I think the rear master cylinder died.

[katoranger]

I haven't ridden in about 3 weeks and I went out to start of the 2 and the rear brake was sticking. Cracked the bleeder and now I can't build any pressure. Resorvoir has plenty of fluid and was not low.

I think that the rear master may be done. I will have to see if I can vacuum bleed it but it may be time to see if I can do a honda conversion.

Allen

[culcune]

I think that was part of the reason Lifan went back to the rear drums on the GY-5's.

I know that Jetmoto has the parts on their site. My Jetmoto, right before taking its final dump, had lost its rear brake after sitting for so long. I would have ordered the part, but the bike went bye bye

[ejcycles]

Allen
I have some new master cylinders in stock... I'll see if they will fit the Lifan.

[katoranger]

I was doing research a few months ago when I was having troubles with it before and it looked like a master from a honda cfr230 I think might fit.

They looked close in design.

Bruce, let me know what you got.

Allen

[katoranger]

This is the rear master on the GY2.
http://www.chinariders.net/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=5385&g2_serialNumber=2

And this is one from a late model honda cbr600.
http://i20.ebayimg.com/03/i/000/d8/22/c7bc_1.JPG



The mounting points on both are opposite of the resevoir line and the clevis on the plunger is similar.

Might be close enough for a swap.

Allen[/img]

[AZ200cc]

Looks like the one my Maxfine had also, Probably a standard china part

[katoranger]

I am sure that most of the china bikes had a similar unit. I found that master on ebay and ask the seller to measure the mounting points for me.

I think most of the trouble being had with the rear brakes is caused by the master cylinder.

Allen

[fatboy250]

I think most of the trouble being had with the rear brakes is caused by the master cylinder.
Allen

Ours wasn't really a problem with the master cylinder, but rather the location in relation to the push rod for the the cylinder which was causing the brakes to not completly disengage.

Jason

[katoranger]

The master seems to have quit completely not. I have adjusted it out and that worked great for months. Now I either have some large air bubble in the line or the piston seal is gone giving me no pressure. I am going to try to vacuum bleed the system to see if the works.

I got a response back on the CBR master and the mounts are 1.75 inches apart. I will have to measure to see if that will fit.

Probably going to be my alternative if the bleeding don't work.

Allen

[katoranger]

I spent about an hour trying to bleed the system and I got nowhere. The master just won't build any pressure.

Anyonw have any suggestions?

Allen

[AZ200cc]

Is it leaking past the seal that You can tell?

[katoranger]

I think that is where the problem is. I some some air bubbles down there.

I believe I am going to try the cbr master and see if that works.

Allen

[culcune]

I spent about an hour trying to bleed the system and I got nowhere. The master just won't build any pressure.

Anyonw have any suggestions?

Allen

Not being too familiar with brakes, but having the exact same thing happen to my Jetmoto, the cylinders seem to give up, and you might as well replace it. I had priced one for under $40 direct from Jetmoto, but if the CBR one fits, you should be in business.

Like I said a few posts up, I think this is why A. Lifan went back to a rear drum brake!

[katoranger]

I believe that is what happen. I can get a honda one for about $20 shipped off ebay.

Probably last forever on there too.

They are lots of them on ebay. They don't seem to sell quick and it is probably because they don't break.

Allen

[AZ200cc]

I've never torn one apart, I wonder if it just uses an O ring on the piston.....Coudl be a simple rebuild job.

[katoranger]

It is probably pretty simple inside. I may have to take it apart and find out.

Allen

[culcune]

It is probably pretty simple inside. I may have to take it apart and find out.

Allen

I would still have the new one at the ready. Bruce would be a better source of information (heck, source of a cylinder, too!) on taking one apart.

[katoranger]

I plan to replace, but I can take the old one apart to find out.

Allen

[katoranger]

Just won a master on ebay. We will see what happens.

Coming from Florida so hopefully I will have it quickly.

Allen

[AZ200cc]

If You tear the old one apart I would be real curious what it looks like.
If it is truly easy to rebuild it would be a great thing for everyone to know...Could save some cash and time.

[montanaoffroader]

I've had quite a few small master cylinders apart and most of them had a piston with a cup type seal and a spring inside, nothing else. Pretty simple design.

[katoranger]

I will take it apart and post some pics. I have taken the fronts apart before and they are simple plunger seal ect.

Allen

[katoranger]

The CBR master arrived yesterday and I installed it this afternoon. Not an exact match, but close enough that slight modifications and it is working.

I had to trim the plunger shaft down and use the lifan pledal clevis. Also the mounting holes were alittle bit further apart on the honda unit so the holes need to be redrilled to mount it to the flange on the bike.

The stock hose attached directly to the master and I used the honda resorvior, but I had to attach it with a zip tie to the frame.

I need to do some more bleeding, but it is working.

Allen

[fatboy250]

Good to hear!

[katoranger]

I am still wondering if there is a more direct replacement from a jap bike. The mounting holes are only off by about an 1/8th inch and the stock screws threaded right in.

Allen

[fatboy250]

If I found something that fit even that close I'd consider it an upgrade either way.

[katoranger]

It is a definate upgrade. The pedal travel is better too. It only took me about 30 minutes to make it fit and be riding.

Allen

[katoranger]

The brake is dragging again. The master didn't fix the problem. I am wondering if the real culprit is the caliper.

Been trying to research out a direct replacement. The stocker appears to be a nissin copy and closely resembles those found on the front of a lot of dirt bikes.

THe mounts look close to those on CRFs, but reversed.

It also appears that I may be able to get a complete setup from a 125-450 CRF and bolt it on. The bracket looks to be of similar design and will place the caliper toward the front of the bike.

Just need to find out some more specs on the rotor size and axle size etc.

Allen

[fatboy250]

Keep us posted. This is very valuable information when we can start nailing parts down as to what they are copies of.

[katoranger]

I really need to go to a honda dealer on take some measurements. The local china bike seller also sells used Jap bikes and services them. He is pretty friendly and may be able to help me with some measurements.

Allen