My engine is pretty much stock except for endcap mod, jetting and a K&N. My question is, if I were to put an 11:1 Piston in it, would I need to run race gas or can I still run regular fuel?
Also will this affect my jetting, I mean will I have to re-jet? And I guess while I am at it, will I feel a noticible difference after install?

Thanks guys

 

11:1 compression requires only pump premium(92-93).Jetting can be effected by very high compression but 11:1 should not require a jetting change.Yes you will feel quite a difference from the stock piston and compression.

 

I jetted mine up to 165 from a 160 in my TM45. On a stock carb I am not sure but I ran a 175 in my stock carb with just a K&N and end cap. The engine sounds different with the 11:1 piston....like any engine with more compression. More pop to it. I didnt feel a monster difference for a seat of the pants feeling. However, when I went to the dunes to shoot the hill with the guy I always ride with I was VERY SHOCKED at the difference! We raced over and over just to see if it was the driver I even swapped rides and with him on mine. That proved it was just that much faster. I am talking about 4 bikes on the hill at armagosa (steep). I did some head port and socket cleanup and I have a bigger carb and ported intake....so that just sounds unfair right? But not untill the piston head porting/cleanup did I see this difference. So the TM45carb and ported intake didnt do much by itself.

 

Oh, and yeah I run premium just to be safe. You may need to run a thicker base gasket depending on what brand piston you use. I called HPR for gaskets and help. I am sure they could answer every little question you have.

 

BajaX04-not sure, but I wonder how much of your increase on the hill was due to the head porting and not the piston..Sounds like you did a couple mods at once. I would too be curious as to an increase with just a piston change?

 

it all works togather. like if you were just to put a ported head on, you wouldnt notice that much. just a piston, noticable but when you do a piston and ported head you will see more, add cams and notice alot more. every thing has to mesh togather.

 

I went from a stock motor to 11.5:1, TM45, Vortex CDI, and a end cap all at once. I cant answer your jetting question because I switched carbs but I did notice a power difference, although not huge, it did have alot more throttle response and low end torque.

 

I did a piston and a port, with the stock carb, and was able to notice a difference. I run a min of a mix premium and 110 race and like being on the safe side if it does go lean on me with a weather change during the day. I also jetted up from a 170 on the stock carb to a 175.... I had a vortex cdi, HMF pipe, and K&N filter when this was done...

 

Its all plumbing if you think about it. You have to match everything up......

 

I fully understand that the more you do, head porting, carb, cams etc. all help the system incrementally improve, but I think the original thread poster was asking about a 11:1 piston and thats the only change. Everyone that has answered his question either had porting or a carb done at the same time. Not everyone is Bill Gates and can afford it all at once! LOL!!