Knocking Issue, preceded by a Purring

[F6MoRider]

My 2000 Standard Valk (28600 miles) began a high pitched "purring or whistling" on the trip home from the recent Daytona Biketoberfest.  As we were leaving, I recalled needing gas as we got on the interstate and so we hit the first station.  They were out of premium fuel, and with the Valk trigger wheel, I was worried about having to use 87 octane but didn't have a choice.   We were riding two up and cruising at 80 - 85 and I noticed about 30 miles after getting gas, when I ever so slightly backed off the throttle, so the motor it wasn't pulling, I could hear the purring/whistling.  Now this was not a wind whistle, it was more like a tea kettle or high pitched fog horn type of whistling as it seemed harmonically interrupted.  If I simply released the throttle, the whistle would stop just as if I twisted the throttle but, if I backed off slightly, just enough to let her stop pulling, I'd hear the purring/whistle.  Got home a few of hours later and put her up.  Two days later, I cranked her up after checking her over and she cranks strong as ever.

However, immediately after heading out for a ride and curious if the whistle still existed, I notice an engine knock/rattle that has replaced the whistle.  Now when I back off the throttle, knock, knock, rattle, knock from the front of the engine.  Sounds like dieseling in a car, but the engine is on and running - just not under power.  If I apply power, she responds normally and the knock subsides but only until I release the throttle pressure.

I installed a K&N Air Filter before going to Daytona but made no other modifications but did change the plugs,  and have have the triggger wheel on it since ~1000 miles.   Honda cert mechanic took a look, changed out fuel to premium (no change), and he confirms the knock issue but has no immediate inclination as to the problem.  As this could easily become a boondoggle money pit problem, I thought I'd ask if anyone else in the VRCC has experienced similar and if so, could point me in a specific / right / better direction?

[Michvalk]

This is just thinking out loud, but, is it possible belt or belt tensioner. You did say the noise was coming from the front of the motor. Wouldn't be too big a chore to remove the front cover and check it out. I had a belt tensioner go bad on a 1200 Goldwing and it made a whirring noise before it started rattling. This would be a fairly easy fix if that's it.

[fstsix]

Ditto, on the the post above,I would think you should stop and check AZAP.you dont want to throw a belt Not good, The tensioner  will even make clicking sound if set to tight, see shop Manual for procedure.

[John Schmidt]

+1 on the above suggestions. If the belt tensioner is either loose or  sticking (which would make the belt stretch), it can cause the belt to slap the inside of the cover....hence the knocking. The tensioner will definitely cause a whirring/whistling/sometimes a screeching sound (like a bad bearing) if too tight.

I'd start there, but if that's not it then check all the vacuum connections and carb sync. These flat opposed engines will knock like crazy if the carbs are way out of sync, especially the old 4 cyl. flats.

[F6MoRider]

Okay, so I've replaced both timing belts, checked both tensioners (removed) and they rotate freely and feel like of set of wheel bearings when turned by hand, checked the valve's and only had minor adjustments.   Reassembled the machine and drove it this evening.  She responds and runs strong through 3rd gear but as soon as I start to back off the throttle and shift into fourth, I get the same knocking from the front of the engine.   If does not occur in neutral in the shop.  I can go near red line and no noise.  But as soon as I get her in gear and moving, then back off the throttle, she begins rattling and knocking from up front.

I guess I'll try syncing the carbs next.  Any other ideas out there?  Thanks, in advance and will post after having the time to sync the carbs.

Anyone know a great wing mechanic?

[fstsix]

Anytime on (decel) in gear vibration or noise would point to the U joint might transmit to front of bike may need to check it.

[Old Geezer Richard]

 Hey F6MORIDER , I was wondering about the gas ... I went thru Your great Humid State of Florida in Sept. and noticed eveywhere was that up to 10% Craponol gas ..... we just started two weeks ago here in San Antonio with that Craponol gas , but anyway my good mechanic told me that in areas with a high humidity I need to run a ONE step hotter plug range on my Valk from a nine to a seven ... and hell damn boy my Old Fat Lady sure runs gooder than new because  ......... before I was having plugs foul out on me on a reg basis  I would a thought that running that 6 deg triggerwheel would have kept my plugs half way clean ....  and as a result I am running that 104 octane booster to off set that damn ethanol gas ... I tried my favorite the sea foam but it did not help so I tried the 104 octane booster and my Fat Lady purrrrrs like before ....  ethanol gas

[HayHauler]

Anytime on (decel) in gear vibration or noise would point to the U joint might transmit to front of bike may need to check it.

