The Amal on my 1972 Cota 247 is just about worn out and I am thinking of changing it for a Mikuni. Has anyone done this mod and can give a walk through of what is required, jet sizes etc etc?

Thanks!

Also have a 247 and would like to know the same

I'm also in the same position - rebuilding a 247 MK4b and the Amal is worn.

I'm going to fit an OKO as it is a lot cheaper than a Mikuni and they work well. They also seem to work on just about any bike straight from the box. I have a 26mm on an Ossa, all I did was drop the needle, 26mm on a 320 Yam Majesty no changes, 28mm on a 340 Bultaco has smaller pilot jet. All run fine. Problem with Mikunis is the huge variety in needle/needle jet combinations depending on the type of Mikuni. Certain needle jets only work with certain needles and carb bodies. Bit of a minefield. OKO is much easier.

May be worth a try - you'll just need an adapter for the inlet manifoldb as they are push on not bolt on.

I have a 1974 Cota 247, with a 24mm Mikuni on it. Bolts right onto the cylinder, without a problem. Had to machine an aluminum adapter to go from the carb to the stock rubber boot, for the air cleaner. The adapter is held onto the carb with epoxy. The boot attaches to the adapter with the standard hose clamp.

I have a 247 with a 26 MM mikuni on it. Jetting is:

pilot - 30

main - 130

needle jet - O-2

needle - 5f21

slide: 2.5

float jet: 2.5

It starts well and runs well, but is a little too abrupt at just off idle, kind of like having a fast-turn throttle, even though I have a slow amal throttle fitted. It is a spigot-type carb, and it has an aluminum adapter between the cylinder and the rubber carb mount. There is also an adapter for the mouth of the carb to mount to the airfilter boot.

I have another 247 with a rebuilt amal (replaced all jets and needles, had the body straightened and the slide sleeved last year), and it is MUCH nicer at low throttle. It comes on smooth and linear, instead of on-off like the mikuni. I would love to have another amal...

I have verified the jetting with a reputable dealer, and although I have tried different pilot jets, needle jets, and needle postions (don't have another slide with a different cutout) i can't seem to improve it. That's because i am not very good at 2-stroke carb tuning.

Good Luck! The 247 is a great bike!

Edited October 13, 200916 yr by mjfriesen

I'm also in the same position - rebuilding a 247 MK4b and the Amal is worn.

I'm going to fit an OKO as it is a lot cheaper than a Mikuni and they work well. They also seem to work on just about any bike straight from the box. I have a 26mm on an Ossa, all I did was drop the needle, 26mm on a 320 Yam Majesty no changes, 28mm on a 340 Bultaco has smaller pilot jet. All run fine. Problem with Mikunis is the huge variety in needle/needle jet combinations depending on the type of Mikuni. Certain needle jets only work with certain needles and carb bodies. Bit of a minefield. OKO is much easier.

May be worth a try - you'll just need an adapter for the inlet manifoldb as they are push on not bolt on.

woody did you find much differance between the oko 26mm and 28mm carbs ? thinking on trying one on my 330 mont , but cant decide on which size to get. currenty have standard knackered amal 27 mm .

if you like the amal carb why not just buy a new amal, they are not expensive and look like they are available from stock, I have thought about trying a new mark2 concentric on my TY but not gone through with it yet.

woody did you find much differance between the oko 26mm and 28mm carbs ? thinking on trying one on my 330 mont , but cant decide on which size to get. currenty have standard knackered amal 27 mm .

I haven't tried the 26mm and 28mm carbs on the same bike so can't make any comment on a direct comparison. I used a 28mm on the 340 Bult as 28mm is the standard size, so just went with that. However, a 26mm Amal works fine on an early 325 Bult so 26mm should be okay on the 330 Mont. Majesty 320 also uses a 26mm carb.

When I get around to finishing my Cota 330, if the Amal is worn I will probably go with a 26mm as it should quicken up the bottom end a bit. From trying it before I stripped it, it was a bit lazy, but it was also a bit worn so difficult to asses at the time how it really should have gone. However, if the OKO are still as cheap I may get a 26mm and a 28mm and try both.

if you like the amal carb why not just buy a new amal, they are not expensive and look like they are available from stock, I have thought about trying a new mark2 concentric on my TY but not gone through with it yet.

A new MK2 Amal is about

Just checked amal website again and according to website it is

Edited October 26, 200916 yr by ausy300pro

Just checked amal website again and according to website it is

according to site there is not a brass slide available (maybe it is available by special order but if that's the case then that would push the price of any carb up) but you can customise a carb to any spec you want and it's all at no extra cost, the more I look at it the more it seems the people at Amal carb are doing a good job of putting the carb on the market at the right price at any spec you want, as I say no vested interest and have not purchased from them but am impressed by whats on offer on website.

Out of interest, where have you seen them for that price - the Amal (Surrey Cycles) website has them for the prices I mentioned. My MK1 cost just short of

Edited October 26, 200916 yr by Woody

according to site there is not a brass slide available (maybe it is available by special order but if that's the case then that would push the price of any carb up) but you can customise a carb to any spec you want and it's all at no extra cost, the more I look at it the more it seems the people at Amal carb are doing a good job of putting the carb on the market at the right price at any spec you want, as I say no vested interest and have not purchased from them but am impressed by whats on offer on website.

Have a look here :-

http://www.surreycycles.com/carb_01.htm

yes see what you mean, I have been looking on the amalcarb.co.uk site prices are much better there, looks to me like surrey cycles are an agent adding a mark up onto the amal price.