Engine noise and delayed throttle response after valve adjustment and carb clean

[gdvd]

Hello all,

Before I begin let me apologize for the long post. Here's my story.

I did the 7500 mile valve clearance inspection on my 2008 250r in August and found that the all the clearances were within spec but towards the tighter end of the spectrum. So I left the valves alone, put the bike together and it ran fine for the next two months. In November, on a somewhat cold day the engine started to bog down when given throttle. It was idling OK but would die if I opened the throttle too much. After some reading, I decided to clean the carbs and adjust valve clearances.

The carbs looked very clean and all the orifices were clear but I followed the cleaning procedure anyway. However, I forgot to take note of the mixture screw setting. So when putting things together I set both screws to 2.5 turns from just sitting position. I re-shimmed the valves so that the clearances were on the loose side of the range, but within spec.

This is what happened after doing these things:
1) I started getting this noise that I didn't have before.
http://www.youtube.com/watch?v=KvVLHhVw8do

I don't have the expert ear to recognize if I did something wrong with the valve adjustment or if it is the CCT or something else?

2) Once warmed up, the engine did not die when given throttle but there was a significant delay in both acceleration and deceleration. This was not due to any slack in the throttle cables. I should also note that the carbs were synced after adjusting the valves. So I took out the carbs, cleaned them again, set the mixture screws to the service manual recommendation (2.5 on left, 1.75 on right) and the engine dying issue came back.

I am thinking of fiddling with the mixture screw settings to see if I can get a proper throttle response. I am not too sure if the noise is normal. Any suggestions will be greatly appreciated. Thanks for taking the time to read all of this.

[csmith12]

That don't sound good man. I wish I could help you more but I would think you are very very lean or the valves are still not right.

[Joshorilla]

I know this isn't going to be a very helpful post, but if it were me, for peace of mind i'd take it to a motorcycle mechanic and just pay them to fix it, you gave it a shot, not so good, get them to fix it.

[allanoue]

Link to original page on YouTube.

[gdvd]

Yeah, it doesn't sound good at all. Thanks for embedding the video allanoue. Joshorilla, I am leaning very heavily towards your suggestion. I can only find time to work on the bike a few hours each weekend so it takes me a long time to get anything done . May be I will try to recheck everything all over again once.

If that doesn't fix it, anybody know good mechanics in the Atlanta area? How much would something like this cost?

[csmith12]

Hold fast! Your thread is young my friend and we have some great wrenchers on this site that are pretty active. I bet by this time tomorrow, there will be at least 5+ really good answers to what may be the cause and possible solutions.

If anything, it's additional info to tell your local mechanic.

[DaBlue1]

Does not sound good at all, but it could be worse. Your oil level and condition might be something you want to check to see if there is any evidence of metal in it. To be honest, the engine sounds like it would if there was no oil in it.

Just out of curiosity, did you try to ride the bike after the valve adjustment?

[gdvd]

DaBlue1, thanks for your reply.I was too scared to sit on it after hearing that sound, so no riding yet . The oil thing occurred to me quite late and you are right, it did look rather bad. I changed the oil last night and cleaned the oil screen. While I didn't spot any metal in the drained oil itself, the screen showed up a little piece of metal shaving. I have not started the engine again after the oil change. Would it help if I post another video with the sound after the oil change?

[lgk]

did you reset your cam chain tensioner correctly?

[DaBlue1]

Originally Posted by gdvd

....While I didn't spot any metal in the drained oil itself, the screen showed up a little piece of metal shaving. I have not started the engine again after the oil change. Would it help if I post another video with the sound after the oil change?

What color was the metal you saw (silver or brass)?
Does the sound change any after the oil change? Also run it while off the stand.

[gdvd]

I think I reset the CCT correctly. I followed the procedure in the service manual and used a screwdriver to hold the spring while tightening the bolts. I had to do this multiple time because it was hard to hold the screwdriver in place.

DaBlue1, the metal piece was silver. I have not started the bike after changing the oil. If it stops raining here I will be able to tell you what it sounds like tomorrow. Do you mean I should keep the bike off the side stand and in vertical position when running?

[DaBlue1]

Originally Posted by gdvd

.. Do you mean I should keep the bike off the side stand and in vertical position when running?

I meant the rear stand.
You might want to double check that CCT as well. From what you describe the engine basically was fine until you did the valves. There may be a possibility the valve clearance is incorrect or you have a broken/weak valve spring. Worse case a broken cam cover.

