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High Compression Piston

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I'm looking to replace my top end right now on my 08' CRF450r and want to get a JE high compression piston and Hot Cams Stage 1 or 2 cams 

http://www.ebay.com/itm/JE-PISTON-KIT-02-08-HONDA-CRF450R-450X-13-5-1-STD-w-OEM-Head-Base-Gasket-274756-/300836795601#vi-ilComp.

 

I have a couple of questions concerning this. 

1. Will my bike run better with race gas when I have a high compression piston?

2. Do I need to get different cams or anything other engine component in order for the piston to withstand the different compression or would you guys recommend any? 

3. Will using a high compression piston run the risk of blowing up my bike any more than a standard piston would? 

4. Lastly should I buy other components with the piston that would help it push even more hp out of it? 

 

Desert season is upon us and I just want some more pep in my bike to scream up those huge dunes. ;)

Edited by Bigtyme07

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I was told that the cam and head work is where you get MOST of your hp from. I'm going through the same thing and I'm sending my head to fastheads and getting the stainless steel package along with the stage two cam and 13.1 piston. Not done yet so I'm no expert on this. but from everything I'm gathered head work is def worth it. And it makes your compression go up as well

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I'm looking to replace my top end right now on my 08' CRF450r and want to get a JE high compression piston and Hot Cams Stage 1 or 2 cams 

http://www.ebay.com/itm/JE-PISTON-KIT-02-08-HONDA-CRF450R-450X-13-5-1-STD-w-OEM-Head-Base-Gasket-274756-/300836795601#vi-ilComp.

 

I have a couple of questions concerning this. 

1. Will my bike run better with race gas when I have a high compression piston?

2. Do I need to get different cams or anything other engine component in order for the piston to withstand the different compression or would you guys recommend any? 

3. Will using a high compression piston run the risk of blowing up my bike any more than a standard piston would? 

4. Lastly should I buy other components with the piston that would help it push even more hp out of it? 

 

Desert season is upon us and I just want some more pep in my bike to scream up those huge dunes. ;)

 

1. not necessarily, its a very loaded question, high compression, cam lift duration, elevation all dictate octane requirements. there is power tobe gained on any engine, stock or mod with some fuels. But trying to stay within pump fuel range making good power isnt that difficult.

 

2. no, but it depends on what fuel you want, what compression ratio you are after, and what cams you run.

 

3. yes, hardly.  A slight bump in compression is a little bit more stress on the crank but very little. Its not a factor i would even worry about.

 

4. It sounds like you are in dunes alot,  IF it was my bike. this setup would give a boost in power from off idle all the way to the rev limiter.

  • 13.5:1 compression piston, wiseco, cp, je pro x
  • hot cams stage 3

this setup would be pump fuel safe on premium 91, if you go hot cams stage 1, pump fuel may not be enough. And while the bike would be a lowend monster there would be less power in the mid-topend. not ideal for the kind of riding you mention. stage 3 is geared towards topend power.  The 13.5:1 piston is a big jump in compression from the stock 12:1  this will give the bike more power on its own. Bottom end power loves compression. So the stage 3 cam will give you your topend back (and than some) All on pump fuel.  

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1. not necessarily, its a very loaded question, high compression, cam lift duration, elevation all dictate octane requirements. there is power tobe gained on any engine, stock or mod with some fuels. But trying to stay within pump fuel range making good power isnt that difficult.

2. no, but it depends on what fuel you want, what compression ratio you are after, and what cams you run.

3. yes, hardly. A slight bump in compression is a little bit more stress on the crank but very little. Its not a factor i would even worry about.

4. It sounds like you are in dunes alot, IF it was my bike. this setup would give a boost in power from off idle all the way to the rev limiter.

  • 13.5:1 compression piston, wiseco, cp, je pro x
  • hot cams stage 3
this setup would be pump fuel safe on premium 91, if you go hot cams stage 1, pump fuel may not be enough. And while the bike would be a lowend monster there would be less power in the mid-topend. not ideal for the kind of riding you mention. stage 3 is geared towards topend power. The 13.5:1 piston is a big jump in compression from the stock 12:1 this will give the bike more power on its own. Bottom end power loves compression. So the stage 3 cam will give you your topend back (and than some) All on pump fuel.
So 13.1:1 with a stage 2 and head work still be good using pump gas?

