Manky's XS650 Yamaha

[the coppersmith]

I see that Villiers has a concentric carb, maybe that's why the strangler is upside down. An old friend of mine used to start his bike with a bath plug inserted  but it had a 8mm hole drilled in it

[Manky Monkey]

I was thinking about maybe a little muslin hood I could pop over the filter to start it then whip off & put in my pocket. We'll see how it starts once it's properly sorted. Just finished my delivery for the day -still nursing a sore ankle after the bike kicked back last week -so I'm off to Burlen Fuels in Salisbury for some larger jets & new floats.

[Olds]

It should be somthing rigid and well fitting to the bellmouths, otherwise it might ruin the domed mesh as the engine tries to suck it inwards. Had this happen with a rag while cleaning a running engine.

[Dslam]

Those carbs have a choke setup as standard which, I think, Andy removed. May be able to cobble something up. We shall see.

[Manky Monkey]

Non standard carb tops with no choke fittings. I've got the choke slides & probably the original tops, but no cable or handlebar choke lever. They do a carb mounted lever don't they? (operates on a cam & sits on the carb top).
New floats & aluminium valves bought.

[Dslam]

OOOOO! Stickers

[Baychimp]

Oooo after tomorrow they must be yours.

[fifer]

Andy , I know you said that the jets were as fitted to another XS and gave them as

For those that like to know these things, these are the carb details:

MK1 AMAL 930 concentrics

Throttle Valve #3 1/2. ( Part No~40-928060/3.5 )

Main Jet #140.( Part No~40-376100/140 )

Needle Jet #106.( Part No~40-622122/106 )

Throttle Needle

(2 Indent) ( Part No~40-622124 )

The needle position is set to the 2nd groove down, (midway).

On all the many Bonnie motors I have owned , the Main jets { with standard settings and choke slides fitted } were always between 180 and 220 .
I always removed the choke slides and blanked off the carb tops and , depending on what spec of tune I had applied to the motor , upped the main jets to suit .

Standard Bonnie motors were fitted with either a #2  1/2 or a #3 slide cutaway
A smaller slide cutaway will really richen it , as will lifting the needle position

Throttle Slides

Throttles Slides are stamped with their identifying size on the bottom surface. Typical markings will be either 622 for a 600 Series slide, 928 for a 900 Series slide, an MB number which is a foundry mark, and a stamped number from 2 to 5 indicating the height of the cutaway on the inlet side of the slide.

The angled cutaway on the slide manages the transition from the pilot circuit to the needle jet when the bike is running. Smaller cutaways will richen the mixture, larger cutaways weaken it.
From the Burlen site ;

Slides
600 Series P/N     900 Series P/N       Stamped as     Height of cutaway
 622/0602             928/0602                    2                      1/8"                    RICH
 622/06025       928/06025            2 1/2                         5/32"
 622/0603              928/0603            3                             3/16"
 622/06035     928/06035            3 1/2                          7/32"
 622/0604              928/0604            4                               1/4"
 622/06045     928/06045            4 1/2                           9/32"
 622/0605              928/0605            5                                 5/16"                  LEAN 

I only had to tickle the carbs till the petrol flooded out of the plungers and { set up correctly } one kick and they would start with only the tiniest bit of throttle from cold .


 

[Manky Monkey]

Hiya. I showed my scrap of paper with my jet sizes on to the guy in Burlen's this afternoon & asked what he recommended. He said what I had should be more or less right. I think the pilot jets are fixed in my carbs & can't be changed & the main jets will affect top end running, rather than starting & tick over, which we're looking at at the moment. 3 1/2 throttle slides are also roughly right I'm told. It's more than 30 years since I last played with Amal carbs & I have trouble remembering what I did this morning, so I'm happy to take advice. We'll see how we get on tomorrow.

[Olds]

You are correct about the pilot jet being fixed. It's a very small diameter hole in a piece of brass and tends to get blocked and suffer from lacquering.  It may be that with use, the fresh fuel will help remove any restrictions as might compressed air, (or air in a can) but pumping some carb cleaner through it, may speed up the process. Sometimes though it may have to be cleared with a piece of wire. The high e string from a guitar can be used 0.010" to 0.015".
You need to throw these new fangled concentrics away and fit some proper 376 monoblocks.
Good luck with this today.

[morrag]

Mr. M, it really is worthwhile checking your cylinder pressure, honestly, takes no time to do, and if nothing else can then be rules out, after all by your own admission it's been standing a spell. You have a relatively short stoke motor, which may not be developing sufficient "suck" to get sufficient fuel in, should pumping pressure be low. Over the years I have used all types of Amal carbs. and although sometimes evident, have seldom required choke slides to start an engine, maybe in the depths of winter!. The "tickler" gives you all the extra richness required for start up. Forget the main jet at this stage, and the throttle cut away is adequate, the fixed pilot must of course be clear, as per Olds advice,needle valve 11/2-21/2 out and........ , just got to..... Morrag

[Manky Monkey]

We do indeed have life. Many, many thanks to Mssrs Dslam & Oily Bike for their time today, (& the cake). I realise how frustrating it must be trying to explain the finer points of carburation to a 4 year old, but I appreciate them trying!
Hopefully Andy, (Dslam), will run through the details cos I know I'll get them wrong, but it's now firing first kick & ticking over, though fluffing a bit on blipping the throttle.
All sorts of muck in the float bowls & one fuel tap partly blocked by crud from the bottom of the tank didn't help, (now cleared with an air line & the small foam inline filters replaced with larger paper element ones).
Blowing exhaust at the head produced a bit of popping & banging but now hopefully fixed.
Compression test showed 6 1/2 bar on both cylinders.
I've left the bike at Andy's place for now, so he can have a think about it & fine tune it/poke it with a stick, but it's very nearly a fully functioning motorcycle now. Thanks again chaps. 

Andy at work while I supervise. 

[Manky Monkey]

Note the mis-matched kickstarting boot. You look cool mate. You can carry off that look, honest.
You'll have to take our word for it, but it is running in these pics.

[Baychimp]

He looks right at home on that bike. And you left it there. You might not get it back,especially if he decides to move house.

[hydro]

thats a lovely bit of news, bet you are very happy