ST 1300 Spark Plugs my 2 cents

Apart from lube and filters I'm not one to follow the recommended PM schedules. I checked my valve clearance for the first time last winter at 32,000 miles and I probably won't check them again until 90,000 miles. I did check a spark plug Denso U22FER9 when I did the valve clearance and it looked good so I put it back in. I have noticed a drop in mileage so I thought the book recommends 16,000 mile change on the plugs and I now have 35,000 miles so I changed them. What surprised me is the old plugs although they are at the upper end, the gaps were still in spec. I'm guessing I could have easily gotten 60,000 miles out of the stock plugs. I did replace the stock plugs with Iridium CR8EHIX-9 only because they were only a $1 more than the regular plugs. I'm guessing the reason for changing plugs is so they don't get seized in the cylinder. I can say mine came out with little effort almost like they were not even at proper torque but I guess 144" lbs is not much.

One thing I recommend and I will do in the future is have the cowls off the bike when I change the plugs. The #2 plug wire was tight to get off with the cowl in place but I got it. The #4 was even tighter and I noticed a little band of white glue or something around the end of the wire where it goes into the cap as I was pulling on it. It scared me enough to where I loosened the right cowl and lifted the tank to re attach the #4 wire to the plug.

The color and gap of the old plugs looked great so my next step will be to change the air filter. I only have 10,000 miles on the air filter but I guess that will be my next step to figure out what's causing my loss of mileage. My guess is these Iridiums will have at least 50,000 miles on them before I check them. I'll report back how well they came out of the cylinder when that happens.

Pay close attention to how long it takes to get to operating temp of three bars on the temp gauge.
When I first got my ST1300 it was still quite cool (50*F and colder) out and it took at least 8 miles to warm up. During that time the fuel consumption was poor. For whatever reason (and before I got to changing the thermostat) other than an extended ride with some pretty spirited (for me) riding it ever since has warmed up much quicker and have even run a few tanks over 50 mpg. The ST likes it warm.
Failed stats are common, especially on early production models. Failed coolant sensors can also send wrong data to the ECU with same result. Low coolant readings result in low mpg.
This is pretty well documented all over the forum, so probably nothing you didn't already know.
Of course, if your air filter ends up looking like this, a new one can't hurt either.

There are members here with 90k miles on original spark plugs.

I have over 100,000 on mine. I guess I will change them this winter. Probably overdue, Maybe?

I checked my valves at 60,000 miles and they were fine still no adjustments necessary, since I was in there I changed my spark plugs--seriously dont think they needed changing.

jettawreck said:

Pay close attention to how long it takes to get to operating temp of three bars on the temp gauge.
When I first got my ST1300 it was still quite cool (50*F and colder) out and it took at least 8 miles to warm up. During that time the fuel consumption was poor. For whatever reason (and before I got to changing the thermostat) other than an extended ride with some pretty spirited (for me) riding it ever since has warmed up much quicker and have even run a few tanks over 50 mpg. The ST likes it warm.
Failed stats are common, especially on early production models. Failed coolant sensors can also send wrong data to the ECU with same result. Low coolant readings result in low mpg.
This is pretty well documented all over the forum, so probably nothing you didn't already know.
Of course, if your air filter ends up looking like this, a new one can't hurt either.

Click to expand...

engine temp need to hit a certain parameter before the ecu and go into full fuel control mode (closed loop)

Worth reading, especially the second page.

--Mark

jettawreck said:

Of course, if your air filter ends up looking like this, a new one can't hurt either.

Click to expand...

Looks to me like someone helpfully packed additional aftermarket filtering media into your air filter. This can only improve the quality of air reaching your engine (what little that does...). And, it might even be scented with eau du mousse.

SMSW said:

Looks to me like someone helpfully packed additional aftermarket filtering media into your air filter. This can only improve the quality of air reaching your engine (what little that does...). And, it might even be scented with eau du mousse.

Click to expand...

Yep, the prior owner apparently had some house (garage) resident rodent guests. Vacuumed and blew it out with compressed air until a replacement was ordered.