TS 250/1 amal concentric

[DAVIDGUEST123]

My recently seized 250 is now back on the road and running ...sort of. The cold starting is a real pain but once warm runs fine, all be it with a little piston slap from the oversized rebore. I'm now looking into the carb. When I orginally bought the bike it came fitted with a Amal Concentric Mk2 carb and after a bit of digging the carbs mainjet had been drilled and float sticks. Another issue is the brass 'spray' is a four stroke one. I have tried the setting from the 'Sweller' carb web page but nothing seems to work.
I'm now a great beliver in standard is best, so I'm weighing up the options for a replacement carb. The options seem to be..
1) BVF Orginal ... If you know any about let me know
2) BVF non orginal copy cheap but are they any good?
3) Mukuni vm34 Seems to be difficult to get the rights jets without ordering fron the states
4) Change the spray tube in the amal...how's it done?

Any input greatfully taken on board

Thanks Dave

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVIDGUEST123]

Hi Puffs. You really are the font of all mz knowledge.
I've decided to have another go at the Amal. This is what 'Sweller' recommends

Amal Concentric Mk II - Type L2 - 903 - 303 Throttle Slide Part 2928 No. 3 (28mm carb?)
Needle Type 2D1 - middle groove
Needle Jet 105
Main Jet 210
Float Height Factory Set (nylon type float)

When I bought the bike it came with a hole box of various Amal concentric bits and bobs and a complete
spare carb(2930 30mm I think). I have however stopped using any of these spares as I've decovered that a few of
the jets are only for four stokes, the others have been butchered by them being drilled through. So I'm starting
from scratch and buying in the above jets. The carbs that's on the bike, after a dig around the net is a 2032-303
whichis slightly bigger than above, some I'm guessing I'll need slightly bigger jets.

I believe I'm travelling down the same route as a prevoius owner. If I can't get to the bottom of it by
Chrsitmas then the only option will be to get Father Christmas to buy me a new Mukuni/Bvf/OKO.

I will not be beaten.

Once again many thanks for the help.... Dave

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVIDGUEST123]

Thanks again Puffs.
Well after a day of fiddling I found the answer. It may be of interest to anyone else think of going down the same route. The carb I have installed is
a 2930-303 with a Norton type Needle 'Spray tube. I managed to dig out from the bits that came with the bike a small plastic container with variuos jets. On dismantling the
carb the main jet and the needle jet were more or less correct 220/ 160 this is where the fun starts. the difference between the two stroke version and the four are.
Spray tube
Hole in in the side of the needle jet.( from top to bottom it's..Spray tube thingy. Needle jet. jet holder then main jet)
Main jet holder collar
And finally Two positions for the idle jet to sit.
This is where the problem was with my carb. The previous owner had installed two pilot jets one in the main body and another in the bowl. The reason for the wto position
is so that if neede the jet can be placed nearer the venturi exit which would be required for a two stroke.
So the only part which is incorrect now is the 'Spray thingy' and see that the bike now starts on the first kick and appears to run ok I may well leave alone.
When the weather improve here I'll give it a decent run and fine tune it.
Thanks Again Dave

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVID THOMPSON]

i find carbs and hydraulic to be a bit of a problem they are both a mystery and a help
and may GOD help you if you use the wrong part or turn the adjustments the wrong way
and i have been helping a friend with his mess in a car ...things have not improved
there is now a computer involved
Dave

[DAVIDGUEST123]

Hi. Here some answers, or at least what I found out

Amal mk L2932-303 Two stoke carb left handed which means the adjustment screws are on the left.Makes life easier for something like a twin to have left and right adjustment 'Sides'
Swellers Amal mk2 carb number don't make sense.

#13 Pilot jet 25 in the front position ie near the barrel for a two stroke. Apparently two stroke don't suck as sharply as four stroke
#50 Small blocking screw shuts the other hole off. One and a quarter turns out on the air screw.

#17 Main jet is a 220. the number is not a physical hole size but a flow rate.ml/minute or something like that. Might try a 225 if it wasn't so bloody cold out.

# 7Slide is a two stroke 2928

#6 Needle a 2d1 matched with above.

#15Nozzle jet . My mistake not a 160 but a 106. Again this is flow rate but with the needle in.

#16The main jet holder without the collar. They are shown on the website and is sometime to do with how deep the main jet is in the float bowl

#2 And last but not least the 'Spray nozzle thingymebob' This surround the nozzle jet and is there to spread the fuel. Two strokes have a relativly slow suck as compared to a four stoke
There are three type One slopeing cut two stroke another flat as per#2 and one with a stepped cut I think this the one I have and can't see it's going to make that much difference.

p.s #31 is for an alcohol 4t

Any how with the settings and the carb above bike starts first kick and ticks over at 1500 rev without problem.

Hopefully this is of use to anyone

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVIDGUEST123]

Hi Puffs,
Yep that's me done for a while. It starts really well and quick run up the road all seems well, any further and my old bones won't take it....done my winter riding a good few years ago.
The piston rattle still bothers me a bit and as the orginal barrel has a corner missing from one of the fins ,I'm gonna keep an eye out over the winter months for a good un and rebore that on
to the correct size. Now if anyone one knows of such and item........
Many thanks Dave

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[Blurredman]

I'm glad you are getting the performance out of your bike as you hoped..!

[DAVIDGUEST123]

Hi again,
Test run done, inbetween the rain showers. All seems to be good, probabally should go to 225 on the main as the plug is a more milk chocolate than dark choc, but for now it's ok.
Yep the rebore is a bit of a pain, kind of blame my self for letting the chap decide what was the right gap. Saying that, the rattle sound bad when it's ticking over and on the overun but out on
the road under load it sounds ok. just need to keep an eye out for a barrel then get it done correctly to spec. I've had a quick look on ebay Germany but they're all a little salty. There's one listing for
a barrel with half the top fin missing and the chap want 220 euro for it..suppose there's no harm in him trying.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVIDGUEST123]

https://www.ebay.co.uk/itm/MZ-250-2-196 ... Sw~ERd2rK9

Enough said