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Just bought 98 model. It runs perfectly....rev it up i hear nothing. However, in gear going down road you can hear a knock when up in rpms. Please tell me I didn't just by one with engine about to let go
 

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Thior
T off the oil pressure port you should see 70# at 5k. Let us know what it reads at idle first should be at least 10# when warmed up.
 

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Thior
T off the oil pressure port you should see 70# at 5k. Let us know what it reads at idle first should be at least 10# when warmed up.

Thank you...I'll have to get a pressure gauge I guess. I do hear a slight chain noise I believe. Tensioner maybe. I read on cbr bikes you can rotate a screw in the tensioner to tighten? Is that correct? This was a theft recovery. Engine sounded smooth when started and ran. But when ridden I hear that knock and slight rattle. I do understand these motors are bulletproof and also I'm reading the knock a bit

I'll try to get a pressure gauge soon. I'll have to look at this port you talk about . Location?
 

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Thior, a worn out cam chain tensioner (cct) will rattle like marbles in a can, especially loud at 3-4000 rpm. Worn out cam chain guide and/or cam chain can make lots of noise at any or all rpm.
The cct is self adjusting, however, as you say, temporarily rotate/push on, with a small flat screwdriver in the end of the cct with the engine running. If this eliminates or markedly changes the noise, you may have found the problem.
Also, make sure the engine oil isn't diluted with fuel. If in doubt, change the oil and filter.
 

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🏍Bird 1 - Carb 1998 🏍Bird 2 - Carb 1998
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Just in case, are you sure it is coming from the engine itself?
I read your text as a occasional clock, which could be muffled backfire sound under the gas tank. Just a thought.
I have these occasional noises and it has been diagnosed as the carburettor diaphragm rubbers in need of replacement.
Cheers.
 

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Thank you...I'll have to get a pressure gauge I guess. I do hear a slight chain noise I believe. Tensioner maybe. I read on cbr bikes you can rotate a screw in the tensioner to tighten? Is that correct? This was a theft recovery. Engine sounded smooth when started and ran. But when ridden I hear that knock and slight rattle. I do understand these motors are bulletproof and also I'm reading the knock a bit

I'll try to get a pressure gauge soon. I'll have to look at this port you talk about . Location?
Thior
The port or oil pressure sensor is on the rear of the engine left side inboard from the front sprocket cover. If you go to the resources center and download the factory service manual. It will give you the proceedure and the sensor location as well.
Also yes as Fizzy states remove the inspection bolt and turn the screw very gently counterclockwise to see if the sound reduces. You could also use a mechanic's stethoscope to locate the sounds origin. Or a long screwdriver or wooden broom handle. The later 2 place the handle against the bone just behind your ear.
 

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Discussion Starter #7
Thior, a worn out cam chain tensioner (cct) will rattle like marbles in a can, especially loud at 3-4000 rpm. Worn out cam chain guide and/or cam chain can make lots of noise at any or all rpm.
The cct is self adjusting, however, as you say, temporarily rotate/push on, with a small flat screwdriver in the end of the cct with the engine running. If this eliminates or markedly changes the noise, you may have found the problem.
Also, make sure the engine oil isn't diluted with fuel. If in doubt, change the oil and filter.

I have a friend with one those doctor deals you talk about. I'll have to get that tomorrow.

I didn't notice any these noises when I bought the bike the other day, but I'm 50 and my hearing is going.. It definitely sounds like a chain. I have a triumph 955i I'm rebuilding also , and like an idiot when I put the head back on I forgot the chain tensioner ...I'll never forget that sound. Cost me a valve job.

Any knocks worry me. This was a theft recovery. Has 24.000 miles and I paid total of 1800 with shipping. Have quite a bit of work to do cosmetically. However it ran true and engine sounded good...that day. Now I'm noticing little noises. I'll test it with the hearing advice tomorrow or monday
 

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Roger that
Good news is they are pretty damn tough. We've had cam chain Tensioners get pretty bad. But I don't think I've heard of one jumping timing even with a bad one. Good thing is aluminum is very light. Bad thing is it'll carry noise a long way. So hoping with the scope you can narrow it down and clear the bottom end.
 

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Ummmm, are you sure your chain and sprockets are in good order? The best test for a worn out (unevenly stretched) chain is to check the slack at the rear sprocket (in several spots) - put the BB on the center stand and hold the chain up tight towards the swing arm (ie where you would measure the normal chain slack) and then try to lift a link pin off the rear sprocket at the center point (eg near the adjusters).......... if you can easily lift a roller off the sprocket with your fingers while holding the chain taught, then your chain is long gone and the sprockets will be badly worn/hooked. These worn sprockets and drive chain will make horrible clunking noises while riding ........

