Help ME With My Compression Ratio Pleas! - Honda TRX Forums: Honda TRX 450R Forum
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post #1 of 17 (permalink) Old 08-04-2016, 07:25 AM Thread Starter
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Help ME With My Compression Ratio Pleas!

I have been so Frusterated with this!
I for some reason cannot get the math right and even using Calculating Software I CANNOT GET IT RIGHT!!!!

So My specs, here...

I have a 2005 TRX450R, I did a fresh 100% Rebuild Top and Bottom end

I put an 11:5.1 Dome Top High Compression Wiesco Piston in it
Decked at .30 Thousandths
OEM Head Gasket "Squished Thickness is 0.25 Thousandths"

That would be about 13:5.1?? Right???? That still don;t seem right to me...

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.

Last edited by RyanW; 08-29-2016 at 03:22 AM.
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post #2 of 17 (permalink) Old 08-04-2016, 10:05 AM
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what is the CC's of the dome of the piston and the CC's of the head?

The squished thickness of the head gasket is actually .027".

How much is the piston in the hole at top dead center?

Last question, is this a stock bore stock stroke, or is it a bigger motor? If it is a bigger motor, what is the bore and stroke?
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post #3 of 17 (permalink) Old 08-14-2016, 08:14 AM Thread Starter
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It's a Stock 94mm Bore and Stock 64mm Stroke.

The Combustion Chamber I'm not sure, "I know stock is 35cc's" and I had Racers Edge Machine off .30" to bump the Compression up a little more.

My guess is the head now is about 33.5cc's

And yes you're right the Head Gasket is .027"

The piston is +5cc Dome

Head has .30" Shaved off.

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.
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post #4 of 17 (permalink) Old 08-14-2016, 10:41 AM
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Quote:
Originally Posted by RyanW View Post
It's a Stock 94mm Bore and Stock 64mm Stroke.

The Combustion Chamber I'm not sure, "I know stock is 35cc's" and I had Racers Edge Machine off .30" to bump the Compression up a little more.

My guess is the head now is about 33.5cc's

And yes you're right the Head Gasket is .027"

The piston is +5cc Dome

Head has .30" Shaved off.
A guess isn't going to help much, it be better if you knew the cc's, half a cc off is a difference of about .4 in compression ratio.

And the big piece of info you are missing that makes a big difference in compression ratio is deck height, or how far your piston is in the hole. Without knowing that, you could get way off in your calculation. Just a difference of .005" in deck height is about .25 difference.

Assuming your deck height is set correctly at .040" and assuming your guess of head cc's is correct, your compression should be about 13.6:1. But to get a more accurate number, it be better to know what your head acctually cc's out to be and know if you actually have the deck height set a at .040" (but if you don't have it set there, I'd suggest you get your cylinder cut down to get it set a .040" because that makes a big difference when it comes to compression, and overall performance.)

05 TRX480R

Last edited by SDTRX450R; 08-14-2016 at 10:53 AM.
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post #5 of 17 (permalink) Old 08-14-2016, 12:43 PM
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Quote:
Originally Posted by RyanW View Post
It's a Stock 94mm Bore and Stock 64mm Stroke.

The Combustion Chamber I'm not sure, "I know stock is 35cc's" and I had Racers Edge Machine off .30" to bump the Compression up a little more.

My guess is the head now is about 33.5cc's

And yes you're right the Head Gasket is .027"

