The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Frenchy on 25.08. 2010 15:09

Title: no power
Post by: Frenchy on 25.08. 2010 15:09
I finally...  FINALLY... heard some life from my A7.  But there are some problems.  The biggest of which is that there's absolutely no power.  It'll take off in first gear, but at no more than 5 mph.  Has anyone else experienced this? 

Other problems include a wicked oil leak behind the primary.  I've got a gasket set, though, so I might be able to track that one down myself.  Also, the rear wheel spins true, but is at a bit of an angle.  I'll post a picture later.  It's like the swing arm might be bent. 

Any thoughts?  Or other posts that might address any of this?

Title: Re: no power
Post by: lawnmowerman on 25.08. 2010 15:31
Possibly a blocked main jet if it has been standing for a while - does it rev up ok in neutral?
As far as wheel alignment goes - I remember a post a while ago from LJ where he made up a wheel alignment jig from a piece of timber and some studding.
Keep us posted - you will find all the advice and information you need on this forum.

Jim
Title: Re: no power
Post by: a101960 on 25.08. 2010 15:52
Might be that the needle clip is weak and is not gripping the needle. In which case the needle will not lift. Put your finger into the carb and operate the twist grip. Can you feel the needle lifting? If the engine revs in neutral you might have a slipping clutch, or binding brakes.

John
Title: Re: no power
Post by: beezalex on 25.08. 2010 16:13
Could be a whole lot of things.

Does it smoke or pop/misfire?  Can you open the throttle, or does it die?  Is it running on both cylinders?  Does it rev at all?  Clutch slipping?  Is it blowing oil out the breather?

More specific info on symptoms would help.
Title: Re: no power
Post by: bsa-bill on 25.08. 2010 18:14
A wicked leak behind the primary ????
not to many places behind the primary that should produce a wicked leak - other than wet sumping, in which case there just might be a connection to your lack of power, tell us more about the oil that is leaking is it - black (engine) - oil coloured  (primary), smells metallic ( gearbox)
Title: Re: no power
Post by: a10gf on 25.08. 2010 18:53
Quote
I finally...  FINALLY... heard some life from my A7.
*clap* Congrats, good work. You'll sort out the rest over time, and learn a lot in the process. Maybe start with a check of magneto + timing, valve clearances & carb.
Title: Re: no power
Post by: Frenchy on 25.08. 2010 22:34
Hmm, what does a slipping clutch feel like?  I don't really feel anything out of the ordinary...  'Cept for no umph.

I took some photos and will put a link up tonight with some more specifics.  Thanks again for everyone's expertise!
Title: Re: no power
Post by: a10gf on 25.08. 2010 23:03
Quote
what does a slipping clutch feel like?
lots of revs and no go
Title: Re: no power
Post by: cus on 25.08. 2010 23:56
G'day Frenchy,
This is going to sound a bit obvious, but are you aware that gear selection is one up the rest down,
you might be taking off in 4th. Just thought I'd mention this because you might only be
familiar with more modern bikes!

Cus
Title: Re: no power
Post by: Frenchy on 26.08. 2010 00:19
One up, three down.  Please feel free to point out the obvious, I'm new at this!

Yeah, I've got lots of rev and no go.  Dang.  How much of a task is repairing the clutch?  Financially and otherwise.  I've got some guys coming over Friday to help out with my timing and to work on the oil leak.  Maybe it's as simple as that.  The Haynes lists both clutch and timing as a possible source of "no go."
Title: Re: no power
Post by: cus on 26.08. 2010 00:43
Frenchy,
Take your primary case cover off, you'll see if it slips on takeoff.
Take off the pressure plate, pull all your plates out, wash with petrol,
put all back. Make sure you get the press. plate spinning even with lever
pulled in, & before you put the cover on experiment with how far down you
screw the springs in. Also, while the springs are out, check they are all
the same length, you may need new ones,

Cus
Title: Re: no power
Post by: Frenchy on 26.08. 2010 03:28
Thanks, Cus.  I'll do that Friday.  In the meantime here are some photos.  I put some notes on a few of them. 

http://www.flickr.com/photos/36327282@N07/
Title: Re: no power
Post by: brackenfel on 26.08. 2010 07:26
Hi Frenchy,
As Cus says, get the cover off & have a look..
The hardest part on mine was getting the footrest off (shaft slightly bent and put in the wrong side with the head on the primary end!) - this makes it easier to remove the primary cover.

There are a couple of types, obvious when you get in there, 4 or 6 spring.
The springs have round slotted adjusters - if you can see lots of thread hanging out (which makes adjustment difficult - don't ask how I know!!) the plates are probably worn. They're freely available & not expensive..

Good luck,

Adrian
Title: Re: no power
Post by: Pete Gray on 26.08. 2010 09:50
Some very nice engineering there particularly the toolbox, well done.

