Rattle/knock in engine. Possible starter clutch problem?

[JIMLARCH]

On Wednesday I rode my bike 500 miles down to Front Royal, Virginia, to ride the length of Skyline Drive and the Blue Ridge Parkway. The bike appeared to be running fine until I got to Front Royal yesterday morning. As I pulled off the interstate and stopped at the first light, my bike was idling and I heard this rattle/knock at idle (90% rattle with a little knock thrown in).

I pulled over to listen. It is difficult to describe engine sounds, but here goes. Above 1500 rpm the noise goes away, and when revved it sounds fine. At idle, intermittently there is a rattle/knock similar to a very loose valve, or a small end bearing failure. It is as I say intermittent so I really don't see that it can be a valve or bearing.

I had to decide whether to continue my trip and put on another 2000 miles or ride the 500 miles home. I rode home. Thinking pretty much that the problem wasn't terminal I decided to ride the bike normally. I wasn't redlining it but I sure wasn't sparing the horses. After about 60 miles I pulled into a truck stop to listen. The rattle was still there now and then, but the engine sounded fine.

I got home alright and the rattle is there but not any worse.

I'm wondering if the rattle has anything to do with the starter clutch. The day I left basically everytime I started the bike the starter caught, but there was slight graunching. Funny thing is as soon as I noticed the rattle, the 30 times I've started it since, the starter has worked normally without the graunch.

Any thoughts or knowledge on the problem would be appreciated.

[steve93]

Coincidentally I have almost the same issue. I will be watching for replies as I can't figure mine out either (sorry!) My '93 first made the rattle/knock a couple months ago when I got the bike out for the season. Does seem to go away whe the bike's warm, and only does it at idle. Hasn't gotten any worse in the 1500km since, although it might have been a little noisier this morning. Makes the same sound whether the clutch is engaged or not.

Sorry about your trip! I haven't done the Blue Ridge in years and I am looking forward to going sometime too. Front Royal is a bit of a hike to have to turn around and come home :(

[JIMLARCH]

I sure wasn't happy to basically get to the starting point, and then find I couldn't continue. I'd pretty much ridden the main highways (with the usual police presence) so that I could get to Front Royal fairly quickly, and then have some fun in the twisties.

On the way back I took the twisties and had a pretty good time, nice roads and scenery. It's the first time since buying the bike last year that I have been able to use it as it was intended, and found it's a pretty good ride. Did the front fork seal and fluid change, and it made the bike handle much better. Even with the stock shock, it handled the corners at speed pretty well through the Allegheny Mts. Slightly imprecise though, so a new decent shock would make a great difference. Mind you I had full givi luggage and a tail pack, so it was loaded somewhat.

Seeing as you live in Hamilton you probably do the Ice House on a regular basis. I'll probably be there on Sunday around 11. If you come I'm the guy with the red VFR with the blue tail pack. Provided my VFR doesn't blow up, that is.

[tinkerinWstuff]

my money says it's most likely as simple as your engine not running balanced. 3rd gen will knock and sound like a rattle bucket of bolts if the carbs are not sync'd just right or if things get unbalanced in the idle circuit of the carbs.

for example, if the bike is sitting there idling and is starting to run out of gas (fuel in the float bowls start to get low and uneven from carb to carb) the thing will start to knock like there's a rod going out.

Try a carb sync before getting to concerned or elbows deep in wrenches.

[JIMLARCH]

my money says it's most likely as simple as your engine not running balanced. 3rd gen will knock and sound like a rattle bucket of bolts if the carbs are not sync'd just right or if things get unbalanced in the idle circuit of the carbs.

for example, if the bike is sitting there idling and is starting to run out of gas (fuel in the float bowls start to get low and uneven from carb to carb) the thing will start to knock like there's a rod going out.

Try a carb sync before getting to concerned or elbows deep in wrenches.

Thanks. I don't think it is the carbs out of balance, as it idles pretty well. I'm familiar with the sounds of a bike running out of gas, but it is not that type of rattle/knock, much quieter, and is heard only over the sound of the engine when idling. Guess it only does it when hot. I have a stethescope and next time I get back from a ride I'll try and find the noise. Started the bike today and used the scope. Engine noise was normal, no rattles.

[tinkerinWstuff]

my money says it's most likely as simple as your engine not running balanced. 3rd gen will knock and sound like a rattle bucket of bolts if the carbs are not sync'd just right or if things get unbalanced in the idle circuit of the carbs.

for example, if the bike is sitting there idling and is starting to run out of gas (fuel in the float bowls start to get low and uneven from carb to carb) the thing will start to knock like there's a rod going out.

Try a carb sync before getting to concerned or elbows deep in wrenches.

