Topic: Does my cylinders need boring? With pictures

[Nicolai]

Hi

I'm in the process of rebuilding my cb500 engine. I had hoped to avoid boring the cylinders because of a tight budget and only buy new pistons/rings. But after looking at the actual state of the cylinders I'm not sure if I can avoid boring them? What do you think? Do I need to take better pictures for you guys to judge?

[Nicolai]

I actually have a spare cylinder. Maybe its better?

[MCRider]

We used to do "overhauls" all the time which did not involve boring. Measure your pistons and bores (or have a machine shop do it, as it takes a bit of a "touch" and an internal gauge) If they are in spec, hone it (or have a machine shop hone it) with attention to not removing much material, ring it and go. Check the valves and guides, assuming they are OK (most likely) lap them in and go. Replace the guide seals. It'll be all perked up, You'll love it.

Don't let some minor scratches here and there bother you, it will be fine.

Unless you're looking for an excuse to do more...  

PS: A cheap way of checking your bores is to get a new piston ring, put it in each cylinder down about an inch from the top and 2 inches also,  and check the end gap of the ring in each cylinder. They should all be close and around 13thou inch (sorry no metric from me) check the manual for end gaps on a 500, may be less. Your ring may need to be gapped if its too tight to begin with, but the purpose of the exercize is to see if the bores are worn different from each other.

Once you get the ring in the cylinder, use a piston to push it further in to keep it level. Also oil up the cylinder a bit so the ring slides without scraping.

[strynboen]

er der en slidkant hvor stempelringene vandring slutter..hvis ikke ville jeg bare køre den gennem med en flex honer..og sætte nye stempel ringe i..
hvis det skal være mere prof..skal du montere en stempel ring i cyll..og måle ring gabet..og evt ovalitet i cylenderen..du kan finde data for slitage i værksteds bøger...men hvis den har kørt rimeligt..ville jeg bare flex hone den og give den nye ringe
jeg ville ikke være bekymret hvis der er nogle små prikker,,bare det er nede i den laveste del af cylenderen..
hvordan er stemplerne,,på min 550 var det ene stempel lidt buet i kronen af overophedening,,de bliver meget varme hvis kaburatorene køre magert

[Fritz]

er der en slidkant hvor stempelringene vandring slutter..hvis ikke ville jeg bare køre den gennem med en flex honer..og sætte nye stempel ringe i..

strynboen, your English has transformed into a real strange dialect  

Maybe I should take my CB north next summer, and learn how to cope with it  

[sandbarsurfer]

here i used translate to get basicly what he was saying...


is a hard edge where the piston rings hike ends .. if not I'd just run it through with a flex honer .. and put new piston rings in..
if it has to be more prof. you must mount a piston ring in cyll .. and measuring ring gap .. and any ovality in cylenderen .. you can find data for wear in the workshop books ... but if it has run fairly. . I just wanted to flex honing it and give it new rings
I would not be worried if there are some small dots, as long as it is down in the lowest part of cylenderen ..
how are the pistons in my 550 was one piston slightly curved in the crown of overophedening, they get very hot if caburator run lean

[MCRider]

here i used translate to get basicly what he was saying...


is a hard edge where the piston rings hike ends .. if not I'd just run it through with a flex honer .. and put new piston rings in..
if it has to be more prof. you must mount a piston ring in cyll .. and measuring ring gap .. and any ovality in cylenderen .. you can find data for wear in the workshop books ... but if it has run fairly. . I just wanted to flex honing it and give it new rings
I would not be worried if there are some small dots, as long as it is down in the lowest part of cylenderen ..
how are the pistons in my 550 was one piston slightly curved in the crown of overophedening, they get very hot if caburator run lean

I'd say that works.

[bryanj]

Fourth picture down sezs yes needs boring, need better pictures of "spare" cylinders to comment more

[Nicolai]

Thanks for all your help. I will take some better pictures of the second cylinder and post today.

[Nicolai]

Okay so here are some new pictures...don't know if they are any better. The new pictures are from my spare cylinder. What do you think...need boring?

[greenjeans]

I think MC hit the nail on the head.  That set looks much better to me than the first set.

I'll vote for just honing the cylinders and slapping some new rings on there.

[strynboen]

+1... sorry for my danish.. ::)renember to use the pistons who belong to that silender you use..
think ve danish sohc ,,and scandinavians alså must meet next summer,,i have an littel viking raid plan  vith  some norvegian sohc..vikings

[Sam Green Racing]

Fourth picture down sezs yes needs boring, need better pictures of "spare" cylinders to comment more

Fcuk me Bryan, I knew you were good If you're that good with a photo (a crap one at that) you must be brilliant with a micrometer.

Sam.

[tlbranth]

If there's no ridge at the top of the cylinders, I'd just hone them.

[Whaleman]

I must be missing something. Cylinders are bored for each piston. Can you really just take 4 standard pistons and switch cylinders and expect to have .0015" clearance on each one? I think the odds on that is small. Smarter people will know but I am not sure you can just change cylinders. Dan

[Sam Green Racing]

It's quite easy Dan, ya just take a picture of your cylinders, take it to the Honda shop and they will give you pistons to fit.
The machine shop do the rest.

Sam.

[Nicolai]

My initial plan was to take the best of the two cylinderservice and them buy a new piston kit...not switch cylinder and use the old pistons.

[Whaleman]

If you ARE going to bore to an oversize the condition of your walls (unless severe damage) does not matter. Dan

[Nicolai]

I was hoping not to bore, only hone and new piston kit.

[Whaleman]

Again, the chance of buying new pistons that have a .0015 clearance to your honed cylinder is almost impossible. If money is tight just do what others have said and lightly hone you origional cylinder, buy new rings and use your old pistons in the same holes. If you are going to buy new pistons and rings why not get .25 or .50 oversize. All you are saving is the boring charge. Dan

[bryanj]

I was comenting on the bad corrosion not the wear Sam!! as to getting pistons the same size if you can find any Honda piston that varies by more than .0001MM i will be very surprised, their quality control and machining is unbelievable.

Old adage is bore cylinder to fit piston but with all the jap motors i have done plus the more modern cars in UK (Hepolite pistons) you can say that the size it says it is is 100% accurate