LCGB Forums

Hi.

I'm just trying to find a ball park jetting for my Ts1 225 . It's sx200 gearing but with a 17 tooth front sprocket and a Harry Barlow expansion exhaust and timing at 18 degrees.

It was running a 34mm Dellorto but I was struggling with it at low revs.

I've managed to get and fit a tmx35 Mikuni and it's running slightly better. Ticks over smooth, starts fine, top end good. but still quite spluttery at lows revs.

The settings of the tmx are

300 main jet
20 pilot
58 needle on middle groove
Mixture 1.5 turns out

I've had a look about on here and elsewhere but jetting seems anywhere from 370 to 280

Thanks
Kris

Thing is, the TMX35 mm runs a fixer atomiser. Over time/use these wear out so the jetting needs changing depending on this wear. It also means giving advice is a risky job. I've known folk running 55 needles, others up to 58. 22.5 or 20 pilot jets and then 300 to 340 mains, all on TS's.
I would recommend a dyno visit if you can.

Have you tried the needle on the top notch? As already said, the needle and atomiser wear so measure the needle on the area before the taper starts if it's a used carb and then compare the size to what it should be when new.

No, I haven't altered the needle yet, but I'm guessing from the symptoms its running rich at quarter and half throttle so I was going to drop the needle a notch and see.

It is a used carb but hardly used , needle and atomiser seem new but I will check them.


Ive ordered some larger jets to try also but will just alter the needle first to see where I am.

It does need a dyno but I need to get some miles on it first as its just been rebuilt.

Go up 1 notch at a time on the needle but listen and feel if the motor feels zingy ie weak. I run a 300 main but with a Ramair filter so to be safe try 330/350 main open mouth and do chops through the rev range. Be aware that some TS's have a stuttery area usually around the 4 k/40 mph mark that can be hard to eliminate.

Thanks Wack. I will,

I thought it would be lean with that needle and that main jet.

Im running at 4% mix at the moment what plug should I use? Its on a br9 at the moment.

A B9 should be fine although an 8 is ok for town and I've not used 4% since the 80's Agreed that a 58 is the weakest but it can depend on how efficient the exhaust is.BTW have you tried turning the airscrew out a few more turns and testing?

Cheers will have a play with the airscrew too.

try 33;1 fully synth
jets are ok (my main is 315, but trying to lower that shortly, after plug chops)
your spluttery area @ 40mph, are you fixed timing? or do you have ky-tronic (other timing adjusters can be used)
my expansion is a Franny tourer

Timing is fixed at 18 degrees.

I'll bet that @ 40mph+ it clears up & runs smooth?
classic case of fixed stator buddy, by having the timing set @ 18 deg btdc you've sacrificed your low down revs for a safe mid to top end rev range, if you get a plug n play variable timing gadget you'd get the best of low down town work revs + the top end safe revs

Which do you recommend?


I've dropped the needle a notch and put a 330 main jet in, it's cleared it up really well, but slightly flat top end but that might be my gearing which 46-17.

I know Harry likes torquey pipes but I think you'd be better off trying a 16 front sprocket with the SX box and see how it goes, maybe even dropping to 15. It will be a lot easier to ride and not struggle on hills and wind.

Took it out today and it's no better to he honest, not sure why I thought it was better yesterday but I did run it without side panels.

Back to square one with the fueling I think.

A mate of mine has a TS1 which was running a bit ropey. Taking the panel off made a huge difference. The panel had no hole for the carb to breathe.

you only need a 10mm hole in the cans as recommended by Taffspeed, been running my TS1 SX for 18yrs like that

Wack wrote:I know Harry likes torquey pipes but I think you'd be better off trying a 16 front sprocket with the SX box and see how it goes, maybe even dropping to 15. It will be a lot easier to ride and not struggle on hills and wind.

Agree totally, I think your fundamental problem is gearing and not carb or settings. Admittedly I do not know the exhaust but sx 200 on 17 /46 is a final drive ratio of something like 12 mph to 1000 rpm, it is huge for the port timings of this kit, you should be aiming likely for something in the 10 - 11 range. Change to a 15 front sprocket and see if you are happier, then you can work on the carburation. good luck.

I have now dropped the needle to the last clip setting and put in a 320 main jet.

It seems to have cleaned it up a bit low range but the mid range is suffering now. Which I agree might be the gearing.

So I might take the casing off and check the gearing and change it to a 15 front and a new chain.

Kris

Right so after bottoming out my 'harry barlow ' exhaust which wasn't a Harry Barlow exhaust.

I've changed it for a devtour,

The gearing has been changed to 46-15 sx200 box which is a lot better.

Carb settings are as above but I've changed to a 57 Needle and 320 main jet .
Air screw 1 turn out .

Pretty smooth up to 3/4 throttle then it's just spluttery which won't clear to full throttle .

Do a plug chop where it splutters and hopefully it's too rich so you can come down on the main one step at a time.