Agreed, that the site I checked with isn't accurate. But it is a site run by a fully authorized Honda/Acura dealer, though, and everything in their catalog is genuine Honda/Acura stock.

I also obviously agree with you that the staff at this dealer site messed up the SKU transcription. But I continue to maintain that Honda's part numbering system is a problem here. A part that looks similar but isn't functionally compatible needs to have not only a different part number, but a visibly much different part number.

And other non-part-number codes should not be shared across similar-but-incompatible parts. Both the GSR and the Type R belt say "126RU26" on them, in the largest lettering on the belt. Easy to make a mistake.

The LS/RS belt says "125RU26". That reflects good practice. Greatly reduced risk of a mixup with a GSR 126RU26 unit.

If they had carried over that nomenclature and changed the leading numeric, I would have looked at my old GSR belt, which says "126RU26" and then looked at the R belt saying "127RU26", and that would have been much more obvious. And I probably wouldn't have wasted any time at all on this matter.

As noted, other people are obviously experiencing the same confusion as I did (including probably some parts desks in the dealer network).

As far as ebay goes, I've bought lots of parts there and have only rarely had bad experiences. I have never been burned by any seller with 100% positive feedback and over 50 sales. People who have worked that hard to build a good record are pretty protective of it.

Anyway, following up on the trick to artificially tighten the belt by pulling on the tensioner spring during the tensioning procedure -- it seems to have worked as intended. Engine has been running fine and making good power from idle to redline. I'm still mildly nervous about pushing this hack hard, and I will probably put a proper GSR belt in the engine in a few weeks, but for now the car runs happily.

 

lets think about those numbers.
the LS/RS belt is a non-vtec head
the GSR is a VTEC head
the ITR is a VTEC head

in fact the GSR and ITR head are very similiar, and are also probably of a similiar casting. meaning that is why they have the same initial part #

but again ITR definitely has different cams, so i would imagine that small differences between two similiar motors...like cams or cam gears...would translate into a small numerical difference in part numbers.

~boom

 

Maybe a CRX engine belt? It's a B-series with Vtec and the deck is just a weeee-bit taller than the GS-R and the Type-R.

Good luck on the tapping problem. My car suffered from this for about a year until I finally got so tired of it and the shoddy machine work I had done to try to fix it that I had to junk the block and bought a B18C from japan. Keep looking though. Ensure your valves are checked good and that there's no flat spots on the cams. Compression and leakdown checks are great too. Take a crack at it and don't get frustrated. It's general advice, but it's very easy with a problem like this to get frustrated and start making mistakes.