low compression. found out why, need some advice on what to do now - Honda TRX Forums: Honda TRX 450R Forum
 
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post #1 of 8 (permalink) Old 05-09-2017, 10:31 PM Thread Starter
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low compression. found out why, need some advice on what to do now

trx450r 2005. so i just got my motor put back together from the top end rebuild i did and i couldnt start it. so i went through all the trouble shooting and such, gas is good, carb cleaned, timing is good, valve clearance is to spec, it gets spark, wiring is good.

so yesterday i try a compression tester and find i only have about 25 compression when i should have around 108. i check valves for a bent valve, but theyre all good. while the head was off i ran my finger along the cylinder wall and feel a horizontal line down the cylinder that feels like its sticking out past the wall.

so i read that a bad cylinder or rings could cause bad compression so i did the test i read about on here to see if the cylinder was the problem. you take 2 teaspoons of oil, put it in cylinder head so it creates a seal that the now deformed cylinder isnt and you do the compression tester again. if the compression is higher, then your cylinder is why you have low compression, if its the same, then thats most likely not your problem.

today i tested compression and it was 0, the needle wouldnt move at all, and after i did the test it was the same. why is my compression 0 now??! also right after i kick it i can hear air escaping from somewhere, like a flatening tire sound. the compression tester gauge is in tight, so air shouldnt leak. what should i do now????? buy a new cylinder and rings? can i still re use my new wiseco 11.5.1 high comp piston i bought for this rebuild? i dont understand is wrong. everything checks out, even valves, the only thing that MAYBE doesnt is the vertical abnormal line in the cylinder. why is my compression 0 now and last night it was like 25!????? help i need some advice please!!!
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post #2 of 8 (permalink) Old 05-10-2017, 09:14 AM
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First of all let's see a pic of this cylinder..

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04' Black/Red
HRC Kit
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Rossier Full System
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post #3 of 8 (permalink) Old 05-10-2017, 10:42 AM
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Sounds like you need to adjust the decompressor. Throw the specs out the window and adjust it by compression instead of using feeler gauges.

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FLEXX BARS/TRAIL TECH CLAMP
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post #4 of 8 (permalink) Old 05-10-2017, 01:01 PM Thread Starter
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Quote:
Originally Posted by L1TECH View Post
Sounds like you need to adjust the decompressor. Throw the specs out the window and adjust it by compression instead of using feeler gauges.
how do i adjust the compression??
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post #5 of 8 (permalink) Old 05-10-2017, 01:12 PM Thread Starter
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Quote:
Originally Posted by socksandammo View Post
First of all let's see a pic of this cylinder..

Sent from my SAMSUNG-SM-G891A using Tapatalk
https://imgur.com/a/VSfEE Here it is. You can see a line going down the cylinder. It doesnt looks so bad in the pic but when you feel it, i dont know really but it doesnt feel ok haha
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post #6 of 8 (permalink) Old 05-15-2017, 02:49 AM
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Quote:
Originally Posted by Charlie Nelson View Post
how do i adjust the compression??
It tells you how to do this in the service manual. You do have the service manual right?

HIPERS W/RAZRS & HAULER EXTREMES
FLEXX BARS/TRAIL TECH CLAMP
05 CRF CAM RE GEN 1 P&P
12.5:1 CP PISTON
175 MAIN/40 PILOT/35 LEAK/2 TURNS
MONSTER EXHAUST SHORT CAN
DASA INTAKE
DFR HUMP SEAT
LT FOX FLOAT 3 EVOL RC2
JET DUAL RATE REAR W/GTT SHORT LINK
LSR AXLE, SPROCKET & ROTOR GAURD
+2.25 HOUSER SLICAST LT A-ARMS
PRO ARMOR NERFS
POLY SKID
T.M DESIGNWORKS SLIDE N GLIDE
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post #7 of 8 (permalink) Old 05-18-2017, 10:16 PM
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Have seen works cylinder working

Must be that you don't have the compression adjuster properly, it was hard for me the first time

Check out this Hott Boys Racing - TRX450R Valve Adjustment should help you

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post #8 of 8 (permalink) Old 05-20-2017, 09:31 PM Thread Starter
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i have a service manual. i tried to hone the thing i showed on the cylinder out, it made the groove better but its not totally gone. also the valves were adjusted correctly and the decompression valve was @awheellock67 so the compression should be correct. im currently splitting cases because theres a ton of scratches around the crank on my case. something is wrong on the bottom end now and theres metal shavings so ill see.
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