Why is my S3 such a nightmare to start?

[Darrell Taylor]

Anyway today i had to warm the plug up with a heat gun to get it to start, then it wouldn't run when i turned the choke back off and needed tweaking to keep it running.
Any ideas?

Thanks.

sounds like a blocked pilot jet or poss too small because of the requirement for choke to keep it running.

[muffster]

I have thought about the fuel issue after reading a few things on here. i have been trying to run as much fuel through it as i can to flush the tank out. It's running though a filter, and having the carb off dozens of times i do get a bit of sediment in the carb bowl but the jets are always clear.
So today: Iv'e actually got the air scoop off at the minute. NGK B7ES plug which was very slightly under .5mm.
It started after a few kicks. Much easier than when it's been left for a month. But after fiddling around i have to start it with the carb throttle screw all the way out, (i.e. slide down) then i have to feather the throttle to keep it running, wind the screw fully in(slide up) and only then can i turn the choke back off. If i turn the choke off as soon as it fires, it just dies.
When it warms up it seems to be ok.
Spent some time trying to set the air mixture but when it cut out it wouldn't start for a good half hour and 30+ kicks!!!

So, any offers on whats going on? This is really doing my head in now and begining to take the enjoyment out of the build.

Thanks for reading.

[mick1]

Try a different carb....

[bristolmod]

my money is on a crap Jettex- some work some don't.

I've used Jettex's with good results only to find that they go "off" after a while, or they don't work at all.

Had one on a S3 TV175 that ran well for ages and then suddenly wouldn't start- changed all the jets, slide and atomiser but to no avail- replaced with a standard 20mm delly and its perfect

Chris

[muffster]

Roger that!!
Any recommendations. And will i have to change the standard inlet or air hose.

Thanks to all for your input.

[bristolmod]

if you're going down to a standard 20mm delly then you will need to change inlet manifold and airhose.

[Supereibar]

my money is on a crap Jettex- some work some don't.

I've used Jettex's with good results only to find that they go "off" after a while, or they don't work at all.

Had one on a S3 TV175 that ran well for ages and then suddenly wouldn't start- changed all the jets, slide and atomiser but to no avail- replaced with a standard 20mm delly and its perfect

Chris

Chris, I was a blind beleiver of the jettex... until I started having problems with a tuned bike. I guess jettex become death traps on the long run

J.

[muffster]

Ok tried to suss it out again today but me the novice and a seasoned scooterist couldn't get it started, gave up after half an hour. Tried heating the plug up twice, still no joy.
I'm sure part of the problem is it's constantly flooding, the plug is aways wet. (22mm jettex)
So what causes flooding and how can i prevent it.
And where should the slide/throttle screw be on starting?

Thanks.

[Muttley McLadd]

How much is your time and your mate's time worth?

A Jetex is never going to be a good carb. You know it's a piece of sh it. Chuck it on the pile of cheap asian garbage that wont fit at the back of your garage. Get yourself a decent carb. A 28 or a 30 mil delorto can be had for the price of two hours' aggro in the garage. Your 175 kit will work much better if it can breath better.

[bristolmod]

Ok tried to suss it out again today but me the novice and a seasoned scooterist couldn't get it started, gave up after half an hour. Tried heating the plug up twice, still no joy.
I'm sure part of the problem is it's constantly flooding, the plug is aways wet. (22mm jettex)
So what causes flooding and how can i prevent it.
And where should the slide/throttle screw be on starting?

Thanks.

As stated above- its PROBABLY the Jettex carb itself (blocked jet(s); internal drilling etc etc)

If you are sure EVERYTHING is clear, then I set mine up with a very small gap between the bottom of the slide and the "throat" of the carb- i.e. the slide falls to a stop on the adjuster just leaving a tiny gap. Another point is the air bleed screw- the carb should have a little sticker on it which states "Max 3/4 turn"- ignore it and go to a max of 1 &1/2 turns out.

Re the flooding- it could be the float valve damaged on the tip- replace. Or it could be the float itself catching and remaining open- fettle so it doesn't catch.

Trouble with Jettex's is that they can either work very well or be real pigs to set up- I'm running a Jettex on a Mugello kit at the moment and it performs very well indeed. I used to run one on my other TV which again worked very well, then one day started playing up- I never did find out why.

Good Luck

Chris