Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: McCabe-Thiele (Ted) on June 02, 2021, 10:29:59 AM
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This morning I fitted the two crank case halves and it all went well - all torqued up fitted the primary gear shaft etc.
After fitting the shaft in the primary drive all went together ok.
I held up the timing chain and rotated the crank all seemed okay - I checked the conrods for free movement and number two just seems a bit tight occasionaly compared to the other three that would flick left & right as I expected.
I added some extra oil it seemed to help but at the top of its travel I can feel (or imagine) a slight tight spot.
With the conrod at the bottom of its stroke the rod will move easily to the left & right if you get my meaning - not quite the case when its near the top of its travel?
When I plastigauged the conrods the clearance were the same on all four rods - with each rotation of the crank the issue seems to have improved.
Do I need to seperate the case again & examine number 2 con rod bearings ?
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Did you rotate the con rods on the crank before you fitted the crant Ted to test for any tight spots?
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Hi Ted,
As a matter of interest, what readings did you get with your Plastigauge on the Con rods and the Main bearings.
Thanks
Dennis
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Did you rotate the con rods on the crank before you fitted the crant Ted to test for any tight spots?
No I didn't - clearly I should have done.
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Hi Ted,
As a matter of interest, what readings did you get with your Plastigauge on the Con rods and the Main bearings.
Thanks
Dennis
All four were 0.0010 thou or 25 microns. All four fitted with Green shells.
Ted
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I'm thinking as I have not gone any further I will have to split the crankcase to see if there are any bearing marks - not looking forward to removing the Honda bond.
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I'm thinking as I have not gone any further I will have to split the crankcase to see if there are any bearing marks - not looking forward to removing the Honda bond.
When you had the engine apart originally Ted, did you torque up the con rods to see if there was any tight spots which may indicate ovaling of the con rod big ends. If the shells are now marked in any way, it usually means the con rod needs re claiming due to ovaling.
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Hi Ted,
I found that using a small paint brush dipped into a shallow cup of cellulose thinners, then gently brushed over the Hondabond joint face and left for 5 minutes, will soften it dramatically, sufficient to wipe off with a cloth.
Do you know what big end shell colour was installed previously ?
Dennis
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Hi Ted,
I found that using a small paint brush dipped into a shallow cup of cellulose thinners, then gently brushed over the Hondabond joint face and left for 5 minutes, will soften it dramatically, sufficient to wipe off with a cloth.
Do you know what big end shell colour was installed previously ?
Dennis
Only one and four had the original Geen markings still visible. The shell codes were all the same but that is probably meaningless. Conrod 2 & 4 were marked 1B conrod 1 & 3 were marked 1A. The Green shell code was still visible on conrods1 & 4.
I will try some thinners when I dismantle. I should have checked the rotation before I fastened it up.
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I'm thinking as I have not gone any further I will have to split the crankcase to see if there are any bearing marks - not looking forward to removing the Honda bond.
When you had the engine apart originally Ted, did you torque up the con rods to see if there was any tight spots which may indicate ovaling of the con rod big ends. If the shells are now marked in any way, it usually means the con rod needs re claiming due to ovaling.
I will look at that when I take the crank out - I'm just annoyed at myself for not checking - good new its only cost a small amount of Hondabond & my time. I might have to ask you about how to check for ovaling!
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At least you caught it early Ted. If the engine had been fully built up and in the frame that would have been soul destroying.
As you say it has only cost a bit of Hondabond (and it goes off in the tube anyway so at least you are getting VFM!) and time. The bright side is you will know your way around the engine and it's all part of the learning process.
Good luck finding the problem and I'm enjoying the posts.
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Must admit to never finding an oval rod on a Honda motorcyle and not sure it could be recyified due to the tight tolerances Honda work to.
Also never seen a measurably oval pin but everything is older now so anything is possible.
Check back of shell and inside of rod eye is clean and dry
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Strange that something can be felt in rotation, and a bit puzzling.
The only "oddity" there is the oil supply hole but the shells should run clear of it for the oil to get round the centre groove. It's the only thing that could immediately be seen in the context of crank pin up or down in orientation I can think of. Wondering if there's anything snaggy on those shells for that rod.
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Seen hundreds of oval Honda rods in my time. I measure up rods on a con rod reclaiming machine as, it has a dial on it.
Do you have all the rods on the correct way ?
It is always good practice to put the shells in the crank case, fit the crank without the rods, torque up and rotate by hand. And see if any shells are marked. Take the crank out and do the same with the rods on the crank. Checking while building is the best way to go ;)
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Seen hundreds of oval Honda rods in my time. I measure up rods on a con rod reclaiming machine as, it has a dial on it.
Do you have all the rods on the correct way ?