Another source of knocking is steering head bearings, but that is usually over bumps. As stated above if the CCT and cam chain are buggered, the noise is continuous and loud though it may take 500kms of hearing funny noises before it finally lets go and rattles badly.

(y)
 

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Discussion Starter #10
Man I got alot to look over. Rear sprocket almost came off today while I was putzin around neighborhood. Tonight I have no start as pistons full of fuel.

But I'm in love with the bike
 

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Tonight I have no start as pistons full of fuel.
I suspect you also have fuel in the oil. do not run like this. Might be the source of the knocking. Not an expert on carbs here, maybe others can direct you on exactly what to check re: pistons full of fuel.
 

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Ahhh, yes, Carbies....... I remember them......... first thought I had about them is they may have blocked jets and malfunctioning needle's and seats - typically this causes the float bowls to overflow onto the crankcases and the floor.

Blocked jets will make starting and idling difficult and it will run rough anyway. Hopefully the vacuum diaphragms on the CV slides are in good condition and everything just needs a good wash and blow clean. Dismantle and layer the parts out in order as you work down to a bare body so it is easy to reassemble after all bits have been cleaned.

Others will also recommend removing the sump to inspect the oil pick up screen if the bike hasn't been used regularly or not had an oil change for several years and the oil has gone coal black and sludgy. If the oil still has a hint of brown color in the sight glass (does a carby BB have a sight glass?...... my FI only has a dipstick).... then it may have been changed just a few thou ago.

It is a good idea to drop the oil regardless, and smell test for fuel contamination...... as fizzy and the boys warn, oil will be diluted by fuel and running the engine will cause extensive damage to bearings etc.

At this age the bike will be a restorers project if it hasn't been maintained well, but hopefully all you need do is clean a few bits and check/adjust a few others and replace the usual culprits like plugs, filters, coolant, brakes etc etc. Be careful if you go as far as greasing the swing arm - there is a set procedure for tensioning the swingarm axle so a good read of the workshop manual in the reference section of the forum is a must.

I'm not sure why fuel has leaked into the cylinder head, unless it's just from flooding while cranking the motor..... you'll have to go over all the ageing, neglected bits, and replace any cracked hoses etc as you find them. There will be info in the workshop manual trouble shooting section, and the forum members will help whenever you ask........

Lets hope it's just few gaskets and hoses and a clean up and tune.........

(y)
 

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While you're in there....... how many kms/mls has it done?........... this was my original fuel filter which I replaced in September at 15yrs and 129,000 kms (it is from an 05 FI BB with the fuel pump and fliter inside the tank.......
 

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Discussion Starter #14
Thank
I suspect you also have fuel in the oil. do not run like this. Might be the source of the knocking. Not an expert on carbs here, maybe others can direct you on exactly what to check re: pistons full of fuel.
Yes, there was gas in oil. I hadn't ridden it far.
I suspect you also have fuel in the oil. do not run like this. Might be the source of the knocking. Not an expert on carbs here, maybe others can direct you on exactly what to check re: pistons full of fuel.
There was fuel in the oil. Lucky not much and didn't run it long at all. Changed oil and it helped quiet it.

Now my issue is it looses power. It runs well for a bit. Then seems to starve out for air fuel.or maybe spark. It is intermittent like Im turning off and on a cylinder with a switch. I have to play with throttle at stop signs to keep running. I thought fuel related so off came the tank and it was dirty bad. The petcock no diaphragm, instead filled with silicone? So I cleaned all that out, added me a shut off valve I can get to...not much difference. It doesn't seem heat related. When it's running like crap it's hard to restart, backfires....but if I wait couple hrs it starts fine. I don't see evap anything. Two top hoses coming off my carb don't go anywhere.

Can someone send me a real picture of the top of their bike so I can see what mine doesn't have
 

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Discussion Starter #15
Ahhh, yes, Carbies....... I remember them......... first thought I had about them is they may have blocked jets and malfunctioning needle's and seats - typically this causes the float bowls to overflow onto the crankcases and the floor.

Blocked jets will make starting and idling difficult and it will run rough anyway. Hopefully the vacuum diaphragms on the CV slides are in good condition and everything just needs a good wash and blow clean. Dismantle and layer the parts out in order as you work down to a bare body so it is easy to reassemble after all bits have been cleaned.

