My travails with a 260 Linhai By scjbob (Read 4,715 times)

[scjbob]

Thanks JR. I'll set the idle a little higher to see if that does the trick.

[scjbob]

OK. I think I am finally near the end of this long endeavor. I set the idle at 1700-1800 and it starts right up with no problem. It also takes off like a scalded dog with strong acceleration at WOT. However when I let off the throttle to slow down to a stop it dies. It won't let me cruise at a slow speed (10-25mph) smoothly either. The stalling happens consistently with each braking to a stop. Is it my air/fuel ratio? What do you suggest?

[tduhon48]

my mc54 250b has a bog if i don't have the idle at 1900.. just a note there

[scjbob]

OK. So I'll set it a little higher and see if that does the trick.

[scjbob]

OK. My patience has run out. I've done everything short of rebuilding the engine and still cannot get a decent throttle response. Idle set at 2000. Starts right up...no problem. WOT...no problem. Initial throttle at 1/4 turn and it bogs. I have adjusted the air/fuel screw multiple times...always starting out at 2 1/2 turns and cannot find a smooth 1/4 throttle. Anyone want to buy a 260 Linhai with only 350 miles on it cheap?

[JR]

Bob let's try one more simple thing and it's a 5 minute job. With the carb in place just take out the top's two screws and pull the diaphragm needle assembly and lower the clip one notch to richen it up a bit. I've seen a time this will help a bog like this.

Are you sure you have absolutely no air leaks around the carb?

JR

[kz1000st]

Are you sure you have absolutely no air leaks around the carb?

Yeah what he said. I had a problem with a lean surge on mine and I did the WD-40 test. When I sprayed the intake manifold with WD-40 the engine started to race. Turned out the O-ring on the intake manifold was squashed and letting in air.

[scjbob]

Well after a very busy winter, between work travel and moving into a new place, I am finally getting back to fixing this problem. I pulled the diaphragm needle assembly and there is no clip on the needle. The needle also has no notches in it. Either I lost the clip or there never was one on this needle.

Should I use a small washer to lift it slightly? If so how thick should the washer(s) be to simulate a one-notch adjustment? By the way there is no intake or carb leak that I can find. I sprayed WD40 liberally around the intake manifold and the carb-intake connection with no change to idle.

Since posting this comment earlier today I have discovered what I believe to be the problem. And it's embarrasing to say what it was. When I cleaned the carb I installed the needle holder into the diaphragm before he needle. This caused the needle to be held almost 20mm higher than it should have been. I haven't test driven it yet but the bog is now gone at 1/4 throttle. It also idles nicely and accelerates smoothly while on the stand. I'll posst my test drive results later.

[scjbob]

Travails are finally over. I took it for a test ride and it reacts appropriately to the throtle now in all conditions...no more bogging, idles and starts nicely, cruises evenly at all speeds etc. I was ready to toss it off a cliff last fall but I suppose I'll keep it now. It's two years old with only 350 miles on it because of the length of time it took me to figure everything out. Thanks to the Professor and others on this site!!!

[rcq78]

I'm happy for you Bob....wish I could get my issues fixed...my 54b bogs down when I hit 55-65..it loses all power for a short time then will pick back up & do it again down the road.....seems to run good on stand for the most part...I've been working on this for 2 weeks..replaced coil,fuel filter,cleaned carb twice,cleaned air filter & still the same.....Think I may see a crack in the airbox where the pipe going to carb goes into it...going to take it apart again today....I hope to get some help on this site like you did.....Bob

[scjbob]

No matter the level of frustration that these Chinese contraptions bring you there are some pretty bright people here. I'm sure you'll figure it out with their help. I posted my series of "fixes" so that perhaps others who have similar problems can learn from mine.