GS425L with long brake lever travel.

[Guest]

My son just picked up a 79 GS425L and the front brakes are really bad.

A good stiff squeeze will bring the lever in contact with the grip and this amount of travel does not produce anywhere near sufficient braking effort. Slows you down somewhat but scary indeed. The system has been bleed with no change.

I noticed that the master cylinder is not the OEM unit. By all apperances it is this unit http://www.ebay.com/itm/FRONT-BRAKE-...c6767b&vxp=mtr

The above unit is advertised as having a 12.7mm bore. It is my understanding that the OEM unit had a 14mm bore?

Could this smaller bore be the cause of my long lever travel?

I am also suspicious of the rubber lines swelling as I can feel them bulge ever so slightly when I squeeze the lever.

Perhaps a combination of these two factors?
I may get SS lines regardless but I would also like to determine whether this smaller than stock bore is a killer.
Should I also be looking for a different MC?

Thanks!

[BassCliff]

Greetings and Salutations!!

Hi Mr. bjones,

Stainless steel braided brake lines will certainly help. So will rebuilding the calipers and master cylinder. There may be a bubble trapped behind the plunger that the lever pushes. Of course, the proper master cylinder is also very desirable. I'm sure you can find a new aftermarket unit if you aren't concerned with keeping the bike 100% original.

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[pete]

Hey mate, the rubber lines are a definite throw out item.

Replace with braided steel lines and you won't look back!

While you're at it, give the master cylinder and caliper a really good go over and make sure everything is in top notch condition.

The piston and seals in the caliper should still be available from Suzuki for a reasonable price if they're looking a little sad.

You're right that the stock M/C is 14mm bore. I actually replaced mine with a 13mm bore which gives me a bit more feel at the lever but there is definitely increased lever travel to go with it.

I have a braided steel line on it and while I get the extra lever travel it's nowhere near coming back to the 'bar.