The piston is +5cc Dome

Head has .30" Shaved off.
John should be able to give you a # are you tryin to figure it out for race gas octane or its just buggin you lol
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post #6 of 17 (permalink) Old 08-15-2016, 12:39 AM Thread Starter
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Yes Compression Ratio for 1 because so I know the octane I need to run... 2 it just would be nice to know the Ratio. Main reason is because because I wanna know if I need to run Higher Octane or not, Because ever since I have Rebuilt the Entire engine top and bottom, installed the 41mm FCR it's just not Responsive like it should be "Carb Used is a 2007 CRF450R FCR Carb" in my TRX450R, it's been pissing me off just don't have the Bottom end power like a YFZ450 or newer TRX450 has "Best way to explain, when you rev the 06+ trx and YFZ450 it's a Short quick rev but the power is there Immediately and hits the rev limiter" Just mine is Sluggish as **** to build RPM's in a drag race, I lose all the time even after all this ****ing work... When it was all bone stock with pipe, jetting air box lid removed it was responsive and fast as **** well mostly stock... I was able to stay side by side with a YFZ and 06+ trx450... Not sure if I need to have it Dyno Tuned one of these days when I get the extra cash to toss in a couple weeks. I will for sure have Racers Edge Dyno Tuning it, I think that's what I'm going to have to do and have john look at it and figure my Compression Ratio. I just hate to spend that **** much more, Because after all this work installing a 41mm FCR with proper adapter, Ported & Polished Head, HRC Cam, Big Gun Rev Box, High Compression Piston, .30" Decked off the head, Millions of Different Jetting settings I tried.... Still it's like a turd... I'm about to just go buy a **** 06+ trx450R!

Sorry just Frustrated with this **** quad I feel like I don;t know how to tune crap....

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.

Last edited by RyanW; 08-15-2016 at 12:41 AM.
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post #7 of 17 (permalink) Old 08-15-2016, 01:21 AM
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Quote:
Originally Posted by RyanW View Post
@Gustav
Yes Compression Ratio for 1 because so I know the octane I need to run... 2 it just would be nice to know the Ratio. Main reason is because because I wanna know if I need to run Higher Octane or not, Because ever since I have Rebuilt the Entire engine top and bottom, installed the 41mm FCR it's just not Responsive like it should be "Carb Used is a 2007 CRF450R FCR Carb" in my TRX450R, it's been pissing me off just don't have the Bottom end power like a YFZ450 or newer TRX450 has "Best way to explain, when you rev the 06+ trx and YFZ450 it's a Short quick rev but the power is there Immediately and hits the rev limiter" Just mine is Sluggish as **** to build RPM's in a drag race, I lose all the time even after all this ****ing work... When it was all bone stock with pipe, jetting air box lid removed it was responsive and fast as **** well mostly stock... I was able to stay side by side with a YFZ and 06+ trx450... Not sure if I need to have it Dyno Tuned one of these days when I get the extra cash to toss in a couple weeks. I will for sure have Racers Edge Dyno Tuning it, I think that's what I'm going to have to do and have john look at it and figure my Compression Ratio. I just hate to spend that **** much more, Because after all this work installing a 41mm FCR with proper adapter, Ported & Polished Head, HRC Cam, Big Gun Rev Box, High Compression Piston, .30" Decked off the head, Millions of Different Jetting settings I tried.... Still it's like a turd... I'm about to just go buy a **** 06+ trx450R!

Sorry just Frustrated with this **** quad I feel like I don;t know how to tune crap....
I feel you on that! I don't know about pricing or availability but Morgan knows these things as good as anybody as well,if you've tried a bunch of jetting could be the carb itself or s-thing else?
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post #8 of 17 (permalink) Old 08-15-2016, 01:36 AM
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Not sure what air intake your using or if that big gun exhaust is doin you any favors, I know that's besides the main issue at hand,Dyno is defineately going to verify what's happening,wish I knew more to help you...
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post #9 of 17 (permalink) Old 08-15-2016, 01:49 AM Thread Starter
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Yeah man, big gun is junk I agree, i'll admit that lol I just happened to get it for free.

Later in Time I'm gonna get a DASA. Currently I'm also running stock head pipe, Uni Filter, No air box lid, OEM Intake with the FCR Carb connected up with the Adapter I may sound stupid saying this almost as if I'm answering my question but I think that is allot of the issue. But I don't think 100% that should make it this sluggsh. I mean yes it tops out at 86MPH but just sluggish at bottom end almost like a 400ex Acceleration.

