atomik valve clearances

[tono18]

Can any one tell me what my vaulve clearces should be?? I get told .004 an .006...

an also my friends tell me it should be 003 an 004.. so im toataly confused.. my bike is a 2014 atomic nitrouse mid size 150cc big bore...

 

[gottagetacheaperhobby]

from my understanding either will work, most ppl seem to run 003 and 004 but i watched the walk through from oo racing and they run 004 and 006.

 

[my67xr]

.004" and .006" are just a touch larger clearances,
i run and recommend .003" (close to .08mm) for the intake and .004" (.1mm) for the exhaust as do most guys here

 

[tono18]

cool thanks guys!! 003 an 004 sounds good!

 

[gottagetacheaperhobby]

any reason on ooracing running the larger clearances?

 

[my67xr]

i'm not sure, it is only about .02mm more it might be what Honda recommend ?
might be for so they can go a bit longer between services ?

but less clearance also means more lift at the valve too

 

[gottagetacheaperhobby]

ah, ok. i was just curious, its not the first time ive heard of ppl running those clearances

 

[my67xr]

we run a slightly smaller clearance in my mates drag car Cleveland too,
it got him almost half a second quicker down the quarter when compared to the recommended clearance

 

[gottagetacheaperhobby]

half a second is insane for such a small adjustment... love the sound of the clevo's hammering down the track.

 

[Qwerty1234]

0.003/0.004 gets plastered everywhere on this site and I don't like it. Valves are somewhat important, and it irks me when this is repeated across the board without any research into the matter.
Granted, it's hard to find exact clearances for individual chinese engines but still... I know on one of my Loncin engines the actual exhaust valve clearance should be 0.15-0.20mm, thats quite a bit off 0.004/0.10mm

Is there a way to verify what it should be if one can't find specific documentation?

 

[my67xr]

^^ which Loncin engine needed that exhaust clearance ?

Honda specifys for the CT style horizontal engines .05mm +/- .02mm, so up to .07mm, or .002" +/- .008", so .003"
with the exhaust valve getting hotter than the inlet we recommend a touch more clearance.
this way when the engine gets hot, theres not a lot of chance that it will damage the valves/seats etc

and a pitbike is generally ridden a lot harder than a postie delivering the mail.
so a touch more clearance is needed as a safety factor.



pdf Manual Honda CT110, for Valve Clearances see pages 62 and 63

 

[Qwerty1234]

250cc Loncin 3rd gen water cooled (vertical)

Valves tend to tighten rather than loosen over time, particularly the intake valve. If you were to run close to spec i'd be inclined to go a bit looser, so if it is indeed 0.002 minimum i'd be more inclined to go around 0.004/5 on the intake.

However I fail to see how 'Hondas CT recommendation' applies to all chinese engines? They aren't made by the same company or in the same factory so............. yeah. Surely if you had a Zongshen engine, you'd want your specs from Zongshen. I mean I don't get my Suzuki valve clearances from Yamaha.....

 

[tono18]

neither can atomic company tell me nor is there any specs in the book,last time I called atomic they guy goes OWWW SOOWW SOWWWWRRRY ME DONT KNOW WHAT VALVE CLEARANCE ISss...I felt like bashing my head against a brick wall hahaha

 

[my67xr]

250cc Loncin 3rd gen water cooled (vertical)

Valves tend to tighten rather than loosen over time, particularly the intake valve. If you were to run close to spec i'd be inclined to go a bit looser, so if it is indeed 0.002 minimum i'd be more inclined to go around 0.004/5 on the intake.

However I fail to see how 'Hondas CT recommendation' applies to all chinese engines? They aren't made by the same company or in the same factory so............. yeah. Surely if you had a Zongshen engine, you'd want your specs from Zongshen. I mean I don't get my Suzuki valve clearances from Yamaha.....

i don't think anyone mentioned the valve clearances getting looser ?
and i cant see where i have mentioned that all china engines have the same valve clearance setting either?

and yeah, as the valve wears in, it seats lower into the valve seat, this makes the rocker arm/valve stem clearances tighter.
so with what you have written above, you are agreeing with me.

the china copy engines are almost a direct/exact copy of the original Honda engines.
so setting them up, uses the same sort of torque settings, clearances etc etc as the original Honda engine.
most of the china horizontal engines use the same rocker arms, but there are some variations too.




sorry i can't remember telling you what to adjust your valve clearances to on your china copy CG250 Loncin ?
i'm pretty sure i wouldn't have got the specs from a Yamaha XT250 service manual.
and if i did, then please accept my most sincere apologies....because clearly i was wrong


these guys sell manuals for a lot of the china engines, they might have the correct one for you ?
Cg125 Cg200 Chinese Atv Engine Repair Manuals - Om-cg125set - Service and Repair Manuals - by Service

 

[Cordogs]

The verification is in the blokes who have been building these engines for the past decade!

I'm no spanner spinner but I would take the advise of the boys in the know on this site over a Chinese motor manual any day!

 

[tono18]

agree with you there mate ^^^^^