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 Post Posted: Tue Jun 14, 2016 4:47 am 
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Hornet Baby

Joined: Thu Jun 09, 2016 6:53 am
Posts: 31
Location: Vietnam
Hi everyone, I am new here.

Just yesterday I have problem with my hornet 250. It is 1998 model.

The day before it was good, just small notice that I feel it was running a little bit rich (exhaust has some smell of fuel and black smoke at high RPM), and also small fuel leakage on the petcock.

Yesterday morning it became worst. Huge fuel leakage on petcock and engine gave strange sound and very low torque. Then I had the mechanic guy to fix the petcock. After fixing, still small leakage, but we noticed another problem that 1st engine is not running, its exhaust head was completely cool while the others heat up. We checked no fuel stuck, air is OK, but we didn't have tool to check the plug. Gave up on that day.

Today morning after small round riding, 1st engine starts to fire (don't know why), now it gives correct sound and torque, however I noticed while smoke exhausts and the exhaust open is wet. My mechanic guy is not professional but he said that maybe oil leakage into cylinder??? his experiences are black smoke = fuel rich, and while smoke = oil in cylinder.

So is my mechanic guy 's assumption correct? what are possibilities to give white smoke exhaust? Can running the bike while one engine is not firing cause this problem? and what to check now?

Thank you very much.


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 Post Posted: Tue Jun 14, 2016 4:43 pm 
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Hornet Baby

Joined: Thu Jun 09, 2016 6:53 am
Posts: 31
Location: Vietnam
Update:

Today after leaving the bike for whole day, in the evening I start the bike and the same thing happened: 1st cylinder not running and white smoke exhaust, after few minutes riding the 1st cylinder started to fire and white smoke disappeared.

I ride home. On the way (3 km), there were 2 times when I was releasing the throttle to slow down, the engine suddenly off, I push start button but the starter motor did not move, until I switched off the head light and push start then it again running fine. And last time when I almost reach home, engine and head light suddenly off, but ODO light is still ON, I have to switch off and on the key, then it is again fine.

This messy lead me think of electrical failure, I then check the side stand switch and the Ground connection from battery to frame, they are all fine. Please help me out, this started to hurt my head, even don't know it is mechanical or electrical failure.

Also previously I have noticed some time I can start the bike with side stand out, and gear is not neutral, I just have to pull the clutch and start. But some time I could not, the starter motor does not run, I have to make it neutral and side stand in then only it will start. Any guess? Could anyone share the wiring diagram for hornet 250 please?

Thank you.


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 Post Posted: Fri Jun 17, 2016 1:06 pm 
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Joined: Sat Feb 20, 2010 1:13 pm
Posts: 577
Location: Kaohsiung, Taiwan
First of all, please fill in your approximate location at your user profile. This can often help to solve problems.
I assume you live somewhere with pretty hot and humid climate!? If so, corrosion of electrical connectors could be a problem.

In your case I would take the following initial steps...
- check/replace the battery
- check/replace fuses and clean fuse connectors
- check for burnt or corroded wires and connectors (especially the ones near battery and regulator/rectifier)
- check your spark plugs and ignition coils/leads
- check charging system incl. R/R

From your description I would generally think it's an electrical problem. But make sure the fuel system is clean and working correctly as well.
Regarding the side stand problem... the switch might be partially stuck, dirty or corroded. I'm not sure about the details, but cleaning or replacing this side stand switch might help. If this switch comes on randomly, it could also be the reason for your sudden engine shut-offs.

Either way, it would surely be good if you could locate a mechanic who knows the Hornet and can really help you.

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 Post Posted: Sun Jun 19, 2016 8:37 am 
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Hornet Baby

Joined: Thu Jun 09, 2016 6:53 am
Posts: 31
Location: Vietnam
Thank you Borschtsch,

I filled my location, I live in Vietnam, yes as you said: hot and humid climate.

And you are right, it was electrical problem. Actually it was combination of many problems cause many doubts to me:
- At cold start, one of the engines fail, and it work only after warm up for some time: this is spark plug failure, change all 4 spark plug and problem solved.
- Sudden engine shut off: a piece of wire of the head light scratch and short to frame, put isolation tape and it is fine.

White smoke is not a problem, it is just water steam and disappear when engine is hot.

And now another issue: I once run out of fuel and switch to reserve, since then I feel the engine 's throttle response is not smooth as before. I then had mechanic guy to clean the Carbs, he set all fuel/air screws to 2.5 turns and didn't touch the Carb sync screws, we could not do Carb sync due to lack of vacuum sync tool. Now throttle response is OK but at RPM > 4000 I start to feel vibration in the foot pedal. Do you think this is due to unbalance of the engines? Will Carb sync help? I plan to make an electronic vacuum sync tool and do it myself, I will post the result when I have done.

Thank you again.


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 Post Posted: Sun Jun 19, 2016 4:57 pm 
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Good to hear the electrical problems are solved.

As for the vibration... can you only feel it at around 4000rpm and does it disappear again at higher revs? Or is getting worse with even higher revs?

This problem could be caused by a lot of things... carburetor imbalance might be one of them. But it could be something more serious like worn out crankshaft bearings... which in turn could be caused by using inappropriate engine oil or other general maintenance issues.

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 Post Posted: Fri Jul 15, 2016 7:41 am 
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Hornet Baby

Joined: Thu Jun 09, 2016 6:53 am
Posts: 31
Location: Vietnam
Borschtsch wrote:
Good to hear the electrical problems are solved.

As for the vibration... can you only feel it at around 4000rpm and does it disappear again at higher revs? Or is getting worse with even higher revs?

This problem could be caused by a lot of things... carburetor imbalance might be one of them. But it could be something more serious like worn out crankshaft bearings... which in turn could be caused by using inappropriate engine oil or other general maintenance issues.


The vibration is only at around 4000rpm and disappear at > 5000rpm.

Last week I had a long travel, so had chance to test my engine, and it was showing very good performance, top speed is 180km/h. So I think the vibration is just minor issue and I can leave it for now.
However I noticed my fuel mileage is quite poor, around 20 km per litter with normal speed 100 - 140 km/h. Is it normal? how about yours? Even daily riding in city I also have 20 km/l fuel mileage. I think my cabs are in good setting at 2.5 turns, I also check the spark plugs and exhaust, no sign of lean or rich mixture. Anything else may cause poor fuel mileage?


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 Post Posted: Sat Jul 16, 2016 8:25 am 
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mgdaubo wrote:
However I noticed my fuel mileage is quite poor, around 20 km per litter with normal speed 100 - 140 km/h. Is it normal? how about yours? Even daily riding in city I also have 20 km/l fuel mileage. I think my cabs are in good setting at 2.5 turns, I also check the spark plugs and exhaust, no sign of lean or rich mixture. Anything else may cause poor fuel mileage?

That sounds like normal. Mine is about the same.

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 Post Posted: Sat Jul 16, 2016 6:00 pm 
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Hornet Baby

Joined: Thu Jun 09, 2016 6:53 am
Posts: 31
Location: Vietnam
Borschtsch wrote:
mgdaubo wrote:
However I noticed my fuel mileage is quite poor, around 20 km per litter with normal speed 100 - 140 km/h. Is it normal? how about yours? Even daily riding in city I also have 20 km/l fuel mileage. I think my cabs are in good setting at 2.5 turns, I also check the spark plugs and exhaust, no sign of lean or rich mixture. Anything else may cause poor fuel mileage?

That sounds like normal. Mine is about the same.

Thanks Borschtsch, I just did a search on this forum and found lots of helpful information related to fuel consumption such as air filter, spark plug, brake, tire pressure... great site :)


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