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Front Brake Plunger


unicronicus
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not a clue!! call kelcoat in leek staffs and speak to Simon..

also check ebay listings (just a punt) that are bike specific the difference is from the 96 bike and 97 bike but i dont know which would be which??..

are they siezed? mine were and looked terrible but freed up quite easily.

Dan

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Does anyone know what the plunger size is for a 1997 gas gas jtx 250 to go inside the front brake master cylinder? A place that does them sells them in 20mm and 22mm variations.

Generally, 9.5mm. The 20/22mm is probably for a larger vehicle.

Jon

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Do you mean length or diameter? There is no way a 20 or 22mm diameter plunger will fit in the master cylinder. I think the others are correct about the bore being approximately 9.5 mm diameter. The length of 20 to 22mm makes more sense.

Unless the current plunger is completely seized you can probably remove the circlip and plunger and clean up the plunger and bore. It is fairly common for water and dirt to get inside the rubber boot causing rust which affects the operation of the plunger. A good cleaning will often fix most problems. If the rubber seals need to be replaced it might be better to get the rebuild kit that includes the plunger, seal, spring and boot.

Does anyone know what the plunger size is for a 1997 gas gas jtx 250 to go inside the front brake master cylinder? A place that does them sells them in 20mm and 22mm variations.

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Do you mean length or diameter? There is no way a 20 or 22mm diameter plunger will fit in the master cylinder. I think the others are correct about the bore being approximately 9.5 mm diameter. The length of 20 to 22mm makes more sense.

Unless the current plunger is completely seized you can probably remove the circlip and plunger and clean up the plunger and bore. It is fairly common for water and dirt to get inside the rubber boot causing rust which affects the operation of the plunger. A good cleaning will often fix most problems. If the rubber seals need to be replaced it might be better to get the rebuild kit that includes the plunger, seal, spring and boot.

He said "plunger size", which makes me guess he means bore diameter but there may be other measurements I'm unaware of. The 20/22mm measurement may be circlip stop to effective piston seal area rather than plunger length. A longer stop-to-seal measurement may not allow the seal to retract back far enough to clear the orifice connecting the reservoir to the bore, effectively resulting in a "closed system" unable to "self adjust" (like what happens when the lever adjustment is screwed in too far).

I'm guessing he needs the #BT27722208 kit (9.5mm bore, DOT-4) that fits the 97'-04' clutch/brake MCs.

Jon

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I will try and clarify this for you. The AJP 9.5mm seal kits http://www.splatshop.co.uk/ajp-master-cylinder-seal-kit-9-5mm.html are available with 2 different sized plungers, the piston in both kits is identical.

The plunger is the part that sits in between the piston and the lever. It fits in the rubber boot and has a spring around it.

For some reason different AJP master cylinders come with different length plungers over the years, most bikes use the 22mm plunger. Both kits will work, using the right length plunger will mean you won't need to adjust the free play screw on your lever.

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Hi, sorry I haven't replied in a while to my own topic! Splat shop, it was your shop I intended to buy this part from and yes I do need the 9.5mm diameter plunger, but I was unsure about the length. The front brake on the jtx works but when I was adjusting the lever the other day I noticed the plunger just kept coming out from the master cylinder and I could actually see one of the seals! My guess is that the circlip is missing or something so I may as well just get a complete service kit. This is where I got confused with the 20mm or 22mm plunger length, I didn't want to remove it to measure it without getting the part first. My ultimate goal was to get the lever closer to the throttle tube so I could easily use one finger to operate the brake, so I'm guessing 20mm will be better for me?

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