Carburettor

rab1 · Post: # 62439Post **rab1** Sun Apr 24, 2011 2:51 pm

This is a long shot but does anyone know much about small engines?.

I have a Tecumseh 4hp engine (mdl no 535008) fitted to an old lawnmower (24yrs old) that has a Dellorto carb fitted model no FHC 20 13 F that is a bitch to start when cold, the engine has compression etc and does spark etc but could do with a new HT lead.

The fuel is fresh etc but it`s not starting and I think its the carb...?. Any advice welcome lads
???

Sun Apr 24, 2011 6:17 pm

Easy start spray..... In the air filter

Stuarty · Post: # 62448Post **Stuarty** Sun Apr 24, 2011 6:43 pm

easy start isnt a cure, just masks the real problem by letting it start. Is the air filter clean? and after a shitload of pulls does the engine flood? Could be something fuel related like its not getting any, if theres gunge in the bowl or its not drawing enough air to let it combust properly.

rab1 · Post: # 62462Post **rab1** Sun Apr 24, 2011 9:12 pm

yes it floods after pulling on the started repeatedly.

Stuarty · Post: # 62471Post **Stuarty** Mon Apr 25, 2011 8:41 am

The plug might not be giving it a good enough spark, perhaps down to the lead as you mentioned it could do with a new one, or if its old they degrade slightly. Can always trying removing the plug, put in a tiny bit of petrol in the hole, screw the plug back up and give it a pull. Its all just a process of elimination really

henpecked · Post: # 62473Post **henpecked** Mon Apr 25, 2011 8:55 am

Check your gaps, clean your plug. Good idea is to take your carb off and clean the needle holes by the float chamber, also, give it a once over with an airline ,if you can
Easy start is a no-no ofr small engines, it makes your piston run a 4 or 5 times its normal compression, can cause a cracked head , have photos somewhere if you want a look.

Oh, and change the HT :;):

Pablo · Post: # 62475Post **Pablo** Mon Apr 25, 2011 9:06 am

If the engines 24yrs old your piston rings will be worn out this causes bad compression and is hard to start. Possibly? Gumtree is full of mowers the fix will probaly cost the same as a decent second hand one.

henpecked · Post: # 62476Post **henpecked** Mon Apr 25, 2011 9:09 am

Pablo wrote:If the engines 24yrs old your piston rings will be worn out this causes bad compression and is hard to start. Possibly? Gumtree is full of mowers the fix will probaly cost the same as a decent second hand one.

Not necessarily , I have a nice Clifford Mk1 rotovator, dates from 1955 with great compression, age doesn't denote usage :;):
(as I keep telling the wife)

Pablo · Post: # 62479Post **Pablo** Mon Apr 25, 2011 9:28 am

Haha you're not wrong hen I've got a howard gem it's deisel but has never broken down once since I've owned it. It used to have a .22 cartridge starter that you twated with a hammer but I changed it to a crank handle which is cheaper but good at breaking your wrist. A mower engine is much more highly strung though it uses high revs for power a rotavator type engine used lower revs for more torque.

wantalc · Post: # 62493Post **wantalc** Mon Apr 25, 2011 11:10 am

rab you could have a worn needle valve assembly in your carb...deffo dont use easy start engines get addicted to that stuff ...you can get carb repair kits for dellorto carbs they are very cheap...another thing you could do strip the carb get a can of carb cleaner and spray away at all internal jets...do not poke wire into jet holes......cheers

rab1 · Post: # 62519Post **rab1** Mon Apr 25, 2011 6:57 pm

cheers for the advice lads.

rab1 · Post: # 62521Post **rab1** Mon Apr 25, 2011 7:09 pm

anyone know where I could buy the HT lead, tryed on the net without any success?.

rab1 · Post: # 62522Post **rab1** Mon Apr 25, 2011 7:12 pm

compression seems fine, I personally feel its a carb problem but I know nothing about them (practical side of things) :O

Post: # 62532Post **Dave_L** Mon Apr 25, 2011 9:00 pm

Howard Gem, used to use one with a twin cylinder hand cranked 1000cc engine, what a beast that was.

henpecked · Post: # 62577Post **henpecked** Tue Apr 26, 2011 11:34 pm

Dave_L wrote:Howard Gem, used to use one with a twin cylinder hand cranked 1000cc engine, what a beast that was.

You can still get them, Howard Gem is what your looking for, but beware ,you will have to have a good reason for owning one ie. massive allotment as they're a beast and a half to lug/transport.

Pablo, didnt know that about lawnmowers, but now you've said it, it does make sense.

Hp :;):