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.
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post #10 of 17 (permalink) Old 08-15-2016, 02:01 AM Thread Starter
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Yes Compression Ratio for 1 because so I know the octane I need to run... 2 it just would be nice to know the Ratio. Main reason is because because I wanna know if I need to run Higher Octane or not, Because ever since I have Rebuilt the Entire engine top and bottom, installed the 41mm FCR it's just not Responsive like it should be "Carb Used is a 2007 CRF450R FCR Carb" in my TRX450R, it's been pissing me off just don't have the Bottom end power like a YFZ450 or newer TRX450 has "Best way to explain, when you rev the 06+ trx and YFZ450 it's a Short quick rev but the power is there Immediately and hits the rev limiter" Just mine is Sluggish as **** to build RPM's in a drag race, I lose all the time even after all this ****ing work... When it was all bone stock with pipe, jetting air box lid removed it was responsive and fast as **** well mostly stock... I was able to stay side by side with a YFZ and 06+ trx450... Not sure if I need to have it Dyno Tuned one of these days when I get the extra cash to toss in a couple weeks. I will for sure have Racers Edge Dyno Tuning it, I think that's what I'm going to have to do and have john look at it and figure my Compression Ratio. I just hate to spend that **** much more, Because after all this work installing a 41mm FCR with proper adapter, Ported & Polished Head, HRC Cam, Big Gun Rev Box, High Compression Piston, .30" Decked off the head, Millions of Different Jetting settings I tried.... Still it's like a turd... I'm about to just go buy a **** 06+ trx450R!

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.
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post #11 of 17 (permalink) Old 08-15-2016, 11:39 AM
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Quote:
Originally Posted by RyanW View Post
@Gustav
Yes Compression Ratio for 1 because so I know the octane I need to run... 2 it just would be nice to know the Ratio. Main reason is because because I wanna know if I need to run Higher Octane or not, Because ever since I have Rebuilt the Entire engine top and bottom, installed the 41mm FCR it's just not Responsive like it should be "Carb Used is a 2007 CRF450R FCR Carb" in my TRX450R, it's been pissing me off just don't have the Bottom end power like a YFZ450 or newer TRX450 has "Best way to explain, when you rev the 06+ trx and YFZ450 it's a Short quick rev but the power is there Immediately and hits the rev limiter" Just mine is Sluggish as **** to build RPM's in a drag race, I lose all the time even after all this ****ing work... When it was all bone stock with pipe, jetting air box lid removed it was responsive and fast as **** well mostly stock... I was able to stay side by side with a YFZ and 06+ trx450... Not sure if I need to have it Dyno Tuned one of these days when I get the extra cash to toss in a couple weeks. I will for sure have Racers Edge Dyno Tuning it, I think that's what I'm going to have to do and have john look at it and figure my Compression Ratio. I just hate to spend that **** much more, Because after all this work installing a 41mm FCR with proper adapter, Ported & Polished Head, HRC Cam, Big Gun Rev Box, High Compression Piston, .30" Decked off the head, Millions of Different Jetting settings I tried.... Still it's like a turd... I'm about to just go buy a **** 06+ trx450R!
Maybe it's a long shot but you said you just installed a big gun rev box,why don't you put the stock one back in to make sure that's not the problem? Only take a few minutes
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post #12 of 17 (permalink) Old 08-17-2016, 03:52 AM Thread Starter
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Stock one makes it even worse, then it's like riding a 300ex lol no joke.... I have done Comparisons. It's almost as if it's just not "Peppy" like it was back when it was Stock. It has to be the Carburetor.... Especially Now that is is all mostly Performance Rebuilt still not as Peppy as it was new. Allm y Yamaha Douche friends just are like "oh that just how slow the TRX450R's are" which is Bullshit because Back when it was Bone stock and new it was keeping up side by side with YFZ's. Now it's just like boggy at the bottom end. Just not Peppy at all anymore..... Hey Thinking about it..... Weak ignition Coil maybe???

