Author Topic: Hesitancy and running rough at 3500 rpm  (Read 766 times)

Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #25 on: August 21, 2019, 04:49:49 PM »
Yes I know the buckets  come in 0.05 mm steps so anything at 0.13 mm will have to either go to 0.18 mm or 0.23 mm. Chris Harris always says loose is OK so I might go over spec In those cases. What do you think?
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Offline Laitch

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Re: Hesitancy and running rough at 3500 rpm
« Reply #26 on: August 21, 2019, 04:54:40 PM »
Yes I know the buckets  come in 0.05 mm steps so anything at 0.13 mm will have to either go to 0.18 mm or 0.23 mm. Chris Harris always says loose is OK so I might go over spec In those cases. What do you think?
Spend your money as you see fit and define in spec however you like.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #27 on: August 21, 2019, 05:49:04 PM »
My tingling spidey senses lead me to believe you do not agree with that idea...
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Offline Laitch

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Re: Hesitancy and running rough at 3500 rpm
« Reply #28 on: August 21, 2019, 07:14:50 PM »
My tingling spidey senses lead me to believe you do not agree with that idea...
Maybe you're recalling what I wrote in post #20, if you read post #20, or maybe you're getting a touch of hay fever.
Chris Harris always says loose is OK so I might go over spec In those cases.
To quote Chris Harris from the 2V valve clearance adjustment instructional video, I have never in my life seen a 16 valve K engine with tight valves—yet, your bike's engine has two of them. Measure them again; maybe they'll be in spec—however you have chosen to define that.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #29 on: August 21, 2019, 08:16:31 PM »
In all seriousness I would say I have 6 out of spec and 2 in - if I cannot pass a 0.15 mm feeler gauge then that valve is out of spec, no?


So I was thinking the 3 which can pass a 0.10 mm but not a 0.13 mm I need to bring up by 0.10 mm so a 0.20 mm will pass but  0.23 mm will not. 


The 3 that are at 0.13mm passing but not a 0.15 mm I was going to add 0.05 mm to make it so a 0.18 mm will pass but a 0.20 mm will not.


The last 2 where a 0.15 mm will pass but a 0.18 mm will not I was going to also add 0.05 mm so that a 0.20 mm will pass but a 0.23 mm will not. 


Is that the right way to do it or do I base it on the size that won't pass?


Yes I remember CH saying that as well, in fact I reached out to him today to ask about that.  I will report back if he responds.



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Offline Scott_

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Re: Hesitancy and running rough at 3500 rpm
« Reply #30 on: August 21, 2019, 08:47:48 PM »
Maybe you're recalling what I wrote in post #20, if you read post #20, or maybe you're getting a touch of hay fever. To quote Chris Harris from the 2V valve clearance adjustment instructional video, I have never in my life seen a 16 valve K engine with tight valves

Not trying to discount what Mr Harris is saying, but I don't buy his comment about no tight valves in a 16v engine.
I've had tight valves on BOTH of my 16v K bike engines...... one is at 50K+ miles and the other is at 110K+ miles.
It is simply physics, as valves wear and seats wear they are naturally going to shrink the gap and go tight in relation to the cam clearance.

Maybe he meant to say he's found no loose valves in a 16v engine.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #31 on: August 21, 2019, 09:00:21 PM »
My engine is at 130,000 + miles so no surprise I have some tight valves then...
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Offline Laitch

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Re: Hesitancy and running rough at 3500 rpm
« Reply #32 on: August 21, 2019, 11:31:15 PM »

I checked them I had two intakes at 0.13 and two at 0.15 with two at 0.18 and two at 0.20 so I have two under min two at min and four within spec.  All exhaust valves are within spec.
In all seriousness I would say I have 6 out of spec and 2 in - if I cannot pass a 0.15 mm feeler gauge then that valve is out of spec, no?
So I was thinking the 3 which can pass a 0.10 mm but not a 0.13 mm I need to bring up by 0.10 mm so a 0.20 mm will pass but  0.23 mm will not. . . .
Is that the right way to do it or do I base it on the size that won't pass?
View it differently. Fine adjustments can't be made. If a 0.15mm blade goes and the 0.20mm blade doesn't go, it's good. If the 0.15mm blade doesn't go, it's tight. If a 0.10mm blade goes, the space can be increased by either 0.05mm or 0.10mm.  If the 0.20mm blade goes, it's loose but if the 0.20mm passes through tightly,it's acceptable. If you want to loosen clearances until the valves rattles like castanets, that's still your choice.

