Carb.selection & Tuning for RGS 'wanabe'

[Lord Flashheart]

Hi All,
My '60 Super Rocket motor continues its reluctance to start, and persists with rich running.  I have now decided to get the (worn) carb. bored and sleeved, in an attempt to resolve some of the problems. Over the winter, I also intend to strip the engine and carry out any work which is indicated, including replacement of the cam (357) which I know to be badly worn on the ramps.
The bike is an RGS 'Wanabe' in most respects, with a long ram-pipe on the monoblock, twin 'Goldie' silencers ( did I say silencers ?) .
While, I like the traditional look of the mono' i'm wondering if a change would bring significant benifits.

Questions are;-
1. with the set-up described, is it always going to be a difficult bike to start.
2. What carb set-up would be recommended as a starting point. ( 1 5/32" monoblock)
3. Does anyone have experience of a switch to Mikuni ( or any other brand ), and with what effect.?
   ( I know many of you have had largely favourable results from your concentrics. ( from earlier posts)

Flash'

[Clive54bsa]

My Liege, I have some interesting articles on carb changes including the Mikuni, but unable to post on this forum. If you contact me through the members tab, I could email them to you and possibly help with your dilemma.
your servant
Clive54bsa

[bsa-bill]

Had similar (extreme) problems with my Rocket Gold Flash, spent a lot of my time and members patience looking for an answer.
Changed to Electronic ignition and it now starts first kick, Magneto has to be 100% to start higher compression, mine had been "done up" the same place my other bike's(Flash) had been, swapping the magnetos from one bike to the other made no difference, when (if) I ever get organized I'll send it to guys here for proper refurb and try again.
I take it you've tried the obvious things , clean slip ring, check points et all you might also try an extra washer below the safety screws (2 of) It's possible with higher compression the spark would prefer to jump this gap than the plug gap. (ever wonder why Lucas made racing magnetos)
I'm not suggesting you go to Electronic ignition just emphasizing the fact that fitting it on my bike proved it was ignition at fault. I prefer the look and independence of a magneto, also like having two non fatigued legs and a low revving ticker

357 cam - yep I have one, it's a got to have thing init, but unless your going to flog the thing along motorways or a track stick to 356, my originla wish list was for a Rocket type bike with quick acceleration, I abandoned that spec blaming the gearing and everything else under the Sun for it not starting, Pazon proved it was ignition so I'm probably going to try very slight gear reduction and 356 if I need (read have an excuse ) to go into the engine again

[Lord Flashheart]

Hi all,    Thanks for the prompt replies.

I should have reiterated that i've done the mag conversion - to electronic - (SRM) some time ago, only to discover that sparks were still absent. ( turned out to be 'blue box'
failure, -replaced by Boyer under guarantee ).   Now sparking well, timing checked and double checked, carb stripped checked for obstruction, flange flat and sealed, internals new and correctly spec'd. for '60 S.R., body/throttle clearance  12-15 though hence decision to sleeve.(now in the long queue).

Do you you guys concur that things like H.C., "Sports" cam, Goldie silencers, and open induction can all play their part to a significant degree in making starting difficult.?

I understand that each of the above can have an influence when tuning the carburetor and I'm currently seeking what data I can on tuning sequences etc. when faced with these "complications".  I have some books in the post, so i'll either educated or confused in time.

Bearing in mind the bike is something of a mongrel (with pretentions)  I'd be interested to hear your views on induction 'filtration' (or lack of it).  I've avoided same to date purely on appearance grounds (most models of the late '50s early 60s ran without) and only became common-place with unit construction ???.   With low milage in the UK I consider 'wear' not worth the worry.
Should all or some of the jetting take this omission into account.? (1 5/32",25,106,350(+).

Hope the above 'fleshes-out' somewhat.
Flash'

[alanp]

My RGS rep (has everything possible in the pursuit of power) was parked next to a Flash the other day and its owner started it up with a gentle push down on the kick start, hardly lifted himself off the seat.....I had to jump from a great height (I exagerate of course, but you get the idea) to get my kick starter to swing and start the engine.
On the road though he didn't see which way I went, if you catch my drift. 'You pays yer money...'

