stock or 11:1 piston???

[400man]

im new to the 4 stroke thing (been a 2 stroker since ive been riding) and I got a question about different compression ratio pistons. how much difference in compression is there between the stock 10:1 and a 11:1 piston? ive done a little searching and seen that if you go 12:1 then you need to run race fuel, which I dont want to, and 11:1 is still safe to use premium pump gas. my 400 is a 2000 model and it smokes pretty good after its warmed up, a little too much to just be valve seals I think. im not sure if the motors ever been took apart, since ive only had the bike about a week or two. I plan on checking out the topend fairly soon too see what size/shape its in. if its stock I plan on just going to a 86mm, but I dont know much difference in power i'd get from either a stock 10:1 or a 11:1 piston. I dont plan on doing any other mods to it, maybe a stage 1 or 2 cam at the most, since its already got a Big Gun full system. i'd like to just keep it reliable mostly instead of making it a screamer (my 250r takes care of that :) ). right now it does make some good power in the lowend and midrange, but its pretty weak on the topend.

[thebig450es]

in my honda manual, it says its a 9.1:1 compression stock, i think you would feel abit of a difference foing to 11:1, a cam would help also.

[400man]

and I forgot one more thing, the sparks advance timing key. ive read that it will give a big increase in the throttle response and lowend power on a stock compression motor, but shouldnt be used on a higher compression ratio piston like 11:1 or 12:1 because it will make it run alot hotter.

I'd kind of like to keep the same powerband its got now, good bottom end and midrange and not as much topend. I know both mods will help, but which would be more reliable? a 11:1 piston or a stock 10:1 with the +6 advance timing key? and when the time finally comes and I replace the piston im going with some HD head studs.

[Snipe]

If your wanting to keep lower end then do the 10:1 with a stage 1 cam.

You will want to go with a cam if doing a piston increase as they go hand it hand. You dont have to but they work very well together.

You would feel alot of power when you really start feeling the power increase is when you stroke them. Having a stroked std bore piston I think would run better than just a 10 11 or maybe even a 12:1 piston.

Oh and some ppl do run the sparks key with the 10:1 and 11:1 setups but there also running spal fans and some running another oil cooling system with there stock one. Wheelie also makes + degree keys as well I think he can make from +1 to +5 they come with the flywheel bolt puller and there $19.95 shipped if I remember right.

[400man]

thanks for the info. I may just stay with the stock ratio when I bore it to the next size. ive been looking around and RMatv has pretty much the best deal on a 86mm wiseco piston kit. and depending on the money at the time I may also just get a stage 1 hotcam along with the piston and do it all together.

my plans for this bike is just gonna be a trail rider and ocasional harescramble/GNCC. like to try and keep it reliable mostly but still have some grunt to keep up with the 450s. When I first got the bike I was kinda disapointed with the power, just felt like a big turd compared to my 250r. but ive put alot of ride time on it this past weekend and got used to the power and I like it alot better now. I guess it was the way I was riding it, trying to rev the guts out of it through the trails like with the 250r.. now I learn to ride it a gear higher and use the torque to pull it around in the lower rpms. it does make it alot easier to ride fast through the technical/tight trails, but im still alot faster on the 250r cause I think it handles alot better.

[Snipe]

If your riding stock shocks it dont take much to be better than them lol.

I am planning on keeping a STD bore and going with a piston upgrade you can get 10:1 11:1 and even a JE 12:1 STD bore piston at 85mm keep the reliability of an unbored motor and getting more displacement.

I am thinking of havin it bored but I dont know lol I like the idea of going up and keeping it STD. With the cam it will give it even more. A cam alone will actually drop compression that is why they go hand in hand and if ya cant afford both at once its cool do one then the other but I would wait to install until I had both as would just cost more to open it up again in gaskets and such. Just install all at once.

[400man]

yea front shocks are deffinatly on the list lol. I have just some cheap non-rezzie triple rate works front shocks on my 250r and they work awesome on it for my riding style. keeping an eye out for some works for the 400 now.

its hard to say what I want to do to the motor untill I actually open it up. might even get away with just some new rings if the piston still measures within spec. just hard to say right now.

[Snipe]

I just bought a set of Works triple rate AT Steelers with remote rezzies for $174 shipped lol. Not top of the line but for what I do they should be perfect and the price I just couldnt let them go.

They are for a 250R but will work great for my 400 and will drop my front end a bit as well. I cant wait to get them and try them out. My next mods are gonna be a steering stab and then a rear shock. My motor runs really good right now. One thing you can do and gets alot of locked up power is doing the sparks timing key it advances the timing +6 degrees and gives alot better throttle response and more power to the real wheels and oonly runs around $47 total.