+1

Sounds like the dreaded U-Joint going, almost gone.
JoeValkIS can verify for us... 

Hay 
Jimmyt

[F6MoRider]

Thanks for the pointers...

Thought about the (ethanol and 87 octane) gas I was forced into using (almost ran out and stopped at jump off station, no premium), especially with a 6 degree trigger wheel.  Changed the gas out but no change and I've been running sea foam off and on for a while.   Can't find non-ethanol fuel here in the hot, humid central Fl area.

I'll try the hotter plugs next.

I already ran it with the timing belt cover removed and still had the noise so it isn't a belt hitting the cover.   

Think I'll pull the timing belt tensioners/adjusters off completely and drive it to see if the noise recurs but they rolled smooth and felt tight.  Then on to the U- joint, will look it up - new to me.

Thanks,

[fstsix]

Had some problems with my almost new lawn tractor stored it for a while and carb clogged ran Seafoam through it, and it also had a loud smell for a while that could be it.  BTW still had to take that dang carb apart Seafoam coud'nt handle it.

[F6MoRider]

Pulled the timing belt cover and removed/reinstalled both tensioners/adjusters (again).  Both rolled and felt new.  Left the cover off and jacked the machine it up on a jack stand to get the rear wheel off the ground.  Tranny in neutral, engine is smooth through the sweet spot to red line and back and the belts rarely vibrate.  Even stopping midway through the range and holding 3200 rpm, smooth and no rumble. 

Back to idle, put it in gear (rear wheel off the ground), ease out on the throttle in 1st and nothing new at first, then a clug, a lug a clug a!!!!!  What the heck is this?!  I could feel it in the left handle grip more than the right and even heard it -- it felt like a bolt ot two in a tire.  Got up under it while in gear but still can't pinpoint the source, felt like the noise was possibly originating at the rear of the shaft but it was elusive.  Couldn't feel it at the u-joint location but felt a small vibration at the rear of the shaft.

I'm now thinking spline or possibly u-joint but almost certain it is shaft/tranny oriented.   I'll pull the bags off and then drop the rear wheel tomorrow to see if there is anything wrong in the rear gears and reassemble.  If there is I can fix whatever that is.  If not, I'm planning to take to the the local dealer unless I can find a certified wing mechanic locally. 

Anyone else experienced a failure in the tranny or shaft on their Valk?  With 28K miles, I find it difficult to think it could be the tranny.  But, changing out that rear tire so often might give gear contamination a better chance?

[fstsix]

Sounds like dry rusted splines or U joint. If you have removed the tire you might just do all it yourself, with some help here you could save a bunch of money them Steelers aint cheap. shop manual is a must follow directions and torque sequence.

[Misfit]

If you had your bike on a jack with it running in gear your swingarm was fully extended and your u joint was trying to rotate at an extreme angle. I'm sure it was making a racket.

[9Ball]

If you had your bike on a jack with it running in gear your swingarm was fully extended and your u joint was trying to rotate at an extreme angle. I'm sure it was making a racket.

good call on that one....not a recommended thing to do.

[fstsix]

Sounds like dry rusted splines or U joint. If you have removed the tire you might just do all it yourself, with some help here you could save a bunch of money them Steelers aint cheap. shop manual is a must follow directions and torque sequence.

If ya got Her up on the lift and back to the original complaint of noise on (Decel) you might just pull the tire and check those splines and U joint.

[F6MoRider]

Final drive flange / rear wheel splines and bearings all look good, all splines on bottom of the shaft at the rear gear case also look great.  Drive shaft also looks good on both ends, need to get the U joint out but need a special tool (wrench) to get the L swing arm pivot lock nut off so I can remove the swing arm and check the U-joint.  Tomorrow I'll head to the dealer to see if they have the special tool 07908-4690003.   Anyone know the dimensions of the pivot bolt - I don't have one that large and the service manual doesn't indicate so I need to pick up a hex wrench to fit it when I get the pivot lock nut tool.

