155z Cam Chain stretch

[DHZ_XR8cing]

good afternoon.
I cant get my cam chain to tighten up. The adjuster is working fine and the guides appear to be in good working order but still no luck. Is there a chance it could of stretched a fair bit?
The engine has 32 hours on it

 

[clunky64]

when i dropped a bolt out of my cam gear it jammed and broke the timing chain,when trying too source a new chain most the shops i called said dont carry them cause we rarely replace them so being stretched may seem unlikely,but stranger things have happened

 

[The_GDFP]

Not uncommon for them to stretch. Your tensioner won't take all the slack out? You can convert your tensioner to manual. You can check and see if the cam dot lines up when flywheel's at TDC. They're loose new, and stretch a lot. A new chain is about $45 shipped. Long-rod and/or strokers that use a base spacer, can run a KLX OE chain.

 

[DHZ_XR8cing]

The cam retainer plate had a carry on and bent and let the cam float which caused the cam chain to jump off the bottom sprocket. It bent a valve which I have replaced and when I put it back together the cam chain adjuster does not take the slack up in the chain at all.
When I look down at the tensioner it is about 10 mm away from the guide. I am a bit baffled at this stage.

 

[clunky64]

just thinking does it have an idler sprocket in the middle of the chain and if so is the bolt in it?

 

[DHZ_XR8cing]

I cant see 1. I dont think there is meant to be. Looking at how slack the chain is there is a major drama some where

 

[sean01]

nah no idler sprocket in these engines..

going by what you said happened originally id be replacing the cam chain.. chances are if you took the slack up somehow that it would soon fail and you would once again need to replace valves..

 

[DHZ_XR8cing]

Thanks for you input Sean. Do you think that the problem with it that its stretched? Where is the best place to get a new one?

 

[sean01]

you might need to re-word your above post a bit...

Do you think that the problem with it that its stretched?

(i had a big weekend and may be just stupid lol)

but as for the new chain,, umm Terry could probly help you out ( YX 160cc Timing Chain )or just try all the site sponsors first then move onto tbolt as im pretty sure i seen them there.. other than that a good second hand one may be suit ya...

DHZ would more than likely have a s/h one..

also i am assuming you are talking about a zonger/yx klx style engine as you mentioned the cam retaining plate..

but i dont think cam float in the head would cause the chain to fall off.. id be more thinking something obstructed the chain's path and forced it off..

it happened to me once and it was one of the bolts in the cam retaining plate come loose and fubar'ed everything.. actually snapped the chain.. but no bent valves and this was a v2 head.. got lucky i guess

 

[DHZ_XR8cing]

Sorry mate. Its been a big weekend. I drank too much and did not sleep enough.
Basically what I was trying to say is that there is allot of play in the chain. So much so it slips teeth when I try to turn it over by hand. Do you think the cam chain could stretch enough to cause this or could it be something else?? Hope that made a little bit more sense.

The plate I used to hold the cam in was the wrong 1. The little finger that hold's the cam in bent and let the cam float pretty bad. So much so the plate was not holding the cam in at all. I'm guessing and hoping that this caused the chain to throw off and stretch it.

Its a 160HO and running a v2.

 

[The_GDFP]

10mm slack, beyond the end of tensioner travel, would have the runs nearly touching. A picture is worth 1,000 words Certain you're still on the crank sprocket? I'd pop the stator plate to verify. The silent chains are pickier about tension.

 

[DHZ_XR8cing]

Im positive the chain is on the crank sprocket.
When the tensioner is all the way out its missing the top guide by atleast 10mm and putting no pressure on the chain at all.

 

[The_GDFP]

Yeah, that's a problem. If that's the chain it came with, it's now junk.

 

[DHZ_XR8cing]

I have seen chains stretch before but nothing like this. Think ill be grabbing a new 1

 

[dafunk]

id be inspecting the crank sproket as you may of lost some teeth ?
but it shouldnt affect the tension that much ? hmmm???

 

[DHZ_XR8cing]

Ill split the engine during the week and have a look. I'm not expecting much good news inside.

 

[sean01]

yeah i wouldnt expect a chain to stretch normally like that.. which brings the next question..

has it ever been low on oil and overheated?
or even low oil pressure?

well depending on how much the cam was floating in the head the cam could of traveled out of the cam journal allowing oil pressure to drop, then comes the heat.. may not be like this but its all worth a mention..

 

[wogtaz ryder]

When my silly pitster lxr/klx mounts came loose allowing my engine to twist , just the mis alignment of the 2 sprockets annihilated my chain/stretched etc.

I haven't read much of this , but is that what could of happened?

 

[DHZ_XR8cing]

yeah i wouldnt expect a chain to stretch normally like that.. which brings the next question..

has it ever been low on oil and overheated?
or even low oil pressure?

well depending on how much the cam was floating in the head the cam could of traveled out of the cam journal allowing oil pressure to drop, then comes the heat.. may not be like this but its all worth a mention..

I get the feeling the cam may of traveled out of the journal. It was all in place when I pulled it apart but 1 of the rockers had a bur on the roller so its looking likely. I was not riding the bike when it let go but I was told it just stopped.
If it did drop in oil pressure what else do you think I should be looking at?

The cam chain was in a bit of a tangle around the crank sprocket when I pulled it apart so thats why I was thinking it may of stretched.

 

[sean01]

are the cam and rollers black or a hot blueish colour? if so then a very good indication of no oil which in turn creates heat. iv seen v2 rockers actually wear a flat side on the roller from no top end oil pressure..

hopefully the bottom end wouldn't of suffered any issue's but it may be worth inspecting the big end and main bearing for wear..

just inspect everything mate.. more so the top end but like i said it wouldn't hurt to check the bottom too..
also inspect the oil pump just in case..