Neils 1978 CB550 F2 Project - Newbie Let Loose

[Laverda Dave]

Bryan or Nurse Julie can probably comment further but I am aware of the pistons failing on the edges like this as a result of previous owners ragging the engine before it is properly warm. You have likely caught it just in time, not sure if I would reuse them.

[Bryanj]

Thats probably due to corrosion, worst one where valve was open, will run for a 2-3000 mile a year fun bike, not good for one used daily and/or hard.

You could rering it and hone but hone may give too big a piston clearance.

Piston kits or rings from cruzinimage in japan, std same price as oversize so you pay extra for rebore and then its as new if you wish

[Neilw]

Thats probably due to corrosion, worst one where valve was open, will run for a 2-3000 mile a year fun bike, not good for one used daily and/or hard.

You could rering it and hone but hone may give too big a piston clearance.

Piston kits or rings from cruzinimage in japan, std same price as oversize so you pay extra for rebore and then its as new if you wish

I like the bike to run for probably less than 2,000 miles a year. I've broken the rings on 3 of the pistons, so you think I could get away with a light hone and std rings, keeping the pistons I currently have? The ones with the chips on the edge are a bit sharp, so can I just file those down a touch to remove the burr, or does that need to be replaced?

If i can avoid a rebore i'd like to.

When I removed the values, a couple weren't making a good seal, which I guess could be the cause. I'll lap those to improve things.

I'm new to all this, so I'd like to make a reasonable decision that gives me the best chance of having an engine without undoing everything. Your advice is greatly appreciated.

[Nurse Julie]

You need to measure the bores to work out if they are still within spec to use those pistons with new rings. Personally, I would not use those old pistons anyway, I would have a rebore and fit a new oversized piston / ring kit. If you try and cut corners or do things on the cheap, these old engines have a habit of coming back and kicking you in the backside.

[Neilw]

You need to measure the bores to work out if they are still within spec to use those pistons with new rings. Personally, I would not use those old pistons anyway, I would have a rebore and fit a new oversized piston / ring kit. If you try and cut corners or do things on the cheap, these old engines have a habit of coming back and kicking you in the backside.

Thank you, i assume i'd have to get a rebore on all the cylinders to keep things uniform?

[Nurse Julie]

You need to measure the bores to work out if they are still within spec to use those pistons with new rings. Personally, I would not use those old pistons anyway, I would have a rebore and fit a new oversized piston / ring kit. If you try and cut corners or do things on the cheap, these old engines have a habit of coming back and kicking you in the backside.

Thank you, i assume i'd have to get a rebore on all the cylinders to keep things uniform?

Yes, all 4.

[Nurse Julie]

Also, only get the rebore done by someone who understands Hondas tight tolerances. We've retired now but Bryan may be able to do it for you.

[Neilw]

Also, only get the rebore done by someone who understands Hondas tight tolerances. We've retired now but Bryan may be able to do it for you.

Other than Bryan, do you have any recommendations? Sorry for the stupid question, but would I just send someone the Cylinder head, or would they need more of the engine?

[Nurse Julie]

Also, only get the rebore done by someone who understands Hondas tight tolerances. We've retired now but Bryan may be able to do it for you.

Other than Bryan, do you have any recommendations? Sorry for the stupid question, but would I just send someone the Cylinder head, or would they need more of the engine?

You just pack the barrels in a box and send in the post, Parcel Force costs about £12, 48 hour tracked. It was very, very rare for us to see customers, complete engines were delivered by couriers on pallets and heads or barrels came by and were returned by normal post.

[Neilw]

Also, only get the rebore done by someone who understands Hondas tight tolerances. We've retired now but Bryan may be able to do it for you.

Other than Bryan, do you have any recommendations? Sorry for the stupid question, but would I just send someone the Cylinder head, or would they need more of the engine?

You just pack the barrels in a box and send in the post, Parcel Force costs about £12, 48 hour tracked. It was very, very rare for us to see customers, complete engines were delivered by couriers on pallets and heads or barrels came by and were returned by normal post.

 That's brilliant, thank you. I've just spoken to D&M Engineering who work on Classic Hondas, so fit the bill regarding experience.

[taysidedragon]

Also, only get the rebore done by someone who understands Hondas tight tolerances. We've retired now but Bryan may be able to do it for you.

Other than Bryan, do you have any recommendations? Sorry for the stupid question, but would I just send someone the Cylinder head, or would they need more of the engine?

You just pack the barrels in a box and send in the post, Parcel Force costs about £12, 48 hour tracked. It was very, very rare for us to see customers, complete engines were delivered by couriers on pallets and heads or barrels came by and were returned by normal post.

 That's brilliant, thank you. I've just spoken to D&M Engineering who work on Classic Hondas, so fit the bill regarding experience.

They will need the new pistons as well to measure the clearance accurately.

[Neilw]

They will need the new pistons as well to measure the clearance accurately.

Thank you. i thought it best that they supply them as they can get the correct ones to fit the work they do.

[Oddjob]

Personally I would not recommend that. From experience I know that firms take every opportunity to make as much profit as possible. So they’ll supply whatever they can find that makes the most money. They may last but most don’t. 2 years or so later and you need it done again due to a poor job. Do it once and do it right.

Try and find genuine pistons and rings if at all possible. Not as cheap as say Cruzinimage but better quality.

[Neilw]

Try and find genuine pistons and rings if at all possible. Not as cheap as say Cruzinimage but better quality.

I've had a good look for NOS oversize pistons and rings as a set, and i can't find any, most sites seem to sell pattern parts. i'll keep looking - are any of the aftermarket brands better than others?

[Oddjob]

Have you had the bore measured yet? First oversize 0.25 may not be enough to clear the bore, 0.5 might be a better bet. CMS used to sell the rings in that size although they come in non standard boxes even though they claim they are genuine Honda. I reported them to Honda for that. They are made by the same manufacturer as the genuine rings though. I did have some spare 0.5 genuine Honda pistons but can’t remember how many I have, at least 2 maybe 3.

The other alternative is to risk staying standard. They are shed loads of standard pistons around, second hand as well. Someone on here will have a full set after having a bore. Replace the pistons and buy some genuine standard rings, should be some of those around as well. Use a set of new standard rings and check the end gap and see what it comes out as, still in spec, stay standard. If out of spec then rebore the barrels.