It was completed yesterday, but the details continue below.
The biggest challenge is carburettor synchronization.
For those who remove the head cover themselves: the spark plug hole gasket has an integrated steel washer. This gasket usually stays on the head side, and when you pull it off, the steel washer remains behind.
If you carelessly tap this stuck washer, it can fall all the way down to the crankshaft’s camchain gear. It fits in there perfectly, almost like it was meant to. Getting it out requires removing the cam and so on, so be careful. We’ve had customers call saying they broke it this way, so it’s definitely something to watch out for.
Cylinder #2 seemed to be running a bit rough, so I checked the coil too. This is a story from a few Bandit 1200s I’ve worked on.
Slightly off? Not quite bad enough to call it that. I honestly couldn’t figure out this symptom no matter how many test rides I did. The customer would say, “It feels like the torque is a bit thin,” but I couldn’t quite put my finger on it.
When I checked the spark, it seemed a bit weak, but all four cylinders are firing, and the mileage is low, so…
We decided to try replacing the coil, and after swapping it out, it ran great! Wow, that really made a difference. It felt good. Since this happened on several bikes, I started wondering if there’s something specific about certain model years of the Bandit.
#1 IN
#1 EX
#2 EX
#2 IN
#3 IN
#3 EX
#4 IN
#4 EX
The valve clearances didn’t have any major deviations. There was no scoring, and the condition looked good overall.
There’s an image that adjusting valve clearance reduces valve noise and makes things quieter, but depending on the situation, it can actually get louder. You don’t narrow the clearance just to eliminate noise.
From experience, on bikes with rocker arm systems, wear between the cam and rocker arm is probably the main culprit. With rocker arm systems, the cam is asymmetrical, so when the rocker arm’s slider wears down, it develops play at a certain position, which seems to make the noise louder.
Replacing the cam and rocker arm with new ones often makes a dramatic difference in noise. The performance improvement might not be as dramatic though.
I was a bit disappointed because the clearances were surprisingly close to spec.
These days I don’t skimp and replace the cap too.
I happen to have breather covers from both a GSX-R1100 and a Bandit, so I wondered: can the latest gasket be adapted? Here’s the situation.
Basically the mounting pitch is the same.
The 1100 has an idler, while the 1200 has a tensioner (or slider?) to secure, so the center shape differs slightly.
It looks like it should work, but it doesn’t quite. The position of the upper wall is somewhat different.
So the gasket doesn’t seat where it should = blowby might increase. That’s the issue.
Replacing the entire breather cover might be the way to go.
I mentally traced the blowby path and thought, “Ah, I see.” The story wasn’t that interesting, was it?
While we’re at it, let’s clean up the coil color too.
Thinking ahead to the next time I remove it, I’ll use a label maker.
Once you start using a label maker, you realize you’ve gotten old. Sigh…
Waiting for the M8 bolt for the engine slider.
