Can you solve this problem? HORNET

[kmor110]

Hi all,

I am reaching out for help... I've been riding a 1996 250 Honda Hornet since last year and I love it.

Recently saw a 2001 come up cheap on TME, bought it on impulse for $2500 even though it wasn't running great thought it might just be stale fuel. ANYWAY>>>

Full service from Motorcycle Doctors, still running like poo...cue carb overhaul...still no improvement...cue sticking a rag in the air intake...OOOHH some improvement...

Basically it bogs down if you use heavy throttle, is worse when engine is under load. Restricting air intake by about 15% seems to improve the top end it but definitely not achieving the peak power band they are famous for.

Struggling to sell it...even for what I paid for it as I'm not prepared to rip off some poor noob.

Any ideas what it could be? Considering replacing ECU but don't want to go down that path to find it was something else. I'm at a loss, my mechanic is really clever he thinks I should sell it but I'm kinda stuck between a rock and a hard place, it's stressing me out!

Cheers for your time and advice...Kieran

[Big Dog]

Does opening your fuel cap help?

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[Big Dog]

Sounds to me like you're running too lean. Check the things that control your fuel flow rate. Including your tank vent.


May also pay to drain your tank from the pipe to the carb into a clear or nearly clear bottle and look for water or sediment.

No good? I'd be asking why it is still not running right after a service... unless you kept this issue a secret from the mechanic he should probably have either fixed it or told you how much w fix would be.

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[nzspokes]

First. Take it for a ride then as you get back run it in the rev range that is the worst. Pull the clutch in and hit the kill switch. Push the bike into your drive. Don't start it. Pull a plug out and post a photo on here.

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[kmor110]

Sounds to me like you're running too lean. Check the things that control your fuel flow rate. Including your tank vent.

Have tried running with tank cap open to aid vacuum, no luck - also mechanic adjusted floats to run richer when he had it apart and it didn't make a difference.

Will try the suggestion regarding spark plug, it bogs down at like 0 RPM if i apply full throttle so I should be able to do this in my drive way :)

[Asher]

Have you checked that the carb jets are factory sizes?

[Maha]

Don't waste/spend any more money on it, trade it on something that'll have a warranty.

Nice little Hyosung --> http://www.trademe.co.nz/motors/motorbikes/motorbikes/sports/auction-911564250.htm

I'd be all over something like this if I were in your position --> http://www.trademe.co.nz/motors/motorbikes/motorbikes/sports/auction-786858064.htm

[sidecar bob]

Does it have no air filter, or possibly an aftermarket air filter, such as a K&N.
These bikes rely on having a restriction to run properly.
Simply fitting a free flowing air filter with no other mods will fuck them up completely in the way you describe.

[spanner spinner]

I have lost count how may times I have been presented with either these or cbr250's that run just like yours, what you have described is usually bought on by low compression. Do a compression test dead cold and then get it hot and repeat. You should have at least 150 psi cold and over 170 hot. if it is only a couple of cylinders that have low compression it may be worth checking the valve clearance as it might have tight valves as they never get done as most learners baulk at the cost of setting the valves. If they are all low it still may be valve clearance but in my experience they are usually just stuffed. The reason the rag trick works is if you can be bothered you can get them running "ok" if you jet them spot on BUT!!! when the weather warms up come spring you will have to go through the whole process again. When they have low compression they get really picky about carb set up, you just about have to adjust them every time the weather changes. The reason for doing a cold then hot compression test is if the valve clearance is tight you may have good compression cold and if it falls off when hot or one cylinder drops more than the others this points to valve issues. If it needs a rebuild good luck it's a full engine tear down as the bores are part of the top crankcase.

[nzspokes]

I have lost count how may times I have been presented with either these or cbr250's that run just like yours, what you have described is usually bought on by low compression. Do a compression test dead cold and then get it hot and repeat. You should have at least 150 psi cold and over 170 hot. if it is only a couple of cylinders that have low compression it may be worth checking the valve clearance as it might have tight valves as they never get done as most learners baulk at the cost of setting the valves. If they are all low it still may be valve clearance but in my experience they are usually just stuffed. The reason the rag trick works is if you can be bothered you can get them running "ok" if you jet them spot on BUT!!! when the weather warms up come spring you will have to go through the whole process again. When they have low compression they get really picky about carb set up, you just about have to adjust them every time the weather changes. The reason for doing a cold then hot compression test is if the valve clearance is tight you may have good compression cold and if it falls off when hot or one cylinder drops more than the others this points to valve issues. If it needs a rebuild good luck it's a full engine tear down as the bores are part of the top crankcase.

