other description?

Avatar
Swing42
NSW Australia
Second Gear User
Site Member
Forum Posts: 45
Member Since:
February 5, 2019
sp_UserOfflineSmall Offline
5
November 16, 2020 - 8:57 am
sp_Permalink sp_Print

An update ...

First of all ,thanks heaps for your responses... greatly appreciated..

Ok.. the piston is not in backwards ..good.

I've already bought the CDI,so the one which was lent to me will be going back.They got good reviews here ,so that's the way we went.

Now to the power issue .... I spoke to Bones ,designer of the CDI unit and owner of OZ Bantams today, and I think he's worked out what the problem is... power (the Bikes') to weight (mine) ratio ...

" a D3 is not over endowed with horses anyway" .. me being a reasonably rotund sort of a chap at 92 Kgs,riding a 150cc Motorcycle was expecting too much from his machine ...

.. And what made things even worserer 😉 ... was the fact that we fitted a 16 tooth gearbox sprocket.We live in rural Australia and as I thought that all the riding to be done would be done on the highway,the 16 toother would make for a lower revving ride.Seems as the donk is not powerful enough to cope...

We've ordered a 15 tooth sprocket and are hoping for a good result .. progress report to follow.

What do you think about this ? does it all make sense as a diagnosis ?

Thanks gents ...

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3558
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
6
November 16, 2020 - 9:21 am
sp_Permalink sp_Print

Well, I have a '56 D3 too, which is on standard gearing and fairly flat rural roads. She is happy at around 40mph and I am about 86kg, so a bit more streamlined. In comparison, I have a 125cc Honda Pantheon scooter which blows the D3 into the weeds...

However, here's a short clip of the D3 on a hill...

Avatar
Swing42
NSW Australia
Second Gear User
Site Member
Forum Posts: 45
Member Since:
February 5, 2019
sp_UserOfflineSmall Offline
7
November 16, 2020 - 9:30 am
sp_Permalink sp_Print

Cheers Coco .... do you have a 15 tooth sprocket fitted ?

Avatar
Swing42
NSW Australia
Second Gear User
Site Member
Forum Posts: 45
Member Since:
February 5, 2019
sp_UserOfflineSmall Offline
8
November 16, 2020 - 9:32 am
sp_Permalink sp_Print

Is a 15 tooth sprocket standard gearing ? ... my rear sprocket is 47 tooth ..

Avatar
Sponge
Lancashire (A chip shop somewhere near Preston)
Top Gear User
Club Member
Forum Posts: 754
Member Since:
November 6, 2016
sp_UserOfflineSmall Offline
9
November 16, 2020 - 11:24 am
sp_Permalink sp_Print

Swing42 said
Is a 15 tooth sprocket standard gearing ? ... my rear sprocket is 47 tooth ..  

Mate I weigh about 155kgs and ride a D1 with a Bones ignition. Set up properly it goes OK so I wouldnt be too worried about yr weight.  15/47 T sprox is a good set up on roads through rolling countryside but if it truely dies when you open the taps I would suspect it, has a blockage,  needs a decoke or has an air leak. 

Hope you get it sorted soon. Songs 

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3558
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
10
November 16, 2020 - 11:32 am
sp_Permalink sp_Print

I think mine is 15/47, but it's a few years since rebuild...

Avatar
GlenAnderson
Dover
Top Gear User
Club Member
Forum Posts: 471
Member Since:
August 27, 2013
sp_UserOfflineSmall Offline
11
November 16, 2020 - 3:04 pm
sp_Permalink sp_Print

16 tooth front sprocket is definitely too big. They can barely pull the 15. 

Avatar
Swing42
NSW Australia
Second Gear User
Site Member
Forum Posts: 45
Member Since:
February 5, 2019
sp_UserOfflineSmall Offline
12
November 16, 2020 - 10:58 pm
sp_Permalink sp_Print

Cheers Amigos ... a 15 tooth sprocket is on it's way to me ... progress report to follow.

Forum Timezone: Europe/London

Most Users Ever Online: 223

Currently Online: rusty1
16 Guest(s)

Currently Browsing this Page:
1 Guest(s)

Top Posters:

cocorico: 3558

Cornish Rooster: 2917

Blue Heeler: 2434

bart: 2433

David Dale: 2144

Sprung Chicken: 2121

sunny: 1928

Piquet: 1846

Mags 1: 1753

mike p5xbx: 1688

Newest Members:

RobF

Forum Stats:

Groups: 9

Forums: 48

Topics: 10913

Posts: 96029

 

Member Stats:

Guest Posters: 1367

Members: 3504

Moderators: 0

Admins: 3

Administrators: Bantam-Super, JMD, Stoo63