4TH Generation rattle/knock engine noise. Possibly the starter clutch?

For a while when starting my bike the starter has graunched slighly. Riding it the other day I noticed when idling that there was a rattle/slight knock coming from the front of the engine. It sounds somewhat like a very loose valve. It is intermittent, and once you rev. the bike to 1500 rpm it goes away.

The bike runs fine other than the noise. Since I first heard the noise the starter works flawlessly. I'm wondering if the problem has anything to do with the starter clutch. Any thoughts or opinions would be appreciated.

 

I have a '95 with some noise at idle - but which has definitely had the starter clutch replaced - you're welcome to listen to mine and compare these sounds.
I think this noise on mine is just the camshafts knocking end to end when it's warmed up.

 

Thanks for the offer. The bike has now been making the noise for about 2000 k. It only does it on idle and very intermittently. It is more of a loose rattle coming from the engine. I can be riding on the QEW, pull over for gas and it is rattling. I can gas up, ride a few hundred metres and it's not there. Always goes away above 1500 rpm. When not rattling the engine is super quiet, with the clutch in or out.

For some reason it has never done it when started from cold, or on returning from a ride, idling in my driveway. I have a stethescope, and am just waiting for the opportunity to use it when it happens. I didn't hear any rattle until I changed from regular Castrol 10/40 to Amsoil 10/40 synthetic. The bike seems to make the noise when the oil is hot. I'm holding off changing the oil until I take the side case off and examine the starter clutch.

Other than this problem the bike runs very well, and loves to be revved.

 

Yes, you are describing my bike exactly. Amsoil in mine as well.
How many km on yours, and how many since the oil change?
For the benefit of future readers, we should all remember that the heads are aluminum and the cams steel, so there's going to be quite an increase in camshaft axial clearance when it's hot due to different thermal expansion of the two kinds of metal (aluminum having almost 2x that of steel). And the oil's at its thinnest coming in hot off the highway, so less able to cushion the ends.

You might already have read this: http://vfrworld.com/forums/mechanics-garage/9454-1993-vfr-knock.html

 

Thanks for the info. Makes sense to me. It's too intermittent for me to believe that it is anything serious. It does make me reluctant, until I do for certain find out what the problem is, to take any long rides. I was halfway to North Carolina when it started, just at the start of Skyline Drive. Turned back and ran the bike somewhat hard. Noise didn't get any worse.

I have 43.000 k on the bike. Noise started after I had done about 1000 k after an oil change. In traffic, idling, you are basically not really going to hear it, because of other noises.

 

Same mileage here.
I am more than a bit psycho-moto-somatic, every new noise is surely impending doom, makes me crazy.
Found a cure though, just wear good earplugs all the time, presto, no more problems.

 

Yes DIY valves and carbs this spring, we should do a carbsync-fest in the GTA.

I also have the clutch-out grumble noise, which I can feel through the frame and handlebars, maybe even when rolling in gear. Bothers me enough to consider pulling off side covers or even splitting the cases to search for a bad bearing. These bikes have been around for a long time, is there any real information about this? Technical bulletins?

 

That is absolutely correct. How do I know? Just re-synced my carbs last weekend and WOW!!! no more shitty sounds at idle!!!

 

Thanks for the video, that sure does sound familiar. Will get the carbs right first, should smooth everything out.

 

Can't remember where I got the info. from, but someone stated that if it was the starter clutch causing my problems, lean the bike to the left when idling, and if the noise started then it was probably it. Rode it a few days ago and got home. Upright the rattle/knock was not there. Leaned it to the left a few times and the rattle started every time. Bike is now put away, but come the spring I will be taking the engine case off and checking out the starter clutch. Thanks for all the advice.

 

Omg !!

Who would ride the QEW, 401, 403 or DVP during daylight hours and NOT expect backups ?? Since the GTA is so fantastic an area and with all the population increaSe from wealthy immigrants, it's only getting worse, soon like LA.

 

Took a while but I took the clutch cover off today. The 3 bolts on the clutch starter body are tight and there are no cracks. One thing I did notice was that the started idler gear had some sideways slop on the shaft. I could move it from side to side and could cause a fairly loud noise, which would be amplified if the clutch cover was on. Will continue the work on the starter, and update this thread.

 

UPDATE. I examined the starter clutch body thoroughly and it appears all normal. Since putting everything back together I have done about 200 miles. No rattle/knock from the engine at any time. Previously I used Amsoil synthetic, and have now switched back to Castrol 10w-40 regular oil.

I believe strongly that the rattle/knock was caused by the starter idler gear rattling on the shaft at idle (guess there is a little wear there). I believe that the Amsoil did it's job too well causing less friction between the idler gear and it's shaft, and it rattled at idle.

I can't come up with any other explanation, and am not going to worry further on this problem. At the next oil change I will be going back to Amsoil, and if the rattle/knock starts again , I definately won't be worried. :smile:

 

Thanks for the update Jim.
I've done the valve clearance check and carb sync on my '95, and while it was opened up, an angel drilled the cam-holders for me, to create that oil cushion effect. I haven't taken it out for a good hot weather ride yet, but so far there has been no cam-walk-knocking, I'll let you know how it works out.
Fyi at 48000km, 14 of 16 valves were perfect, but on cylinder #1 one intake valve was -0.002, the other was -0.001, spec is +/-0.001 so I corrected them both.
The thing still grumbles when the clutch is out, I'll see if this weekend's oil change improves that, or if I just need better earplugs.
Hey check out the awesome V4-style carb-sync gage!

 

Impressive gauges, lol. How did the valve adjustment go. Was it easy, a pain in the butt, anything to look out for in particular? Have 45000 k on mine and will be checking the valve clearances just for peace of mind.

 

This is all I can remember right now.
Overall it was a medium level diy job for effort and skill req'd. Did it with a friend over a few winter weekends, between the two of us there were enough brain cells to pull it off but we photographed everything before and during. Best to do it in a garage or shop so that you can take it apart out of the weather and not be under pressure to finish it the same day, plus you may need time to purchase/exchange shims. The main fairing was easier to remove than I expected and the fuel tank should of course be (nearly) emptied before starting (it's awkward enough to handle without the weight of fuel in it). Left the bike in 6th gear to help keep the crank & cams immobile, plus with the timing hole cap off you can use a socket wrench to turn the engine. The rear cylinder bank is easy to get to, but for the front we removed the rad, which made it way easier and reduced the chance of pranging the rad. The cam holder oil hole drilling is worth doing while in there -- if you have the right tools and patience to work with #72 wire drills, which are the diameter of nose hairs -- '
The shims look like watch batteries, the buckets can be pulled with help of a magnet.
Perfect time to service the air filter of course while the tank is off.
Have a good look at the location of carb sync vacuum ports and adjust screws in case you are ever tempted, but diy carb sync only if you have a friend with a motorcycle trailer, lol. I made one little tiny adjustment, and spent the rest of the weekend trying to un-**** it. Worth paying a shop to do it.
I regretted separating the valve cover rubber gaskets from the valve covers. They are re-useable and were glued on quite well and it was alot of work to clean them up, I should have left them alone and just cleaned and resealed to the heads on re installation.
Btw if your clutch slave cylinder is leaking, just replace the whole assembly, its only $55.
Remember to turn the fuel petcock back on before you close it up.

 

Thanks for the info. I happen to have a spare engine I got off ebay. It apparently has about 33000 miles on it. I don't believe the valves have ever been touched as the cam bearing holder bolts look untouched. The cams are pristine and all the valves were within spec when I checked.