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Author Topic: 836cc tear down ... need advice  (Read 652 times)

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Offline y2kc0wb0y

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836cc tear down ... need advice
« on: February 11, 2019, 05:24:42 pm »
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Few years back I purchased freshly "built" and polished 836cc from a guy in the North East. I enjoyed performance of this engine especially compared to the stock engine but after a 5 or 6 thousand miles it developed a tick that I couldn't explain. Sounded like valve train but not really?

Tore into the engine a littler further today to investigate. (see pictures)

1. Looks like the guide on the wheel for the timing chain has abnormal wear? Do you agree?
2. Found abnormal stamp marks on the jugs from the lower pins of the guide. Weird How does this happen?
3. Cylinder #2 lower wall looks to be broken? Could this have been assembled this way?

I will say the rod and crank assemble turns well and I don't see any obvious scars down the cylinder walls. They look "clean" with no obvious marks and the damaged wall doesn't look bad just broken. Overall the engine is clean. Has anyone seen this type of damage before? Do you think I'm onto the source of the tick given the wear on the timing chain wheel or do you think I should split cases?

Thanks-
Scott
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #1 on: February 11, 2019, 05:36:08 pm »
Also need to say that the exhaust port on #2 was badly coked in oil. I'm wondering if this broken sleeve was contributing to this condition. Makes sense.
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Offline Tews19

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Re: 836cc tear down ... need advice
« Reply #2 on: February 11, 2019, 07:08:20 pm »
Weird how the one sleeve looks to be cut? Were you able to find the material of the missing sleeve?
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #3 on: February 12, 2019, 04:38:46 am »
Indeed it is very weird. I did not find any material anywhere in the cases.. I did some Google searches and its not uncommon to see these cylinder liners cut down on big stroke builds. Like I said the cylinder wall and pistons look fine.

My immediate concern is with the tensioner and tensioner valley. Does the inside of the cam chain area look like it has bee rubbing on the sides? I'm not that familiar with what this area should look like normally. Review of the guide is clean and the chain looks undamaged. IDK know what's going on besides the pulley that look worn to one side.
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Offline BenelliSEI

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Re: 836cc tear down ... need advice
« Reply #4 on: February 12, 2019, 07:05:43 am »
If your rod/piston show no damage and there are no bits, the damage is from a previous failure. Probably a broken rod.

Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #5 on: February 12, 2019, 08:33:59 am »
If your rod/piston show no damage and there are no bits, the damage is from a previous failure. Probably a broken rod.

(re:cylinder #2) Its certainly plausible. I've been doing some reading on the roller tensioner and it looks like its common failure point for 40 year old rubber. What I cannot understand is the punch marks on the jugs from the guide pins. One thing I notice when pulling this apart was how loose it was. Is is possible the wrong PINs/Guide have been used here?

I don't know enough about the jugs/chains/guides to know any better.
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Offline bamacb

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Re: 836cc tear down ... need advice
« Reply #6 on: February 12, 2019, 08:58:14 am »
Wear marks from the pins is not uncommon. Replace the rollers and guide and it will be fine. Make sure to clean out the pan and oil pump screen as I'm sure you will find ground up rubber there. Myself, I would replace the cylinder or at least the one sleeve.

Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #7 on: February 12, 2019, 09:46:24 am »
Wear marks from the pins is not uncommon. Replace the rollers and guide and it will be fine. Make sure to clean out the pan and oil pump screen as I'm sure you will find ground up rubber there. Myself, I would replace the cylinder or at least the one sleeve.

I think this is the current strategy. Is there a good solid aftermarket upgrade for these the roller and guides? I'm on the fence about machine work to correct the jugs. I need to review that area some more and take some measurements. Very odd.
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Offline 754

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Re: 836cc tear down ... need advice
« Reply #8 on: February 12, 2019, 10:54:35 am »
 What cam does it have ? Did you note the rocker clearance before pulling cam?
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 836cc tear down ... need advice
« Reply #9 on: February 12, 2019, 12:08:26 pm »
What do those punch marks look like? on each piston? Pic?
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Offline bamacb

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Re: 836cc tear down ... need advice
« Reply #10 on: February 12, 2019, 12:49:00 pm »
Cyclex has a good upgrade for the rollers and guide otherwise use new Genuine Honda parts.

