7 replies to this topic

[Tedious93]

Hi All,

 

After spending too much time on carb tuning yet another test ride finally yielded good results. It took some time to get the float level and needle where it would respond well to off-idle pick-up and partial throttle cruise.

 

All of that came on the heels of re-shimming the valves on the intake side which took some doing when replacing the cam and trying to keep it in time. I'm pretty sure I did it right as I suspect if was off it would never run like it does (great!).

 

Still, to my chagrin, I'm hearing a distressing noise (sans earplugs) from the right side of the engine. The thing is, it ONLY happens under the load of decel when rolling in any gear (clutch engaged). It's quiet during acceleration ... nothing while revving at a stand still. No ticking noise that I can decern at idle. It's done this since the first test run after the valve adjustment which is why I think it might be the CCT.

 

Never had any issues with the clutch and haven't been in there since new. Seems to work well. The bike has only 27K miles so obviously has sat a good bit during it's life but I have tried to maintain it well during the off season and otherwise she's tip-top.

 

I know the gearbox is and always has been a bit noisy at first, but this is new, and louder.

 

I looked at some photos of the new and old parts and confirm I have the old one.

 

I'm trying hard to remember exactly what I did when reinstalling the CCT. I'm thinking I installed it w/o the top bolt in place so as not to apply too much tension and let it take up what was needed when putting the top bolt back in. After installing it I rotated the crank several times and the marks lined up as they should.

 

Could the noise be too much tension? Can I remove the CCT w/o risking a timing issue

 

I've read here about folks having issues with the cam chain tension though symptom descriptions there are a bit sketchy. Is there a way to check/adjust the CCT in-situ w/o going back into the cam box. I've been to the JBX site and hate to pay $$ for advise that may be marginal or may not apply.

 

Your thoughts are welcome.

 

Thanks

[fixitsan]

I've taken my CCT out a couple of times, carefully

I wouldn't recommend it unless you're a risk taker, or don't mind having to time it all up again yourself if it jumps a tooth, otherwise it's a job for a mechanic

I don't think you can overtighten the chain to the point it makes more noise, unless it's so tight it's chewing the chain guides ?

 

Not everyone is as daft as me...

[dapleb]

If year is 1992, model is 3VD rather than 4TX. Though both have the same design cam chain tensioner (step type).

Crazy Frenchmans site might not help you much anyways as its probably mostly 9er focused which has a spiral of doom design.

Did you just change the shims, no new chain or udder bits? Because of the step design to tensioner they do get noisy before the chain has enough slack to move to the next notch, this could possibly be your noise.

[Snowbird]

Maybe loosen the cct slowly until you hear a single click and tighten then try and see if it quietens down with the next step of adjustment.

[Tedious93]

Sorry about the 4TX thing, I meant 4DT.

 

Not to confuse the issue I did replace the drive chain and sprockets. That was pretty straight forward tho I'll check the slack again today as I'm going for a real test ride instead of putting through the neighborhood. A noise from the drive chain would seem to come from the left side of the bike, No?

 

It's been so long since I've ridden the thing I may have forgotten what 'normal' sounds like especially w/o earplugs.

I've only been back on it a couple of times since the shim replacement which is all I've done mechanically. Took the opportunity to change the coolant and have cinched up a couple of leaks at hoses which was no big deal.

 

It seems kind of weird to me that it only makes noise on deceleration in gear and not when I back off when revved out of gear. Still, running the engine under load both accelerating and decelerating is far different then out of gear.

 

I'll report back later with a better characterization of what's going on.

[Tedious93]

That's an interesting thought Snowbird. Kind of makes sense in light of what dapleb said about the chain getting noisey before it pops to the next notch.

 

What naws at me is the fact it only make the noise in the condition above as you would think it would make noise out of gear as well. Wierd.

 

I may try that after I do another ride. Thanks

[Tedious93]

Well I went for a good ride yesterday long enough to really listen to the what the bike was telling me. It seems post valve adjustment paranoia had me thinking about the cam chain and tensioner but I have allayed that fear. It's just the same old gear whine I've had forever in that noisey box. Still, I replaced the drive chain and sprockets before the valve adj. so I’m going to go back and do a visual to make sure nothing is adrift at the primary sprocket. Hopefully it's nothing more than what a set of earplugs would fix

 

I've heard of a condition (with the seal?) where if something is amiss it cuts off lubrication to the output shaft bearing. I remember seeing a guy on U-tube chatting about this when changing out the primary.

[dapleb]

The seal thing...."tang theory". There are a coupla tangs on the output shaft seal that could be aligned with oil holes. This was with regards to oil use...the theory being it could create a "fine mist" of oil (by the tangs partially blocking the oil ways) that would cause oil loss.

I put up some pics a lonnnnng time ago that showed all this in detail and showed orientation of seal that would in theory potentially cause the issue (so there is no need to remove the seal to check).

This is not your noise and regardless of tang position ALL 850s will use oil if you spank them good enough.