Thanks. I don't think it is the carbs out of balance, as it idles pretty well. I'm familiar with the sounds of a bike running out of gas, but it is not that type of rattle/knock, much quieter, and is heard only over the sound of the engine when idling. Guess it only does it when hot. I have a stethescope and next time I get back from a ride I'll try and find the noise. Started the bike today and used the scope. Engine noise was normal, no rattles.

idles well but has a knock - fix was carb sync

[JIMLARCH]

my money says it's most likely as simple as your engine not running balanced. 3rd gen will knock and sound like a rattle bucket of bolts if the carbs are not sync'd just right or if things get unbalanced in the idle circuit of the carbs.

for example, if the bike is sitting there idling and is starting to run out of gas (fuel in the float bowls start to get low and uneven from carb to carb) the thing will start to knock like there's a rod going out.

Try a carb sync before getting to concerned or elbows deep in wrenches.

Thanks. I don't think it is the carbs out of balance, as it idles pretty well. I'm familiar with the sounds of a bike running out of gas, but it is not that type of rattle/knock, much quieter, and is heard only over the sound of the engine when idling. Guess it only does it when hot. I have a stethescope and next time I get back from a ride I'll try and find the noise. Started the bike today and used the scope. Engine noise was normal, no rattles.

idles well but has a knock - fix was carb sync

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If my bike had sounded as bad as that, I wouldn't have ridden it back from Front Royal. My rattle/knock goes away above 1500 rpm. I still think it unlikely that it is carb. sync, but on the other hand, worth a try, seeing as it is rpm related.

[tinkerinWstuff]

Like I said in another similar thread; it's not that the problem "can't be" or "isn't" something else. But working on planes and industrial machinery has pounded into me that you start with basics. Doesn't matter how monotonous it is, you don't skip ahead until you've eliminated the easy and basic stuff first.

Good luck. I'll be interested to hear what you find and how it works out in the end.

[JIMLARCH]

Like I said in another similar thread; it's not that the problem "can't be" or "isn't" something else. But working on planes and industrial machinery has pounded into me that you start with basics. Doesn't matter how monotonous it is, you don't skip ahead until you've eliminated the easy and basic stuff first.

Good luck. I'll be interested to hear what you find and how it works out in the end.

I'll definately post the problem when I find it. I'm surprised more people haven't jumped in to give me advice. Seems these engines must be so bulletproof that my complaint is unusual.

[Guest]

Gear driven cams or chain?

J

[JIMLARCH]

Gear driven cams or chain?

J

Gear driven cams. If there had been a cam chain, I would have suspected a loose tensioner.

[auggius]

I don't know if this is what you are hearing but check out this thread http://www.vfrdiscussion.com/forum/index.php/topic/59540-96-vfr750-engine-tick/, especially post #11. Might help.

[JIMLARCH]

I don't know if this is what you are hearing but check out this thread http://www.vfrdiscus...50-engine-tick/, especially post #11. Might help.

Thanks. The info. was useful. Took the bike out today. Quiet on start up, then after a few miles at idle is rattled at low rpm. Did about 100 miles, cames home. Couldn't hear rattle at all, but starter has started graunching slightly. One thread I read the poster stated that the starter clutch bolts were loose on his bike. I don't know much about starter clutches, but it seems to me that if it is slightly loose it could rattle at idle. Once the revs build up centrifugal force causes it to spin, hence no rattle. Will take the cover off and take a look, if nothing else, I may find the cause of the graunching.

[JIMLARCH]

I'm still waiting on a clutch cover gasket before I take the cover off. While waiting I started the bike in my driveway. I have a stethescope and was going to ascertain where the noise was coming from. Ran the bike for a good ten minutes. Not a rattle to be found. Switched if off a few times and restarted, still no rattle. All I hear is a whirring from the valve gear. Clutch and clutch area sound quiet.

I have ridden 2000 miles since I owned this bike. During that time I used 10/40 Castrol bike oil. Day before my trip I put in Amsoil 10/40. Took it out for a brief ride just to make sure was running right. My notchy tranny did not feel any smoother. Engine sounded the same.

One thing I immediately noticed when checking the oil on this bike after buying it, is how the dipstick is not vertical but somewhat diagonal, I followed the instructions on how to read the dipstick and filled what I thought was too the top level on the dipstick. On my oil change I put in what I thought was 3 litres of oil, but when I read the jug I see that it contains only 3.78 litres, so in fact I only put in around 2.8 litres. I topped up the bike with about 0.4 of a litre and it now reads slightly above the top line on the dipstick.

I've heard bike engines which are low on oil at idle. Some of them like my CB900F tend to rattle a little until the revs are up. When I first heard the rattle on my VFR I checked the oil, and thought it was fine, but now I am wondering.

Will have to take the VFR out for a spin and get it hot, to see if low oil was the actual problem for my rattle. It will be a relieft if it is, but somewhat embarassing for a guy with my bike experience to make such a silly mistake.

