Rebuilding Carburetors – 1999 Nighthawk 750
Part 2: Carburetor Separation
The carburetors are off the bike – what next? In this post, I will explain how to separate the four carbs from each other. FYI, I took the photos while I put them back together – that explains why the carbs are so clean and shiny. They were much (much!) dirtier when I took them apart.
Before you do anything else, put a piece of painters tape on the top of each of the carburetors and number them like this – it’ll save you a lot of headache later:
The separation process begins by separating carburetors 3+4 from carburetors 1+2. Here’s how you do that:
1. Loosen the four starting enrichment valve arm screws and pull out the shaft:
2. The spring and three starting enrichment valve arms will come off once you pull out the shaft:
3. Remove the three carburetor synchronization screws and (upper) springs:
4. Take off the front bracket and the rear bracket.
In order to ensure perfect carburetor alignment, the brackets are installed with quite a bit of tension on the bolts – I wasn’t aware of this and it took an impact driver to get the bolts out:
The impact driver finally got the bolts out – not without stripping two of the bolts – I ordered OEM replacement bolts at BikeBandit.com (and clearly, this is not my arm …)
The bolts are installed in a very specific order – taking them off in reverse order might make things a lot easier – particularly if you don’t own an impact driver (my manual impact driver is one of my favorite tools – you can get one made by Craftsman for about $20). And make sure you use a screw driver with a large head (#3 works best). This is the reverse order:
Same goes for the rear bracket:
5. Once the brackets are off, you can easily pull carburetors 1+2 and carburetors 3+4 apart.
You will end up with two pieces: the carburetor 3 synchronization spring (left arrow) and the three-way fuel joint pipe (right arrow).
This completes the first stage of the separation process. Next, separate carburetor 1 from 2, and carburetor 3 from 4.
6. Gently pull each pair apart – you’ll end up with the carburetor synchronization spring (arrow), the thrust spring, the air vent pipe, and the two-way fuel joint pipe.
7. That’s it – the four carbs are separated and ready for disassembly. Make sure to keep all those itty-bitty parts and pieces in one safe place. I use plastic containers (with a lid) or Ziploc bags. If you loose any pieces, even just a tiny bolt, you might end up paying an annoying amount of money to replace them. Here is where I would buy OEM replacement parts – I ended up have to replace some of the big bolts I stripped when I tried to remove them in the wrong order.
This useful schematic from the service manual helped me keep track of where all the little parts belong (and, coincidentally, they are numbered in the order of disassembly – No. 1 and 2 are for California models only, by the way).
In the next post, I will do a step-by-step disassembly of the carburetor itself, clean it and replace some o-rings. And then: put it all back together as if nothing ever happened.