Bad brake master cylinder - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 10 (permalink) Old 07-27-2009, 04:41 PM Thread Starter
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Bad brake master cylinder

I recently turned my 86 Vulcan 750 in just to get checked out since buying some months ago. I was told the Master cylinder is not keeping pressure so they wanted me to purchase the entire assembly, $276.00. I was told Kawasaki discontinued this part any suggestions on where to purchase this part? They are also charging 75.00/per hour, Is this easy enough to change out for a beginner? The shop also said that it could be the viewing window being sealed with epoxy, Could this be the problem?
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post #2 of 10 (permalink) Old 07-27-2009, 04:53 PM
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I recently turned my 86 Vulcan 750 in just to get checked out since buying some months ago. I was told the Master cylinder is not keeping pressure so they wanted me to purchase the entire assembly, $276.00. I was told Kawasaki discontinued this part any suggestions on where to purchase this part? They are also charging 75.00/per hour, Is this easy enough to change out for a beginner? The shop also said that it could be the viewing window being sealed with epoxy, Could this be the problem?
Lots of gaskets and such that make up the master cylinder, so it could be a number of places. Might be a wrong assumption, but are you losing fluid along the way?

You can buy a master cylinder rebuild kit (I saw one on eBay recently - I'll see if I can find it); you can also purchase used MCs on eBay; I also have a used one off an '85 that I could sell you for $35 shipped.

As far as changing out the MC, it's not too difficult for a beginner, and there are plenty of folks here who could walk you through it. A couple of things to keep in mind:
1. Brake fluid is ridiculously corrosive, so you'll want to cover any and all painted parts. Or even non-painted parts.
2. The front brakes are a closed system - once you empty out the old brake fluid, you'll pull the master cylinder off. Put the new one on, and the you'll do the brake bleed/refill as has been posted elsewhere here. It's messy and you need to be patient, but it's a straightforward process.
3. How do your brake calipers look? Jsut wondering if there's somewhere else in the system that might be the source of the trouble.
4. Where are you located? There might be one of us nearby who could lend a hand, if you need it.

C
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post #3 of 10 (permalink) Old 07-27-2009, 05:02 PM Thread Starter
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It's not leaking anywhere, when they did the diagnostic on it they said loss of pressure so they wanted to change out the whole system. I'm in Virginia Beach, VA. Don't know alot about motorcycles, but it doesn't sound that difficult. They didn't say anything about the calipers. Thanks for responding.

T
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post #4 of 10 (permalink) Old 07-27-2009, 05:14 PM
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Doesn't sound like they know alot of about bikes either.

"A loss of pressure so replace the whole system"?

A vague problem and replacing everything to fix it is odd, especially in the simple brake system where alot of problems can be "repaired".

Hows the fluid level in the MC, and what shape does the fluid appear to be in? Dark? Dark and cloudy? Yellow? Clear? etc.

Do you have another place you can take the bike for a second opinion?
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post #5 of 10 (permalink) Old 07-27-2009, 05:31 PM Thread Starter
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The fluid level is good and not leaking anywhere, it isn't clear though. Dark.

T
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post #6 of 10 (permalink) Old 07-27-2009, 05:45 PM
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So there's some crud in the brakeline - not unusual on an '86. Maybe -since there's no leak - see if you can bleed the system first and refill with fluid? I have to agree with Doug, that the shop may just be way off-base with this one (I know, I know - shocking!).

C
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post #7 of 10 (permalink) Old 07-27-2009, 07:05 PM
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You can get rebuild kits for about $35.00, look at the vendor's page for a place I posted there called cyclebrakes.com They have the kit and while you're at it get a set of SpeedBleeders, you can bleed the brakes yourself with these. Sounds like you need to really clean out the MC to me. I would start there. Check all your connections and make sure you aren't losing fluid anywhere else. You can buy a new MC at cheapcycleparts.com for about $100.00 or so, but a good used one is all you need! I have 2 for later years, they are round and not rectangular, but will work fine on your bike. Crobins365 has one too that is closer to the year of your bike. Send me a PM if you need to be walked through the process, I've done it on my bike a couple times, it really is not difficult. I'd certainly put a rebuild kit in a used MC so everything internal is new. The dealer you went is smoking something, sounds like he wants you to be his personal bailout!

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post #8 of 10 (permalink) Old 07-27-2009, 07:42 PM
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The dealer you went is smoking something, sounds like he wants you to be his personal bailout!
LOL

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post #9 of 10 (permalink) Old 07-28-2009, 03:42 AM
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Quote:
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The fluid level is good and not leaking anywhere, it isn't clear though. Dark.

T
The piston/o-ring assembly is bad, it's an internal pressure leak. Get a rebuild kit, they are easy to do. You can use a 91' and up M/C.


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post #10 of 10 (permalink) Old 08-02-2009, 06:42 AM
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try using dot 3 brake fluid if this wont work a master off agpz will do
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