Speedfight 2 Standard Caburettor Settings

Hey,

I know this must be a common one, but I've searched all over and can't find the answer!
I have just picked up a 51 plate Speedfight cheap.
Open the throttle and it decides for a while what it should do, then revs up, but it's lacking in power.
I presume it's over fueling?
Checked the plug also - picture below.
Main jet was a 60. It's a Gurtner 12, with a manual choke?
It's running a Leo Vince TT pipe.

Thanks!

 

Is it a 50cc or 100 id put a new plug in it and clean the carb and go from there

 

it's under-fueling -running too lean.

If it's a 50cc then the standard jet is a 72 on a 12mm carb. If it's 100xx, then the main jet should be 83 on a 17mm carb. With a Leo Vince on it, your main jet should be around 76 to 80 for a 50cc and 88 to 92 on a 100cc. Your bike is running way too lean and you risk seizing the bike up, so don't use it until you fix the jet issue.
The carb needle should be in the top notch for a 50cc and the second notch for the 100cc. You can adjust the mid-range slightly using the needle notches but you really need to geta jet kit and put an 80 jet in it (if it's 50cc) and go from there.

Also check the choke over to see if it actually closes when you lower the lever or push the cable in.

 

Mine is a 100 running a gunter 17mm 92 main jet standerd air box and tecnigas next R exhaust if that helps

 

Thanks for the replies!

Sorry, I should have mentioned it's a 50cc.
That's strange, I wonder why someones put a 60 jet in there!?
I checked the choke yes and it was ok.

Is it worth checking any other bits? Pilot was 42.
Should I reset the air / fuel mixture screw too? If anyone knows the setting.
And thanks for the other tips, will get a jet kit and check the slider too.

Thanks again all.

 

Am I after the 6mm threads?

 

Here is the jet pack start from 80 and work down from there your best to buy a few spark plugs as well to do a plug chop test your aiming for a coffee brown colour on the plug as for the air and fuel mixture screw turn it all the way in till it stops DO NOT FORCE IT IN then go 2 turns out http://www.pedparts.co.uk/product/465/gurtner-jets-box

 

Thank you

 

As we're semi-on the subject,
Here's my Zip plug - which looks similar?
It bogs at full throttle but it's never bothered me as I potter about town using no more than 3/4.
(I did clean the carb, and air filter but made virtually no difference)

Just some info:
- Fully standard, but derestricted.
- Dellorto 17.5
- 53 main jet
- Brass plate is still in
- Secondary air box still connected?

Feel free to let me know what you think!

Thanks.

 

Take the brass plate out and it will increase the air flow slightly. The brass plate is a restrictor and is the cause of the bogging down. It may improve the colour of the plug as well.

The Speedfight manual says 1 1/8 turns out from screwed in for the idle and a 42 pilot jet is correct. The needle should start in the top notch (weakest setting) and if the bike is 'almost' there with an 80 jet in it but is flat in the mid-range, lower the needle circlip one notch to make the mid-range slightly richer. Rinse and repeat as required.

 

Thanks for all the help.
Read all different things online to do with carbs etc. Some say leave the plate in some say don't!
But I'm happy to take your word for it!
There was a thread on here from 2009 saying Piaggio recommend an upjet to a 56 after de-restriction, and possibly up to a 60?

And that's great. I will let you know how I get on.

Cheers.

 

Update:

Ok, so it turns out everything was rather 'backwards'
Mixture screw was all the way in! So that's now 2 turns out.
Slider circlip was at the bottom notch, so I have put it at the top.
Idle and choke are both fine.
With the 80 jet it wasn't doing much and was struggling, so I have settled for the moment with a 76, which runs smoothly, but take off is slow and it sits at around 20mph and won't go any quicker.
So progress has been made atleast.

Next I've noticed the oil feed which has standard fuel hose attached - Will this be letting too much oil through? As they're normally reduced down at the carb, correct?

 

Wont make any difference. The oil pump is regulated to supply a fixed amount at different throttle positions.

 

Personally I'd change it and get the 5mm × 9mm then it's all the same size and looks neater http://www.pedparts.co.uk/bikes/peu...rtingSelect=&d=ASC&o=&bike=12&q=Oil+hose&l=12

 

OK, so try raising the needle one groove (by moving the needle to the middle groove) and try the bike again. If it improves the performance, try the bottom groove.

If the bike starts acting poorly again as you raise the needle, put the needle circlip back in the top groove and drop the jet size to 72 (i.e. stock) with the needle in the bottom groove (richest mid-range mixture). Test again and if it's OK, all well and good. If not, raise it to the middle notch and try again. This is the best way to check jetting, start too rich and work downwards, as you won't risk a heat seizure.

 

Thanks for the replies all!

Will give the above advice a go, and let you know how I get on.

 

Hi there I know this is a very late reply but would you know what your set up was on your speedfight 100cc