Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Acro1985 on August 10, 2024, 04:38:14 PM
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Hi All
Just stripped my engine down, and wanted people's thoughts on the crank bearings as to whether they are good or need replacing.
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Oil and filter have not been changed often enough but unless you plan on racing they should be fine looking at the pictures but enlarging goes fuzzy
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Try these one Bryan
I don't plan on racing it
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I would suggest changing the ones with the marks / nicks out of them.
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If you have gone as far as splitting the crank cases a lot depends on the situation with the pistons. I've always replaced crank bearings if an engine is being rebored.
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It’s a hard thing to determine from a couple of small photos but they are a bit grey and matt looking so would agree with the opinion about lack of oil changes, or possibly stood for a long time with old oil. It would be helpful to have some photos of the crank journals to see what they are like. The journals should be smooth with no ridges or groves you can feel using your fingernail. Measure bearing clearance with plastigauge to see if they are within specification, if they are and crank journals are good then you have to make the call on the info you have. I guess a full bearing change is in the region of £300-400, assuming you can get a full set of the sizes/colours you need.
I will have exactly the same job and decision to make soon, I will be factoring the future usage that the bike will be having into my decision ie it’s going to have a pretty gentle well looked after life.
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Those pics are clearer and i agree with Julie, now i can see the knicks i would change that one
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Weird optical illusion on my phone with one bearing looking like it should - the second looking convex!
I need to go to Specsavers?
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I think after sleeping on it despite the cost if I can get a full set of bearing I will replace them as well as the Conrod shells, as I have no history for the bike or how long it been off the road. Plus someone has clearly had it apart before judging by the excess sealant that squeezed out everywhere.
So the next question is do I need to replace all the bearings for the gearbox shafts as they do seam to be is good condition
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If gearbox ball bearings are smooth when rotating with no visual signs of surface "pick up" only ones I would replace as matter of routine are the primary drive ones. Some of the special needle rollers are pretty much impossible to find.
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In all honesty whilt i have heard of the needle rollers failing on 500 i have never actualy seen a worn out gearbox bearing
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Thanks again for all help and advice.
Although I was hoping someone wasn't going to say the needle bearing are like rocking horse poop.
I am missing one the little rollers for bearing on the main shaft (NR 15 on the part diagram) it fell off as I was taking it of the case to put into bag to keep everything together for the shaft and they scattered all over the floor. I have found 15 but the 16th has vanished 😭
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Try looking up a local bearing supplier and taking one needle in to compare, they frequently sell loose balls and needles
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Am I right in thinking you can no longer get the yellow crank bearings?? Having done some searching on the forum, and much head scratching, from the marks I can find on the crank it's 1A or A1 on at least three of the journals. On the others I can only make out the 1. Conrods are stamped 2D for three of them and 2C for one.
Sorry for all the questions this is the first motorbike engine I have completely stripped down to rebuild
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You are unlikely to need Yellows, as a starting point for your mains look at your crankcase codes, then accurately measure your crank mains in mm. If you use the search facility here there are lots of posts on the subject.
As Bryan said earlier check your crank first for any wear ridges. Beware of confusing conrod weight codes with crank web conrod codes.
PS The crankcase mains starting point codes are easily visible as they are stamped on the back of the crankcase, five letters containing A,B or C. It's extra confusing as the tables for the mains and Conrods use different axis in the parts book.
When web codes are illegible you need to rely on a combination of micrometer readings and Plastigauge. It's always a bonus if the edge of your old shells have colour markings that are still visible - it's just a dab on the edge - the numbers stamped on the back of the old shells are just casting batch numbers so are of no help.
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The crank journals look fine no wear ridges that I can see or feel just a darker line in middle of them all which matches up with the oil channel in the middle of the bearings.
The crank journals measure 33.48mm if I have read the micrometer correctly
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Are you talking mains or big ends with your measurement?
I don't have the tables to hand.
Posting your crankcase codes will help.
PS If you can only measure to 0.01 mm you will definitely need to use Plastigauge or have the crank professionally measured.
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The code on the back of the case is BBBBB
The mains measure 33.48
The big end measure 35.48
I think I will look to get it professionally measured just in case I have done it wrong
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Honda work in Microns for crank clearances, have you managed to find any colour codes?
Good news is that BBBBB should mean you can find the right shells easily enough provided there is not much mains journals wear.
It's worth hunting down the shell side colour marks - out of ten shell edges you are in with a chance.
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What can I clean the shell edges with, as they are dirty and don't want to damage them or wipe off any slight colour mark
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I would use Meths though petrol might be okay using a small paint brush rather than a cloth.
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I doubt after this long you will get a colour from them
For new try Yamiya in Japan
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And try using a very powerful magnifying glass, you may be lucky and see a fragment of paint colour on the edge of the shell. I have a jeweler's eye glass and it's pretty good.