Not being that well up on carburation but isn't the extra distance between the head and carb with the manifold adaptor a possible cause of the power problem ?
Title: Re: no power
Post by: lawnmowerman on 26.08. 2010 10:14
Nice looking bike Frenchy - I am sure it will be worth the final fettling to get it right. The only thing I would point out is the carb manifold extension. There has been many posts about carburation problems and heat resistant spacers and bias spacers. The induction tract seems to be quite critical both in length and shape although I am no expert in this area and many others on the forum are and will no doubt have views. IMHO, it looks like the manifold extension is longer than it need be and you may get away with a heat reducing spacer (or two) with extended studs which will shorten the inlet tract. Also I think I read somewhere on the forum that the iron heads run quite hot so benefit from the spacer. It looks like the extension piece is solid steel so would transmit head heat to the carb - although the length may dissipate the heat.
Hope you get her running properly soon.

Jim
Title: Re: no power
Post by: bsa-bill on 26.08. 2010 10:36
That's a fun looking bike Frenchy, nice bit of work to make the carb extension  *respect*  but I agree with the other guys, it MIGHT make a difference. Thick carb washers are available ( Draganfly and others).
That black gearbox inspection cover appeals to me if I could get three rifles on it also, I feel a time wasting idea brewing  *whistle*
Title: Re: no power
Post by: tombeau on 26.08. 2010 11:11
I'm also suspicious of the long manifold. I'd also fit s a carb drip tray, I know of a few A10s that have been lost to fire for want of one. Looks like a fun bike though.
Cheers,
Iain
Title: Re: no power
Post by: Triton Thrasher on 26.08. 2010 11:55
If the clutch was slipping so much you could only do 5mph, the kickstart would not turn the engine over.
Title: Re: no power
Post by: brackenfel on 26.08. 2010 12:49
Hi Frenchy,
I've just looked at the photos & must agree with the others. Junk the carb extension, get a thick fibre spacer in its place with a good gasket either side and fit a drip slope / tray asap..
Cheers,
Adrian
Title: Re: no power
Post by: RichardL on 26.08. 2010 13:40
According to the caption, Frechy needs the manifold in order to clear the Hunt magneto. From the photo, that appears to be correct. So what was Hunt thinking?

Richard L.
Title: Re: no power
Post by: Frenchy on 26.08. 2010 14:54
Quote
If the clutch was slipping so much you could only do 5mph, the kickstart would not turn the engine over.
Thanks.  I have a complete gasket set, so I'll probably take a look at the clutch anyway.

Quote
So what was Hunt thinking?
I was wondering that, too.  I had to grind a bit on it to get it to bolt on, too.

As for the carb extension, I'll look more into that.  I have family stuff today, so I'll be back at it on Friday.  I'm sure you'll hear from me then!
Title: Re: no power
Post by: beezalex on 26.08. 2010 15:54
So what was Hunt thinking?

He was thinking: I could take some fairbanks-morse tractor magnetos and stick them on just about every motorcycle known to man....some better than others.

So let's get some more specific symptoms before you start tearing into stuff:
Does it start and idle OK?
Does it rev in neutral?
Does it smoke?
Does it run on both cylinders? (If you can't tell by the sound, pull off each plug wire one at a time while it's running and see if anything changes)

....wait....I just noticed something from the pictures....

Turn the choke off once the bike's running.  Everything will be OK.
Title: Re: no power
Post by: A10Boy on 26.08. 2010 18:23
All comments from me deleted as I don't want to be banned. Suffice to say I'm reading this thread with a fair amount of disbelief....
Title: Re: no power
Post by: bsa-bill on 26.08. 2010 18:43
Andy - your not by any chance thinking about the fuel delivery, which is a tad over engineered but should still deliver petrol to the carb, or have you spotted something else.
Do tell - politely
Title: Re: no power
Post by: lawnmowerman on 26.08. 2010 19:58
Think I have spotted the same thing as you Alex - the choke cable is slack at the carb top meaning it is full on. Also looks like the adjuster is missing so probably will not be able to be turned off completely anyway.
Interested in what you have noticed Andy.

Jim
Title: Re: no power
Post by: bsa-bill on 26.08. 2010 21:21
ignition switch  - no battery - magneto -  do we take it the electronics are no longer used ?   
Choke should be the back one Jim which although out of the adjuster would withdraw, however the throttle has no adjuster and may well have slipped down into the carb  so the slide and needle don't lift         
Title: Re: no power
Post by: cus on 26.08. 2010 22:56
This is turning into a bit of a saga, but is interesting just the same.
Frenchy says he has lots of rev & no go! I don't think it would be reving OK
with full choke, but anyway, we'll have to wait & see,

Cus
Title: Re: no power
Post by: Frenchy on 28.08. 2010 03:35
I didn't get much time to tinker today, unfortunately.  I took the carb off and made a shorter manifold out of wood with no better results.  The needle lifts fine, and the choke turns on and off fine.  Way less oil leakage today, though.  The highlight of the day was when a muffler fell off on my street, at 5mph of course, and the neighborhood kids all offered to help push me home.  I had some spare shorties loosely bolted on to keep the noise down...  This thread IS turning into a saga, and I appreciate all your interest/ideas/advice. 
Title: Re: no power
Post by: Triton Thrasher on 28.08. 2010 08:13
According to the caption, Frechy needs the manifold in order to clear the Hunt magneto. From the photo, that appears to be correct. So what was Hunt thinking?

Richard L.

From the photo, it looks like the extension doesn't need to be nearly as long as it is.  A thick spacer might be enough.

With that long rigid pipe, expect fuel frothing, leading to untuneable richness and vibration-induced float valve leakage, leading to worse richness.