Out of 4 belts on one character, I can only add Nitro Boosts to an iLevel 207 belt. None of my 385-496 iLevel belts are accepted in the interface, nor enchantable.
Nothing has changed on the Nitro Boosts tooltip to indicate an iLevel restriction; and other tinkers (e.g, Goblin Glider) function as normal, i.e., regardless of iLevel.
Very much hope this is an oversight.
Goblin glider enchant still works.
Same here.
This better be a f***ing bug, Blizzard.
This is no longer working for me. Boots I had just tinkered last week still show it. They all show red now when I try to tinker.
Edit: [Flexweave Underlay still works…/yay?} It does NOT work anymore. GRRRRRRR
This needs a response.
Really annoying that this is happening.
Me four. 
Interesting. Quite interesting.
Maybe a bug. Maybe they’ve implemented a ilevel cap because we’re supposed to start using an TWW engineering schematic instead. (Which doesn’t help us now, so I guess I won’t be replacing my belt any time soon.)
They’ve jumped the gun on level caps a lot these days. Legacy content rescaling for 80 instead of 70 and requiring 80 to walk into if their Heroic mode is a TWW rework, for instance.
Nitro boost is at LEAST 25% of why I am still an engineer. There has been no new utility added in a very long time. If this is intended I’ll be dropping engineering immediately.
PS Why cant engineers drop a summoning stone?
Response please! This is one of the only reasons to stay with this gold-sink of a profession.
Please revert this change if it’s not a bug; if a bug, please fix!
The change is not limited to Nitro Boosts. Removing an actual useful tinker is downright mean spirited. It took a lot of effort on my part to master all the expansion recipes.
If an alchemist can concoct potions that can turn one into dragons since… cataclysm?, and that hasn’t been nerfed… it’s just way unfair. Level 1 potions need to be nerfed.
Fair and balanced. Is that so much to ax for?
not working on any of my current belts either, this is a huge L for engy
I believe it might be a bug because I’m still able to add the Mind Amplification Dish to my belt, which is also from Northrend Engineering. THIS IS THE ONLY REASON I STICK WITH ENGINEERING!
Nitro Boost + Flex Underlay is something I’ve used since 2009…don’t end it.
Can we get some kind of answer one way or the other on this? It will effect which character I am maining going forward.
I’m able to add Nitro Boosts to various belts on various toons now! So this seems to have been fixed!