Octane's SSI Thread

[Octane]

Ok so I'm veeeeery new to these carbs. I've only ever worked on Webber carbs on vintage cars etc. So I'll use this thread to ask stoopid questions and try to learn as much as I can about them.

Firstly, its still tuned for Canadian 95 octane fuel, and the Silentium pipe.

But I'm running the factory race style pipe, and local (Sydney) 95 octane fuel with a valve protection additive. So I'm not entirely sure what size jet to start with.

At the moment, the only way I can keep the bike idling is to wind the idle screw IN untill the engine idle's at around 3000rpm (which I know is too high) and even then it'll stall unless I occasionally give the throttle a blip, so I'm assuming it's too lean and needs a bigger jet.


Secondly, I accidentally left one of the fuel taps open overnight, and found a nice puddle of fuel on the floor the next morning which had leaked from the carb somewhere. The idle screw appeared to be leaking a little through the thread, but I found traces of fuel higher up on the carb, but couldn't pinpoint exactly where it was coming from.

So is this normal for these carbs to weep a little bit of fuel of the engine's not running or do I have a slight leak somewhere?

[JimF]

One thing I really like about the SSI is how simple it is, and a little light reading of the manual while looking at the carb brings it all together.

The overnight leaking is likely a float valve issue. It's easy to remove the float bowl from the carb. The float needle is brass (I think) and it should make for a tight fit against the seat in the float bowl lid. You could hold the float valve to the seat and blow air through a fuel tube into the banjo fitting and no air should flow past the float valve.

If air passes you could maybe clean the float needle and seat or perhaps lap the two a little.

If no air passes you could try dropping the float itself into some water perhaps and make sure that it doesn't take in fluid overnight.

My Mach 1 idles pretty high, over 2K I think. It's been a few months since I had it running.

Jim

[Octane]

Thanks Jim,
I'll download the manual and peruse through it at work since I'm not doing much else at the moment

[wcorey]

You may want to check your oil to make sure gas didn't go down the carb throat and into the sump by way of the cylinder, as can happen with a leaking float valve...

Bill

[JimF]

I should also add that you should close the petcocks rather than rely on the float valve to stop the flow of fuel.

You don't want a garage full of gas fumes to ignite.

[JasonB]

Hi Octane,
as I am in Sydney and have had the joy of playing around with Dellorto's SSI, I have sent you a private message.

JasonB

[Bevel bob]

The screw on the side of the carb is more of a mixture adjustment ,out is more, the throttle stop adjustment is on the top,under the tank(where you can't reach it!.

[Octane]

Bit of an update and a couple of questions...

I tried to kick the bike over today to go for a ride, and it's still not running well on the megaphone pipe.
after switching from the sillentium to the megaphone, I also went up in jet sizes from a 122 to a 128 and it's running fine through the rev range, but it refuses to idle.
I cant keep it running without constantly blipping the throttle. The only thing that helped was adjusting the throttle cable tension to keep the throttle slightly open when it idle's but I know this isnt the correct way to tune it. Adjusting the mixture screw in either direction only made it worse.

I removed the idle jet and blew it out and it gave a sliiiight improvement, so I'm thinking I might need to go up 1 size from a 50 to a 65?

Thoughts? I can get jet's from here.

[Bevel bob]

The idle speed adjustment is on a rod from the top of the carb which is pretty well inacessable with the tank on, I set mine to just hold the slide up a mm . It is just possible to lift and wedge up my tank which has a rubber band securing the back .Don't have the slide hanging on the cable as it will race the motor on full lock turns.

[Octane]

Aaaaah... Silly me! I thought that rod was the throttle-open stop, not the throttle-closed stop

And yeah, I can lift the tank off easily enough and rest the back end of it on the seat and the fuel lines are still long enough to get to the carb.

Thanks Bob! I've got tomorrow off, so I'll try adjusting that rod and report back.