[bsa-bill]

Ah so your already converted Clive
Do have a friend with SRM ignition that failed (after years of good use) can't recall what it was but remember him being annoyed at missing it as it was something really simple.
Not due to see him again for another nine months or so unfortunately but might be worth checking all wires and pickups (I'll try to dig it out of my mind)

[muskrat]

G'day Flash.
You might need to go a tad richer with the carb, 30 pilot, 2 1/2 slide, lift needle (clip in bottom notch), your main sounds about right.
Battery on it's way out or a bad connection will send the ignition timing to the advanced side which will hamper starting.
If the carb and ignition is set up right it should be a 1st or 2nd kick starter. Both mine have straight through exhausts, no air filters and 357 cams and both start 1 or 2 kicks. The '51 A7 has a 930 (1-5/32") and the cafe has two 30mm Kehins.
Cheers

[Lord Flashheart]

Guys,
Monoblock now away on holiday    (gone for a re-sleeve).   Also looking favourably on the JRC 30 as a second string carb.

Meanwhile as many of you (and SRM) are suggesting, ill go through the ignition wiring terminals and solder the joints to eliminate current or future voltage drops,(and tendencies toward advancement). Battery is good and always kept fully charged. .
Looking forward to getting jetting sorted once I can start reliably and get in some high speed running.

Thanks to all for your interest and input.
Flash'

[Lord Flashheart]

Musky,
Your set-ups, and ease of starting give me encouragement, and the confidence to persevere. My one concession may be to an air filter .("You know it makes sense")
But we don't always want to be sensible do we ?.
I assume there was significant 'porting' needed on the A7 ?     I'm thinking your Keihins are prob. similar to the JRC 30 (Keihin moded with flange fitting) that i've been looking at ?
what model are they ?
What level of care have you taken with matching port to carb.?

Cheers!
Flash'

[muskrat]

G'day Flash. My '51 has my original '57 SS top end and was running a 32 on the track, so had to build up the port to take the 30. I match the port to carb.
The one's I have  http://www.ebay.com/itm/Carbs-30mm-TRIUMPH-NORTON-BSA-Amal-Mikuni-alternative-carburetor-parts-/380753142134?pt=Motorcycles_Parts_Accessories&hash=item58a6a7e176&vxp=mtr on the cafe but they are both left hand (don't make right hand) so the choke is awkward and the pilot screw almost impossible to get to on the right. A single carb would be too easy.
Cheers

[muskrat]

Not so easy to tune when they are put on a special. It took me months to get them close on my cafe (sort of a SR Special). Two 30mm with the flange removed, rubber hose mounted. In saying that once there in there great.
Cheers

[bassgreg]

I am completely new here so stick with me for a moment.

Been building a flash special for ages around a Bowden carb that my Great Uncle bought to solve a running problem on his Flash in 1957.
I am yet to figure out if there are any benefits to this carb, but since it is where the whole bike started I am soldiering on. ( I was given the carb in it's box when he passed away)

An expert once told me the carb couldn't possibly exist but since I have all the paperwork from the Bowden factory stating it was for the A10 and a full set of spare jets to go with it it seems he might have had his facts wrong. Does anybody else out there know of any Bowden carbs in use on A10s? There is remarkably little by way of information about them.

I am fully aware that the bike should have an Amal if I were trying to keep it standard.

Cheers for any info, you may throw things at me if you wish, but encouragement and or help would be preferred.

Greg.

[bsa-bill]

Go here Greg might be of interest
http://www.ebay.co.uk/itm/BOWDEN-CARBURETTOR-INSTRUCTIONS-PARTS-LIST-6-PAGES-/151297757248?pt=UK_Collectables_OtherTransportation_RL&hash=item233a0c9040

[bassgreg]

Cheers Bill,

That is now ordered. Nothing like working completely blind to make life difficult.
The bike runs but it is a bugger to start, hopefully this will shed some light on the matter.