Your partial measurements in post #29 contradict the measurements you gave in post #16. These measurements shouldn't change like tidal flow or molting turkeys. When you write that your engine has two valves clearing at 0.13, two at 0.15, two at 0.18 and two at 0.20, then I must believe your engine has two valves clearing at 0.13, two at 0.15, two at 0.18 and two at 0.20 just like when Chris Harris says tight, I must believe he means tight and not loose; just like when johnny writes poast I must believe he means poast and not toast.

The measuring process is simple. You either haven't quite grasped it yet or can't fully and accurately express it. This is another case for the intervention team from the Five Boroughs Sisyphean Society.

. . . I don't buy his [Harris's] comment about no tight valves in a 16v engine.
The point of introducing that quote was to demonstrate Chris's fallibility—a condition he shares with the rest of humanity—by using Filmcamera's tight valve predicament as an example.
 
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Offline daveson

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Re: Hesitancy and running rough at 3500 rpm
« Reply #33 on: August 22, 2019, 12:19:52 AM »
"The leak down test was very different to the first time..."

"I did the test with the cam cover off so I could see where the lobes were to verify TDC... "

Check the head bolts.

Probably good to do the test a few times until you get consistent results.

The lobes will tell you when the cylinder is on the compression stroke, but is not accurate enough to verify TDC. Place a dowel on the piston, when it extends to its outermost, you have TDC.

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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #34 on: August 22, 2019, 07:13:59 AM »
Daveson, Ok I will try it again but it is not like there is a very fine adjustment to where the piston is.  Using a 19mm wrench on the upper cam when I turn the engine over it moves in spurts.  It is not a smooth movement where I can infinitely adjust it, rather it seems to jump between positions. 


Laitch i post #16 I was quoting the measurements I got last time i checked the valves about a year ago. In post #21 I published the clearances I got yesterday. In post #29 I was referring to the latest measurements.  I am still unsure what to call the measurement the gauge size that will go through or the one that won't.  So if a 0.15 mm is a go and a 0.18 mm is a no go I am saying the clearances is 0.15 mm making the valve in spec but at the lower limit. In that case I am planning to add 0.05 mm to bring to the upping limit of spec since it has been established that valves are more likely to tighten over time rather than getting looser.  If that is wrong and it is better to leave them at the tighter end of spec please let me know and I will leave them alone, saving me $35 per bucket.


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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #35 on: August 22, 2019, 01:55:03 PM »
I checked all the head bolts today and none moved using 36 ft lbs on the torque wrench so I guess they are ok.


I then put the cam cover back on a rechecked the compression on cylinder 4 - this time I got 120 psi meaning it is the same as the others (I had a suspicion the battery was running out of punch before so I fully charged it before redoing the test today)


This weekend I will remove the buckets to measure them, I am more than a little nervous about the process - it involves digging deeper into the heart of the beast than I ever have before but I will take it slowly and do my best.


However I do not feel like I am really any closer to solving the problem that started this thread, the rough running and hesitancy I was getting at 3500 - 4000 rpm.  The compression is the same as it has been for ages and so are the valves. 
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Offline Laitch

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Re: Hesitancy and running rough at 3500 rpm
« Reply #36 on: August 22, 2019, 10:22:03 PM »
 
please let me know and I will leave them alone, saving me $35 per bucket.
If something is at specification, leave it alone and adjust something that isn't at specification.
  • Along the Ridley in Vermont.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #37 on: August 27, 2019, 02:09:39 PM »
Today I finally got to remove the buckets from the intake valves and see what sizes are in there so I can get the correct replacements.


1a =2.75, 1b = 2.70, 2a = 2.75, 2b = 2.75, 3a = 2.75, 3b = 2.70, 4a = 2.75, 4b = 2.80


the measures valve clearances for the largest size that WILL go under the gap between the bucket and the cam shaft are


1a = 0.10, 1b = 0.10, 2a = 0.13, 2b = .15, 3a = 0.15, 3b= 0.15, 4a = 0.13, 4a = 0.13


So my math gives me the following buckets I need to buy to get all the intake valves into the higher end of spec


1a = 2.65, 1b = 2.60, 2a = 2.70, 2b = 2.70, 3a = 2.70, 3b, 2.65, 4a = 2.70, 4b = 2.75


Agree? Disagree?


I have heard some people say it is ok to reuse an existing bucket on a different valve and others say it is not.  It would only save me 3 buckets so I am not that bothered either way but what is the general consensus?


