bottom end and port

[desertdeweller]

How long do bottom ends usually last before needing a rebuild? I know it will vary from rider to rider and bike to bike.I am thinking I may be due to rebuild the bottom end. it is 10 years old 3 seasons of desert racing and practice, some flat track time as well, on it some dune trips never been apart 4 or 5 top ends though. I was thinking on going 4 mil with some porting. but the way they are talking around here on cracking down on decible noise and spark arrestors. I am not sure if there are any decent spark arrested silencers out there that wouldn`t kill those mods. currently I am running t-5s I have torn the bike down and replaced the bent frame and other worn out items shocks etc.. I was thinking since I have gone that far might as well tear into the motor. It runs fine just can`t make up my mind if I should and if it would be worth changing it. I mainly just trail ride it now might do some more desert races. but more power is always good :ermm:

[trex banshee]

How long do bottom ends usually last before needing a rebuild? I know it will vary from rider to rider and bike to bike.I am thinking I may be due to rebuild the bottom end. it is 10 years old 3 seasons of desert racing and practice, some flat track time as well, on it some dune trips never been apart 4 or 5 top ends though. I was thinking on going 4 mil with some porting. but the way they are talking around here on cracking down on decible noise and spark arrestors. I am not sure if there are any decent spark arrested silencers out there that wouldn`t kill those mods. currently I am running t-5s I have torn the bike down and replaced the bent frame and other worn out items shocks etc.. I was thinking since I have gone that far might as well tear into the motor. It runs fine just can`t make up my mind if I should and if it would be worth changing it. I mainly just trail ride it now might do some more desert races. but more power is always good :ermm:

 

as the old saying goes, if it aint broke don't fuck with it. :biggrin: check your compression to see if the topend is starting to go south. and if you gotta pull the top end off check the side clearances on the rod bearings. 10 years is a long time, ive got a crank in my black bike though that is out of a 2000 that is still completely stock and untouched and i ran it on alcohol and lots of timing and big porting with no problems, now the crank is back in my stock motor working great, so no tellin on yours just check the clearances on it. More power is always good though your right.

[desertdeweller]

The top end is in good shape it only has about 10 hrs on it. I didn`t check the crank the last time I had it apart, the compression was 165 and 164 with 19 domes.

[trex banshee]

The top end is in good shape it only has about 10 hrs on it. I didn`t check the crank the last time I had it apart, the compression was 165 and 164 with 19 domes.

 

well then if i were id maybe leave it alone unless your just really worried about the crank. Unless of course you just wanna pull it apart to get it ported.

[desertdeweller]

I will probably wait until it needs a new top end and do it all at once. The motor is still out on the bench the chassis is back to being a roller. I think I will go ahead and get it back together and work out those bugs before I create new ones.

[firebanshee]

I think a hush kit is a good arrestor and it meets sound levels, i run one on my blue bike and it doesn't seem to choke it down to bad, heck toomey says they make more power, but i dont' know about that.

[dirtfreak]

How long do bottom ends usually last before needing a rebuild? I know it will vary from rider to rider and bike to bike.I am thinking I may be due to rebuild the bottom end. it is 10 years old 3 seasons of desert racing and practice, some flat track time as well, on it some dune trips never been apart 4 or 5 top ends though. I was thinking on going 4 mil with some porting. but the way they are talking around here on cracking down on decible noise and spark arrestors. I am not sure if there are any decent spark arrested silencers out there that wouldn`t kill those mods. currently I am running t-5s I have torn the bike down and replaced the bent frame and other worn out items shocks etc.. I was thinking since I have gone that far might as well tear into the motor. It runs fine just can`t make up my mind if I should and if it would be worth changing it. I mainly just trail ride it now might do some more desert races. but more power is always good :ermm:

 

 

wouldnt hurt to do crank bearings why you have the motor out,bearings are alot cheaper than cases.sounds like the motor has done alot wouldnt hurt to check to see if it needs them.

[deckheight]

Yeah, you might be getting close to that cranks "estimated economic life" LOL! Only way to tell without splitting the cases is to visually inpect the big end rod bearings under magnification for pitting or scoring. Check the rod side clearance to see if the thrust washers are beyond spec. And last but not least check the top of the piston and head (especially around the intake side) under magnification for signs of a main bearing or seperator coming apart. magnification will reveal tiny little pits where the surrounding metal is pushed out and up (cratered) from a speck of hard metal hitting the aluminum.