[GadiantonRob]

I have just noticed that my '95 has started this tick at idle. Does it clutch in/out--only when warm--only at idle or slightly above it. Performes well anyother time, and the noise is intermittent. Some stoplights I hear it--others I don't. I would really like to see what the issue is (whether it be cams/valves/starter clutch bolts). Please keep us updated, or those who know exactly what it is please chime in.

[mascar]

My 95 has had the very same noise for years. I think its wear in the clutch basket but I can't prove it. 80,000 klm (50k)

I run the snot out of it and ignore the part time noise, no effect on performance.

Hope you figure it out because I gave up a while back.

[JIMLARCH]

This will be my final post in regards to this matter. I took my bike out for a long ride. I stopped repeatedly to listen to the engine at idle. The engine sounded fine, no rattle/knock whatever.

As I have previously stated prior to my trip I used regular 10/40 Castrol mc oil for my oil changes, and kept the oil level at what I thought was the upper mark on the dipstick. For the trip I used 10/40 Amsoil full synthetic mc oil. I also used what I thought was the upper level on the dipstick, but I believe now that I was at least 0.4 of a litre short of the correct amount. I can find no reason but the oil level as to why this should be the case, as the problem went away when I topped up the extra 0.4 of a litre. The reading is now slightly above the upper level mark.

I guess it all comes down to "for want of a nail" a bike trip was ruined.

[cbkenison]

I don't know if this is what you are hearing but check out this thread http://www.vfrdiscus...50-engine-tick/, especially post #11. Might help.

Here's more information on the camshaft hole drilling thingy: (courtesy of http://www.vf750fd.com/vf750f/VFR_road_test.html)

[cbkenison]

More:

[JIMLARCH]

To continue my saga. The noise has come back. It's still intermittent, but appears to start after it has been run fairly hard and the oil and the the engine is hot. It's definately more a rattle than a tick.

I'm waiting until I can get it to make the noise in my driveway. Hopefully my stethescope can tell me where it is coming from. I'm starting to lean towards cam float, as per. the old bulletin. It started after I went from 10/40 Castrol mc oil to Amsoil 10/40 synthetic. I've read different threads where people have had starter clutch problems after using synthetic, which went away when returning to conventional mc oil. If the bike doesn't cooperate and make the noise in my driveway, I'll switch back to castrol and see what happens.

The bike still runs very well, so I am not too concerned about the problem.

[vfr2b]

Hi there.

I am experiencing same symptoms though with a little funny feature. The rattle/tick is sensitive to bikes position as well. On side stand it is loud. When i keep the bike straight (vertical) it vanishes and comes back even louder when i tilt the bike on the right side.... so it definitely comes from the starter clutch. I use the oldtimers stethoscope. A big screwdriver pressed with the handle to my ear and the tip to suspected noise source.

Adjust the mass of the screwdriver to sound's frequency. :-) Try it!

[JIMLARCH]

I have a regular stethoscope, but the noise so far has never occurred when I am home, which is why I still have not removed my clutch cover to check the starter clutch. Mind you I have never tried leaning the bike left or right but will try it and see what happens.

You didn't say whether you heard the noise through the screw driver method.

[JIMLARCH]

I have finally gotten around to taking the clutch cover off to check the starter clutch. I found that the bolts (3 bolts) on the starter clutch assembly are tight. There are no cracks in the starter clutch body.

One thing I did notice was that the starter motor idler gear has some sideways slop on it's shaft. The starter motor idler gear is held in place by the outer cover. I'm wondering how much pressure is put on the idler gear when the cover is on, and whether it prevents sideways slop. When holding the idler gear and moving it sideways quickly, it made quite a loud noise, which would have been amplified if the side cover was on.

A number of people, have not had the rattle problem when regular dino 10/40 was used, but noticed the rattle when synthetic is used. I never noticed this rattle prior to using synthetic oil.

A few people have mentioned that the noise at idle was not present, when the bike was upright, but started when tilted to the left or right/ I tried this on my last ride last year in my driveway. There was no rattle. Then I leaned the bike heavilly to the left and the rattle started. It went away when the bike was straightened.

I will keep this thread updated.

[JIMLARCH]

I took the starter clutch body apart and examined it. No cracks in the body and other parts seem in working order. I put everything back and started the bike. It runs fine. It seems as if all my work was for nothing, but at least I know there is nothing wrong with the starter clutch.

I have gone back to Castrol 10-40. I am of the mind that the starter idler gear was the culprit due to the Amsoil synthetic being a very slippery oil, and the starter idler was rattling on idle. Either that or it is the common problem with the 94-97 VFR750, that the cams have a certain amount of end float when the oil is hot, and that causes the rattle.

Whatever it is I am just going to ignore the rattle, should it occur again, and just ride the bike.

[Guest]

My 93 rattles when it is cold if you pull the clutch in it goes away it has been that way for a few years but only if it is cold and it goes away when you disengauge the clutch.