Also I found one minor issue when I put everything back together again (it is going to be at least two weeeks before the new buckets get here and I did not want to leave all the guts of the engine open until then)


This is a picture of the top camshaft sprocket before I undid it and removed the camshaft



This is a picture when I reinstalled it





As you can see it is slightly misaligned compared to before.


I think that is because the camshaft was put back in a slightly different position?  I am not planning on riding the bike before replacing the buckets so I have to disassemble everything again anyway but I assume it is very important I get the camshaft back in exactly the same place it was before I took it off last time?







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Offline Scott_

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Re: Hesitancy and running rough at 3500 rpm
« Reply #38 on: August 27, 2019, 06:21:54 PM »
The after picture looks like your top gear skipped a tooth on the chain? (I use a couple of zip ties to attach the gear to the chain before I take the gear bolts out, that way the gear/chain timing doesn't change).
Did you turn the crankshaft any? like when trying to break the bolts loose.

I've re-used/swapped buckets between my 2 bikes and haven't noticed any issues.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #39 on: August 27, 2019, 06:33:31 PM »
I may have turned the camshaft yes, when I redo the whole process with the new buckets I will make sure to line it up as it was in the before pic

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Offline billday

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Re: Hesitancy and running rough at 3500 rpm
« Reply #40 on: August 28, 2019, 06:52:33 AM »
You can definitely reuse shims. Half the fun is figuring out how many valves you can bring to spec by shuffling shims from bucket to bucket.

Your price per shim sounds high. Lots of Yamahas use the same (?19 mm) shim, hang out on some of their forums to find suppliers.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #41 on: August 28, 2019, 07:06:44 AM »
My bike is a 4v, it does not use shims, you have to change the entire bucket. That is why they are expensive.  I will reuse some though, it saves me $100 if I do.


What about the math, does it seem right?
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Offline alabrew

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Re: Hesitancy and running rough at 3500 rpm
« Reply #42 on: August 28, 2019, 06:12:59 PM »
+1 on zip ties on the sprockets. Be SURE to use a torque wench on the cam bolts. DAMHIK

+1 on your numbers, but don't trust me There are several calculators out there, search bmwlt.com, if you want another confirmation.

On the rear ends of the camshafts, there is a slot cut. It should be parallel to the slot in the exhaust camshaft. There is a special tool to line them up, but $$$.
Hard to put them back on wrong since it would mean that two valves would have to be compressed.

You relieved the tension on the timing chain before removing the sprocket?

You may want to consider pulling the hall effect cover and making sure the timing is correct.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #43 on: August 28, 2019, 06:34:53 PM »
Yes, I relieved the tension on the timing chain, I actually only took off the top camshaft since the bottom valves are in  spec but when I [ut it back together again I will zip tie the chain to the lower sprocket then remove it so I can use the indents on both to line them up equally, thanks for the tip.


I had to remove the hall sensor to be able to get the timing chain cover off, but I used a sharpie to mark lines on it so it is easy to line it up to the same timing it had before, which always seemed fine.


Ok I will look for a calculator to double check my math.


Thanks again
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Offline Scott_

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Re: Hesitancy and running rough at 3500 rpm
« Reply #44 on: August 28, 2019, 08:03:06 PM »
When you align the slots in the cam shafts, they should be equally horizontal and parallel to each other. (this is what the alignment tool does)  It bolts to the head, and holds the cam shafts in alignment when installing the timing chain and gears.
When you torque the gear bolts, use a backing wrench on the hex surface of the shaft, should be next to cyl 3b lobe.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #45 on: September 18, 2019, 02:45:19 PM »
I installed the new buckets today and put everything back together.  I then went for a test ride.  The engine seems to be running better. I wold say throttle response is quicker and overall the ebegine seems a little more eager.  There is still a hesitancy at around 4000 rpm but it is greatly reduced compared to before.


Now the valves are in spec should I do a new leak down test, compression test and also balance the throttle bodies again?
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Offline Laitch

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Re: Hesitancy and running rough at 3500 rpm
« Reply #46 on: September 18, 2019, 02:57:55 PM »
Now the valves are in spec should I do a new leak down test, compression test and also balance the throttle bodies again?
Balance the throttle bodies first. The two procedures have a combined effect on engine performance. Throttle body balance should always follow valve clearance adjustment.
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Offline Filmcamera

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Re: Hesitancy and running rough at 3500 rpm
« Reply #47 on: September 18, 2019, 04:36:08 PM »
Thanks, I have balanced the throttle bodies.  They were pretty close but now they are dead on and the bike idles smoothly at 1000 rpm.  :twothumbsupp
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