so i got a ec birt hl334wx dominator plus gas carb. i put it on and got it fired up relatively quick warmed up the engine putted around a little kept stalling due to not having set any idle yet per the instructions that came with it. ran awesome when i was hitting the gas. this is a step up from a stock clone carb. engine stalled out never started back up in about 30 minutes of messing with it. low speed set at 1.5 turns from seat high at 1 turn out. engine specs are as follows. greyhound clone, arc rod and wheel, OldMiniBikes super box x cam .265is lift may be .260., 55#springs. OldMiniBikes exhaust. i think that is all. forgive my punctuation.
tillotson troubles
- Thread starter mattfishdog
- Start date
- Tags tillotson troubles
Tillys do not like to idle. The low side is very rich. It's the way they are made. They are awesome wide open and that is where they run best. We run these carbs on our open motor go karts. If you let them sit and idle much they'll fill the bottom end with fuel and contaminate the oil. Sounds like the plug may be fouled out.
It is an awful lot of carb.
I tried that combination with a similar carb and stock valves and felt the engine was just a little over top.
Those valve springs are excessive I feel ( 18 would probably be enough for 6500 rpm 26 pound would work too but there is not much RPM left in the cam ).
This is a giant step sideways and a little backwards from the 334.
Its a simple Tech series 3 with some simple mods too it.
It will deliver a clean idle and works well at all speeds.
But it can;t provide the type of throttle response a Tillotson race car can or the top end power ( being smaller and simple incapable of flowing like infinite radius venturi ).
It just happens that it bolts to the same place as a tilly and uses the same air filter adapter. )
Just tossing it out there, but a GX390 carb can do the same thing maybe even a bit better.
I tried that combination with a similar carb and stock valves and felt the engine was just a little over top.
Those valve springs are excessive I feel ( 18 would probably be enough for 6500 rpm 26 pound would work too but there is not much RPM left in the cam ).
This is a giant step sideways and a little backwards from the 334.
Its a simple Tech series 3 with some simple mods too it.
It will deliver a clean idle and works well at all speeds.
But it can;t provide the type of throttle response a Tillotson race car can or the top end power ( being smaller and simple incapable of flowing like infinite radius venturi ).
It just happens that it bolts to the same place as a tilly and uses the same air filter adapter. )
Just tossing it out there, but a GX390 carb can do the same thing maybe even a bit better.
thanks for the responses. the plug was fouled. however i replaced it with a new plus and it would only start with starting fluid now. i realize the springs are excessive but 18# wear out after 1 day of riding and float the valves. i had it up to 6450rpm with a cl1 cam before the larger dyno cam with the 18# and they only last a day then it tops out at about 4500. i am beginning to believe i have a fuel delivery problem in the carb. i researched the ec birt links page well and have a good understanding of the tuning of the carb. i plan to run wide open most of the time thus my choice in this carb. me and my buddies do huge hill climbs on 4wheeler trails and alot of high speed trail riding. as soon as i figure out how to post video i will. for now i just want to get this damn bike running with the new carb. we have a ride planned this weekend and i dont want to bolt a stock carb back on. i ordered a gx 390 carb kit from nr racing tonight but i dont expect it will be here by the weekend. still want to use this tilly from what i understand it fits my style perfectly. whiskey throttle unless im laying on the ground. thanks a bunch guys
also i wanted to add this thing ran like a raped ape when it started yesterday the first time. i was slinging rocks all over my back yard at half throttle. it now does not work without starting fluid. brand new carb. no junk in it. fuel pump works. im puzzled. calling ec carburetors again tomorrow. i called them at lunch today and we both came to the spark issue conclusion however the spark is now there and strong. ignition gap is correct at .030
Turn the low speed needle screw in all the way then back it out a half turn. Set the high speed needle screw out about 1 and a half turns. This should be a good place to start and it should idle. I was told by EC Birt a long time ago to crank up the engine and go. The bottom end jetting is very rich. It is probably why it won't start or idle very well. The transition from idle to power is like an on/off swtich. Sounds like the GX390 carb may be the best way to go for what you are doing.
My kart engine on methanol idles at 2200-2500 with my tilly carb. We set our clutches to come in at 4500rpm and spin the engine up to 9000-9500. We generally on have about a 1000-1500rpm drop throughout our lap.
My kart engine on methanol idles at 2200-2500 with my tilly carb. We set our clutches to come in at 4500rpm and spin the engine up to 9000-9500. We generally on have about a 1000-1500rpm drop throughout our lap.
