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auto-decomp removal on drz 434sm, Yes or No?


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i have searched for hours and have not found a definitive answer relating to the 434cc kit,

 

Question: Removing the auto-decomp on Stock Ex cam on 400sm fitted with 434cc Kit, Will this be fine with Stock battery? since i have seen some conflicting info about this. I want to know if its fine with a 434kit, or will i need to get a more powerful battery aswell, SM is mainly road use.

 

Bike details: 2009 drz 400sm Just had entire top-end rebuild, new valves, springs etc, all the goods..

434 JE piston Kit, Stock Carb - modified for BB. ( fcr to come soon)

Stock Cams, ( in = .15 ) (ex = .25)

Lock tight mods are all done,

 

Side note: I'm fairly certain that this stupidly loud Auto-decomp needs to go, however people have told me just replacing the OEm ex cam with Stage 2 hot cams  will drop some noise level or at least remove that insanely loud ticking.

Strange thing is i never had this tick prior to the rebuild

Edited by AridersLife
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I wouldn't remove it. I read all over if the factory battery is fine, it will start. So I cut my decomp off. It would not start. My battery is not bad or weak, it was just too much compression.

 

So then I ordered a set of HotCams, and left the auto decomp on, and it starts fine. $225 shipped to your door generally on the HotCams, I'd just go ahead and bite the bullet and go that route.

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Sometimes mine would freeze up at TDC, so I would just have to release the button and press it again and it would fire up.

 

Mine would freeze everytime at TDC, then keep tapping the button and it would make it past, then if you were really lucky it would make it one revolution.

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My personal experience is NO. the decompression is needed for the stock battery and starter to start easily.  The YTZ10  battery will help.  I am leaning toward Hot Cams exhaust with the auto decompression that is reported to be rock solid with no failures in addition to the YTZ10 battery.  You will have problems with the stock battery, 434, and no auto decompression on the EX cam.

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Why remove? Mine didn't fail after 20k rape miles. I ran high comp 400 cc. my current 434 has auto decompression, no issues. Just silly to remove it.

I run the free version of ripoff eddies big batt mod.. decomp costs nothing and didn't break , even in my old oil starved engine!

......

Edited by BLKRAWB
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Why remove? Mine didn't fail after 20k rape miles. I ran high comp 400 cc. my current 434 has auto decompression, no issues. Just silly to remove it.

I run the free version of ripoff eddies big batt mod.. decomp costs nothing and didn't break , even in my old oil starved engine!

......

I don't know what 20,000km to miles conversion is, however i just hate that ticking sound.

i assume getting stage 2 hot cams may eliminate that sound (ticking) if it doesnt at least i got some more power gain thanks to the cams. 

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Why remove? Mine didn't fail after 20k rape miles. I ran high comp 400 cc. my current 434 has auto decompression, no issues. Just silly to remove it.

I run the free version of ripoff eddies big batt mod.. decomp costs nothing and didn't break , even in my old oil starved engine!

......

ImageUploadedByThumper Talk1414848404.291908.jpgImageUploadedByThumper Talk1414848416.246707.jpg

Luckily it doesn't seem to be a super common problem but mine failed. When it goes it makes a wicked tap every time that pin hits the valve bucket. Not to mention if one of those pins make its way into the motor it could cause some major damage. I never found my small pin, I think I got lucky and it came out during an oil change and I didn't notice

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