Author Topic: Rear master cylinder questions  (Read 835 times)

Online desertR

Rear master cylinder questions
« on: May 28, 2018, 02:45:45 PM »
Since my R is not at my current location I have a couple of questions;
1. Does anyone know the bore (diameter) of the rear master cylinder ? EDIT cylinder is marked 14 and is a nominal 14mm piston (13.957mm)
2. Has anyone tried any of the newer CR or CRF rear master cylinders that have a built in reservoir ?
3. What's the bolt spacing where the master cylinder bolts to the frame ?

« Last Edit: May 28, 2018, 06:54:10 PM by desertR »

Online croat1

Re: Rear master cylinder questions
« Reply #1 on: May 28, 2018, 09:45:53 PM »,7294.msg66709.html#msg66709

Gene or Josh a little help please...

@JesseA420 made an adapter to use a CRF mater on our 250R's


Offline Action69

Re: Rear master cylinder questions
« Reply #2 on: May 28, 2018, 10:58:06 PM »
A guy on .net made a 3 d printed adapter .he sent me one to try.he did a thread on it with sizes and what’s needed.He designed it to use a late model master with built in Rez..he goes my madmorgan

Online desertR

Re: Rear master cylinder questions
« Reply #3 on: May 29, 2018, 03:46:30 AM »
OK, so I read all 22 pages here, and 50 pages on .net and have come up with more questions;
While most 450R/CRF/CR master cylinders are using an 11mm or 3/8" piston, they are operating with a single piston caliper.
The 250R uses a 14mm piston, and a dual piston caliper.
No one mentions any incompatibility with the caliper vs. flow needed to apply a dial piston caliper vs. a single piston caliper.
I do not want to increase pedal travel by using a smaller based master cylinder or worse, run out of flow due to piston travel/pressure because of same.....................
Anyone have any answers or input

Offline broken1

Re: Rear master cylinder questions
« Reply #4 on: June 01, 2018, 12:49:57 AM »
The TRX front master cylinder plunger is .050" smaller than the rear & it has to push 4 pistons so you'll be fine with the smaller 3/8" plunger in the dirtbike master cylinder pushing 2 pistons.
overkill is an often underrated achievement