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I am going to take it to a machine shop and get it all measured properly as I am not confident I am doing it right and the last thing I want to do is install the wrong ones and cause more problems.
Plus from my measurements and very limited understanding of the bearing charts both the crank and big end measurements are outside of spec. Even though despite obvious wear on the big end bearings there was no obvious play in them when bolted to the crank 🤷
Thanks again for all the advice
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To compensate for wear you effectively fit thicker bearing shells.
Black is the thickest shell that is made for these old Hondas..
Assuming for the moment you crank mains are within specification.
For your mains as all the casing codes are B it probably had Green or Brown shells fitted originally in the mains.(my B coded mains were brown shells)
Finding a trace of colour would make the starting point much easier.
This photo shows a green colour code on one of my old 400 shells.
(https://live.staticflickr.com/65535/51058480758_c849219e04_b.jpg) (https://flic.kr/p/2kMS4tL)Main bearing shell (https://flic.kr/p/2kMS4tL) by Macabe Thiele (https://www.flickr.com/photos/187487200@N03/), on Flickr
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Plastigauging is very easy I am sure you can do it yourself and make a good job of it. Buy a set of plastigauge, about £13, for the mains you lay the crank back in the half shells in the crank case. Then lay a strip of plastigauge across each crank journal, not around the journal. Then carefully replace each bearing cap with its half shell bearing. Torque bolts to specified torque in stages evenly across all bolts. Remove bolts, carefully remove bearing caps, you will see a flattened piece of plastigauge on each journal, match width to those shown on plastigauge instructions. This will equate to the clearance in the bearing, check this with specifications given in workshop manual. If in spec and bearings are visually ok, no nicks, grooving or scouring then bearings should be ok to reuse. If not then change. I forgot to say wipe crank journal before putting plastigauge on it but do put a thin smear of oil on half shell to stop it sticking to plastigauge strip.
If you do resort to using a machine shop to do your engine, ensure you use someone that knows what they are doing, many say they do but many haven’t got a clue.
I am just looking up the bearings for the primary shaft for when I do my engine , sizes are 22x56x16. 25x52x15, needle roller is 25x29x17, I am going to check to see if they are normal or c3 spec. Will get back on that.
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The shop I am thinking of taking it to I have used before many years ago in fairness that was on a mini engine, but they have been going since the 50s and have a good reputation.
I will give the plastigauge a first though.
Let me know how you get on with the bearings
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Sorry another question.
My rocker cover appears to have a piece missing near the holes for the breather. I can only seem to find ones of earlier engines will they fit mine
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That damage looks really nasty on the cam cover - have you found any of the debris anywhere yet?
I assume you are going to the machine shop to have the crank measured accurately in thousands of a mm - good move.
You will need to buy Plastigauge of the right range o.025-0.076 mm.
Quite a few videos on U-tube on the process.
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No bits in the engine so I can only assume some one has run it like that 😱
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That damage has been caused by somebody being hamfisted it getting a cotter pin out that locks the rocker shaft.
That is the big problem as the shaft cam move in and out now , it probably would not leak but i wouldnt run it.
Any 500/550 rocker cover will fit but only the late 76 onwards have the locked shafts, i am told that earlier ones can wear the cover holes oval but i have yet to see one, you can sort of lock the early shafts by putting an O ring in the end bore before fitting the end cap
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BTW your crank journals look really good, hope mine are that good when I pull the bottom end apart.
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That damage has been caused by somebody being hamfisted it getting a cotter pin out that locks the rocker shaft.
That is the big problem as the shaft cam move in and out now , it probably would not leak but i wouldnt run it.
Any 500/550 rocker cover will fit but only the late 76 onwards have the locked shafts, i am told that earlier ones can wear the cover holes oval but i have yet to see one, you can sort of lock the early shafts by putting an O ring in the end bore before fitting the end cap
Do you need to lock the shafts in place and will my current breather cover fit
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BTW your crank journals look really good, hope mine are that good when I pull the bottom end apart.
I agree with Murf it certainly looks as though you just need to fit the right colour shells.
Have you managed to find any paint remnants at all Acro?
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If the end was not broken out allowing the shaft to move inwards too far it would be ok but as it is i would say not
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BTW your crank journals look really good, hope mine are that good when I pull the bottom end apart.
I agree with Murf it certainly looks as though you just need to fit the right colour shells.
Have you managed to find any paint remnants at all Acro?
Not yet Ted it will be Friday until I get chance to have a go and see if I can see anything, and it's doing my head in not being able to solve the problem straight away 🤣
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Have you tried looking for the size codes on the crank?
