11:1 and stage 1 hotcam

after hearing all of the issues with the possibility of piston valve contact with the stage 2 and 11:1, i decided to get a stage 1 with my 11:1

does the same hold true for a stage 1 and 11:1 pistons?

doesn't the stage 1 and stage 2 have similar lift just different durations? I'd double check a stage 1 just as likely as I'd check a stage 2 clearance. Its just part of engine assembly with aftermarket parts, test fit everything and measure the clearances. I'm sure you know that its not difficult just time consuming, but good insurance to maintain reliability and get peak performance.

Stage 2 will also be less likely to ping as the dynamic compression ratio will be lower.

so the stage 1 is just as likely to make piston/valve contact as the stage 2?

Afternoon Matt, I've been running the stage 1 with the 11:1 650 je piston for about 3000mls. no problems with the valves hitting the stage 2 i tried they hit. I'm happy with the stage 1 good for bush/woods ridding.

ah ok, great. thanks for the info.

does anyone know if the valve clearances differ between 11:1 ross, weisco, or JE pistons?

Morning Matt, Here a pic of the JE it's out of the bike at the moment if you want any measurements if thats any help009-1.jpg

yeah, if you could tell me what the depth of the valve relief is and i can compare it to my ross, which i also have out of my bike right now

Afternoon Matt, First i measured the top of the pin to the piston crown = 19.4mm then the depth of the cuts from there in+ex both are 4.8mm. Then i measured from the lower flat part down the cut outs are 3.0mm. Then i measured the hight of the raised crown from the flat part that is 1.85 mm.So if you minus 1.85mm from the 19.4mm the flat part on the is about 17.55mm above the pin. I hope this is some help i used a dial gauge to measure as best i could i know the figures don't add up exact but close.

awesome, thanks for that! ill go to the shop tomorrow and check what my valve reliefs measure. thanks

I run a Wiseco 11:1 piston and a stage 1 cam in my -00 XRR without problems, the bikes has run 20000km's in total, I put the cam in at say 12000km's.

I must admit I never checked the clearences when I assembled the engine, but it's still running strong, only issue was some slight pinging under heavy load, I went from a 175 to a 180 main and the pinging went away.

I really don't think the stage 2 is worth the risk considering how good the mid-range is with the stage 1.

Evening Matt, I measured my Wiseco 102.4 from the flat top to the top of the pin and it's 17.5mm and the cutouts are in. 2.6mm ex. 3.0mm. Then i measured the stock piston with a flat rule across the top and it's 17.5mm as well and the cutouts ex. 3.0mm in. 2.5mm So i think to get 11:1 comp. with a flat top piston it's the extra capacity that ups the comp.

I studied the two stages before getting the stage two.. The stage one is like the stock cam for lift but has more duration.

But sounds like others have "tried" what your looking for.

I've had on issues with the stage 2,except some idle wierdness that i sorted.

Pikkos aren't you running a 680?

Afternoon Weskc35k, Still in the build stage next week i hope.

Roger that VKC.

Morning All, Just to complicate things i measured my HRC 11.5:1 piston it's 17.5mm from the pin to the flat top as well the cutuot are ex. 4.8mm in. 4.5mm and the crown in 2.0mm above the flat. The extra mass of the raised crown would only make up for the deeper cutouts and HRC claim it to be 11.5:1 comp.:lol:007-1.jpg

If the deck heights are the same for example a bigger piston diameter will raise the comp as it's picking up more area for the same head,.the ratio has to change.

My 02 could be wrong.

If the deck heights are the same for example a bigger piston diameter will raise the comp as it's picking up more area for the same head,.the ratio has to change.

My 02 could be wrong.

You are correct.

You going to take them sharp edges of the reliefs Pikkos?

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