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I have a 03 & did a complete rebuild about 45hrs ago. Installed a hotrods crank & bearings, hotrods stage 1 cam (im a vet rider & wanted more low end) wiseco 13:1 piston (stock in 03 was 11:5:1) ss valves with stock springs & its runs great. Very nice low end gain with no loss on top. I run pump gas with no problems at all. Checked the valves at 20 & 40 hrs & no adjustments were needed. A high compression piston wont bother the crank unless its very very worn. In which case the crank should be replaced no matter what piston your running. Pump gas is fine up to 13:1 compression & Ive read where many run 13:5:1 on pump gas without problems. As for stage 1 or 2 cams it depends on the type of rider you are & what gain your looking for. Being a vet rider I don't rev the bike alot & wanted my gains in the low end. The hotrods stage 1 is designed to make more power at lower rpm & in fact even gives a slight gain across the board. Stage 2 cams are designed to make more power from mid to top & usually cost you just a tad of power down low. You just need to know where you want the power gains at & buy accordingly. Happy riding.

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I,ve started a thread asking about pistons etc should have read this first :)

I wish I would have put a 13.5 in. What he was saying about shifting the power around with the cam is true UNLESS you add the high comp piston and then the piston adds back in that low end torque through the power range and now I have the leak power my bike was making before, just all through my power range not just half of it.
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I have a 03 & did a complete rebuild about 45hrs ago. Installed a hotrods crank & bearings, hotrods stage 1 cam (im a vet rider & wanted more low end) wiseco 13:1 piston (stock in 03 was 11:5:1) ss valves with stock springs & its runs great. Very nice low end gain with no loss on top. I run pump gas with no problems at all. Checked the valves at 20 & 40 hrs & no adjustments were needed. A high compression piston wont bother the crank unless its very very worn. In which case the crank should be replaced no matter what piston your running. Pump gas is fine up to 13:1 compression & Ive read where many run 13:5:1 on pump gas without problems. As for stage 1 or 2 cams it depends on the type of rider you are & what gain your looking for. Being a vet rider I don't rev the bike alot & wanted my gains in the low end. The hotrods stage 1 is designed to make more power at lower rpm & in fact even gives a slight gain across the board. Stage 2 cams are designed to make more power from mid to top & usually cost you just a tad of power down low. You just need to know where you want the power gains at & buy accordingly. Happy riding.[/quot
I have a 03 & did a complete rebuild about 45hrs ago. Installed a hotrods crank & bearings, hotrods stage 1 cam (im a vet rider & wanted more low end) wiseco 13:1 piston (stock in 03 was 11:5:1) ss valves with stock springs & its runs great. Very nice low end gain with no loss on top. I run pump gas with no problems at all. Checked the valves at 20 & 40 hrs & no adjustments were needed. A high compression piston wont bother the crank unless its very very worn. In which case the crank should be replaced no matter what piston your running. Pump gas is fine up to 13:1 compression & Ive read where many run 13:5:1 on pump gas without problems. As for stage 1 or 2 cams it depends on the type of rider you are & what gain your looking for. Being a vet rider I don't rev the bike alot & wanted my gains in the low end. The hotrods stage 1 is designed to make more power at lower rpm & in fact even gives a slight gain across the board. Stage 2 cams are designed to make more power from mid to top & usually cost you just a tad of power down low. You just need to know where you want the power gains at & buy accordingly. Happy riding.

Hi I am a vet rider also, I have a ktm 250 two stroke and my crf 450 has been lying at the back of the garage for about 6 years!!!

I am currently refurbing it and am looking to fit all parts as you have, how did yours turn out and would you do anything different if you were doing it again??

Regards Tom.

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It turned out great. I wouldn't have done a single thing different. Bike runs great & is rock solid reliable. Im totally happy with it. One lil mod I have done since then was a R&D power bowl 2 & a R&D flex jet. I had already rejetted the carb & wired the pump & installed a Merge Racing fuel screw & that did help a lot but it dosent compare to the power bowl. Throttle response is instant & there is zero bog at low rpm. I had read a few reviews in it saying it makes a carb bike feel like fuel injection & it does. No matter how fast I wick the throttle open it responds instantly. No more low rpm stalling either. Plus the added ease of fuel screw & leak jet adjustment locations makes it that much better. It was well worth the investment & if you shop around you can find them for way less than the $250 list price. I got mine for $169. It installs in a half a hour & tuning it was a breeze. Where I live here in Texas its normal to have a 30 to 40 degree temp difference between the morning & afternoon & that much of a temp swing requires a bit of carb tweaking & it couldn't be easier now. Yesterday it was in the low 40's in the morning & 70's in the aftenoon & adjusting for that was never so easy. Took less than 1 minute. Im sold on it. Im extremely happy with my bike. 