Others will also recommend removing the sump to inspect the oil pick up screen if the bike hasn't been used regularly or not had an oil change for several years and the oil has gone coal black and sludgy. If the oil still has a hint of brown color in the sight glass (does a carby BB have a sight glass?...... my FI only has a dipstick).... then it may have been changed just a few thou ago.

It is a good idea to drop the oil regardless, and smell test for fuel contamination...... as fizzy and the boys warn, oil will be diluted by fuel and running the engine will cause extensive damage to bearings etc.

At this age the bike will be a restorers project if it hasn't been maintained well, but hopefully all you need do is clean a few bits and check/adjust a few others and replace the usual culprits like plugs, filters, coolant, brakes etc etc. Be careful if you go as far as greasing the swing arm - there is a set procedure for tensioning the swingarm axle so a good read of the workshop manual in the reference section of the forum is a must.

I'm not sure why fuel has leaked into the cylinder head, unless it's just from flooding while cranking the motor..... you'll have to go over all the ageing, neglected bits, and replace any cracked hoses etc as you find them. There will be info in the workshop manual trouble shooting section, and the forum members will help whenever you ask........

Lets hope it's just few gaskets and hoses and a clean up and tune.........

(y)
That's good info. No, it wasn't well maintained I'm finding out. I bought it with my heart, not my head. It was a theft recovery, I got it for 1
 

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What is your running battery voltage? And battery condition? This problem maybe electrical in nature. Low voltage can affect spark at the plugs. Both stator and rectifier can and do fail on this bike. Running voltage should be 12.5V- 14.5V depending on rpm. . Low voltage would indicate bad stator, bad battery or bad wiring.
Rig up a digital voltmeter so you can observe it while riding.
Also, if the tank has loose rust inside, very small flakes can block carbs (or FI), no amount of chemical cleaner will help. They must be physically removed.
 

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Check again for fuel in the oil....... my FI model has a fuel pressure regulator that can go bad over time but I'm unsure what the carby 98 has........ something from memory of way past carby bikes tells me a leaking fuel vacuum tap is bad news and a new gasket and thorough clean is needed.

(y) Go to the reference section on here and dig out the early models workshop manual - I have downloaded the FI models manual........ it will help problem solve and may even have pics you need.

This link should work......

 

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Discussion Starter #18
Check again for fuel in the oil....... my FI model has a fuel pressure regulator that can go bad over time but I'm unsure what the carby 98 has........ something from memory of way past carby bikes tells me a leaking fuel vacuum tap is bad news and a new gasket and thorough clean is needed.

(y) Go to the reference section on here and dig out the early models workshop manual - I have downloaded the FI models manual........ it will help problem solve and may even have pics you need.

This link should work......

Thank you so much. Im not sure if I have said anything but I think found problem to my power loss. The number one cylinder coil plug keeps popping up. Don't know why but I made a device that holds it down and so far no more stumbling. However, the carbs still need to be gone thru....no doubt about that
 

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Hi Thoir,

The plug cap popping off the spark plug? ......... :unsure: ........ there must be a reason why this is happening to one cylinder and not the others.

Have a good look with a torch, down the plug shaft, for something that shouldn't be there, or check the spark plug is not cross threaded and on an angle, and that the screw on tip has been removed to expose the bare thread the plug cap needs to ratchet onto...... maybe something has broken off the plug cap and is preventing it from staying locked onto the spark plug? Put a flat screw driver into the plug cap end and tighten if loose. Something isn't right if it pops off......

:unsure:
 

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Discussion Starter #20
Hi Thoir,

The plug cap popping off the spark plug? ......... :unsure: ........ there must be a reason why this is happening to one cylinder and not the others.

Have a good look with a torch, down the plug shaft, for something that shouldn't be there, or check the spark plug is not cross threaded and on an angle, and that the screw on tip has been removed to expose the bare thread the plug cap needs to ratchet onto...... maybe something has broken off the plug cap and is preventing it from staying locked onto the spark plug? Put a flat screw driver into the plug cap end and tighten if loose. Something isn't right if it pops off......

:unsure:

It looks as if on this cap I'm should use the bigger cap thing on the spark plug. It seems by using the threaded top of the plug, it's not a fit at all to the coil side. I changed plugs yesterday and also fitted a piece which will hold the coil cap down and everything seems smooth now....but today is another day
 
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