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.
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post #13 of 17 (permalink) Old 08-17-2016, 04:08 AM Thread Starter
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Sorry this Thread has gone on like this, but You know what, now thinking about it... Could I Possibly have a Weak Ignition Coil? Or a Bad Resistor in my Spark Plug boot? Tell me your opinion, I remember years ago I had a little gokart 150cc and the Ignition coil was weak and the engine became sluggish as **** little by little, I could not figure it out, I finally replaced part after part messed wit the carb and tried the Coil and boom all it's power was back.

I'm gonna ohm out the ignition Coil, Spark Plug boot and stuff on my Quad. I Almost feel like may have had Weak spark for a really long time and all the Fuel isn't being ignited properly, because Like I said even before the Rebuild I had this "Loss In Power" Because I remember it used to be SO **** Peppy stock and slowly lost power and even after Valve Adjustments it still seamed "Sluggish" to build RPM's "as if you revved a 200x ATC or something & just not Peppy like a 450 should be" or how it used to be all stock, it was just jetted, but bone stock motor. Then it blew about 3 months ago and then I rebuilt it 100% Top and Bottom, I remember It started getting weaker about 7 months before it blew up and I just figured "it was low on Compression" then like I said it blew so I rebuilt it but still seems a bit weak...

Because now it's got New Valves, Re Shimmed "Properly Set Gap" High Compression Piston, Decked Head, 41mm FCR Carb, HRC Cam & Rev Box.

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.
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post #14 of 17 (permalink) Old 08-17-2016, 05:17 AM
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Who ported the head?

.030 is a lot to cut off a head for a Wiseco piston even with a small HRC cam. Did you clay it?

At the end of the day, regardless of the static compression, it sounds like a really mis-matched combo to me. Small cam, bad pipe, bad "rev box", I'm guessing poor tuning, etc etc.

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post #15 of 17 (permalink) Old 08-17-2016, 07:46 AM Thread Starter
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I ported it, but I did a good job... I say this because when I took it to Racers Edge to have it decked I was scared of their opinion on my Porting job and to my Surprise one of the Guys who does the machine work "Not John" but one of the guys told me "**** who ported this? It looks great!" even said that I can even open it up a little more if I wanted and suggested to use a tad bit Finer Grit to finish it up "Which I did Go A Little Finer" as he suggested but I didn't feel Comfortable opening it anymore because I didn't wanna hit a Water jacket or break through the area where the Valve Spring seat sits. Trust me I spent my time on it and know how Air Flows. The Exhaust port is about Shiny as a Mirror and the Intake is just Finished with a 80 Grit so Fuel will Atomize.

The Wiesco Piston has Valve Reliefs already cut out Racers Edge asked me the Same thing and had me bring the piston to look at because they're the ones who Diamond Honed my cylinder and warned me about taking of that much off my head.

Everything with Electrical ohm'd out to be with in Spec.

How ever figured out tonight that I have been gaping my Spark Plugs at .20" Which you aren't supposed to even gap the IRF8H11 Iridium.
So I opened the gap to 1.01mm ".40" and fired it up, gave it a couple quick whacks to the Throttle and ****. It's really Peppy now wtf A Spark Plug can Cause that much of a Loss in power? or Throttle Response I should say? I haven't Taken it for a Ride yet but I will in a couple days when I have time off work and let you guys know if it's got the Bottom end again.

I know it would run even 100 Times better with a Good Full Dasa or HMF Pipe & Muffler "Rev Box" I meant to say Big Gun Box.

My guess is it wasn't burning all the Fuel in the Cylinder completely with a Super Small gap because I did notice it ran Super rich no matter what jetting I had the plug would be really black only half of it was Black so that tells me it was an Incomplete Burn before.

2005 TRX450R Ported & Polished Head, Decked Head at 0.30, 41mm FCR Swap (2007 CRF450R Carburetor), NCVQ Needle, Uni Filter, Big Gun Exhaust, HRC Cam, 11:5.1 High Compression Piston, & 15T Front Spocket.

Last edited by RyanW; 08-17-2016 at 07:49 AM.
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