Offline MRieck

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Re: 836cc tear down ... need advice
« Reply #11 on: February 13, 2019, 04:05:31 am »
Your cam chain has dug into the cam tunnel quite a bit.
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Offline PeWe

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Re: 836cc tear down ... need advice
« Reply #12 on: February 13, 2019, 07:12:54 am »
Your cam chain has dug into the cam tunnel quite a bit.
The washer on cam is missing?
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #13 on: February 13, 2019, 11:11:02 am »
What cam does it have ? Did you note the rocker clearance before pulling cam?

Looks like a stock R5 cam to me. We always lashed using the stock values and it was quiet and worked well. I did not re-measure before I pulled all this apart. 
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #14 on: February 13, 2019, 11:13:43 am »
Your cam chain has dug into the cam tunnel quite a bit.

Reviewed the head and it appears to be a similar story here too.
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #15 on: February 13, 2019, 11:18:20 am »
What do those punch marks look like? on each piston? Pic?

See attached.
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #16 on: February 13, 2019, 11:21:11 am »
Your cam chain has dug into the cam tunnel quite a bit.
The washer on cam is missing?
Looks like there is one there. Not sure if it is correct.
Scott
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #17 on: February 13, 2019, 11:27:11 am »
More pictures of the damaged cylinder and piston. Not sure what to do here. Logic says tear it all down, clean and re-sleeve the cylinders. I'll pull the pan this weekend take a look at the screen?
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Re: 836cc tear down ... need advice
« Reply #18 on: February 13, 2019, 12:05:44 pm »
 If your going to replace the liners and bore them a used block might be a good option to buy and bore since the liners have already gone through their heat cycles and might be more stable then new of unknown quality.

Offline PeWe

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Re: 836cc tear down ... need advice
« Reply #19 on: February 14, 2019, 05:35:48 am »
The liner might have too much missing. Notching cylinders were a must when using alu rods that were wider. Maybe not a problem when rings are not there except for an eventual wobbly piston with min support.
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #20 on: February 14, 2019, 12:02:15 pm »
The liner might have too much missing. Notching cylinders were a must when using alu rods that were wider. Maybe not a problem when rings are not there except for an eventual wobbly piston with min support.
http://hackaweek.com/hacks/?attachment_id=1605

Thanks for the link PeWe. I'm leaning towards a full tear down, liners, pork chop crank and 915cc and and and......
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Offline PeWe

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Re: 836cc tear down ... need advice
« Reply #21 on: February 14, 2019, 11:10:37 pm »
You'll need better rods too.
One very important detail to be aware of is that 915cc means 68mm bore and fatter sleeves. CycleX sell their "915cc" kit that has 67.5mm bores/pistons which are not 915cc, its . Sleeves are tapered to avoid case machining.
Maybe just a little with dremel. My K2 case did not need it but my K6 did.

Calculate displacement:
((piston diam mm/2) x (piston diam mm/2) x Pi(3.1415926) x stroke mm)/1000
this multiplied with number of cylinders  x4

Bore 67.5, stroke 63 mm gives 901.77 cc
When ordering rings or the entire kit its a good idea to mention the bore just for sure. The kit CycleX sells as 915cc has 67.5mm pistons

Dynoman however sell a 67.5mm kit they call 906cc.

CycleX has a good price on their 67.5mm kit. But it is no next step. Sleeves need to be replaced when scratched or worn out.
They have a 890 kit (67mm) which can be redone using their 67.5mm pistons in the future. But, the CR is higher 12.5:1 so the head might need some adaptation for street use and street gas
http://www.cyclexchange.net/Engine%20Parts%20Pistons%20Page/890cc/890cc%20Pistons.htm
Dynoman has also 67mm kit (888,46cc) and tapered sleeves. 10.5 or 12.5:1  (I have Dynoman DP1000/71r kit, JE pistons (71.25mm)

One very important thing is your head you intend to use.  Are the chambers widened or only the normal port job, the bumbs around the valves grinded off?
If head has open chambers, you'll need higher CR pistons than 10.25/10.5:1
Maybe 12.5:1 can fit then or special order from Dynoman that can adapt the pistons to actual chamber volume. I did that for my head that has 24.4cc. The "normal" volume the big bore kits Cormpression Ratio (CR) are calculated for is around 22.5cc for K heads.
F2  heads need higher domes.

I should check with forum member MRieck that can make the entire package to get a good working solution at once. Easier when one shop can order all correct stuff needed, do the machining/assembling and only one shipment. Maybe you need parts from all CycleX, Dynoman and APE. APE has their own rods as an alternative to Carillo, less $  ;)
« Last Edit: February 14, 2019, 11:35:54 pm by PeWe »
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Offline HondaMan

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Re: 836cc tear down ... need advice
« Reply #22 on: February 16, 2019, 08:43:49 pm »
Interesting: the broken cylinder is right at the site where forged pistons with insufficient lube will seize and stick. The piston looks like it is showing something similar?

