Question about 1996 Honda RVF 400 NC35

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Excessive Cam Noise

I have an 96 NC 35. I've recently given the bike to my mechanic to do the valve clearances, which me measured from the wrong spot (between the cam and the rocker arm) which resulted in the clearances being a far way out. Also an Awful knocking noise from the rear cylinders, it is consistent and steady and changes with the RPM of the motor. It is of some concern as you can hear the knocking up to 8M away from the bike at idle. I have removed the valve cover three times now to try and find the problem, and can find no obvious signs of damage the cams do not look scored and the gears look to be in good condition, ANY thoughts on it would be great.

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  • elitenewbie May 26, 2009

    The valve clearances are all with in spec, I have checked them myself. I have also given the big end some thought, the only thing that makes me think twice about that is the fact that the knocking is isolated to the rear two cylinders, I have had the faring off and have listened with a screwdriver to the bottom end and the front bank of cylinders and the knocking can still be hurd but it is loudest from the top end of the rear bank of cylinders. Could it still be the big end?

    Cheers.


  • Paul G
    Paul G May 11, 2010

    has the valves been done properly now ?
    if yes then, the problem is not at the top but rather down below, sounds to me like your crank shaft bearings are gone,
    let me know




    Cheers!!

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  • 132 Answers

Sounds like the valves are hitting the pistons. recheck cam timing and valve clearance.

Posted on May 25, 2009

  • goose3 May 26, 2009

    if the noise is comming from the bottom of the rear cylinders then i would definately check the big end bearings and also the gudgeon pin and small end bearing

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2006 cts 2.8 making loud ticking noise ,running rough and has misfire codes po300,301,303,305


codes p 300 is a random/ multiple misfire===causes spark plugs---HT leads ---injectors/s--ignition coil/s--low compression---wiring
codes p 301,303,305 are misfires detected for no 1,3 5 cylinders === causes listed are engine mechanical fault---wiring---ignition/fuel systems ---injectors---ECT/MAF sensors---ECM
You do not mention if this is a v6 engine in which case no 1,3 5 will be all in the one bank head
With the loud ticking noise that amounts to a mechanical fault associated with that bank
could be loose valve seat inserts , cam lobes failure or cam follower failure or hydraulic lifters problem even loose cam shaft bearings / caps
I would be inclined to remove the rocker cover and check for metal , loose bolts , excessive valve clearance before I went plugs etc
the main indicator for the answer is the loud ticking noise which indicates a valve train problem which will cause the rough running

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What are tools required/procedure for adjusting tappets?


A good feeler gauge set and a basic set of sockets, wrenches, and a screw driver set will work for most engines. I hope this helps. Rod
Now first you check the clearance and record the clearances. If they are out you need to change the valve bucket (which comes in different sizes). This involves removing the camshaft to change the buckets and then reassemble and recheck the clearances. This is a big job and dealerships will often charge $1500 plus to do this job. I am going to post some info from a thread which will explain further. Many motorcycles are similar as well.

The general procedure for checking and adjusting the clearance based on having done this on bikes is;
Before removing old belt
Measure and record each intake and exhaust valve clearance using feelers gauges. Use the crank rotation sequence and measurement order listed in the manual, else you may get erroneous readings due to cam journal clearances and the valve springs pushing the cam around in the bearings. Some are not measured on the exact base of the cam (i.e suzuki)
Compare the readings to specification
If any are out of tol, calculate the difference between the reading and spec.
Remove the camshaft with the out of tolerance readings (usually both if one is out of tol).
Record the markings on the bottom of the buckets that are out of tolerance. (I usually like to measure these with a mike to verify markings and or determine if there is any measurable wear and adjust accordingly)
Refer to the list of available bucket sizes (from svc. manual or dealer parts counter)
Add or subtract the difference you calculated above to determine your new bucket size. (bikes typically tighten up so you end up going with a thinner shim, er bucket)
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Last winter I checked the valve clearance on a 2001 Focus ZX3 with the 2.0L DOHC engine. It had about 85K on it. The clearances were all pretty close to nominal. I don't know the history on the car since new so they may have been adjusted at some time in its life. IIRC the interval for that car was 75K.

As I said above, bikes typically tighten up with this type of valve train. This is due to the valves seating deeper in the valve seats due to wear. This increases the installed height of the valve, decreasing the clearance to the cam. The rate of seat wear exceeds all other wear causing them to tighten.

Tight valves are worse than loose valves. Can eventually lead to low compression, and burnt valves.

If the wear of the cam, bucket, cam journal exceed that of the valve seat, the clearance will increase.

I don't know what the general trend on these engines are as far as tightening or loosening, but if they are like a bike, they will tighten.

I can tell you that on bikes if they are operated a significant amount of time near the red line, they will require more frequent adjustment compared to one operated more conservatively. A bike that is operated conservatively may not need any adjustment at the first inspection interval (not unusual for my Yamaha FZ1, 26,000 mile interval)

Sorry about being long winded, but I thought I would do a brain dump to help people understand the process.

I hope this helps. Rod

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abe5193.gif b3c3550.gif Please rate this solution. Thanks!

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