Do valves loosen or tighten with time?

[tc1446]

My Can Am calls for valve check/adjustment at 28,000 miles. Do valves tend
to loosen or tighten as the miles wear on? I ask because now at 22K at slow steady
speed I can hear what sounds like my old Yam triple which had a smooth singer sewing
machine sound.

 

[Trav]

Intakes tend to either stay the same or loosen slightly, exhaust get tighter.
After a few adjustments they don't change much if the oil is doing its job and cam lobe wear is minimal.
Looseness of the intakes is usually due to cam lobe wear and tightness of the exhaust is due to seat recession.

 

[SumpChump]

Originally Posted By: Trav
Intakes tend to either stay the same or loosen slightly, exhaust get tighter.
After a few adjustments they don't change much if the oil is doing its job and cam lobe wear is minimal.
Looseness of the intakes is usually due to cam lobe wear and tightness of the exhaust is due to seat recession.


Trav you need your own tou tube channel. I'd subscribe for sure.

 

[beanoil]

It's been my experience that they tighten, but that's not a rule. Best example I can think of was the original Suzuki/Kawasaki joint effort 250 MX. The valves were dung, and as they wore, they receded into the head, closing the gap. The oiling system on one cam lobe was poor: the head was drilled into the oil valley for one cam lobe, but the other lobe was supposed to survive repeated WFO on splash alone. Drilling the second cam pocket,replacing the worn cam, Kibblewhite Black Diamond valves and leaded fuel helped back then. It's funny how Can-Am wants your valves touched regularly, but they avoid oil changes in a shear machine for 9000 miles.

 

[sciphi]

Our Honda's valves have tightened. When it gets quiet, they're getting ready to do something naughty. As they say, "tappy valves are happy valves"!

 

[bmwpowere36m3]

Usually the clearance tightens up and when they get quieter.... valve adjustment time.

 

[bmwpowere36m3]

Originally Posted By: beanoil
It's been my experience that they tighten, but that's not a rule. Best example I can think of was the original Suzuki/Kawasaki joint effort 250 MX. The valves were dung, and as they wore, they receded into the head, closing the gap. The oiling system on one cam lobe was poor: the head was drilled into the oil valley for one cam lobe, but the other lobe was supposed to survive repeated WFO on splash alone. Drilling the second cam pocket,replacing the worn cam, Kibblewhite Black Diamond valves and leaded fuel helped back then. It's funny how Can-Am wants your valves touched regularly, but they avoid oil changes in a shear machine for 9000 miles.


28k I wouldn't call regular... my two other bikes want 10k and 15k. However I check my DS/dirt bike MUCH more often due to possible issues with valves receding.

Personally I like to check them after a 1-2k miles when new... to get a baseline and then check them periodically to see if their receding or not. Since a lot of new valves are Ti, they rely on a surface treatment to harden them. The harden surface is only microns thick, once that wears... valves start to move quickly (as in possibly needing adjustment with hundreds of miles).

 

[sunruh]

trav is off in the weeds.

as the valve face recedes into the valve seat the clearance on the valve tip gets less (ie tighter). this goes for ANY valve...intake or exhaust.

now, does your mfg have the proper seats to prevent this?
does it have the right valve material?
does that valve have a dlc type coating on the valve face?
did the valves get lapped and ruin that coating?

 

[JTK]

I thought exhaust valves "burn" because they don't seat long enough in the cylinder head to cool-off properly? I'm assuming cam or stem wear to the point the valve doesn't open fully = tight?

 

[Trav]

Originally Posted By: sunruh
trav is off in the weeds.

as the valve face recedes into the valve seat the clearance on the valve tip gets less (ie tighter). this goes for ANY valve...intake or exhaust.

now, does your mfg have the proper seats to prevent this?
does it have the right valve material?
does that valve have a dlc type coating on the valve face?
did the valves get lapped and ruin that coating?


