Carb

[gasman]

Still not running correctly even with Ram filter.
Spoke to Surrey Cycles, superb guy, even remembered me buying carb from him.
Anyway he thinks the 2D1 needle I have fitted is wrong, should be 2F1 as fitted to the 36mm Silk carb. He also thinks my pilot jet is too small as the bike try's to run better when I screw fully in the pilot screw. So as i've got a 25 fitted a 30 is on the way. So I also need to check what needle jet I have fitted. One day it will run properly.

[Hendred]

Are you using a 38mm carb?  I've been told there are several different transfer port/inlet covers for the Silk.  I don't know whether Silk matched the bore of the transfer port/inlet cover to the carb originally fitted.  My bike had a 38mm carb from new.  I have checked the bore of the the inlet and that is 38mm as well.  Might be worth checking your bore as a mismatch would cause all sorts of carburation problems.  

[gasman]

Hi, yes there are several different sized inlet manifolds, fortunately I have the 38mm one. It seems that whatever I do things are just not right. The engine is the very first, but I have had new liners to match the late Peter Greens last porting, 38mm carb as per last bikes, ignition set to last bikes, as far as I can check no air leaks, pazon ignition system, several sets of ngk plugs, I have even thrown away the purple ignition leads and fitted copper wire. It is defiantly running weak on partial throttle but as I've a small oil leak from the pump and that is in bits to replace seals I am unable to run with higher needle etc, but see when it does run right it will fly.
One day I will be able to just go out on it and enjoy.

Will update after next test's.

Kev

[Smokey_Paul]

Hi Kev I would definately follow my jetting as per the 36mm carb as that seems fine and would be a good reference point. I have the needle suggested too and as you my bike seems to be spot on at present.

[gasman]

Hi Paul, I was going to buy a 36mm carb as per jetting but Surrey Cycles said they are pretty unobtainable at the moment due to manufacturing problems. I have now got a superb tick over, but bogs down at 1/4 throttle, I sent a video to Surrey and he said defiantly a weak mixture. So after rechecking for air leaks i'm going up sizes in different jets, I told you I had the special one. Kev

[Smokey_Paul]

Hi Kev I may have a spare 36 body I will send you a mail.

[gasman]

I may have to take you up on that but today I have ordered a 109 and a 110 needle jet along with a 35 and 40 pilot so tomorrow should be interesting. Take a look at the link, this is what it was doing Friday. 30 pilot and 2F1 needle fitted..


http://youtu.be/OQm1klXArG0

[Smokey_Paul]

MMM that's not so good I will have to look thru my carb bodies and with what I have and your new jets you should be able to copy my carb and settings.

I think I would go straight for the 40 pilot first and see what happens, one thing at a time remember

[Smokey_Paul]

How did the jet go?

[gasman]

Wellllllllllllllll, its like this, ^%$%^$£$%@%$%^$^$£@£%@$££$&£%@$£!$£@%@%$!$@^%$^%$%@$£@$%£^$^$£%@%£^$^U$%$^
I have tried 25,30,35,40 pilot, 108,109,110 needle jet, even got to the point  where it wont even run, bad plugs I thought so new iridium type still no go, left it overnight and it started first kick. too rich on cold start now, revs from slow slowly, no high performance i.e. from about 2000revs, carb is very close to getting it so have put it too one side for the moment and getting the spraying done on the Scott Special.
I have also resealed the inlet manifold just in case, have even siliconed the two bolts holding the barrel down at the rear where they break through the casting into the inlet tract. may have to get a Mikuni. Kev

[Smokey_Paul]

Best I go look in my man cave to see if I have that 36mm to try, I spoke to Surrey Cycles about the issue, very helpful chap really.

[gasman]

Have had a thought, going to try something tonight will let you know. Heres a bit of paint for you to look at, Kev

[Smokey_Paul]

someone is going to get a Scott hate letter

[gasman]

Yippeeeeeee, getting somewhere with the carb. Gone back to 30 pilot, 108 needle jet, 480 main jet, 2 1/2 slide, 2f1 needle.
Runs fast on tick over with cold start on, idles fine with cold start off, throttle response not bad but I think a touch weak, will go for a 35 pilot as screw in to about 1/2 to 1 turn out, went down my dirt track spinning the back wheel, happy days.
The fault it would seem was Amal, after long suffering day's and night's for some reason last night my brain worked, the brass bit that sits in the airstream which the needle goes into has a cut out, this cutout was facing the airflow, so the airflow would actually cause a blockage across the hole for the fuel, tonight I took that bit out and fitted it with the cutout on the engine side so the airflow would go round the tube causing a vacuum at the needle sucking fuel out. It is now soooo much better and the carb may well live another day or two. Happier day's are coming, Kev

[Smokey_Paul]

Yep that's the correct way around for a two stroke cutaway and I think a 35 pilot would seem about right for the 38mm compared to my 36mm. I would leave the rest well alone and see how she rides

[gasman]

Yea will do and she might even get to go for an m.o.t this week if the running is good.