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1500 Timing belt whirring

4K views 16 replies 10 participants last post by  TourNut 
#1 ·
Last May I replaced my '91 1500 timing belts at 30K miles because of being 21 years old. I set slack /tension to what was specified in GL1500 workshop manual then which was identical to your Timing belt tutorial on this site today. Since I changed them , I hear the belts whirring louder than the originals , especially in 2000 rpm range before I engage clutch and moving. I did notice new belts were stiffer than originals after I got originals off the engine. I bought the new belts at Honda MC Dealer. The bike runs otherwise perfect as it always has.
I did measure the old belts : had about 20 mm slack in them before I loosened up tensioner pulleys to get them off. Is there some sort of a dry lubricant you could/should put on timing belts to quiet them and thus I would think make them last longer if it is some kind of a wear problem between belt and toothed pulleys ?
 
#2 ·
Just to be safe you may want to double check your work and make sure the belts aren't too tight or you don't have a bent pulley or excessive runout on the cams. You could observe them working with the belt covers off. However, I've heard (what I would describe) as the same thing on assorted different 1500's, some worse than others. Back in the day, I tried to fix one (under warranty) on a customer that complained loudly about it. I replaced both belts and all pulleys to no avail. The noise was still there 70K later, and the bike ran strong as new. The owner got used to it and never complained about it again.
 
#3 ·
Did you check the tensioners for wear when you installed the new belts? A new belt will of course be stiffer than an old used one. It's also important to double check the part number of the new belts you bought. It's possible that the dealer may have sold you the wrong ones.
You could use some belt dressing sold in a spray can in most auto parts stores, but to me that is just a temp fix and just masks the problem. You need to go back in and recheck the belt free play, and tensioners which should spin without drag or noise, and have no wobble or play in any direction. It's important to recheck the belt tension after you have rotated the engine a few times. This is critical stuff, so triple check evrything.
 
#4 ·
Welcome to the forum TourNut

No lube on the belts.

Tension to be set by allowing the spring to set the tension.

How many miles since you put the belts on?

Did you inspect the bearings in the tensioners?
They have been know to go bad. I think there is a tutorial on changing those bearings in the reference and faqs section forum.
 
#5 ·
There are two things that cause noise from the timing belts. The most common one is the belts being a wee bit snug and the other is a bad idler roller bearing. Whenever I check idlers I remove them and spin them in my hand to feel and listen for noise. A good idler makes none. There will be a little bit of play when you rock the idler against its axis. The new ones have it too. There should only a very little play. One thing that causes the belts to be too snug is that they are normally set with the engine cold. When the engine heats up the case and heads expand tightening the belts a bit. Pretty typical of an aluminum engine, aluminum expands with heat more than steeo or iron. The solution is to slack them off just a bit.
 
#7 ·
I have seen belts installed by other people that were WAY too tight, and in many cases, one was correct and the other WAY too loose. The latter is due to incorrect information that was in some aftermarket shop manuals. I worked on a friends 1500 that had one that was loose. The belt was rubbing on the engine case and making noise.

A good way to tell if they are set correctly is (with the bike NOT running) to twist the belt on the opposite side of the tensioner when there is tension on that side of the belt. You should be able to twist it with your fingers to about 90*. If you can't get to 90 than its too tight, if more than 90 its too loose.


Bill
 
#15 ·
...A good way to tell if they are set correctly is (with the bike NOT running) to twist the belt on the opposite side of the tensioner when there is tension on that side of the belt. You should be able to twist it with your fingers to about 90*. If you can't get to 90 than its too tight, if more than 90 its too loose...
+1... Using this method, the belt feels way too lose, yet it actually works perfect. I had to do mine 3x the first time, before the local shop suggested this method... Before that, I tried setting them per the manual, yet they kept coming out too tight and singing at 3k rpm.
 
#8 ·
I replaced them at 30K , I checked the tensioners for smoothness, I rechecked slack tension per the manual after everything was tightened. I noticed the louder whirring immediately; - it hasn't changed in the 3.5 K miles since. Since it was an immediate noise change , I assumed the stiffness was the cause and it would get less stiff soon after but noise hasn't increased , or decreased either yet. Maybe they stay stiff for years. I wonder if the belt dressing would help and stay there helping -long term.
 
#10 ·
I've set belt tension to manual specs on a couple of bikes that sang afterward. It just required a very slight loosening of the belt to stop the noise. With a new belt sometimes the engine is quiet until it gets warmed up then you can hear the belt begin it's sound. That's a good indication it's just a bit tight because when the engine is cold the belt will be a bit slack compared to when the engine is at operating temp. I don't believe the noise comes from the cam bearings but more likely just the belt vibrating under tension. With the proper tension you should be able to press about 1/4-3/8" of slack on the long or pulling side of the belt.
 
#13 ·
That deflection measurement alone could actually reflect a pretty large range of actual belt tension depending on how much belt slack is left on the bottem. With the engine turned in such a way that all the slack is on the top, I'd say those measurements are plenty tight. I usually go for more like .5 inches.

I do agree that belts tighten significantly as the engine gets hot. You can pretty easily observe this leaving the covers off and running the bike until hot...comparing belt tension before and after.
 
#11 ·
I just replaced the idler pulleys on my `98 S.E., and I think they could have easily gone further. They are at 147,000 miles now. Replaced the belts at 100,000. Replace them again at 200.000. If I haven't gotten the 1800 itch by then anyway. (Idler pulleys were $100.00 each.)
gumbyred
 
#12 ·
I changed the belts on my 1500 with 100,000 thousand miles. The idlers were in good shape. I'd ordered new ones before I started the job ($60 ea. then) so I put them in but if I'd had a chance to compare the new and old ones first I'd have seen there was no difference I could see or feel in the bearings of any of them. I think they could easily have gone 200,000 miles.
 
#16 ·
The main thing about belt tension is that it's snug enough not to flap or whip and loose enough not to sing.
 
#17 ·
I 'm thinking that this next spring when it warms up in my garage again, I have 2 tires to replace anyway, I will get into the timing belt deal again ; inspect everything again & loosen up the belts a tad to not make noise and ease up on the bearings. After all , the originals had 19-20mm slack in them and the bike was running fine. I will set them to something in the middle of that and the much less factory spec. tension. In a few years I will then re-inspect . I won't wait to do it after 21 years the next time !
 
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