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I'm looking to replace my top end right now on my 08' CRF450r and want to get a JE high compression piston and Hot Cams Stage 1 or 2 cams 

http://www.ebay.com/itm/JE-PISTON-KIT-02-08-HONDA-CRF450R-450X-13-5-1-STD-w-OEM-Head-Base-Gasket-274756-/300836795601#vi-ilComp.

 

I have a couple of questions concerning this. 

1. Will my bike run better with race gas when I have a high compression piston?

2. Do I need to get different cams or anything other engine component in order for the piston to withstand the different compression or would you guys recommend any? 

3. Will using a high compression piston run the risk of blowing up my bike any more than a standard piston would? 

4. Lastly should I buy other components with the piston that would help it push even more hp out of it? 

 

Desert season is upon us and I just want some more pep in my bike to scream up those huge dunes. ;)

 

I did the JE 13.5 in my 2007 (same as 2008 basically) and kept the stock cam.  It was really nice.  Took an already great motor and jst gave it more pull everywhere.  Worked perfect on 91 pump gas.

 

As far as adding the cam, I also put a 13.5 in my 2012 and it was fine on pump gas until I added the stage-2 cam.  Then it started pinging under load.  I changed to 100 octane race gas and it's great now.  I maybe could have tuned out the pinging by richening up the mapping or retarding the timing so it might be possible to do the same thing with jetting on the 2008, if needed.  Me personally, i would just go with the piston and not worry about the cam.

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the 12 was lean.  i did almost the exact same setup on a 12 for a local expert with head porting and had to go about 16% richer on top with more fuel throughout.

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Yes, that was a lean knocking. A stage 2 Hot Cam typically reduces octane requirement, believe it or not. So adding the race fuel made it worse (leaner) if it was oxygenated, but the octane made it sound better with the slower burn. That thing must run hot as heck, get it remapped yesterday.

Edited by Eddie8v

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My 2012 was already remapped running Eddie's for an aftermarket exhaust witha Yosh pipe so I was not running the stupid-lean stock mapping. 

 

I don't know about the whole stage-2 reducing octane requirement.  Bike was fine with 13.5 piston until I added the cam.  That is when the detonation started.

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Stage 2 cam reduces cylinder pressure vs stock cam. You can run unleaded premium pump gas with a 13.5:1 piston no problem.

Edited by Eddie8v

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Stage 2 cam reduces cylinder pressure vs stock cam. You can run unleaded premium pump gas with a 13.5:1 piston no problem.

 

Like I said.. yeah, I did run the piston no prob.  But as soon as I added the stage-2 cam it started pinging.  That tells me it runs leaner (or the compression is higher) with the stage-2 vs. the stock cam.

 

The race gas stopped the pinging pronto.  I don't think it's oxygenated.  At least it's not specifically labled that it is.  And, no, it does not run any hotter than it did before.  Runs great and no probs.

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It's called "Lean detonation". Band-aid fix is higher octane fuel. Proper fix is proper octane fuel with proper jetting. Your engine is likely running very lean. Be careful.

Edited by Eddie8v
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It's called "Lean detonation". Band-aid fix is higher octane fuel. Proper fix is proper octane fuel with proper jetting. Your engine is likely running very lean. Be careful.

 

If that's the case, then everyone running Eddie's map is lean.  You might want to let them know!

 

And considering I ride mostly between 3,000 and 4,500 feet, I really feel bad for the guys at sea level.  They've probably all blown up already!

 

Please read what you said again and think about this....  If I was lean on pump gas and going to race gas stopped the pinging, then I am running the "proper octane with the proper jetting" (mapping in this case).  Instead of richening the mixture to match the lower octane, I went the other way and increased the octane to match the leaner mixture.

 

Been running great for about a year now like this, so I think I'm past the imminent failure.

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If that's the case, then everyone running Eddie's map is lean. You might want to let them know!

And considering I ride mostly between 3,000 and 4,500 feet, I really feel bad for the guys at sea level. They've probably all blown up already!

Please read what you said again and think about this.... If I was lean on pump gas and going to race gas stopped the pinging, then I am running the "proper octane with the proper jetting" (mapping in this case). Instead of richening the mixture to match the lower octane, I went the other way and increased the octane to match the leaner mixture.

Been running great for about a year now like this, so I think I'm past the imminent failure.

I thought about it, before, when I originally typed it: I am sticking to my thoughts... You need less octane at higher altitudes, generally, so I think your logic is flawed. Pull the spark plug and have a look at it.

Edited by Eddie8v

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