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Cam chain  theory (Read 216 times)
bentwheel
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Cam chain  theory
12/15/06 at 22:36:02
 
So a few guys  have blown a cam chain. In the last year or so there has been increased concern about what to do about the early demise of the Savage cam chain.  Is it true that it should be replaced before only 25,000 miles? Will frequent oil changes stem the premature wear? Should one use better quality oil? Should the engine be babied and not subject to an overrun? Is it just the nature of a single cylinder long stroke engine design that puts unusual stress on the cam chain?
Is there even validity to any of these theories?
Personally I don't think oil has anything to do with it. The cheapest oil available today is vastly superior to what you bought only five years ago, never mind what Suzuki R&D was testing with in the eighties when they designed this engine.
Try this theory on for size. Does Suzuki produce another single cylinder motorcycle  with a similar cam chain tensioner design that also is subject to early cam chain failure? Yes they do. The DRZ400 first produced in 2000 came with an automatic cam chain  tensioner that put too much tension on the chain. Suzuki improved the tensioner several times over the years until the problem was finally solved. Guys who have the early DRZ's have switched to an aftermarket manual tensioner   or adapted the one from a Hayabusa.
So could our automatic tensioner be ratcheting too much tension on our chains leading to premature failure?
By nature, an automatic tensioner is always seeking to unwind its spring and apply tension whenever it detects slackness. Also by nature long stroke engines  develop slackness or whipping of the chain due to its elongated length and longer power stroke. Imagine quickly bringing the Savage engine to red line then backing off abruptly causing the cam chain to slightly whip about in its cavity varying its tension only to be caught by the ratcheting tensioner looking to put a stranglehold on your already too tight chain.
So is the ACCT at fault?
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SavageDude
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Re: Cam chain  theory
Reply #1 - 12/15/06 at 23:13:51
 
I don't know all the mumbo jumbo about cam chain; but if you riding between 45-70 mph and depend on what gear you're on, your rpm compare to auto almost double. Therefore, common sense would tell that the cam chain wear out twice as fast. I don't know the exact rpm/mph between MC and car.  I would give a more exact comparation. We have cam chain/ timing belt tensioner in car too. So it must be the relative RPM/MPH. Just my thought!
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Rockin_John
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Re: Cam chain  theory
Reply #2 - 12/15/06 at 23:45:28
 
Now THAT's and interesting theory! Sounds very plausible too. Can't wait to hear what some gear heads have to say about it.

I've read that Suzuki addressed the known failure mode of the starter flange weakness on later models. What other known failure issues have been fixed? Has there never been an upgrade/change in the cam chain tensioning system?

Ahh... I've found the NHTSA's record of the Suzuki TSB (Technical Service Bulletin) for the DRZ models cam chain tensioner adjustment procedure change. Listed under "2003 Suzuki Motorcycle" in this search engine:

http://www-odi.nhtsa.dot.gov/cars/problems/tsb/tsbsearch.cfm

The plot thickens...

Does the Savage cam chain really fail prematurely?

Do we have a possible beef with Suzuki to issue a TSB on our engine's CCT?
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Re: Cam chain  theory
Reply #3 - 12/16/06 at 00:07:58
 
SavageDude wrote on 12/31/69 at 16:00:12:
I don't know all the mumbo jumbo about cam chain; but if you riding between 45-70 mph and depend on what gear you're on, your rpm compare to auto almost double. Therefore, common sense would tell that the cam chain wear out twice as fast. I don't know the exact rpm/mph between MC and car.  I would give a more exact comparation. We have cam chain/ timing belt tensioner in car too. So it must be the relative RPM/MPH. Just my thought!



I've thought about the revs the thumper turns in exactly the same terms as you... As a comparison/ratio of what my truck turns. It's a 6 cyl. and at 65mph in OD it's only turning a bit over 2K. Without a tach on my Savage, and not doing the math, I'd guesstimate your "double" figure to be pretty close. Even at that rate, what should be an acceptable failure mileage for the cam chain or even the tensioner itself? 15K? 30K? 50K?

Just my opinion, but I'd think an average of 25K-30K miles would be an acceptable preventive maintenance point considering we are discussing an air cooled single cylinder motorcycle. I might do mine earlier (15K?)  because I'm big, and I ride my bike HARD!

We do have to accept that most of the technology in the Savage is at least 20 or more years old. And even at that we don't even have the advantages of some known high mileage motorcycles from the past. No water cooling like the old "water bufflo" not even an oil cooler. Crude fuel and spark delivery systems by comparison to the EFI and EMS on modern day engines.

The Savage is what it is. Love it for what it is, improve it yourself, or...
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Re: Cam chain  theory
Reply #4 - 12/16/06 at 07:00:35
 
My Savage has now  just gone over 24900 miles (40000km) and I don't know if something has been done to the cam chain in its previous life's(2).  How difficult is it to see if it needs replacement or in worst case change the cam chain..

