So this seems to be a common issue with Alusil coated Honda engines. Advice seems tor range from leave it to rebore/sleeve. I was after a bit of sensible advice on how to proceed.

this is my 99 900RR with 52,000 miles on the clock. Compression is fine on all cylinders and no major symptoms of oil burning etc. As prt of a winter project I decided to strip my engine right down to inspect after I had an issue with the vacuum petcock failing and filling the crankcase oil with fuel. I noticed the scoring to the cylinders on disassembly and found a lot online in similar positions.

I believe atleast 3 of the cylinders are 100% fine with just surface level/ aesthetic marks only. The one I am slightly hesitant about is cylinder 1 which is he same as the others but there is one very slight ‘score’ that isn’t deep enough to catch your finger nail on, but when running your finger over it you notice a slight change in texture to the smooth wall. I have seen many on eBay in a far worse state than mine.

As compression was good and there are no other symptoms, with the bike mileage and value in mind I am leaning towards reassembly and keeping an eye on things. As far as I can tell other options - sleeves, oversized pistons etc. will be incredibly pricey especially considering the age/mileage. Also with Honda no longer selling these parts it will be aftermarket only.

Just wanted to see if anyone found themselves in a similar position and what they did?






Cylinder 1 (worst one)

Cylinder 2 - only surface level so think fine.

Cylinder 3 - same as cylinder 2
[img alt="Cylinder 4 - similar to cylinder 1 but completely smooth to touch.
"]https://cimg0.ibsrv.net/gimg/cbrforum.com-vbulletin/2000x1504/img_9984_549653b961fa8b668eb2031592c2be8fa9da4541. jpeg[/img]
Cylinder 4 - similar to cylinder 1 but completely smooth to touch.

 

I’m a great believer in “if it ain’t broke, don’t fix it” - if the compression is good and it’s not burning oil then leave well alone.

 

Sounds good to me… cheers!