It is always good practice to put the shells in the crank case, fit the crank without the rods, torque up and rotate by hand. And see if any shells are marked. Take the crank out and do the same with the rods on the crank. Checking while building is the best way to go ;)
Hi Trigger - yes the rods are all in the rightway round - as well as my original markings & photos this tallied with the bearing shell notches facing the exhuast side of the engine. It might be a coincidence but when I purchased the shells from Ziggy he only had 7 half bearings - all in sealed Honda NOS packets. I bought one Green shell from DS they had a different batch number that might be a factor.
I'm even thinking could a dog hair have got in on assembly.
When I split the crankcase later today I will look for any marks on No 2 big end for an idea as to what is wrong.
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Hi Ted,
I found that using a small paint brush dipped into a shallow cup of cellulose thinners, then gently brushed over the Hondabond joint face and left for 5 minutes, will soften it dramatically, sufficient to wipe off with a cloth.
Do you know what big end shell colour was installed previously ?
Dennis
Thanks Dennis I did that this morning its coming off quite easily especially as it isn't baked on hard. Ted
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At least you caught it early Ted. If the engine had been fully built up and in the frame that would have been soul destroying.
As you say it has only cost a bit of Hondabond (and it goes off in the tube anyway so at least you are getting VFM!) and time. The bright side is you will know your way around the engine and it's all part of the learning process.
Good luck finding the problem and I'm enjoying the posts.
I was really nervous when I assembled the crankcase halves for the first time - adrenaline rush _ I was elated when it went smoothly until I found the conrod issue. Now tbh I feel more confident for next time! Ted
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Hi Ted,
Glad that the Hondabond tip helped you. Thinking about the Conrod bearing issue. Keep a note of what is being changed, but if I had the problem I would swap the shells from one of the unaffected rods and see if this resolves the problem. If so, it could be the problem shells are in some way defective. This is all assuming that there is no contamination behind the shells when you dismantle.
To measure your crankshaft journals for ovality or taper, you need an external mic for the crankshaft. Ovality - measure at several places around the centre of the circumference of the journal. Usually most wear will occur at the “top” of the journal due to thrust on the power stroke of the engine, measuring at 90 degrees to this gives the ovality.
Taper is measured side to side.
Conrod ovality and taper are measured in a similar way but with an internal mic or dial test mic.
Hope this helps.
Regards
Dennis
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Hi Ted,
Glad that the Hondabond tip helped you. Thinking about the Conrod bearing issue. Keep a note of what is being changed, but if I had the problem I would swap the shells from one of the unaffected rods and see if this resolves the problem. If so, it could be the problem shells are in some way defective. This is all assuming that there is no contamination behind the shells when you dismantle.
To measure your crankshaft journals for ovality or taper, you need an external mic for the crankshaft. Ovality - measure at several places around the centre of the circumference of the journal. Usually most wear will occur at the “top” of the journal due to thrust on the power stroke of the engine, measuring at 90 degrees to this gives the ovality.
Taper is measured side to side.
Conrod ovality and taper are measured in a similar way but with an internal mic or dial test mic.
Hope this helps.
Regards
Dennis
I have removed the shells from No2 Conrod - the two green shells were batch coded differently as DOE A & D10A both have the green edge markings in place. They do not have any drastic looking binding marks to me ?
Not sure what more experienced folk here have to see when looking at the pics.
Other thing I have found is the bare conrods have what looks like burnt circular bands of burn oil on them on the surface where the shells mate.
I have cleaned this off completely with some fresh Brasso Wadding - re-fitted the cleaned shells with some light oil.
Haven't time now to Torque them up as I have to see the Nurse to have some sutures removed shortly.
Will update my progress later today or tomorrow.
.(https://live.staticflickr.com/65535/51223437325_758c665e8d_b.jpg) (https://flic.kr/p/2m3rvjv)Number 2 conrod shells (https://flic.kr/p/2m3rvjv) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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This is the staining on the conrod journals I have mentioned there are no grooves its just burnt oil I guess.
I have cleaned it off with some Brasso Wadding re-fitted the existing shells to No2 - re-plastgauged - reading 25 microns as before.
Removed all traces of Plastugauge from the shells - re-fitted with Red Lube - torqued up the bolts...... no high spot at all it rotates freely like the other three big end bearings.
For peace of mind I have cleaned all four conrods whilst the casing is split.
On Sunday by BiL is visiting in the morning to have a look before I close up the crankcase again.
(https://live.staticflickr.com/65535/51221908252_ae9c936404_b.jpg) (https://flic.kr/p/2m3iEMb)staining on conrod (https://flic.kr/p/2m3iEMb) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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If it now spins free and the clearance is OK I would say you have sorted it, doesn't take much to loose the clearance, had somebody oil the back of the shells once and that caused problems
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If it now spins free and the clearance is OK I would say you have sorted it, doesn't take much to loose the clearance, had somebody oil the back of the shells once and that caused problems
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Looking back I just don't know why I didn't clean the bearing faces - I did Evaporust the outside light surface rust from the conrods ages ago - just missed cleaning this bearing surfaces. I also double checked the mains for any high spitting as I had rotated the crank quite a lot.
Had I Torqued the crank on the bench I might have found the problem before fastening up.