Maybe check the piston clearances between their skirts and the bottoms of their bores (not the broken one, too late for that..), and see what piston clearance was used? That will likely tell the story.

The 'pin marks' across the bottom of the cylinders: I have seen this after a frustrated wrench had struggled to get the rings into the bores and when they finally went, SLAMMED the cylinders down before aligning the slipper tensioner's pin into the grooves in the lower cases (he didn't get to work for me much longer...). That didn't have much to do with the noise, though.

The noise was likely coming from that nasty tensioner wheel. Honda still sells them: get theirs if you can. While at it, maybe also get their roller arm unit as well...the pivot pin and bushing in some aftermarket versions of these (sold from 2006 thru 2010) had nasty burrs on them that prevented the arm from swinging easily to follow the cam chain during high-RPM excursions. This made the chain go into a 'standing wave' pattern that then battered the lower roller, tearing chunks out of it prematurely. Not everyone who bought these parts back then noticed that the arm was not swinging freely during installation, so many of them failed in less than 5000 miles, sometimes because of poor tensioner setting. They ended up being 'recalled' by the many aftermarket vendors, and Honda stepped back up to make the properly-machined versions again. If installing one of those aftermarket ones, just make sure to sand off the burrs in the punch-steel roller arm so the pivot moves freely when installed.

BTW: if you find the pieces of the cylinder laying in the bottom crankcase, someone used the wrong piston-bore clearance for those Wiseco pistons...and they probably also used 10w30 or 10w40 oils...
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Offline y2kc0wb0y

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Re: 836cc tear down ... need advice
« Reply #23 on: February 17, 2019, 07:24:28 am »
Interesting: the broken cylinder is right at the site where forged pistons with insufficient lube will seize and stick. The piston looks like it is showing something similar?

Maybe check the piston clearances between their skirts and the bottoms of their bores (not the broken one, too late for that..), and see what piston clearance was used? That will likely tell the story.
 

Thanks for chiming in Mark - This sounds very logical to me. I will gather some measurements.


The 'pin marks' across the bottom of the cylinders: I have seen this after a frustrated wrench had struggled to get the rings into the bores and when they finally went, SLAMMED the cylinders down before aligning the slipper tensioner's pin into the grooves in the lower cases (he didn't get to work for me much longer...). That didn't have much to do with the noise, though.

Ha. We found a soda bottle cap RTF'd into the starter hole. I couldn't figure out how those marks could be caused while running. Once again logic that this happened during assembly.

The noise was likely coming from that nasty tensioner wheel. Honda still sells them: get theirs if you can. While at it, maybe also get their roller arm unit as well...the pivot pin and bushing in some aftermarket versions of these (sold from 2006 thru 2010) had nasty burrs on them that prevented the arm from swinging easily to follow the cam chain during high-RPM excursions. This made the chain go into a 'standing wave' pattern that then battered the lower roller, tearing chunks out of it prematurely. Not everyone who bought these parts back then noticed that the arm was not swinging freely during installation, so many of them failed in less than 5000 miles, sometimes because of poor tensioner setting. They ended up being 'recalled' by the many aftermarket vendors, and Honda stepped back up to make the properly-machined versions again. If installing one of those aftermarket ones, just make sure to sand off the burrs in the punch-steel roller arm so the pivot moves freely when installed.

There is a lot in this paragraph. "standing wave" of timing chain make sense giving the damage in the cam chain valley and head. I figured it had to to with the tensioner wheel that is clearly compromised but I wan't sure how it could wavier off course that much. Do the aftermarket wheels, like CYCLEX's which seems like a design improvement, create more chain noise thus continuing to recommend OEM Honda?
 
BTW: if you find the pieces of the cylinder laying in the bottom crankcase, someone used the wrong piston-bore clearance for those Wiseco pistons...and they probably also used 10w30 or 10w40 oils...

We always ran Honda motorcycle oil in this bike. Not sure weight off the top of my head.
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Online bryanj

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Re: 836cc tear down ... need advice
« Reply #24 on: February 17, 2019, 08:44:14 am »
I had a 750 years ago where the cam chain tensioner didnt work right and the chain rattled sideways a wore holes in both sides of camchain tunnel in block.
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