Hello guys!

Im Stev from germany. Hello!

I own a 95 Triumph 1200 homemade Turbo bike. Turbo is TD04-13T. Carbs are Mikuni BST36SS. Carbs are rebuilded. Stock jetting. Pitottube 6mm ID in to chargepipe to carb vents.

Low pressure 25 psi fuel pump, 1:1 boost referenced FPR. 2 psi fuel pressure at idle. Fuel return line 6mm in to tank top fuel level.

I reset the floatlevel from 12.5mm to 16mm. Its the most the floattans can be adjusted.
Needles at top first clip position.
Fuel pressure raises with boost + 2 psi.

It runs very rich, AFR 10 and lower from 1/8 throttle and up.

When I pull the Vac-line from pitotube to carbvents it starts getting very lean and stops while idleing.

Carbs dont leak on testbench and while idleing.

I removed the tank and carbs many times, no idea how I move further.

Any help would be super!

Many thanks!

 

I would try reducing the pitot tube diamter a small amount.

 

No real need to raise float levels from factory. I'd go back to stock levels. When you're ready to tune the pitot tubes, drill small bleed holes in the line to adjust pressure to bowls and figure out where you're going.

 

I had to lower float height because it overflooded the carbs.
Ok, I try pitottube diameter and bleeding first.

 

Ok, that makes more sense, I misunderstood. Is it originally a gravity fuel system? If so, It might be worth your while to source some needle a seats so that you're able to bring float levels back up, and run some base pressure to keep to bowls full.

 

Yes, gravity feeded.
Needles and seats are new. Stock float height will overflood it. Setting it to a lower float height stops overflooding. Disconnecting pitottube plumbing while idling makes it very lean because turbo is so small, it even pressurizes very very little the system while idling. Just my thinking.
I tought the pitotsystem is just there to keep pressure equal under boost and affects only the mainjets under boost. But I can be very wrong with this guess.

 

Its very possible its lean because of the float levels. Float level is a key part of jetting. Gravity feed n&s's are usually big and pushed open very easily. If you go to a smaller set you'll be able to raise the float levels up where they belong, and then your tuning will be much more in line. The nice thing about mikuni carbs is that there are usually choices for your n&s's.

 

Ok, I will try that.

Thank you.

 

What are you calling the pilot system?

Thanks

 

low speed circuit, what are the mods and why... newbie here

 

You typically don't need more than a jet change or air screw adjustment in the pilot circuit, the pitot tube is something very different.

 

Hey! Hello and welcome! I'm new here too