some questions

ok speaking of Yz400 maintenance I have some questions. First of all Ive had my 99 yz400 for 5 seasons now, I am the second owner and have been meticulous with maintaince, oil changes,valce checks etc and I know the previous owner was too. She has been bullet proof for me year after year. I have replaced the timing chain 2 years ago(preventative maintenance), i have replaced all bearings at some time or another(wheel, swing arm, shock, steering head) as part of maintance I replaced the clutch 2 years ago but that was just preventitive the old one was still ok.

so here is my plan, I was thinking about going for a new yz450 originally but that would cost me excess of 7grand plus id have to enduroize it like ive done to my yz400(i wouldnt get a WR 450 cuz i don't like them) anyways my new plan is to keep my old reliable 400 that i still love but to give her an overhaul so she feels like i have a new bike(ok i know it won't feel as light but thats ok cuz there is no money in womens' racing here in canada). I am planning on replacing the piston,rings, not becuase i have any problems but just to freshen it up and prevent a failure in the middle of the year, i figure next season is its 8th season and its original so it can't last forever i got a good deal on a Weiseco piston kit on ebay.

question #1 how many ppl with a yz400 are still on original piston? how long do these last with regular maintenance?

question #2 now ive never had any troubles with my valves, always been in spec, should i replace them with titanium or just new ones while i have it opened up and doing work on it? when replacing valves themselves does that mean replacing the guides, springs and everything else as that goes with them as well, should i replace all valves with the new piston

question #3 boyenseed quick shot accelerator pump? is this a good addition? anyone have one is it worth the 80bucks?

question #4 Im for sure going to an auto decompression cam does it make a difference whether i go with the yz450 stock exhuast cam or should i go with HOTCAM ....i know price is a bit cheaper for the stock yz450 cam i think?? I can get a new HOTCAMS exhaust cam for 134.99 .further to that is it best to get both intake AND exhaust or is just the exhaust cam ok?

guestion #5 what other things should i do while i am planning all this work?

question #6 I did the timing chain replacement and valve checks my self with no problems, is it that much harder to get down to changing the piston and rings, im contemplating doing this myself what special tools would i need? I am mechanically inclined and have many of the tools already but ive never done a piston change before....

question #7 does the NGK iridium spark plug make a difference in performance? better for the bike?

ok speaking of Yz400 maintenance I have some questions. First of all Ive had my 99 yz400 for 5 seasons now, I am the second owner and have been meticulous with maintaince, oil changes,valce checks etc and I know the previous owner was too. She has been bullet proof for me year after year. I have replaced the timing chain 2 years ago(preventative maintenance), i have replaced all bearings at some time or another(wheel, swing arm, shock, steering head) as part of maintance I replaced the clutch 2 years ago but that was just preventitive the old one was still ok.

so here is my plan, I was thinking about going for a new yz450 originally but that would cost me excess of 7grand plus id have to enduroize it like ive done to my yz400(i wouldnt get a WR 450 cuz i don't like them) anyways my new plan is to keep my old reliable 400 that i still love but to give her an overhaul so she feels like i have a new bike(ok i know it won't feel as light but thats ok cuz there is no money in womens' racing here in canada). I am planning on replacing the piston,rings, not becuase i have any problems but just to freshen it up and prevent a failure in the middle of the year, i figure next season is its 8th season and its original so it can't last forever i got a good deal on a Weiseco piston kit on ebay.

question #1 how many ppl with a yz400 are still on original piston? how long do these last with regular maintenance?

question #2 now ive never had any troubles with my valves, always been in spec, should i replace them with titanium or just new ones while i have it opened up and doing work on it? when replacing valves themselves does that mean replacing the guides, springs and everything else as that goes with them as well, should i replace all valves with the new piston

question #3 boyenseed quick shot accelerator pump? is this a good addition? anyone have one is it worth the 80bucks?

question #4 Im for sure going to an auto decompression cam does it make a difference whether i go with the yz450 stock exhuast cam or should i go with HOTCAM ....i know price is a bit cheaper for the stock yz450 cam i think?? I can get a new HOTCAMS exhaust cam for 134.99 .further to that is it best to get both intake AND exhaust or is just the exhaust cam ok?

guestion #5 what other things should i do while i am planning all this work?

question #6 I did the timing chain replacement and valve checks my self with no problems, is it that much harder to get down to changing the piston and rings, im contemplating doing this myself what special tools would i need? I am mechanically inclined and have many of the tools already but ive never done a piston change before....

question #7 does the NGK iridium spark plug make a difference in performance? better for the bike?

#1...typically top end must be changed at some point 100-150hrs? or more on your bike.....if original - time to change - also do cam chain and tensioner at the same time

#2 ... check valves for wear, check valve seats for wear....if there is excessive wear - replace...I have seen valves break with too much wear...this gets very costly..cheaper to relpace

#3 not sure quickshot is available for 400 (if it is it is worth 80 on a 400)....BK mod did similar fix for these...also check diaphram for dirt build up...these were notorious for this - dirt behind rubber boot/diaphram shaft

#4 cam mod is good choice if you keep bike -

#5 patience is key - also have a budget as you can go overbored on a older bike like this

#6 - you can do this yourself - valve train/valve seat replacement take to reputable tuner

#7 - I never had much better luck with Iridium plugs....CR8E is fine and less money

thanx, i did the cam chain but not the guide and tensioner cuz it looked brand new still?? so i left it i will check it again when i pull her apart this winter.

yes they do make a boyenseed quick shot AP cover i just bought it now so Im gonna do that too.

thanx for the info .....hoping all get everything by january and can start pulling it all apart.

i know the local shop well i'll have them do the valves if need be..

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