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Hi Bryan
The only thing I could make out on the crank was A1, and the code on the back of the crank case is BBBBB. I am going to give everything a good with petrol and a soft brush and see if that reveals anything else
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You should find 4 letters and 5 numbers, sometimes on different webs sometimes all on one
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The markings can be like a sort of invisible ink - catch the crank web in the right sort of light and you might find them - some light sources are better than others - my garage is LED strip lighting.
When I found some of mine I tried to take a photo - it just did not photograph being so feint.
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Definitely a 1 on four of the webs and an A on three of the website. But will see if I can find anymore after giving it a wash and trying different lighting.
Is it 4 letters and 5 numbers on each web or is it 4 letters and 5 numbers in total spread across all the webs
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It might be worth trying to get hold of a pair of Brown shells for your mains then using Plasigauge see what the clearances are. Likewise a pair of maybe green big end shells & do the same before you splash out on a full set.
I'll have a look in the morning to see if I kept any of my old used marked mains shells.
Can't help with big ends as I had to buy a used crank that came with good big end shells & conrods.
I'll PM you if I find still have them.
PS After talking to a member who is currently suspended he told me If you do find a colour on the mains shells the odds are that if all the shells have the same batch number chances are they are all the same colour as well. Same logic for the big ends.
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Its a letter and number for each combination so as 5 B on case will be 5 numbers on crank, which means 4 letters for big ends so no confusion on crank therefore letters on conrods, you will find numbers on rods as well which are weight codes.
It is all explained in the workshop manual downloadable from ashs dropbox/alladins cave.
I have for my use built an engine with all black shells and run it in carefully, the tolerances quoted by Honda, as i understood the tech talks, are so that a new engine does not require the carefull running in of old but only bedding in before using hard, in fact Kawasaki with the Z1000 fell foul of people treating them too gently to start, glazing the bores and so burning oil. They were reboring under warantee and telling owners not to molycoddle the motors
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If you use petrol to clean the crank webs you should just be able to make out the codes with a bit of luck but it can be very difficult to see as they are feint and you have to move the crank around in the light to see them and maybe use a torch as well. I had one crank where I couldn't see them at all.
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I've sent you a PM I only have a pair of used Green Mains for a 500 for you to try for size using Plastigauge, sorry no used Browns or used big end shells with markings.
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Thanks Ted
I have sent you a reply
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I've sent you a PM I only have a pair of used Green Mains for a 500 for you to try for size using Plastigauge, sorry no used Browns or used big end shells with markings.
Used shells won't give accurate clearance information because of the wear on them. New shells should be used to get accurate information.
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I've sent you a PM I only have a pair of used Green Mains for a 500 for you to try for size using Plastigauge, sorry no used Browns or used big end shells with markings.
Used shells won't give accurate clearance information because of the wear on them. New shells should be used to get accurate information.
Agreed but if a set of half decent used Green shells give you a clearance of say 55 microns you can be pretty confident that a set of Browns will be good. Likewise if your clearance with used Greens is 38 microns then Greens are good!
I've lent a sohc member here some used 400 shells previously - it worked for him as a starting point.
Paying out for a new set of Greens to find you need Browns is an expensive exercise if you have no legible shell colour markings. I would not have offered my shells if they were badly worn. One set out of three Greens I kept for such future use for myself or to help a member here.
If a member here has a spare set on new unused shells to sell at a reduced price or to lend out then clearly that would be better still.
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The numbers or letters are can be really indistinct, just scratched on, I think it was just a production line thing and not for the rebuilder 40 years later. In general one colour will dominate but you can’t rely on that. Look on the side of the shells for any trace of colour. Get a magnifying glass and a torch and check the parts at various angles to see if you can find the marks or numbers. On the CBX they used a mixture of letter, numbers and Roman numerals!!! If all that fails Getting a new pair of shells as a test set is a great idea.
But have checked the original bearings yet because if they are ok then you don’t need to worry about all this. I know it’s nice to change everything and have a virtual new engine, but I also think you have to take into consideration of how the bike will be used in the future. If you are going to thrash it or go long distance touring then change the bearings. If you are going to give it a nice quiet life with regular oil changes etc then maybe it’s ok on the old bearings.
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After cleaning the crank with petrol and WD40 and then trying various different lighting in the garage and the garden (My wife thinks I have finally lost the plot). I can defiantly make out four number 1s on the crank, and from my crude measurement of the journals 33mm this seems to correspond with workshop manual for the crank being a number 1. I haven't been able to find any paint on the shells yet, thought maybe I found some brown paint but think this is just burnt on oil as it mostly rubbed with a bit of petrol/degreaser and a paper towel.
just waiting for the plastigauge to be delivered so I can check the clearance between the crank and shells.
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Any tips on getting the paint of the cases?? mine appears to have been painted silver, then black. the black comes off really easily it just wipes off if sprayed with WD40 or a bit of petrol. but the silver seems to be far better quality (assuming this maybe factory). I was thinking possible paint stripping??
