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Removing Decompression Assembly

traxxas-modifier

Super LOLO
Staff member
im reposting here what bro haen posted in some topics:

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IF NOT REMOVED :
Advantage : easy to start whether using electric or kick start
the kick start wont 'bounce' back when u kick it

Disadvantage : because its working mechanism relies on engine rpm to throw it out of contact with the pin on the cam, sometimes when the rpm hits 1500-2000 its activated and makes ur engine lose compression, try this at gear 3 to gear 4 change, because the gear 4 ratio is soooo different, the rpm drops suddenly and makes this mechanism active and u get loss in performance.

IF REMOVED :
Advantage : no more compression loss of course
no 'sudden performance drop'

Disadvantage : depends on ur cam profile, it need a stronger force to kick start ur engine, if the cam lift is very high (higher compression), you might need stronger battery to start the engine using electric starter.


IN GENERAL,
decompression assy is just a feature with its plus and minus side, so it wont hurt ur engine if you remove it or not remove it.
It's your choice, do u want max performance, or ease of start ?

technically, decomp assy should be activated only on rpm under 1500.. but u know.. sometimes something happen...

yes, thats why gear 4 dropped soooo much....

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Attachments

stroker

Veteran
Both pieces can be removed. But easier to just remove the (smaller pin). Just leave it out. Reversible too.

Vixion pistons users are ok, but those 58.5 / 60mm kit user might have a slight tad harder time kicking it (if kickstarter). For electric starter users, if gone too high a compression, the starter motor might not even turn over your motor to start it.

2cents
 

haen

Super Veteran
yup.. good input stroker.. the smaller pin can be removed (decompression cam).. but i havent tried that.. it would give knocking sound i think.. because nothing holds that lever...
 

joel

New Member
I have removed the decomp lever on mine, but starting was difficult. The self starter would take a hitch to crank first time. Now put it back
However, the decomp lever should not make difference for performance. HAs anyone done a dyno test with and without the decomp lever?
 

vnduck

Super Veteran
so when talking about removing the decom Assy, which one are we talking about, the whole thing, or just the pin?
 

haen

Super Veteran
@vnduck : the pin bro.. but that only would make a bit tick.. tick.. sound..
tats why i remove the inner mechanism on the cam sprocket..
 

Glowplug

Veteran
just a word of caution, electric starting with the decommpression lever removed can burn your starter. I happened to me.
 

haen

Super Veteran
how come glowplug ? u have hi compression engine ? mine is doing fine.. even with vixion block and shaved block base by 0.8 mm..
 

kurarensu

Veteran
can i ask qns:

so i just remove the pin and the "springy" thing inside the timing chain sprocket right??


can any kindsoul PM me more details..!?
 

CarroTT

Super Veteran
u guys believe this wud make ur bike perform better ?

its like the guys who remove their electric starter assembly n claim their bike can go faster :lol:
 

kurarensu

Veteran
not perform better.. but imagine u put a big bore kit.. when u kickstart it's stil the same as the stock feel.. so light and easy..
 

syfull

New Member
mm..my bike is still 99% stock,would it make any difference if i remove it anywayz..?do anyone round here have how to pic of how to remove it??sori im nu here>>
 

kurarensu

Veteran
remove ur engine until the part where u can remove the camshaft sprocket where connect to the timing chain

behind the camshaft sprocket gt this mechanism.. remove it can ordy shld b..
 
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syfull

New Member
kurarensu said:
remove ur engine until the part where u can remove the camshaft sprocket where connect to the timing chain

behind the camshaft sprocket gt this mechanism.. remove it can ordy shld b..
so u have to strip naked da bike,remove da engine(i mean away from da body)?n what kind of tool should i use to perform this..please some one elaborate(n please include the "how to pic")thx
 

kurarensu

Veteran
no pics.. but u check out haen's reply.. he posted a pic..

that "c" shape thingy and the pin is what u suppose to be removing..

u remove ur engine part til u know where's e camshaft.. and u will see it already..
 

syfull

New Member
mm..looks like its "easy" to do it ur self,n ur sure it will work rite,i mean increasing the bike performace(stock) a lil bit,due to some increase in compression(correct me if im wrong) n will not have bad side effect?..i think im gona give it a try..that is if i have the time(n courage:)..
 
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