C-Dub

anyone have any idea why my 636 brakes get spungy after a hour or so of stoppies?? weak master cyclinder?? BTW all brakes are stock, stock mc rotors and calis...... is this common?

also i get a bog when i give it a full twist, **noticed this when i tried to get up to speed in first to pull a quick stoppie** i have ran sea foam through the gas, put in new CR8E plugs, fresh lucas 10-40 semi synthetic oil P.S. seems fine now and pulls alot smoother.... BUT!! before i did all this it was BADDD and back fired badd too.... i have a power commander a full yoshi exhaust from the header back, and the kleen air mod done...... after i did the Kleen air mod, it sounded mean, cleaner, more responsive to the twist, but i got a back fire, a slight bog, and a rattling and vibration under the tank..... ANY IDEAS??? thx for any input!

DARKS1D3

your rubber brake lines are heating up when used freq so its causing a expanding effect which will cause the spungy effect. look into some steel braided brake lines, galfer brake lines are highly recommended.

C-Dub

ahhh i see now, makes since. i looked up steel braided they are about $50 but ill look up so galfer lines nd see how much they run. appreciate the info...

DARKS1D3

pricey but worth it, just be sure to bleed your lines really good when u install neo brake lines.

C-Dub

no doubt, new lines im puttin fresh fluid, start fresh so there is no more problems. any idea on why it bogs? its really affected my low rpm wheelies, hence cant do slow wheelies, its got a power comander with a kleen air mod, didnt seem to do it til i did the mod.... could this effect it?

Sparky88

DARKS1D3 is right, but if your on a budget you could try bleeding your lines through with some high quality brake fluid. I'd be willing to bet that the old fluid has a little water in it and is boiling, turning to vapour giving you a sponge for a lever.

And about your bog. It's probably your power commander. Its Most likely a tuning issue eg running too rich. I've seen 90% of them **** up and your better off without it IMHO. Mind you I was a mechanic and I would rarely see people that didn't have any problems with them

Sparky88

What did the old spark plugs look like? That will give you a good clue on how she is running also...