carb needle

[cadetchris]

having just put a nice HIF44 carb on primrose, (i think that's right, its a HIF carb with a 44mm throat)
she is running rich and lumpy. the consensus is that its the needle.

so what needle do i need in order to make primrose run nicely?

btw,
she has a 1098cc engine, just in case it matters

[hotrodder13]

what needle is in it at the moment

[cadetchris]

emm, pass. the carb came straight from a 1275 metro or mini if that helps

[PSL184]

A 44 is really too big for a 1098 - Ideally you need a 38. If you look on mintylamb website it will give you the needle profiles and you can see what is weaker than yours but you need to take your needle out and find out what's fitted to it first.....

[cadetchris]

is it stamped on the side of the needle or is it a case of match it to the picture?

[PSL184]

It should be stamped on the needle at the top - You may have to remove it or at least remove the needle and damper assembly...

[cadetchris]

all the needle has stamped on it is "BDL" is thats any use

[PSL184]

That will be the number then

Go to mintylamb and experiment.....

http://www.mintylamb.co.uk/suneedle/

[cadetchris]

minty lamb says its the number, but all it brings up is a graph,

[PSL184]

You have to select a second needle to compare it to - The second needle chosen will be shown on the graph alongside your BDL....

[hotrodder13]

use it to compare diffrent needles i used it for the smaller carb

[linearaudio]

Trouble is, its like finding a needle in a haystack (sorry!) as they are not in any logical order. The only sensible way to do it is to put all your details into Burlens "winsu" programme. Costs £10 to download unless someone out there has a copy and feels like putting your figures into it!
You really would be better off e-baying it and getting a 38mm likewise, should be do-able without losing money on the deal!

[cadetchris]

well i would very much like to keep the same carb on it, just change the needle, which i am nit sure what to look for when fiddling with mintylamb. i think ill just ring up burlen's and beg for help, and if that dosent work, ill just put the original su on. might mean drilling the manifold, but if it means i actually get primrose running properly it MIGHT be worth it

[PSL184]

A standard 1098 will run fine with the standard carb - why did you think you needed to change it.....?

[bmcecosse]

You are going to struggle with that big carb, on an otherwise standard 1098 engine ? Or has it been modified in any way ? I would say that BDL should be fine - why do you think it is not ??

[cadetchris]

i dont think i need to change the carb, just the needle, it runs very badly at low speeds or when i change gear, it loses power and coughs and splutters a bit, but then i floor the peddle and all is ok. i have adjusted the mixture both ways and it dosent make a blind bit of difference. i have weakened the mixture so much now, that even though its better than it was, its still as rough as a badger, so if i weaken it any more it will literally be running on fresh air.
hence i think the needle needs changing to a more appropriate one for a 1098 instead of being set up for a 1275. if it dosent settle down or i cannot find a correct needle for it, i am going to take it off and make the standard carb fit the manifold for the sake of better running and piece of mind

[bmcecosse]

The problems are caused by the carb being too big for your engine..........
However - try some heavier oil in the dashpot - 20W50 and see how that goes.

[mike.perry]

You can buy a booklet listing all the SU needle profiles from Burlens. You can then select different needles and run them on the mintylamb program. You can also get the SU Reference Catalogue which will list all the carb and needle applications.

[bmcecosse]

Plenty of on-line sources for needle profiles! No need to buy anything.

[cadetchris]

ooh, i could try the oil idea.