[blurust]

Fellow team-bhpians,
Greetings,

So I am posting after a long time.The journey with the bull(machismo 500 LB) has been brilliant till date.
There was absolutely nothing to complain about, actully I stand corrected, there is still nothing to complain about.
She still rides like a dream, She did not give me a chance ever to take her to a puncture guy in a year and a half. Everything is completely stock except the handlebar.
So, now the issue.
I shifted my base from mumbai to bangalore in september and she came back with me, because of a lot of things she had to put up with packers and movers. They delivered her the way she was loaded back in bombay.Absolutely no breakage of any sort.
The only issue was that when i rode her, she started jerking a lot. I figured it was probably an air filter issue and i got her a new air filter(it was actually due). She wasn't happy still. Because of time constraints and being completely new in the city I did not know where to take her(mechanic). A lot of people from my work suggested Muneer in the city and said he is the best out there. I am still struggling with time on that part as i stay in the outskirts of bangalore(whitefield area). I took her to a local mechanic and he said it is probably the air filter and on his recomendation only i got her a replacement as the older one was clogged with oil(oil spill issue when the engine is overfilled). I thought its probably the air and fuel mixture which is driving me crazy and tried feeding her a little richer mixture but in vain. I changed the spark plug as well thinking its probably that. No use still.

The problem is when she is cold and i try to keep the throttle fixed she jerks a lot as if she is deprived of fuel or something. when she is hot she seems to run perfectly fine but it is only after i have ridden her for like ten minutes continously. when i try to release the clutch suddenly and accelerate(only to test) at the same time she does not respond at all. she does the same thing when i take her uphill. But she is fine when i keep the clutch depressed like 10 percent, and when i let it go she again loses her breath. Pickup seems to be fine, no issues in that department, although i think it has gone down a little bit but i am not sure.

I have given up trying to figure out what the issue might me.
Things that are storming my mind are..

1) air is leeking somewhere.
2) carburetter is faulty.
3) something wrong with the engine ( I hope not though )
4) just the cold weather, although i seriously doubt this.
5) something wrong with the electricals.

Guru's please help me out here.

Thanks in advance for all the suggestions.

[bblost]

Check the manifolds that connect the air filter with the carb and the carb with the engine.

Since the 500 afaik came with a regular carb and not a constant vacuum could it be possible that something inside it is stuck. Maybe opening it and having it inspected would help.

Best is to find some time and take it to Muneer bhai

[blurust]

hey bblost,

i think the manifolds are in the place, atleast they look like they are. i completely agree with you about something stuck in the carb, i would check it. I wish I had little more time really.. Is there a way to trouble shoot it at home in the parking . if there is i would be really happy to try that.

[gsferrari]

You can remove, open and clean the carb yourself. Any bike mechanic can do this for you...just find a decent one. This doesn't require the efforts of a specialist. Also open the fuel tank cap and check if the breather hole is clear of dust.

[navpreet318]

Have you tried changing the Spark plug? I have had this sort of issue with 2 of my bikes and after months of hard work checking everything, came to the spark plugs.They were visibly perfect.But just swapping them for new ones solved the problem.Perfect since then.

bblost: And oh yes the Machismo 500 comes with a CV carb the BS29 to be precise.

[adrian]

If the Machine is revving freely while in neutral and gasping while riding, just check if the air jets in the carb are clogged.

[starter]

Also check if the air pipe has some cracks?
If they do, try replacing it with a new one.
Cheers,
Deepak

[qj7081]

Originally Posted by blurust

Fellow team-bhpians,


1) air is leeking somewhere.
2) carburetter is faulty.
3) something wrong with the engine ( I hope not though )
4) just the cold weather, although i seriously doubt this.
5) something wrong with the electricals.

Guru's please help me out here.

Thanks in advance for all the suggestions.

Check the air tube from the rubber intake port to PAV. Mine had cracked near the intake port. Remove the breather pipe from the oil tank top and see if it is clogged. On my bike it frequently gathers oil; in cold weather it becomes mayonnaise. Clean the carb. Does the sparkplug look okay?

[Beast_of_Burden]

Originally Posted by blurust

hey bblost,

i think the manifolds are in the place, atleast they look like they are. i completely agree with you about something stuck in the carb, i would check it. I wish I had little more time really.. Is there a way to trouble shoot it at home in the parking . if there is i would be really happy to try that.

I had a sputtering issue with my LB500. I traced the problem to dust that caked in on the slide surface which was preventing it from reacting smoothly to throttle inputs. For cleaning the surface, you need to take the top off the carb and clean the surface of the cylindrical slide with WD40. Keep the WD40 away from the rubber diaphram. It is quite a simple operation. However, most mechs will be unwilling to do this as it has been drilled into their heads that there is nothing to adjust in the CV carb. The most difficult part of this operation is getting the rubber tubings back in place and seat the carb back in properly, but it isnt too difficult. It is an hour's worth of effort if you know what you are doing, but it might take you a couple of hours.

[Gordon]

1) air is leeking somewhere.
2) carburetter is faulty.
3) something wrong with the engine ( I hope not though )
4) just the cold weather, although i seriously doubt this.
5) something wrong with the electricals.

Why don't you try the following checklist? I guess its a electrical misfire or a manifold issue. Nevertheless, do the following and you'll anyways be doing the bike a favor.

• Carburettor: Clean carburettor thoroughly. Also check accelerator cable and its adjustment. Check/adjust carburettor settings.
• Carburettor Manifold: While the carb is out, check the manifold for any cracks. Its made of rubber so its possible that there may be cracks. Moreover your bike will probably have a small pipe on top of the manifold (PAV). Check if there is any leakage here.
• Spark Plug & Cap: Clean/check/replace spark plug and plug cap.
• Fuel: Empty fuel and use fresh fuel from a good gas station.
• Air Filter & Filter hose: Check if air filter is in good shape, if not replace. Check if there is oil on the air filter. If yes, clean the cylindrical discharge box just beside the battery. Also check for tears in the rubber hoses connecting the carb to the air filter.
• Wiring:
  Check complete wiring.
  Check for open/torn wires. Seal them with electric tape well.
  Spray inside of sockets with WD40 and reconnect.
  Replace any bulbs that aren't working properly.
  Replace any switches (mostly front n rear brake) if they arent working well.
• Alternator Coil & CDI Unit: As a last measure you may have to check the alternator coil and CDI unit.

[niks_devil666]

What is the spark plug used in the LB500 ? Can anyone give me the model number?

[(Alok)]

Isn’t it mentioned in Owner’s Manual?

[JayPrashanth]

Originally Posted by niks_devil666

What is the spark plug used in the LB500 ? Can anyone give me the model number?

Niks,

NGK BR9ES. Stock Mico Bosch WD5C sucks.

Cheers,

Jay

[SamtheLeo]

Dear,

I have had this issue on my STD 350 during my Ladakh trip. The root cause were

1. A blown fuse ( not totally blown but partially & hence)
2. A lot of dust inside carb, (i am sure you are using a petrol filter) but still cleaning will certainly resolve this.

[jingaboysr]

Originally Posted by JayPrashanth

Niks,

NGK BR9ES. Stock Mico Bosch WD5C sucks.

Cheers,

Jay

OT, haven't seen you around for long Jay. Welcome back