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I used Paramose Paint Stripper - it's for trade use only as it contains some nasty chemicals that work. Modern over the counter stuff like Nitromoors are imho useless.
You will need to use the right safety gear, right mask, eye protection plus appropriate long chemical resistant gloves. It's nasty stuff hence the restriction on retailing.
Once down to bare metal after washing off I used wet a dry to remove any bad surface oxidation.
After painting the cases silver - oven baked to cure.
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I used Paramose Paint Stripper - it's for trade use only as it contains some nasty chemicals that work. Modern over the counter stuff like Nitromoors are imho useless.
You will need to use the right safety gear, right mask, eye protection plus appropriate long chemical resistant gloves. It's nasty stuff hence the restriction on retailing.
Once down to bare metal after washing off I used wet a dry to remove any bad surface oxidation.
After painting the cases silver - oven baked to cure.
I will have choose a day when the wife's not in to bake them as she will go spare with me 😂
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Has anyone got an idea as to were I can a 57mm ring set from as whoever put the engine back together last time left this and the 52mm one out. Which explains why drive socket seemed loose and moved in and out from the crankcase as the entire shaft was moving 🤦.
It's showing as out of stock on CMS website and DS don't list it. Done a search of the web and nothing comes up where it's in stock
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I think i have a 550 bottom end lying about and may be convinced to split it
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I think i have a 550 bottom end lying about and may be convinced to split it
Hi Bryan what would it take to convince you to split it or to part with the whole bottom end
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Energy!
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If Bryan can't be tempted to split that engine, we've got a box of assorted half rings here that I can look through.
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If Bryan can't be tempted to split that engine, we've got a box of assorted half rings here that I can look through.
Thanks Julie, if you could that would be greatly appreciated plus I need to buy a set of your brass swing arm bushes too.
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If Bryan can't be tempted to split that engine, we've got a box of assorted half rings here that I can look through.
Thanks Julie, if you could that would be greatly appreciated plus I need to buy a set of your brass swing arm bushes too.
I'll get Graham to have a rummage through the box and I'll send you a PM later.
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Please can I have some help understanding the clearances.
Just plastigauge my crank with the existing shells in and the reading is 0.050mm or 0.002 inches across them all but I have no idea how I use this information in helping select the right shells. The service manual says if they are in excess of 0.08mm or 0.0031 in they should be replaced which I am assuming mine are within the tolerance
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They are fine for tollerances, you just need to sort out what size the damaged ones were
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Your photo is showing the inches scale rather than the mm one - putting that aside the amount of "squash" (Derbyshire techical speak) on the Plasigauge looks pretty good to me.
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The clearances are within spec, but the crank journal looks ridged and marked. I would take the crank to an engineering firm for their opinion. Probably needs a regrind.
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The clearances are within spec, but the crank journal looks ridged and marked. I would take the crank to an engineering firm for their opinion. Probably needs a regrind.
Didn't think you could regrind these old Honda cranks?
My 500 crank was badly ridged found a decent replacement from DK.
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The clearances are within spec, but the crank journal looks ridged and marked. I would take the crank to an engineering firm for their opinion. Probably needs a regrind.
You can't feel any of them with your finger nail so they don't appear to be deep
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It might just be burnt oil (carbon) deposit on the journal - try cleaning it off with some Brasso cloth. I had it on my 400 big ends and on the conrod where the shells sit.
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No you cant regring Honda cranks, well technically you can but undersize shells dont exist!
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That’s strange on the first photo of the crank the journals looked very nice, now on the photos with the plastigauge they look really scoured, is it due to some strange light effects on the photo.
That apart it looks like the bearings are in spec.
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I think it's the camera on my phone and probably the grease I put on to hold the plastigauge in place. As when I cleaned it up afterwards the journals look really good
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As far as I'm aware you don't grease or oil the bearing when using Plastigauge - at least I never have.
It might even give you a false clearance value.
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The instructions with the plastigauge said to use a little bit of grease to hold the plastigauge in place
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I had no instructions so I did it dry.
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Just checked one the big end bearings with the plastigauge and not sure it's squished right or is it just how it's separated when taking the end cap off
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It does that sometimes. The outer measurement is unaffected.
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Are the brown main shells thicker than the greens, apologies I am still struggling to understand the difference thickness of them all.
Ted - you might have been on to something about the grease, I did them again yesterday without grease and on the original shells got 0.038mm this time and the new green shells I got to try was in between 0.038 and 0.050mm. having said that I am still not convinced its not me buggering it up, but its a learning curve.
On a positive note the big end shells where all bang on 0.038mm so I don't need to replace them.
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Black
Brown
Green
Yellow
Red
Abpve are the Honda shell colours in descending order of thickness, not all colours are used on all models.
Black is the thickest.
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Cheers Ted I will give a set of Brown ago