’72 Elan Motor Issue

[jeffy104]

My 1972 elan 250 single with tillotson hr133a is having issues. New engine gaskets and rebuilt tillotson including check valve and new points set to factory spec. Was running good enough to ride around a bit even though there were air bubbles in the gas line. Then it wouldn’t run and just bogs down without coming up to speed so I replaced the gas lines and checked the check valve in the tank to be sure its working. When I give it throttle it tries to rev but bogs and spits gas out of the carb. Starts and idles fine. No more air in the lines. Turning the low speed either way doesn’t seem to do anything. Pulled carb back off and pulled both jets and blew everything out and cleaned the screen on the bottom of the carb. Running premium gas with 40:1 valvoline all purpose 2 cycle oil. Spark is a white color.  New spark plug ngk. Can’t figure it out. Would be great to hear some ideas. Thanks in advance.

[sledrat]

hi Jeff the running or bogging you describe sounds like the high speed mixture screw is turned out to much turn it in just a small amount at atime
when under load or driving it,,now if nothing changes
then try the low screw as you said it doesnt change anything so ...
just a tad at a time it sounds like a carb issue to me
might be a stuck needle flooding it out or check ball valve acting up ok did you replace or rebuild this carb yourself? if so
the needle you put in was it a newer VTIP style needle or just a original flat one?
also when ever you rebuild the carb or who ever did rebuild it did they change the needle seat too or just a new needle? cause if its a old seat with a new needle they stick cause they wear to the needle that was in the carb before.,.
also the metering bar and new needle was it a v tip type? or just a flat type? if its the old flat type find the V TIP type less problems.also the metering bar lever has to be set properly take note in the video i posted below on the metering bar and how he sets it level with the carb,,
the tillys they have to be spotless in the carb or wont run proper.
.One other thing make sure you have rebuilt all the stack diaphrams properly according to diagrams
you can find online for your carb search the model number

try this link below it for THE TILLY HR series

tillotson.ie/wp-content/uploads/2015/07/HR-Series-Parts-List.pdf

another thing you can try is run a tad bit of sea foam from napa in your gas about a ounce to half a tank or whats in your tank
thats what i would try ,,, one other thing is it could be is a manifold leak most likely not that,,
but seen alot of the bottom fuel filters loosening up after running em just check and retighten them
as normal check on those carbs before every use, dont over wrench em..
a leaking air or crack in fuel line somewhere losing vacuum

try another plug aswell I find Champion Plugs are way better in the elan motors i
will find out the number think its a D1 or D11 champion
A7 for NGK
but original Bosche plugs are the best but hard to find..

HERES A great rebuild tips on the old Tilly carbs