SuzukiSavage.com - cam chain drive gear

lordfog

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cam chain drive gear
09/20/12 at 08:23:48

Input please....

I have a 96 that the PO spent $1400 (at a shop) fixing damage from valves meeting piston... He rode it some after then had carb issues... back to shop and decided too much $$... and thats when I purchase not running "as is" <5K on ODO ... Tore into carb and cleaned and massaged a badly buggered up air mixture screw into compliance, she fired right up

did not get to ride because tires etc. And after browsing this site I thought it would be prudent to open her up and check cam chain & tensioner bla... bla...

When I opened the cover I was greeted to small pieces, later determined to be part of the cam chain drive gear upon further inspection that gear is ready to explode :'( The pieces are the flared side to the case. I don't can't find any documentation here about frailty of the cam chain drive gear Shocked

HELP

Browsing around the web I've found numerous images of people holding the same shattered pieces I found in my inspection.

I have a Chinese replacent gear Undecided

to install... Should I seek/use another option?

PS upon opening her up... Other than the gear fragments she looked spotless and in great shape Cool

(That said) I'm going to check the top end ie head bolt torque and missing or misplaced parts per this web sites tips.

I would appreciate any input on any of the above

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28890 L.A. California Gender:	Re: cam chain drive gear Reply #1 - 09/20/12 at 09:01:52 Well foggy, I'm a bit unclear as to what you're explaining... a pic would help.
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Paraquat

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Re: cam chain drive gear
Reply #2 - 09/20/12 at 09:30:55

Only speculation...
This is an interference motor and when the valves were greeted by the piston the whole she-bang came to a grinding halt and the shock must've shattered the gear that drives the cam chain.
That whole "object in motion" law.

So now he has a Chinese gear but he probably feels the same way that I do about junk made in China.

--Steve

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lordfog

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Re: cam chain drive gear
Reply #3 - 09/20/12 at 09:58:03

Question, are the Cam chain drive gears a weak spot on this scoot... As is the stretching cam chain.

The scoot was all together and "ridable" except for carb issues. PO was NOT a wrench and relied on taking to a shop for repairs of any sort... So due to this he could not start it for me...

So when I got her running... I could have gone for a test ride... but was leery of the wrenching PO had paid to have done... thus I pulled off the clutch cover and found the breaking/broken cam chain drive gear... (this blog saved me from going for that ride and potentially lunching the engine again (especially you verslagen1)

DID THE WRENCH PUT IN OLD GEAR WHEN REPLACING CAM CHAIN AND NOT NOTICE STRESS CRACK??? I don't know... for the $1400 PO paid to have dammage repaired I expected all new chain, valves, gear and maybe piston?

Is this as clear as fog?

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lordfog YaBB Newbies Offline onward thru the fog Posts: 10 third coast texas	Re: cam chain drive gear Reply #4 - 09/20/12 at 10:04:43 As far as pic's go I'm a newbie as how to post any thing on the web... I'd like to do simple things like use "QUOTES" on this site...give me some time I'll get her all figured out and I'll make you all sick of me!
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verslagen1

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Re: cam chain drive gear
Reply #5 - 09/20/12 at 10:06:37

lordfog wrote on 09/20/12 at 08:23:48:

When I opened the cover I was greeted to small pieces, later determined to be part of the cam chain drive gear upon further inspection that gear is ready to explode :'( The pieces are the flared side to the case. I don't can't find any documentation here about frailty of the cam chain drive gear Shocked

HELP

Browsing around the web I've found numerous images of people holding the same shattered pieces I found in my inspection.

I have a Chinese replacent gear Undecided

to install... Should I seek/use another option?

The only mention I can recall of a drive gear being busted was with use of an impact wrench to install.

Perferred method is to hand torque everything.

