ST1100 timing belt - any way to tell if it has been replaced?

Larry Fine

Larry Fine

Joined
Aug 21, 2018
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Location
Richmond, VA
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'01 & '96 11, '07 13
Can you tell by looking whether the timing belt is original or has been replaced with minimal parts removing?

My '96 with just over 100K miles. Previous owner has no idea either way.

Update: Remember my $800 ST1100 purchase? | ST1100 Related

Hey, gang. The original for-sale thread was automatically deleted, so I decided to post a new thread. Remember the '96 ST1100 I bought from Lance (@mansell2)? I trailered it home, took it off the trailer with my son's help, took it for a one-mile ride, then parked and covered it for a few...
www.st-owners.com www.st-owners.com
 
I had to grind some of the plastic from the timing belt cover to get it back together, didnot want to remove the clutch .Should be able to see that with only taking off the lower tupperware
 
Let's presume I can expose the belt somewhere. How do I tell if it's the original?

Added: If it says Gates, it's obviously a replacement, but if it says Honda, I still don't know,
 
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If that belt has over 100K miles, you can tell by just looking. There is not much to disassemble - engine service cover (2 hex bolts), than 2 another hex bolts on front head cover (plastic silver part) and than 3 screws (10mm head I think) on timing cover. Then you can see the belt. Right side of the bike is better, that 3 bolts are easier to get to (mainly rear one).

Ideal is to put also lower cover of bike (10 hex bolts) and 2 10mm bolts on plastic cover left of clutch housing (crankshaft cover) and you can turn your engine (right direction!) and look how belt looks - cracks/oil/etc + you can find manufacturer marking on the belt for example.

These are first and really easy steps to check the belt. If you find something disturbing or you are not sure, then you have to put engine cooler radiator out + right exhaust pipe + clutch housing and get directly to timing belt from front of the bike...
 
dwalby said:
from forum experience even a belt with 100k miles is going to look almost new anyway, so I don't know that you'll be able to conclude anything.
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That's really the basis of my question. How do I tell?

I'm hoping for a reply from Ashley. Thank you, UP!
 
Larry, I have the same kind of dilemna : not much mileage but 23 years old. Should I change it ?
I think we should look at the question differently.
What do I prefer : changing the timing belt soon or the whole engine later ?

Plus... don't forget... if the timing belt ever blows while you're riding at a good speed in traffic... followed by a big semi-truck... who knows what can happend.

Your life is precious, man. Precious and fragile.

So, Yes. Change it !
 
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Larry Fine said:
That's really the basis of my question. How do I tell?
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If its a Honda belt, here's a clue. The top one is mine after close to 100k miles, the bottom one is representative of a new Honda timing belt that's currently for sale on Amazon. I couldn't find a picture of the ST belt, so that's all I could find. I'm a bit surprised that the printing appears to be exactly the same 25 years later. So the question is, does the printing wear off gradually with age, or wear off faster when its new, and then stabilizes, nobody knows.

IMG_5505_opt.jpg

Capture.JPG
 
I would ask it this way of Larry: How long have you had your ST and since you purchased it and how many miles have you put on it (EDIT: I didn’t read the original entry carefully and thought this was for the 01 bike)? If it was a lower mileage bike when you took ownership, then it’s less likely the belt was changed- that and if you put more substantial mileage on it (and you‘re ST is up there in mileage, like 70-80+K), then consider changing it. It is some disassembly of course and some time invested (and in parts, maybe ~ $200 or so, assuming you’re doing the under the carb hoses, the main hoses to the radiator, and the metal elbows/ O rings, as well as the belt and I used a Gates belt- I’d personally get new bolts for those elbows as well since they likely will have some corrosion to them). I’ve done the belts on both STs I own- not hard to do (and I had never done one before the ST)- a visual look doesn’t say much (mine looked as new but were changed early in their lifespan (mostly changed due to age).

I was able to look under the timing belt cover originally, got paranoid, then changed the belts out anyway. There’s loads of information how to do this job on ST-Owners.com as well as ST-riders.net, and I studied quite a bit before doing the work- each ST was apart for ~ 1 week while I did the work (was FT on the job then)- when doing disassembly, label all fasteners as it makes reassembly very easy (I used plastic ziploc bags and labeled everything with masking tape and marker. EDIT: Not sure if your have done this work on the 2001.

Here’s the whole procedure: http://www.st-riders.net/index.php?topic=3523.0
 
OK Larry.... here is another one for you.

If your looking for a proof, or a clue, that it has never been done, here is one that might indicate that it is still the original timing belt.

When I flushed my coolant, I saw a date code on the coolant hose, from the manufacturing company : Yamashita, 99 11, just one month before they build my bike, in december 1999.

20200708_131327.jpg

Yes, that hose, at the left hand base of the radiator.
20200708_132038.jpg

What does it have to do whit the timing belt, you would ask...

Well, here is my thinking...

A previous owner who was taking good care of his bike, enough to replace the timing belt before it was due, at 100 K miles, and having to remove the radiator to do that, flush the coolant and all... but he would had keep the original, 20 years old, coolant hose ?
It doesn't make sense.

So, no date code on your radiator hose, prooves nothing. The date markings went away pretty fast when I started to twist and squeeze that hose with my hands.

But if you find the original date code, meaning despite the age, no previous owners never care to replace the coolant hose, then, you can also assume they never cared either to replace the timing belt.

I still think it's best to assume it has never been changed and it have to be done.

Can't be wrong whit that.
 
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I recently changed the timing belt on my 2002 ST1100 ABSII. It had 115k kms or approximately 75k miles. It hardly shows any signs of wear, the teeth on the belt are all intact and still retains its shape. You can still see the markings on the belt. It probably would last me another 10 years.
 

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I'm kind of conservative about old machinery....meaning I prefer to conserve anything I'm likely to put time and money into. Bought our 1991 as a retirement present to myself in 2014. Our previous bikes had been GL1000's but I damaged our new looking one when the left side belt broke damaging the intake valves and guides. So, one of my tasks during my refurb was to replace the belt, inspect the pulleys movement while the belt was removed then to adjust the valves. Relatively cheap peace of mind.

Didn't see anyone mention it but there are some good Youtube videos of the process. One shows the job performed with an engine removed and on the workbench. That made the job itself quite clear. Others show the job performed with the plasticwork and radiator removed...more like reality.
 
What is likely to cause the belt to fail? Age? Or component failure, as in the tension pulleys or water pump? From my reading on various forums, the majority of timing belt failures (rare) tends to be a seizure of a mechanical component that leads to the belt being compromised. That’s what I would be more concerned with.
 
As per Kiltman's post #19 I don't recall ever reading about a belt breaking or wearing to the extent the engine was trashed. Prime concern would be seized water pumps bearings at some point in the future. So, more complete issue is when changing the belt, a relatively low cost repair when doing it yourself, is should you also change out an expensive and hard to source water pump if if is not leaking. How many non leaking water pumps have seized, resulting in a broken belt, mistiming and a trashed engine? Over 20 years on various ST forums I think I've read about 2, maybe 3 incidents, so I'd be inclined to change the belt, but not the pump.
 
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