Jump to content
Sign in to follow this  

a mechanical question

Recommended Posts

going to replace my XR piston soon

so i will need to hone it right?

and also, do i need to bore it before honing?

or just hone it directly? :applause:

will be replacing with stock bore piston... :eek:

Share this post


Link to post
Share on other sites

Why are you replacing the piston? Is it low on compression?

Without measuring the cylinder for wear....I would be making an educated guess at best.

Share this post


Link to post
Share on other sites

hmm.. i have just done a search, stupid me

i may not have to do honing on the XR engine? or do i??

Jim, i do not know if it is low on compression, just that it was burning oil when i do hard acceleration (white smoke), could be a bad ring causing blowby, or maybe i just need to replace the ring?

please advice.

Share this post


Link to post
Share on other sites

could also be blowing smoke due to a valve problem.

haven't done a four stroke yet, but would imagine that like a two stroke, you need to measure cylinder top, center & bottom to determine if worn or not. that will tell you if you need to bore or re-sleeve or not.

Share this post


Link to post
Share on other sites

I'm sure someone like burned will reply soon. If your sure it's not carb related....I would start with a leakdown and compression test to try to pinpoint the problem. And of course a valve check.

I do not know what kind of cylinder is in an xr. I wish you the best though. You say you want to run a stock bore....so boring is out of the question...that will just make it bigger. My guess is that a clean up(hone) and new piston/rings is all it it would need. But more than likely..I think you will find your problem in the valves.

Share this post


Link to post
Share on other sites

if you know it needs to be re-rung i understand. otherwise you need to take it apart & measure.

if it's just the piston, a honing would be a good idea, but probably not required if within spec..

hopefully someone with an xr & more knowledge will chime in.

Share this post


Link to post
Share on other sites

its need to be torn down and measured.

if the piston and bore are still within spec clearance wise,you can just rehone and replace rings.

ive never seen a xr400 that didnt need a bore job and new piston fitted.

there are very few people that can do this correctly.

Share this post


Link to post
Share on other sites

good morning Ed, good to see ya reply here.

so ya mean every xr400 ya seen, always go to the next bigger bore size piston.

hmm... what do ya mean very few people can do it correctly?

is just a simple top end overhaul work doesn't it?

Share this post


Link to post
Share on other sites

yes,they are always worn out.

many people claim to do bore jobs.but it rarely gets done correctly.

Share this post


Link to post
Share on other sites

Dude, if your cylinder's not all jacked up a hone job will suffice. But if you've got bad scoring, bore it out say two sizes, get bigger piston and rings and a little more power.

1. honing out- a little bit of money and lots of time.

2.boring it out- about $80, new piston and ring $150,couple of days, depending on parts availability.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...