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lordfog YaBB Newbies Offline onward thru the fog Posts: 10 third coast texas	Re: cam chain drive gear Reply #6 - 09/20/12 at 10:11:35 Here is somebody's pic's http://www.mywinterproject.com/projects/savage/savage.htm
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lordfog YaBB Newbies Offline onward thru the fog Posts: 10 third coast texas	Re: cam chain drive gear Reply #7 - 09/20/12 at 10:21:03 Impact wrench.... That explains a lot. THANK YOU!!! So the cases & pic's I've seen posted els-wear do not alarm me any-more. They are either a very small percentage of the gears or are shock damaged from installation technique etc.
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lordfog YaBB Newbies Offline onward thru the fog Posts: 10 third coast texas	Re: cam chain drive gear Reply #8 - 09/20/12 at 10:32:34 That explains why I couldn't find any cam chain drive gear specifik posts. Can I remove the cam chain drive gear assembly with-out removing the clutch?
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28890 L.A. California Gender:	Re: cam chain drive gear Reply #9 - 09/20/12 at 11:32:28 I read thru the link you gave, the guy has it wrong, mere chain loads won't bust that gear. If he had a decompression problem, it's more likely that he would have starter gear problems or just plain won't start. That gear was struck, dropped or over torqued. And no, you gotta remove the clutch basket to get at the primary gear.
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Cavi Mike Serious Thumper Offline Thumper n00b Posts: 1005 Rochester, NY Gender:	Re: cam chain drive gear Reply #10 - 09/20/12 at 16:56:56 He said the timing chain snapped. If that happened, it could take out just about anything spinning.
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verslagen1

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Re: cam chain drive gear
Reply #11 - 09/20/12 at 17:17:14

Cavi Mike wrote on 09/20/12 at 16:56:56:

He said the timing chain snapped. If that happened, it could take out just about anything spinning.

His reasoning for it snapping is what I meant.
Quote:

As for what happened to this poor bike, my suspicions are correct - the compression release has failed. This bike has a cable-driven compression release that is activated by a solenoid upon starting. The cable has a specific free-play tolerance. If the cable stretches too much, the compression release will not activate which may cause undue stress on the valve-train upon starting. Same is true if the solenoid does not actuate. Upon reconstruction, I found that the solenoid is not actuating every time the engine is started.

Still believe the gear snapped 1st.

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Oldfeller--FSO

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Re: cam chain drive gear
Reply #12 - 09/20/12 at 18:44:24

Paraquat wrote on 09/20/12 at 09:30:55:

Only speculation...
This is an interference motor and when the valves were greeted by the piston the whole she-bang came to a grinding halt and the shock must've shattered the gear that drives the cam chain.
That whole "object in motion" law.

So now he has a Chinese gear but he probably feels the same way that I do about junk made in China.

--Steve

I have to disagree with this whole chain of logic. At 8.5 to 1 with no valve clearance cuts needed in the piston top and no list history of valves ever hitting piston tops during cam train break downs I think the mechanic simply wanted $1,400 of the P.O.'s money and by golly he got it.

Did he return all the damaged parts to the P.O.? Just curious .....

+1 to Verslagen, the gear was cracked by your mechanic doing something he shouldn't have. Cam train gear sprockets are HARDENED powdered metal and are "relatively" more brittle, not strong and ductile to take crush type events in stride.

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: cam chain drive gear Reply #13 - 09/20/12 at 20:05:28 Ive put mine on w/ an impact twice. I just happen to have enough sense to not Ram the nut home full throttle & once it is home, just a couple of short blips to torque it..REad the book, note the torque specs, use the tool accordingly,
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Paraquat

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Re: cam chain drive gear
Reply #14 - 09/21/12 at 06:12:27

Oldfeller--FSO wrote on 09/20/12 at 18:44:24:

I have to disagree with this whole chain of logic. At 8.5 to 1 with no valve clearance cuts needed in the piston top and no list history of valves ever hitting piston tops during cam train break downs I think the mechanic simply wanted $1,400 of the P.O.'s money and by golly he got it.

lordfog wrote on 09/20/12 at 08:23:48:

I have a 96 that the PO spent $1400 (at a shop) fixing damage from valves meeting piston...

I only based my assumptions off what he originally posted. Who knows what could happen with enough slack, or if the tensioner let go, or even if it were out of time at 6000 RPM.
Or who knows what really happened.

--Steve

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