HOW TO: RHC's Decompressor Mod - Easier Starting!
  • honda401
    Posts: 16
    Joined: Sat Jun 12, 2010 5:07 pm

    by honda401 » Sun Jun 13, 2010 1:54 pm

    so how did the mod go
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    mxracer41
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    Joined: Sat Mar 27, 2010 5:04 pm

    by mxracer41 » Thu Jun 24, 2010 1:04 pm

    I have a tokyomods race cam in my bike, and have the same kind of problem. The bike starts easily when cold (usually no more than 2 kicks), but when it is hot and ESPECIALLY after you crash or even just tip it over, it gets extremely hard to start. Could i do this mod without damaging the cam?
  • Simon-1994
    Posts: 4
    Joined: Sat Feb 26, 2011 8:57 am

    by Simon-1994 » Sat Feb 26, 2011 9:00 am

    I can not belive it!
    I marked up and everything and when i was finished grinding i recognized that i was grinding on the wrong side!!

    DON'T DO THIS WHEN YOU'RE TIRED!! :p

    Is it possible to weld it and grind it to original?

    please thanks for answer!!
  • phantomtracer
    Posts: 11
    Joined: Fri Dec 03, 2010 2:08 pm

    by phantomtracer » Sun Mar 06, 2011 7:20 am

    124 wrote:Just to be clear, this is for CRF250's only correct?



    Would there be any benrfit to performing this mod on a 2008 CRF250X?

    Thanks,

    Phil
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    crfsonly
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    by crfsonly » Sun Mar 06, 2011 7:24 am

    welcome to the site Phil. yes, according to the author it applies to all model years of the CRF250's.

    again, welcome.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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  • mike_k5
    Posts: 24
    Joined: Wed May 06, 2009 12:00 pm

    by mike_k5 » Thu Mar 17, 2011 10:54 am

    I carried out this mod a few months back, and it definately works! my bike starts far easier now!

    take it slow is my advice though, if enough care is taken its hard to get it wrong.
  • honda fan
    Posts: 20
    Joined: Thu Jul 28, 2011 8:54 am

    by honda fan » Thu Jul 28, 2011 9:04 am

    Jst done this mod it does help the bike start. Now if I shut it down wether its hot or not it will start again. After doing this mod I took it out and stalled it as bad as I culd and I kicked if a lil bit and it startd I was surprised. Thanx alot this was well worth doing.
  • kevin132
    Posts: 6
    Joined: Mon Aug 30, 2010 8:23 pm

    ok im confused..lol

    by kevin132 » Sat Aug 27, 2011 2:18 pm

    well i just built a crf250r and i was turning bike over as i always do and i heard this wierd snap sound?? its the decompressor is this supose to make this noise?? im thinking of doing this mod know that ive read this post.. thanks
  • davecinna
    Posts: 4
    Joined: Mon Dec 05, 2011 12:45 am

    by davecinna » Mon Dec 05, 2011 1:59 am

    hello everybody

    this kind of modify is so easy to do, possible that honda never thought to make this on standard bikes?.. what happen after the modify ? the kick start need more force to push with the feet? or is the same? i would like to try this because my crf 2004 has lost of compression and start just pushing no way with pedal.. asap i will check valves and top end,but if necessary i would make even this modify..
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    crfsonly
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    by crfsonly » Mon Dec 05, 2011 6:49 am

    welcome to CRF's Only. if your motor has just started to become hard to start because of loss of compression then it's more likely it's your valves going tight. this is common and will make your motor hard to kickstart. check your valve clearance first.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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  • davecinna
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    Joined: Mon Dec 05, 2011 12:45 am

    by davecinna » Mon Dec 05, 2011 10:43 am

    hello ken

    thanks for your prompt reply, I checked the pressure and normally should be 3,85 bar now is 2,7 so I supposed to check the valve clearance first as you said.. my bike dont start even when is hot and if I dont turn the gas... never start..so I will follow your answer.(sorry for my bad english..)
  • davecinna
    Posts: 4
    Joined: Mon Dec 05, 2011 12:45 am

    by davecinna » Fri Dec 09, 2011 2:02 pm

    hello ken

    you are right! my valves measure are out of range. intake are 0.02 left and 0.00 right and the exaust are 0.20 and 0.22. I have worked the shim with rectifier machine to reach the correct value. now the values are 0.28 both exaust(as standard ) and 0.12 intake left. only intake valve right still measure 0.00. no feeler can goes in!!!.... maybe the valve place in the head cover is broken!!?? what do you think?
  • davecinna
    Posts: 4
    Joined: Mon Dec 05, 2011 12:45 am

    by davecinna » Mon Dec 12, 2011 1:16 pm

    hello ken

    as I thought on the right intake the valve is worn out. i would replace the valves of course ,both intakes,and I read that is better use steel valves most durable and cheaper than titanium type most performance but expensive and not long lasting. what do you think about this 2 choices?thanks
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    crfsonly
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    by crfsonly » Mon Dec 12, 2011 4:24 pm

    you had it correct. if you are looking for maximum performance then go with the titanium. if you are looking for maximum durability go with stainless steel valves. in either case you must have the valve seats professionally cut for proper seal and durability.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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  • jeffmort
    Posts: 2
    Joined: Sun Dec 26, 2010 11:24 pm

    by jeffmort » Fri Jan 20, 2012 3:32 pm

    Great instructions. I decided to perform this mod on my hard to start when cold 07 CRF250R with Athena big bore kit, Ron Hamp ported head, and Ron Hamp Webcams cam. The instructions were very easy to follow and the mod was easy to complete. I am confident that I did the job correctly, used dremel slowly, checked with calipers, etc. In my case it did not help with my starting problem.
    My valves are all in spec, carb is clean and bike runs excellent - is is just difficult to start when cold. I actually called Ron Hamp yesterday to ask him about it. He told me that the mod does not always work and in my case because of the big bore kit that I should probably go back to an unmodified decomp pin which I have done.
    I am stoked for all you guys who this mod has worked for and I would guess by the rate of success it is worth trying - worst case is that it does not work and you are no worse off of for the effort (just a little time and maybe needing to buy a new decomp pin).
    Just letting everyone know my results.
    Jeff
    2007 CRF250R

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