Here's my 2 cents. Hope its helpful.
BRAKE & CLUTCH BLEEDING
First of all, it is my understanding that bleeding means to remove air from the system, whereas flushing means to remove all of the old fluid and replace it with new, clean fluid. In the text below, I am talking about flushing the system, even though I dont use the word flush.
Also, for clarification, I assume that the reference to left side or right side is the same as your left or right if you were sitting on the seat looking forward.
Below is a rough summary of Hondas instruction as how to fill and bleed the brakes. Ill then discuss how I filled and bled my brake system.
In the Honda VTX 1800R Service Manual (part # 61MCV01), page 15-4, Honda describes how to drain the brake fluid. I will skip over to the next page where Honda describes how to fill/bleed the brake fluid. They first describe how to fill the FRONT master cylinder (located on the handlebar next to the front brake lever). They recommend using a brake bleeder tool. My assumption is that they are talking about a vacuum bleeder such as a MityVac. They say to connect the bleeder to the upper bleed valve on the front brake caliper. Note that they describe bleed valve in the singular but in fact there are two upper bleed valves, one on the left front caliper and one on the right front caliper. The upper right bleed valve has a 8 mm hex nut, and the upper left bleed valve has a 10 mm hex nut. Your guess is as good as mine as to why they are different. They go on to describe pumping the bleeder (they do not say to what pressure) and then loosen the bleeder valve. Add fluid to the master cylinder as the fluid is being drained out, to keep it from drawing in air.
Ill skip the next part, where Honda describes on page 15-6, how to bleed the front master cylinder for those who do not have a brake bleeder. Im going to assume that you have a vacuum bleeder.
The next section, on page 15-7, describes filling the REAR (linked) master cylinder, which is located on the right side of the engine just above the rear brake pedal. Note that the REAR master cylinder links the front and rear brakes simultaneously when the brake pedal is applied. I assume this is to provide optimum power braking, considering the beast weighs 800 lbs. Anyway, they describe the following sequence for filling/bleeding the linked brake lines:
1. Right side caliper lower bleed valve
2. Left side caliper lower bleed valve
3. Rear caliper lower bleed valve
Then connect the bleeder to the front caliper lower bleed valve. Again, note that they use the word valve in the singular, where in fact there are two lower bleed valves, one on the right front caliper and one on the left front caliper, which they alluded to above in their recommended sequence. The lower right bleed valve has a 10 mm nut, and the lower left has an 8 mm nut, just opposite of the top bleed valves. I have heard from other VTX owners, that air tends to leak by the 8 mm bleed valves, when they have been loosened and a vacuum has been applied by the bleeder. Pump the bleeder (again they do not say to what pressure) and then loosen the bleeder valve. Add fluid to the master cylinder as the fluid is being drained out, to keep it from drawing in air. And last, do the same for the rear caliper bleed valve. There is only one bleed valve, located on the top of the rear brake caliper.
Below is the method that I used to bleed and refill (or flushing) my brake system:
Maybe Im wrong, but it seems that Hondas instructions for brake bleeding or brake flushing, is over-complicated based on what other VTX members are doing to achieve the same results. So heres the method that I used, which worked for me and apparently has worked for many other VTXrs. I am not a motorcycle mechanic, so if anything that I say is incorrect, please let me know, but it worked for me.
Again, just for clarification, Im riding a 2002 VTX 1800 Retro with spokes. Whether or not that makes any difference compared to other VTX models, regarding bleeding the brake system, Im not certain.
Honda says to start with the front brake master cylinder (on the handlebar). Others say they started with the rear master cylinder (lower cylinder just above the rear brake pedal). Some VTXrs say to start by bleeding the front lower left bleed valve, and others say to start by bleeding the front lower right valve. Since there doesnt seem be a consensus, I d started with the front master cylinder and bled the top bleed valve on the right front caliper first (as recommended by Honda), then the top valve on the left front caliper. After completing the two front brake bleed valves, I squeezed the brake handle, to make sure it wasnt squishy, and then reinstalled the reservoir cover. Then I opened the rear brake reservoir (just above the rear brake pedal), and proceeded to bleed the two front lower bleed valves, starting with the right side then the left, and then the bleed valve on the top of the rear brake caliper. Before I bled each valve, I removed the stock bleed valve and installed a Speed Bleeder valve size 8125L (8125L means 8mm hex nut x .125, and the L stands for Long stem). I used this size for all 5 brake bleed valves to be consistent. The website for the Speed Bleeders is http://www.speedbleeder.com/. The neck on the Speed Bleeder tubing connector is about 1/8 to 1/4 longer than the stock valve. This gives you a little longer neck to attach your drain tube to. Also, speed bleeders, which cost $7 each, have a built-in check valve that makes it easier to do the job by yourself. The check valve prevents air from getting sucked back in. The Speed Bleeders also come with a sealant on the threads, which helps to prevent air from leaking around the threads. I noticed when I removed some of the stock bleed valves (but not all), that they had no sealant on the threads. Again, an inconsistency on Hondas part. Also, I used an aluminum Mity-Vac Series 4000 Silverline vacuum pump ($44.52 on sale now). The website is http://www.thetoolwarehouse.net/shop/MIT-4000.html. You may be able to purchase this same pump at Sears. The aluminum Mity-Vac is more rugged than the plastic ones of course, and includes a vacuum gauge so you can watch the vacuum drop as you suck the fluid out of the brake lines. In my opinion, the Mity-Vac is a must have. Otherwise the job could take you forever, or simply fail.
Wrap an absorbent rag or paper towel around the perimeter of the brake reservoir and the bleed valve to collect any overspill. Wipe up any drips or drools quickly. This stuff doesnt like paint. ALSO, BE SURE TO COVER YOUR GAS TANK OR ANY OTHER VULVERABLE SERVICES, TO PROTECT THEM FROM DRIPPING BRAKE FLUID.
Each time you squeeze the Mity-Vac, refill the reservoir with new fluid. Oh yeah, I used Valvoline Synthetic Brake Fluid. Keep checking the reservoir so it doesnt get too low, otherwise it will allow air to be drawn in. HINT: Get the reservoir on the handlebar level by temporarily loosening the handlebar and rotating it until the reservoir is close to level (but dont do this with the reservoir open). Youll have to loosen the four allen-head bolts on the risers. Mark the handlebar position relative to the risers with a magic marker before you rotate it, so you can return the bars to their original position.
With the clear drain tube attached to the speed bleeder valve, you can also pump the brakes to force fluid out, instead of using the vacuum pump. This is a slower method. Whether you use the vacuum pump method or the pump the brakes method, keep bleeding the valve until the fluid runs clear and has no bubbles in it, then close the valve until it seats. Be careful not to over-tighten the speed bleeder.
Now that youre an expert, do the same thing for the one clutch reservoir and the one and only clutch bleed valve, which is located under the large chrome cover on the left side of your X, directly above your kickstand. BUT .you will want to purchase the Speed Bleeder valve size 8125 for this valve, because the 8125L is too long.
For this brake bleeding job, keep plenty of clean rags and paper towels handy. It can get messy. And dont forget to cover the painted parts.
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