Dirty intake valves
- Thread starter busanewb
- Start date
New engine with just 4,500 miles? You’re not getting a clean burn, wrong octane or FI settings or possibly worn? valve guides/seals. For such a new motor, the former seems more plausible than valve probs.
I’ve never used anything but 89 octane. Runs like a top with no detonation and has over 60K. I also use Amsoil.
Kiwi Rider
Registered
Here's one man's opinion, lifted from Gixer.com forum.
"It's from the crank case vent tube that's routed to the air box.
The oil cools off on the back of the intake valve and leaves a carbon deposit. Connect the crank case vent tube to your pair hose that sucks filtered air from the air box and the exhaust will suck it out.
If ya wanna clean it you gotta get the engine up to operating temp, then turn the engine by hand until the intake valves are closed.
If u turn it to the right position you can pour sea foam into 2 throttle bodies just enough to cover the back of the valves an let it sit for like an hour, then you can suck it out or remove the spark plug from the cylinder you are cleaning, get a rag and cover the spark plug holes to prevent poop from getting all over your bike, and make sure the other spark plugs are removed also and crank the engine with the starter button and it will suck it in and blow it out the spark plug holes .
The pair mod will prevent it from happening again.
Its important when u do it when the engine is hot, because when its hot the carbon is softer and the sea foam or any top engine cleaner will penetrate better. Repeat until you're happy but don't try to start the motor with the plugs in because you can hydraulic the motor and cause possible engine damage"
Sounds feasible.
To test this theory, remove the crankcase breather hose from the airbox, (plug the airbox breather tube the hose was removed from) and put the c/case breather hose into a small catch bottle secured (cable tied) somewhere conveniently nearby.
Also, clean the backs of the valves until there's no more carbon.
After a 100 miles or so, have a look at the catch bottle and see how much oil is in it.
You'll be surprised!
Then have another look at the backs of the intake valves and see if they'r still clean.
Good luck!
"It's from the crank case vent tube that's routed to the air box.
The oil cools off on the back of the intake valve and leaves a carbon deposit. Connect the crank case vent tube to your pair hose that sucks filtered air from the air box and the exhaust will suck it out.
If ya wanna clean it you gotta get the engine up to operating temp, then turn the engine by hand until the intake valves are closed.
If u turn it to the right position you can pour sea foam into 2 throttle bodies just enough to cover the back of the valves an let it sit for like an hour, then you can suck it out or remove the spark plug from the cylinder you are cleaning, get a rag and cover the spark plug holes to prevent poop from getting all over your bike, and make sure the other spark plugs are removed also and crank the engine with the starter button and it will suck it in and blow it out the spark plug holes .
The pair mod will prevent it from happening again.
Its important when u do it when the engine is hot, because when its hot the carbon is softer and the sea foam or any top engine cleaner will penetrate better. Repeat until you're happy but don't try to start the motor with the plugs in because you can hydraulic the motor and cause possible engine damage"
Sounds feasible.
To test this theory, remove the crankcase breather hose from the airbox, (plug the airbox breather tube the hose was removed from) and put the c/case breather hose into a small catch bottle secured (cable tied) somewhere conveniently nearby.
Also, clean the backs of the valves until there's no more carbon.
After a 100 miles or so, have a look at the catch bottle and see how much oil is in it.
You'll be surprised!
Then have another look at the backs of the intake valves and see if they'r still clean.
Good luck!
Last edited:
Kiwi Rider
Registered
Here's another opinion on this same forum piece, interesting . . . .
"Could be useful info in there.
The fact is. NOTHING. You can use all the cleaners you want, all the chemicals in the world will not prevent carbon build up in an internal combustion engine. Carbon is a byproduct of combustion, and as long as an engine runs you will get carbon build up. Using too high of an octane of gas will increase carbon, as well as low mileage lightly ridden bikes. Wide open throttle acceleration prevents build up and also cleans some of the existing build up off internal engine components. Low compression motors can not completely burn high octane ("premium") fuels so they actually hurt your engine more than they help.