[Larry]

You don't have too take the swingarm off to do u joints. See this link:
http://www.rattlebars.com/mtz/ujoint.html

[franco6]

 

Final drive flange / rear wheel splines and bearings all look good, all splines on bottom of the shaft at the rear gear case also look great.  Drive shaft also looks good on both ends, need to get the U joint out but need a special tool (wrench) to get the L swing arm pivot lock nut off so I can remove the swing arm and check the U-joint.  Tomorrow I'll head to the dealer to see if they have the special tool 07908-4690003.   Anyone know the dimensions of the pivot bolt - I don't have one that large and the service manual doesn't indicate so I need to pick up a hex wrench to fit it when I get the pivot lock nut tool.

well i checked; both the honda and the clymer manuals require the swing arm off
it pays to go to inzane. thanks Daniel.

[Larry]

There is a little trick to get the boot back on, use a bit of alcohol on the inside of the rubber to make it "slippery" when popping the lips of the boot on. Folding the edge of the boot back like a rolled up sock so you can pop it on is supposed to work too, although I've not tried that way. The alcohol trick worked well for me though.

[Dodis]

+1 on folding back the lip of the boot, just did that a few weeks ago checking my u-joint. With a little wiggling, I was able to remove the u-joint upwards (behind the starter), so no need to remove the swingarm.

Mike "Dodis"

[F6MoRider]

Thanks for the feedback, support and directions.

Appreciate the comments re: the tranny noise heard while on the lift being caused by the lift method but I did have the swing arm supported from underneath near the center with a small 5ton floor jack and a piece of 2x4 so the wheel was not at full shock extension or max bend of the swing arm--thought I could leave that part out of the explanation.    

The noise I heard should not have been there so that's what confirmed the location of the fault being somewhere in the tranny.  When I add to it that I could not recreate it unless I was moving, it had to be in the rear or the tranny.  But I swear the original sound was knocking from the lower front of the engine at the timing belts.  Never even considered that the Valk would have a u-joint.  Go-figure, 1st shaft bike I've ever had.

So, following Chet's directions (thanks Larry!), I was easily able to remove both the boot and the u-joint without removing the swing arm.  Found the U-joint was failed and was probably a few hundred revolutions from a sympathetic destructive failure.  The bearings had failed on two adjacent ends of the four which allowed the upper and lower spline sleeves to make contact.  Looks like they had been touching for a little while, at least 20 miles I know of, as the ends show signs of wear when they were touching.

The assumption I must make is that the whirring sound I heard as I gently ceased acceleration and just before deceleration began, that little "float interval" as the weight of the bike feels neutral, was the u-joint actually failing while in use.  It whirred as the torque released its binding hold allowing the u-joint to spin freely with the pin flanges open and exposed.  On decel, force was applied from the opposite direction and the resulting torque bind would lock the parts together and quiet the whir. 

The clunking sound I heard the day after the whirring was the actual upper and lower spline sleeve arms of the u-joint turning aand rubbing against each other which could only occur after the two u-joint bearings finished falling apart, e.g. after they cooled.

All that's left now is to find a replacement u-joint, can't replace the bearings like a truck, and both local dealers have to order the part so, as I can order just as easily, I think I'll look it up and order a few replacement chromed bolts as well. 

Funny, u-joint failure at less than 30k miles.  Maybe the 2-up & high speed (avg 80 mph) riding takes an adverse toll on the u-joints  I did notice signs of moisture on the bottom face of final gear where it connects to the bottom of the shaft tube.  Probably the result of condensation collecting in the shaft tube and coming to rest at the bottom of the shaft against the plate.

Again, thanks for the assistance!  Feels good to know I'm not alone as I'm trying to figure out the lady.   

Wish me luck putting her back together in a week or two when the parts I plan to order should arrive.
 
Closure!  Yeah!!!

[fstsix]

Thanks for the update, you know some of these bikes go 100.000+ k no problems some do this.I only have 30k on my Valk 2 up 90% of the time, and i am hard on this thing when solo W/ Dark side, did put new clutch in but not because wear but Blower, makes me wonder Well good you are in safe place not on the road to do this repair good luck.