carb bubble full of fuel

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
hyper 78

hyper 78

Well-Known Member
Messages
962
Location
nottz.
Ive just brought a new engine and am in the process of running it in,ive almost done a full tank upto now, the thing is i found that its flooding from time to time,but the carb bubble seems to be full to the brim with fuel, ive been told that if the bubble is full,its running lean and when almost empty its running rich(????), but how can this be, rich and lean????? im using stock settings to be on the safe side, also ive had to go from the stock 25 pi carb spring to a 12pi as its a hungry engine and needs plenty fuel.
any ideas?
 
Ofcourse the primer only has one function and that’s to bring in the fuel for initial start.After that what shows up inside has nothing to do to what the engine is doing.
Most show around half full or a bit less when running.If you prime up and see a continuous flow of fuel and bubbles then you may have a air leak,if not then you don’t have a problem in that area and you need to re tune.

 
Last edited by a moderator:
Mike1970 said:
After a run -

full bubble = too rich

Empty bubble = too lean

In an ideal world, you're looking to have your bubble half full after a good run.
Click to expand...
cheers mike, i knew it was something like that, makes more sense now!!!! flooding, plus full bubble = rich. so i get it now,thats fine just for the first tank ot two break in..
the funny thing is, it doesn't seem to flood during usage,its when i have stopped using it,go back after a few hours and its already flooded from the previous run, but on the previous run it was running fine??? maybe has something to do with the smaller carb spring im using,might try the origonal spring which came with carb .

thanks guys
 
slipstream said:
Ofcourse the primer only has one function and that’s to bring in the fuel for initial start.After that what shows up inside has nothing to do to what the engine is doing.
Most show around half full or a bit less when running.If you prime up and see a continuous flow of fuel and bubbles then you may have a air leak,if not then you don’t have a problem in that area and you need to re tune.

http://www.youtube.com/watch?v=6tMUfbQCzI8
Click to expand...
thanks for the reply, ive not tuned it for performance yet,only done 1 tank up to now, it will need a retune, thanks
 
run the marder today, used 1-1/4 high and 1 on the low speed needle, even then it seems to be rich
but it doesn't seem to bog when running, when i turn the engine off and try to restart it , i have to take out sparkplug and unflood it before it starts again and i get a fair amount of excess petrol come out!!! also the bubble on the carb is still full to the top, making me think its rich but the plug is a tan colour which should indicate its fine ???
so basically its running ok,the plug is the right colour but i need to keep unflloding it and need to use ' lean settings' as well as the bubble is full ???
any suggestions.
 
46u said:
On my race ported 30.5 I have to run the LSN under 1 turn out or it will not even pull off.
Click to expand...
hi 46u, ive sorted the problem,the spring was too short and wasnt stiff enough, i stretched it very slightly and now it runs almost on stock standard settings on the carb and the bubble isnt full anymore,just under 3/4full,no more flooding, thankyou, how you getting on with your latest engine build?
 
It should run fine on the factory settings and the primer bulb should be 3/4 full always . Less means you have a problem. If your engine is not starting right off after shutting it down then you have another problem. These engines are gas hogs. So fuel shouldn't be the problem . The oil mix is.
bogging is a cause of an air leak. if you ever have that problem it can be inside the carb or around. Nowhere else.
 
jas the last said:
Check the spring in the carb.
Click to expand...
hi jas, yes i changed the spring to a shorter one(pop off spring) as i was told by the engine builder it was thirsty and needed more fuel,but the one i sourced was a 12 psi spring off a friend,ive done the spring mod,(cut the tight coils off) and it seems to be better,ultimatly id like to find a place that sells the springs,as i think i need one between 15 20 psi,the standard is around 25psi .
 
Largescalebuilder said:
It should run fine on the factory settings and the primer bulb should be 3/4 full always . Less means you have a problem. If your engine is not starting right off after shutting it down then you have another problem. These engines are gas hogs. So fuel shouldn't be the problem . The oil mix is.
bogging is a cause of an air leak. if you ever have that problem it can be inside the carb or around. Nowhere else.
Click to expand...
hi,thankyou for your imput, i use 25;1 oil mix everytime, luckily its never less then empty,either full or just under,im trying a different pop off spring tonight,do you know where i can find a 15 - 20 psi spring?
 
I have run 3 different engines stock 26, race ported 28.5 and a race ported 30.5. On all of them the stock settings where rich and on the race ported engines so rich they would not even pull off just bog down. They where very hard to start and would not stay running till I leaned the LSN out some even when breaking it it. On the stock engine it would run with in the limits stated in the HPI manual but on the race ported engines to get them to run properly I had to go under what the manual says is minimum. Plugs look good and if anything a little rich. In my opinion tune for performance and plug color. I run the stock springs in my carbs and my bubble stays about half full.

Breaking a new engine in on TOO rich of a setting, is not good you want it to be just a LITTLE rich. You need to get heat to the motor for a proper break in!
 
46u said:
I have run 3 different engines stock 26, race ported 28.5 and a race ported 30.5. On all of them the stock settings where rich and on the race ported engines so rich they would not even pull off just bog down. They where very hard to start and would not stay running till I leaned the LSN out some even when breaking it it. On the stock engine it would run with in the limits stated in the HPI manual but on the race ported engines to get them to run properly I had to go under what the manual says is minimum. Plugs look good and if anything a little rich. In my opinion tune for performance and plug color. I run the stock springs in my carbs and my bubble stays about half full.

Breaking a new engine in on TOO rich of a setting, is not good you want it to be just a LITTLE rich. You need to get heat to the motor for a proper break in!
Click to expand...


hmm interesting iam breaking in a new rebuilt cy 30.5 moded engine and iam running pretty rich , i figured better then lean , but now u got me thinking maybe a bit to rich. Ial make some adjustment tonight and run another 1/2 tank through it :D
 
Back
Top
✖
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock    No Thanks