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09 low on compression, input please

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hey,

 

this probably sounds stupid to ask but i'm not the best mechanic so am looking for some advice/ideas.  my 09 seems to have lo compression compared to seasons before, which is understandable at the 60 or so hours on stock piston and rings. Starts fine cold with a few kicks (normally 2 or so if i do ti at tdc and don't kick like i'm the flash), can be a fight to get going when it's hot though (after say 20m riding) at times.  It runs great when actually running and all, but seems to be low on compression once i get past tdc kicking it over... not like completely lacking, trying to push the kickstart down is still really really difficult (don't ask, I was bored lol) but the lack of resistance when kicking is worrying me

 

The valves are being checked/adjusted if needed this week, which may be out of spec causing the hot start issue, so I am just looking to get an idea what I may be in for re: the low compression.. I don't want to throw an arm and a leg at it at this point being an 09 but a bit to last another season is.  What else could be the cause of low compression other then the piston/rings?  Like I said i don't have any other problems other then the hot starting issue and kicking it over seems to lack resistance now, though it will start without a fight cold.

 

Any advice/hints would be great

 

Thanks!

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Hot starting issues could be you are just a little rich on the pilot circuit or maybe your float bowl level is too high. You probably know I advise anyone who will listen to get an R&D remoe fuel screw. That really makes a difference. Low compression could be rings/cylinder or leaky valves. Carbon build up can cause imperfect sealing of the valves, for example.

When you are starting hot, you have to pull the hot start from the very first kick to lean things out. If you kick a couple times without it, you are too rich and it makes starting harder. Hope that helps.

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Thanks for the input! I wasn't sure if valves would affect it but I thought just that, just didn't want to sound dumb lol.  Hopefully its just my valves out of speck and nothing more, though in all honesty at 60hrs its due for a top end(or 2 almost!) and has always treated me very well. I was just trying to get a rough idea of what I may be in for, should the topend need rebuilding one way or another piston/rings kinda thing.

 

in everyones opinion, weekend warrior (i ride maybe every 2 or 3 weeks during the summer) would it be worth dropping 5k~ on a 13, or put 1k or so into the 09 and ride it another year.  It's not like the dfi will help me stop being bad at riding or anything, i literally just go to have fun.  thoughts?

Edited by iggle
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Thanks for the input! I wasn't sure if valves would affect it but I thought just that, just didn't want to sound dumb lol.  Hopefully its just my valves out of speck and nothing more, though in all honesty at 60hrs its due for a top end(or 2 almost!) and has always treated me very well. I was just trying to get a rough idea of what I may be in for, should the topend need rebuilding one way or another piston/rings kinda thing.

 

in everyones opinion, weekend warrior (i ride maybe every 2 or 3 weeks during the summer) would it be worth dropping 5k~ on a 13, or put 1k or so into the 09 and ride it another year.  It's not like the dfi will help me stop being bad at riding or anything, i literally just go to have fun.  thoughts?

 

I think you should check valve clearances first and if they are good, leave it alone.  You could do a compression check easy enough.  Warm it up first then put the gauge in open the throttle and kick 5 times.  If you are over 62 psi, leave things alone, since it doesn't sound like you beat it up too bad.  If you do choose to do work, buy a manual and do it yourself.  Lots of fun and you save lots of money.  You could get a new piston in, clean the valves up and inspect the crank for a lot less than 1K.  While you are at it, you could pull the whole bike apart and make sure all of the bearings are in good shape and lubed up.  Your bike is still competitive and very fast.  It is also fun to work on.

 

That is my opinion.   :ride:

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