Sunday, February 12, 2017

More wrenching on the ST

More winter maintenance -

Been working a lot of hours at work this winter, but have still been making it out to the garage as often as possible. Working on getting the Mighty ST ready for spring. This mild winter has me thinking I'll be out on the road in March. Things are coming along.


The ST is known for having issues with the SMC - Secondary Master Cylinder. The part has been revised with an updated part number also, although I'm not sure of the details. Anyway, figured since my ST is at 82,500, might as well slap a new complete unit on the bike.

Below is a picture of the unit. The whole silver bracket complete with the SMC towards the top. Note the plunger on the SMC with clevis that bolts to the fork leg.


The ST's linked brake system is pretty complex. The SMC resides on the left front brake caliper. When the front brakes are applied, the caliper slightly rocks and depresses the plunger on the SMC which in turn applies the two outer pistons in the rear caliper.

Occasionally, the SMC piston has been known to hang up in the bore and not fully release the rear brake, creating a dragging condition. Sometimes even a wheel lock-up.

The ST has some serious brake lines and banjo fittings going on. Bleeders too. This is all on the left front caliper.


Bought a large bottle of brake fluid and commenced to going through the bleed procedure on the whole bike - front and rear. There are seven bleeder valves on the ST ! There is a specific sequence to be followed also.

Continuing on with the "Heat Reduction' mod, the underseat area was addressed. I fed insulation under the frame from the airbox area on top of the lower fuel tank. Then added another whole piece under the drivers seat, extending and doubling over the front area.

Before -


After -


Before doing the heat shield mod in the air box area, I totally removed the throttle body assembly. Let me tell you, it took some serious leverage to pop them out of the rubber intake boots - even with the clamps totally backed off and lube sprayed onto the edges of the boots.

Thorough cleaning and lubricating of the throttle body assembly was done along with the idle speed cable. This is notorious for seizing. One of the reasons for removing the throttle body assembly was also to peel back the rubber mat on top of the engine, exposing the water tube assembly and thermostat housing for inspection. The thermostat has already been replaced, so I just wanted to visually inspect for any coolant weeping at O-rings or hose clamps. No problems detected.

The alternator also resides under the mat, right on top, in the vee, in the center of the engine. I wanted to take a look at it while things were ripped down, so I know what is involved if it ever needs replaced. Hopefully it does not need any attention for many years as they are very expensive. I've heard of them failing at 65,000 miles, but I've also heard of them never failing - even past 200,000 miles.

With everything back together, new Fleetguard ES Compleat coolant was installed in the cooling system. Only the best big rig coolant for the king of the interstate.

Now it was time to perform the Starter Valve Synchronization before wrapping up the top of the bike.

An old friend of mine gave me a rail of antiquated vacuum gauges years ago for syncing carburetors or throttle bodies. He gave them to me in the 90's - and I'm pretty sure he was tuning bikes with them in the 70's. They even have the red plastic in-line squeezers to choke down the vacuum (pulse) signal, in order to stabilize the needle from bouncing.


Procedure has you disconnect and tap into the vacuum lines at the five way connector. I prefer to disconnect each line from the throttle body nipple and hook directly to the nipple. Either way things are tight. But the throttle body is solid and I prefer to manipulate the lines on and off with a long-handle pair of needle-nose pliers with a 45 degree tip, rather than deal with the loose five way connector buried within the plethora of vacuum lines and wiring.

With the upper fuel tank removed, there is much more room to work. The bike can be ran without the upper tank because the lower tank houses the fuel pump.

Warmed the bike up. Followed procedure - and dialed in cylinders 2, 3, and 4 to match cylinder 1. They were only very slightly out and while probably not necessary, I try to keep the ST in as high a state of tune as I can. It felt good to hear that buttery smooth V-4 again. Can't wait to get her out on the road.

A few days ago, a set of the 90 degree machined valve stems were ordered. The high quality Italian made ones from the vendors section on ST Owners Forum. Plan on installing them along with a fresh set of Pirelli Angel GT's. The 90 degree valve stems will greatly facilitate airing up the tires on the bike.

Very soon, an order to Cyclops will be made for another light upgrade for the ST. They have recently made available a 7000 lumen H-4 LED headlight bulb. Prior to this they were 3800 lumen. Going to pop a pair of these bad boys in before buttoning up the side fairings. A riding partner of mine is going to install a set in his FJR also.

No comments:

Post a Comment