Keep us posted.

[Motofool]

This noise is not coming from the service you did to the carburetor but from the last mechanical work you performed: the re-shimming of the valves.

Clearances may be within the specified range, but there are other parts that may have been wrongly re-assembled, like the cam shafts, cam journals and cam chain (timing).

Going back over your steps and rechecking everything is the next thing to do, IMHO.
Hopefully, permanent damage has not happened yet.

[vmax]

Factory default screw mixture L 2,5 R 1 3/4. Set with L 2 3/4 R 2. This work for me if your bike stock needles/shim with stock exhaust/slip on.

[gdvd]

Originally Posted by Motofool

Clearances may be within the specified range, but there are other parts that may have been wrongly re-assembled, like the cam shafts, cam journals and cam chain (timing).

I will go over the assembly again. In case I made a mistake in aligning the cam shafts, journal or the chain, I am assuming that putting everything back the way it is now would not be the way to go. Would it make sense to rotate the crankshaft to align the marks in the alternator cover (TDC position) and then remove and re-position the cam shafts to align the timing marks on the sprockets with the cylinder head surface? Since the cam chain is a closed loop, I am assuming that only the number of links between the timing marks on the two sprockets matters, and there is nothing special about any particular link on the chain?

[Motofool]

The correct way to do it is following the Service Manual.

There is only one position possible for the cam caps, as well as a sequence and value of torque (each sprocket has marks that should align with the edge of the cylinder's head).

There is only one position possible for each camshaft respect to the crankshaft, which can be messed up easily during assembly of if the chain jumps after start up (due to any problem with the CCT).

The proper operation of the CCT should be verified while rotating the engine (in the normal direction only) by hand before closing the valve's compartment.

Check these DIY threads:

http://www.ninjette.org/forums/showthread.php?t=83284

http://www.ninjette.org/forums/showthread.php?t=9924

http://www.ninjette.org/forums/showthread.php?t=9787

http://www.ninjette.org/forums/showthread.php?t=73240

[gdvd]

Thanks Motofool, I did follow the service manual and I have also seen these DIY threads, except for the excel sheet. Evidently I was not thorough enough.

Could you please expand a little on verifying correct functioning of the CCT? Am I looking to rule out slipping or jumping of the chain when the engine is rotated?

[Motofool]

Yes, the CCT may not work correctly, not keeping the chain from slapping around and even skipping teeth of either sprocket, losing the proper timing.

I am not familiar with the CCT of the new gen, but I have seen some of the pre-gen no working correctly right after a valve adjustment and CCT service of it (lubrication and re-setting).

It is important to rotate the engine by hand only in the normal direction.

[gdvd]

Originally Posted by DaBlue1

Does the sound change any after the oil change? Also run it while off the stand.

I ran the engine after the oil change and there wasn't any perceptible change in the sound. I think I will go back and do the valves over again and hope for the best.

[alex.s]

haven't read the entire thread, watched the video. sounds like either the valves are WAY too loose (sounds like you checked that though) or the timing is off

[gdvd]

Alex, I did set the clearances on the loose side of the range. I think I will reshim the valves so that I am closer to the middle of the range. Waiting for the weekend and hoping it doesn't rain!

[alex.s]

it would have to be very far out of spec for it to make that noise. if it was within spec (top side of spec) it wouldn't be causing that noise. more likely timing is off

[Motofool]

Originally Posted by alex.s

.......more likely timing is off

[gdvd]

Hi guys,

As suggested by Motofool, Alex and DaBlue1, I went ahead and redid the camshaft installation paying extra attention to the timing this time. The engine sounds much better now, thanks a lot for your help gentlemen. The loudest sound is once again that coming from the exhaust and not from the engine! Can you guys please take a look and confirm whether the engine sounds ok now?

Before:

Link to original page on YouTube.
http://www.youtube.com/watch?v=KvVLHhVw8do

After:

Link to original page on YouTube.
http://www.youtube.com/watch?v=Yp-Yc15z3LU

[DaBlue1]

Sounds way better.

[ChaoSS]

Still sounds off to me but it could just be your exhaust, I don't know what that normally sounds like. I still have stock on mine.

[gdvd]

Just got back from a quick jaunt. Everything seems to be fine and the bike seemed to do as good as it has ever been. Thanks everybody for your help.

[Motofool]

You are welcome !



Enjoy your ride