F2 Bogging down
#1
06-28-2010, 06:39 AM
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F2 Bogging down
Hi Im new here and im not sure if im posting this in the rite place but heres my problem. If have a 94 cbr 600, when I get up to speeds of like 85 thats as fast as I can go In 5th gear, and It will be full throtle but thats a fast as it goes and then it starts puttering like its out of gas. THen sometime it will go faster then slow down, then go faster, then slow down. Also I can reach speeds higher than 85mph if I stay in 3rd or 4th gear but soon as I shift to 5th gear it starts to slow/bogg down but if I down shift I can go faster, I have full power. So to sum it up in 5th gear I can go full throtle but no acceleration.... Please help Thanks
#2
06-29-2010, 02:04 PM
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not enough horsepower/torque
Your not developing horsepower/torque. The higher gears take more power than the lower gears in order to maintain or increase speed. If you break this down to the reasons why your not developing enough power, you come up with some simple solutions first, getting progressively more complicated and expensive. Lets look at the obvious and least expensive reason an engine fails to develop power.
1. Insufficient or incorrect amount of fuel. (too lean or too rich)
I hope this helps you in a step by step process to find what's wrong.
Good luck..
P.
1. Insufficient or incorrect amount of fuel. (too lean or too rich)
In order to cure this, you can try two simple approaches:
2. Insufficient or no spark.- Use a fuel systems cleaner for several tanks of gas and see if the problem clears. The best by far is "SEA FOAM". It comes in a white can and most well stocked suppliers have it. "follow the directions!!!"
- Low fuel pressure from a pinched or block line, or a fouled fuel filter may cause fuel starvation. Likewise a defective fuel pump may not be delivering enough fuel, starving the engine when power is demanded. Remember, high revs don't nessesarily mean more fuel being delivered to an engine.
- Failing the simple flush and soft cleaning method, and if your fuel pump lines and filter check out, your next step would be to manually clean, or have a professional clean your carburetors. You will need to balance your carbs after this, so unless your willing to spend about $100.00 on a specialty tool for this job, have it done at your local bike shop.
(Are you sure you are running on all 4 cylinders?)
This one is simple at first but can get very expensive as we go along.
3. Carbon buildup.This one is simple at first but can get very expensive as we go along.
- Change your plugs! Make sure they are gaped correctly! A plug may look good, but can have a cracked electrode under the dielectric. They are cheap, so just toss the old ones and put in a fresh set. When you pull the old plugs, make note of its condition and what cylinder it came from. If you see oil or heavy black carbon buildup, you may have to address this problem.
- At the same time, use an ignition tester (they are cheap, some go for as little as $10.00), and check to see that your coils are delivering power to the plugs. With your plugs out, connect a new spark plug to each coil wire one at a time and spin up the engine. DO NOT hold the plug with your hands, unless your are into getting zapped! Make note of how bright the spark is, and if all 4 appear equal. It's not scientific, but its usually a good first indicator. If you see a dim spark, replace the coil. My preference is to change the coils in pairs, as they both have the same amount of run time, and the reason one is failing may have weakened both.
If an engine is suffering from carbon buildup, its usually and indication if some mechanical problem. However it can also be caused by improperly gaped plugs running too cold (too narrow a gap), overfilled engine oil, a rich mixture, prolonged use at idle (city driving), to low of octane fuel being used, dirty or clogged air cleaner, and so on.
4. Low or no compression on one or more cylinders.- Again this can be handled many ways, but lets conclude that the plugs have been replaced and are properly gaped, the air filter is new or good, the oil is clean and not overfilled, the gas you are using is premium, and you are riding the bike, not sitting on it while it runs for hours at a time. So once again I would turn to "SEA FOAM" and follow the instructions on how to remove carbon from valves and cylinder by pouring it into the carbs while the engine is running. WARNING!!! this will cause a LOT of smoke so do NOT do it in a confined space even with the doors open! (you've been warned!) Just follow the instructions and it will do the job of cleaning out most moderate carbon buildup
- In extreme cases, you may need to tear the engine down to clean heavy carbon builup, but that is a last resort.
A compression tester that will reach down to the cylinder head of these bikes are available. What you will be looking for is low or no compression, or a wide variation between cylinders.
Yes, I am a mechanic. No, I'm not a small engine mechanic. So although what I have written here is sound advice for any normally aspirating gasoline engine, for specific questions on motorcycle specific items I would be at a loss to answer. In fact I myself have asked for advice regarding my bike on this forum, and I too rely on a bike shop to take care of some of the things that I dont have the time for, or simply don't want to deal with. Once my hobby starts to feel like work, its no longer fun.- Carbon buildup on the valves MAY be the cause of this problem, and refer the the previous paragraphs to try and address this.
- If carbon buildup is not the reason, you can try some of the soft cure methods first, like an oil additive that loosens rings and rejuvenates valve seals. But unlike an automotive engine, this approach tends to be marginally effective at best in small engines. Again, "SEA FOAM" claims to be useful in loosening stuck rings when used in oil. But I have no experience in using the product outside of the fuel system, which does work as advertised.
- Now your gonna spend some cash, because if you are at this stage and still are having problems, you looking at the very least a top end rebuild (valves), or a complete rebuild if you have low or no compression and can't cure it with magic potions.
I hope this helps you in a step by step process to find what's wrong.
Good luck..
P.
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07-01-2010, 12:48 PM
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07-01-2010, 04:19 PM
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