Fat Bastard.
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Re: Cam chain  theory
Reply #5 - 12/16/06 at 07:08:00
 
The problem of the camchain tensioner is that the tensioner guide and the chain wear-out untill the tensioner piston leaves the cilinder and breaks in 2 pieces and the spring falls down in the casing. This can happen anywere between 5 and 15,000 miles, depending of the driving if the rider.
There is Blue Thumper in the German forum who has designed a camchain tensioner which will extend the life of the system to approx. 30,000 miles.
Check out these links:
http://www.ls-650.de/Thumperbike/html/body_steuerkettenspanner.html

The pictures show you a NEW installed chain and guide, a worn to the limit system, jus before falling apart and the consequences after the tensioner has separated.

Link to the new system;
http://www.ls-650.de/Thumperbike/html/body_steuerkettenspanner_tbks3.html
And link to the post in the forum:

http://www.ls-650.de/community/forum/YaBB.pl?num=1165368220/15

with a schematic of the new design, not in detail. Norbert , the inventor, does not want to reveal all the details as he is trying to make a living repairing thumperbikes and protecting his invention from copycats.

BTW I have ordered the new design and will fit it to an engine with 12700 KM. This engine will be modified and installed next year. Will keep you posted.



Greetings
Kropatchek Grin

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Re: Cam chain  theory
Reply #6 - 12/16/06 at 08:22:05
 
Thanx.. I like threads with pictures. ..  I'll take a look at it...


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Re: Cam chain  theory
Reply #7 - 12/16/06 at 10:44:18
 
As with any chain its not the constant speed of a chain thats hard on it....   Its the hard acceleration and decelleration and the snapping of the throttle that stretches the links.....    my 2 cents
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Re: Cam chain  theory
Reply #8 - 12/16/06 at 21:34:28
 
Mine went about 25K miles and I feel it was because I like to run at lower RPM when not under a load so the load on the chain alternatively goes from one side to the other, at speed I would believe the load to be almost contast except when changing throttle positions.  I'd really like a long stroke to bore ratio thumper, they were the ones that had some torque. Max
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Re: Cam chain  theory
Reply #9 - 12/17/06 at 05:35:05
 
Kropatchek wrote on 12/31/69 at 16:00:12:
BTW I have ordered the new design and will fit it to an engine with 12700 KM. This engine will be modified and installed next year. Will keep you posted.


are you saying that mod is available for sale? (sorry, my german sucks) if so, how and where can we get one?
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Kropatchek
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Re: Cam chain  theory
Reply #10 - 12/17/06 at 05:46:11
 
azjay wrote on 12/31/69 at 16:00:12:
are you saying that mod is available for sale? (sorry, my german sucks) if so, how and where can we get one?


Yes, it is.

Link to the prices and ordering:

http://www.ls-650.de/Thumperbike/html/body_preise.html

Offer is till end of year.

You need the top description for 269 Euro.
System, hardware, gasket and fitting instruction.

Press the "vorbestellung" button on the bottom of the page which opens an e-mail with adress. The guy understands English.

Greetz
Kropatchek Grin
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Re: Cam chain  theory
Reply #11 - 12/17/06 at 05:53:59
 
azjay wrote on 12/31/69 at 16:00:12:
are you saying that mod is available for sale? (sorry, my german sucks) if so, how and where can we get one?


here is a babelfish translation. I get the impression that the first item can be ordered on the website and the other items are inhouse repairs.

Open-loop systems clamping system TBKS 3


TbKs 3 completely with all attachments, coupler cover seal and fitting instruction.



269.00 €


TbKs 3 completely installation, oil inclusive with all attachments and filter change.



349.00 €


TbKs 3 inclusive installation and new open-loop system.


 
449.00 €


On all parts of the tension adjuster system I give a warranty of 10 years with appropiate installation.

$1.32 will buy a euro.
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Re: Cam chain  theory
Reply #12 - 12/17/06 at 06:05:56
 
Thanks Brewbrother. Not being very helpfull, am I. Jus t lazy.

Greetz
Kropatchek Grin
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Re: Cam chain  theory
Reply #13 - 12/17/06 at 06:14:10
 
Kropatchek wrote on 12/31/69 at 16:00:12:
Thanks Brewbrother. Not being very helpfull, am I. Jus t lazy.

Greetz
Kropatchek Grin


no worries. Grin I like to help.
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Opportunities multiply as they are seized.
No spacer,60 pilot jet, 155 main jet, plug door, sportster muffler, k&n drop in, iridium plug, brake pedal mod,de-badged, Dunlops, bullet turn signals.
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Re: Cam chain  theory
Reply #14 - 12/17/06 at 06:39:51
 
Still trying to figureout what one gets for $355 price - do you have the kit in hand yet?
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