Well I would trust mister Spinners advice over mine. Get a compression tester.

[swbarnett]

Well I would trust mister Spinners advice over mine. Get a compression tester.
Ditto. He certainly put me right when I had worn out emulsion tubes in my carbs.

[sidecar bob]

Give my advice a cursory check, but spinner is a bike mechanic, im a car mechanic, so yeah, hes probably seen a lot more of them than me.

[kmor110]

Does it have no air filter, or possibly an aftermarket air filter, such as a K&N.
These bikes rely on having a restriction to run properly.
Simply fitting a free flowing air filter with no other mods will fuck them up completely in the way you describe.

Interesting perspective ... certainly sounds like the issue it could be having. Not sure what air filter it has, whatever it came with. I checked it, looked clean enough so I put it back. Where can I get a suitable air filter to try?? Please? Best lead I've had...

[kmor110]

I have lost count how may times I have been presented with either these or cbr250's that run just like yours, what you have described is usually bought on by low compression. Do a compression test dead cold and then get it hot and repeat. You should have at least 150 psi cold and over 170 hot. if it is only a couple of cylinders that have low compression it may be worth checking the valve clearance as it might have tight valves as they never get done as most learners baulk at the cost of setting the valves. If they are all low it still may be valve clearance but in my experience they are usually just stuffed. The reason the rag trick works is if you can be bothered you can get them running "ok" if you jet them spot on BUT!!! when the weather warms up come spring you will have to go through the whole process again. When they have low compression they get really picky about carb set up, you just about have to adjust them every time the weather changes. The reason for doing a cold then hot compression test is if the valve clearance is tight you may have good compression cold and if it falls off when hot or one cylinder drops more than the others this points to valve issues. If it needs a rebuild good luck it's a full engine tear down as the bores are part of the top crankcase.

Spinner...thanks! My friend just suggested last night to check compression so this will be next stage along with air filter change Sidecar Bob suggested. You are right the valve clearances haven't been checked under my ownership or the previous owner to my knowledge. Here's hoping it's just a couple of the cylinders that are low and re-adjusting will fix it :D. Do you have a shop/business or just a hobby? Sounds like I need you to be my mechanic LOL.

[spanner spinner]

Spinner...thanks! My friend just suggested last night to check compression so this will be next stage along with air filter change Sidecar Bob suggested. You are right the valve clearances haven't been checked under my ownership or the previous owner to my knowledge. Here's hoping it's just a couple of the cylinders that are low and re-adjusting will fix it :D. Do you have a shop/business or just a hobby? Sounds like I need you to be my mechanic LOL.

Sorry not in the bike industry any more, did my 18 years and got out. Now sell car parts for a living as a see more future in the car industry. Even the bikes gone, there's nothing like working in the industry to kill any enthusiasm you ever had for bikes.

[sasas]

Can u take out the spark plug and post a picture in here?
when you say bog down..can u describe when does it happen actually and can it be replicate? early rev? middle? top end..or does it happen when u fast throttle it from 1st gear.? seems like a carb issue...need to do some setting on it.

[nzspokes]

Before you sell it to some poor sap, give it a proper comp test. Get it done by somebody that knows what they are doing. Dont tell people its just a valve adjustment if you dont know.

[AllanB]

Sperm in the airbox?

[Autech]

Interesting perspective ... certainly sounds like the issue it could be having. Not sure what air filter it has, whatever it came with. I checked it, looked clean enough so I put it back. Where can I get a suitable air filter to try?? Please? Best lead I've had...

Definitely worth a look as well as the compression test mentioned by the guru.

The reason I say this is as there is a few flappy things in the VFR's airbox which people from time to time remove and instantly regret it. This causes the bike to run as you have described, turns out the Honda chaps put them there for a reason! So check that there has been nothing removed from the airbox that should be there and that a filter is correct. Some googling should put your right.

Good luck lad!