Ever notice someone accelerating on the highway on front of you and their car puffs out some black smoke when they punch it? That is built up carbon being cleaned out by exhaust flow and gasoline. Carbon build up adds to driveability issues and poor gas mileage because carbon absorbs gasoline, it also restricts airflow. Engines that rarely ever see high RPM are worse than high revved motors.
One of the best things for cleaning carbon is water. Plain water, but I would NOT recommend anyone try it themselves unless they REALLY know what they are doing. Same with most "pour in" top engine cleaners. I have seen 2 motors destroyed by people who thought they knew what they were doing using GMs top engine cleaner.
Best thing to do is just leave it the hell alone. By not knowing what you are doing you are going to hurt something before you do any good. Spraying throttle cleaner and stuffing a rag down your intake is an indication that you don't know what you are doing. By a high quality fuel injection cleaner, one that you add to the gas tank. I recommend Techron. Use it according to the directions and use the gasoline that is recommended, not what someone tells you is the best. Suzuki designed and built the motor in your bike, I think they know what octane is the best to use in that engine. Following these instructions I can guarantee that next time you change you plugs and go poking around inside your motor you will see less carbon build up.
Once again, sounds feasible.
"Could be useful info in there.
The fact is. NOTHING. You can use all the cleaners you want, all the chemicals in the world will not prevent carbon build up in an internal combustion engine. Carbon is a byproduct of combustion, and as long as an engine runs you will get carbon build up. Using too high of an octane of gas will increase carbon, as well as low mileage lightly ridden bikes. Wide open throttle acceleration prevents build up and also cleans some of the existing build up off internal engine components. Low compression motors can not completely burn high octane ("premium") fuels so they actually hurt your engine more than they help.
Ever notice someone accelerating on the highway on front of you and their car puffs out some black smoke when they punch it? That is built up carbon being cleaned out by exhaust flow and gasoline. Carbon build up adds to driveability issues and poor gas mileage because carbon absorbs gasoline, it also restricts airflow. Engines that rarely ever see high RPM are worse than high revved motors.
One of the best things for cleaning carbon is water. Plain water, but I would NOT recommend anyone try it themselves unless they REALLY know what they are doing. Same with most "pour in" top engine cleaners. I have seen 2 motors destroyed by people who thought they knew what they were doing using GMs top engine cleaner.
Best thing to do is just leave it the hell alone. By not knowing what you are doing you are going to hurt something before you do any good. Spraying throttle cleaner and stuffing a rag down your intake is an indication that you don't know what you are doing. By a high quality fuel injection cleaner, one that you add to the gas tank. I recommend Techron. Use it according to the directions and use the gasoline that is recommended, not what someone tells you is the best. Suzuki designed and built the motor in your bike, I think they know what octane is the best to use in that engine. Following these instructions I can guarantee that next time you change you plugs and go poking around inside your motor you will see less carbon build up.
Once again, sounds feasible.
Aren’t we looking at the back of the valves, not the tops in that pic? In carb’d engines (of old) I used to trickle water into the carb at high revs to clean the carbon from the ‘top’ of the valves but that wouldn’t clean the bottoms like shown in the pic. I see old oil sticking to the bottom of the valves in the pic. Am I correct?
Yes it's the bottom side of the valves where you can see them when looking through the throttle bodies. I dont think its oil coming from the crank case breather though because I dont see any signs of oil in the air box or in the throttle bodies just the valves. Is there a way to clean this though? I've even heard about going for a hard ride keeping the rpms up to burn off carbon.
I’ve only heard of carbon buildup on valve tops, not below where the stems are. Running past mid rpms keeps them clean IME. Those who never see anywhere near redline will have more carbon buildup but that will be on the tops of the valves, not what’s in the pic.
Well I definitely dont baby the bike when I ride it. Any solution on how to fix this or if this is even really a problem?
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