What? Do you know anything about how an engine works? You don't seem to have a clue.

I said..
Quote:
tightness of the exhaust is due to seat recession.

How is that different from what you said.
Quote:
as the valve face recedes into the valve seat the clearance on the valve tip gets less (ie tighter).


Intake valves and seats are not subjected to the high temperatures of the exhaust gasses because they are closed during the exhaust cycle except for a slight overlap and less susceptible to recession. This high heat is the reason the exhaust valves are sometimes sodium filled to draw heat away from the face.
Any minimal initial recession of intake valves is just the valve getting mated properly and usually doesn't continue after the first adjustment or 2.

Seats are either a hard material press fit seat like stellite in aluminum heads or induction hardened for cast iron.

The rest of your post is mumbo jumbo. The OP gives no indication this engine has been apart so why would the valves have been lapped or incorrect seat material?

 

[serious_black]

Depends on the engine and what work has been done to it but most they reduce.

 

[Robenstein]

Depends on the engine and the rider a bit. I find that the ones that get loose tend to be low revving and low stressed engines, or the older engines that were flat tappet/pushrods.

In these days of very good oils and better metals, they usually get tighter, especially if ridden hard. When my Triumph was checked, there were no loose valves, only tighter ones.

 

[JetStar]

I doubt that your Can Am has coated Titanium valves, so the coating and lapping business goes out the window. I can quote my experiences with my bikes, but since it's not with the rotax sourced Can Am engine it doesn't help you much. You'd be better served by asking the question to people that have experience with this specific engine. Perhaps on the Can Am forum. Let us know what you find out.

 

[The_Eric]

Originally Posted By: sunruh
trav is off in the weeds.

as the valve face recedes into the valve seat the clearance on the valve tip gets less (ie tighter). this goes for ANY valve...intake or exhaust.


Off in the weeds? Nah...

I think you guys are talking about the same thing. Seats and faces erode contributing to recession and therefor the tightening of exhaust valve clearance.




To the OP- I suppose either loosening or tightening could happen for a number of reasons... Really it depends on what you're working on- they all have their quirks. As a general rule, exhausts will tighten and intakes may to a lessor degree or they may not. This isn't to be confused with a factory lash that was just plain out to lunch.

 

[tc1446]

Been advised by half doz folks on spyder forum that 1330 Can Am motor has hydraulic valves and require no adjustment. That solves
my problem.

Thanks to all above who responded. Still good to get info on
other machines.

 

[02SE]

Hydraulic lifters/lash adjusters can fail and/or stick, too.

 

[tc1446]

BRP doesn not require adjustment; if they fail, I still have 2 1/2 years warranty left.

Its looking like the 1330 motor may be a good one; many riders have extremely high mileage
and no major failures reported that I know of.

 

[02SE]

Originally Posted By: tc1446
BRP doesn not require adjustment; if they fail, I still have 2 1/2 years warranty left.

Its looking like the 1330 motor may be a good one; many riders have extremely high mileage
and no major failures reported that I know of.


Just to clarify: I'm not saying they require adjustment. I am saying that hydraulic lifters and hydraulic valve lash adjusters, can stick and/or fail.

 

[UncleDave]

Originally Posted By: tc1446
My Can Am calls for valve check/adjustment at 28,000 miles. Do valves tend
to loosen or tighten as the miles wear on? I ask because now at 22K at slow steady
speed I can hear what sounds like my old Yam triple which had a smooth singer sewing
machine sound.


They tighten as the valves pound up into the seats.

The exhaust quicker than the intakes but both pound up and close the lash until ultimately the valve stops fully closing.

Not sure how BRP's warranty works, but with Hondas If I had a problem I still had to prove I followed the inspection intervals as per the manual or they could decline coverage.


UD

 

[Mackelroy]

On the street it is mainly the exhausts that take the abuse(intakes not so much), offroad, the intakes tend to take the same abuse as the exhaust(cause of dirt ingestion).