loncin 87cc OHV stalls when hot

[andytyler]

hello
im in the uk and struggling with a loncin engine which i know is used in the us alot
its single cylinder 87cc ohv pull start fitted to a cylinder mower

stalls and wont restart when it gets warmed up 10-20 after starting

im experienced in small engine repair but ive failed to fix this after numerous attempt
i dont know if the engine is overheating or if a componant is failing when hot

tried the following
new plug
tested coil immediatly when cutout/wont start... works fine
checked valve clearances
cleaned carb (carb has no mix screw fixed jets)
new air filter
new oil
fuel tank lid breather checked and engine ran without lid
fuel filter clean

this machine is 18 months old just out of warrenty and little used...
im stuck.. help

 

[andytyler]

more detail..
it is a horizontal crankshaft engine and cylinder is refered to as 'reel' in the usa

 

[pugaltitude]

Never had the problem on the loncin but sounds like coil is losing spark.

I take it you are using a spark tester?

 

[andytyler]

Never had the problem on the loncin but sounds like coil is losing spark.

I take it you are using a spark tester?

yes with a tester. my initial thought was the coil losing a connection when it was hot but we can rule that out.

only other important thing i forgot to mention is also the throttle behaves a little strangly just before the stalling problem occures. if you increase the revs steadily its ok. if you quickly move the lever from slow to fast it cough and stall unless you catch it and immediatly slow it back down. this makes me wonder if it is grabbing some more fresh air from somewhere, a gasket perhaps and this is making it too weak a mix.

 

[Higgslane]

yes with a tester. my initial thought was the coil losing a connection when it was hot but we can rule that out.

only other important thing i forgot to mention is also the throttle behaves a little strangly just before the stalling problem occures. if you increase the revs steadily its ok. if you quickly move the lever from slow to fast it cough and stall unless you catch it and immediatly slow it back down. this makes me wonder if it is grabbing some more fresh air from somewhere, a gasket perhaps and this is making it too weak a mix.

I have exactly the same problem with this 14 month old engine on an English mower (Allet 14L)., Engine is hesitant when revving and will not restart if you shut it off while hot. I discovered two possible causes:-
1. an air leak on the gasket between the carb and the engine manifold. The carb is held on the same screws holding the air filter assembly.
2. If I removed the float chamber and ran some gasoline out and then reassembled it, the dam thing would then start when hot. I did this three times and it restarted after each disassemble and reassembly. Although the float valve seemed OK I suspect it was probably sticking when the engine is turned off. While the engine is running the vibration probably keeps the valve working but not enough to allow the engine to rev up high.
Hope this helps.

 

[andytyler]

I have exactly the same problem with this 14 month old engine on an English mower (Allet 14L)., Engine is hesitant when revving and will not restart if you shut it off while hot. I discovered two possible causes:-
1. an air leak on the gasket between the carb and the engine manifold. The carb is held on the same screws holding the air filter assembly.
2. If I removed the float chamber and ran some gasoline out and then reassembled it, the dam thing would then start when hot. I did this three times and it restarted after each disassemble and reassembly. Although the float valve seemed OK I suspect it was probably sticking when the engine is turned off. While the engine is running the vibration probably keeps the valve working but not enough to allow the engine to rev up high.
Hope this helps.

cheers for you reply.
i got sick of it. stripped the mower into componants and sold them off on ebay.. made enough money back to make it worth it.
allets opinion is there is nothing wrong with the engine.
i have heard from someone at b&q (who sell lots of them) that this problem is very common and they are taking in lots of returned mowers.
my conclusion is this like many cheap chinese imported engines is a sack of **** and best avoided in future.

 

[Higgslane]

cheers for you reply.
i got sick of it. stripped the mower into componants and sold them off on ebay.. made enough money back to make it worth it.
allets opinion is there is nothing wrong with the engine.
i have heard from someone at b&q (who sell lots of them) that this problem is very common and they are taking in lots of returned mowers.
my conclusion is this like many cheap chinese imported engines is a sack of **** and best avoided in future.

That's a pity. As a result of your reply I contacted my local Allett service point. The service engineer tells me that there is a known problem with the carburetor on the Loncin engine. After contacting Allett (Turfmec) they have agreed to replace it under warranty even though it has expired.

 

[andytyler]

That's a pity. As a result of your reply I contacted my local Allett service point. The service engineer tells me that there is a known problem with the carburetor on the Loncin engine. After contacting Allett (Turfmec) they have agreed to replace it under warranty even though it has expired.

ha ha ha... thats amusing.
alletts response to me was, no there is no known problem.. they told me to contact the importers of the engine (cant remeber their name).. and they were no help whatsoever.
i will try and find out what the ''known'' problem is exactly in case i see any of these come up for sale cheap

 

[andytyler]

mind you that was not the only problem the mower had...
the weld holding the right side of the handle to the chassis failed.
also i had a ''small'' fuel spillage onto the chassis which ruined the paintwork.....

ive spilt plenty of petrol on qualcasts version of this mower without the paint failing.

overall i am not convinced allett has quite got the build quality up to the standard it was with qualcast.. yes they have bought qualcasts patterns, machines and tooling but do they have the skills?

always seemed to me suffolk made a brilliant mower in the 1950's,,, this got worse in the 1980's when birmid qualcast were involved.... then deteriorated with the new design in 1996 and finally has bottomed out with allett!

buy a refurbished 60's or 70's mower and your sorted for life.