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Discussion Starter #1
Pulled the plugs, they're sooty and black. Can they be cleaned up and reused or should I just go buy new ones? Also, I'm sealing the gas tank, I poured the gas out and it was brown and full or rust and crap. Putting on Uni filters so now I'll have clean air and clean gas. While I had the plugs out I cranked it and had good compression from both cyclinders, I didn't measure it or anything but could feel a good amount of air coming out of both sides. The carbs were rebuilt last summer, but if it was just pumping crap rusty gas through they'll probably need rebuilt again?
 

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Sensei
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You NEED to measure the compression... ... On most engines, 160 PSI would be excellent.... On a 450, it's re-ring time (163 min)..... The 450 should have about 180/185 PSI to be "normal".... Fresh and rings just seated, you can get 215+....... Plugs can be cleaned, but it's not worth the effort... Buy new....
Steve
 

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I have found that spark plugs can be cleaned -- and sometimes they can't. A shot of brake clean, wipe electrode with a cloth, maybe a few scrapes between the electrode and the groundy thing with sand paper, and check for spark. No spark? Try again. No spark? Pitch em. B8ES spark plugs are a Buck-99 at Advance Auto.
Don't wire brush them!!
Also--
Steve,
Maybe I have a bad compression guage but-- now I have three 450's. One with 23K, one with 13K and one with just under 7K.
Warm engine, open throttle, crank over with starter until needle stops climbing.
All right at 100PSI. Both cylinders. The two that are rideable run great! Rip right to red line in all gears. The one with stock gearing struggles in 5TH and can't quite make red line (like all my bikes used to). The one geared lower hit's it no problem.
Wondering how many of us here get my readings or the 180 + PSI readings.
Maybe I need a new guage?
 

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WOZERD said:
Steve,

Maybe I need a new guage?
I suspect you may - I'd be surprised if you even got them to start easily with just 100 ponds.
My last 450 rebuild is showing 182....
 

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tbpmusic said:
WOZERD said:
Steve,

Maybe I need a new guage?
I suspect you may - I'd be surprised if you even got them to start easily with just 100 ponds.
My last 450 rebuild is showing 182....
Just what I need-- more money for a new guage. On the bright side-- it's cheaper than a rebuild X 3! :eek:

All three start right up!
 

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WOZERD said:
tbpmusic said:
WOZERD said:
Steve,

Maybe I need a new guage?
I suspect you may - I'd be surprised if you even got them to start easily with just 100 ponds.
My last 450 rebuild is showing 182....
Just what I need-- more money for a new guage. On the bright side-- it's cheaper than a rebuild X 3! :eek:

All three start right up!
My 450 started right up on the first kick too and it idled great. Unfortunately it didn't run very well with only 60 psi in one and 130 psi in the other. I did not have good luck using the electric started when checking compression. Try kicking it over about 5 or 6 times and see if there is a difference.
 

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Sensei
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Bill, and all... I've actually had bikes (450's) start and idle with only 90 or 100 PSI on both sides, but not easily, and they produce no real power... You can drive them and get to a reasonable speed (65+) but it takes forever.... Mediocre pick-up, slow rise in revs....Not much fun...

The rebuilt engine pulls like it got hit in the rear by an oncoming freight train...... ( @205 PSI once the rings seated in....I think it was about 180+ immediately after rebuilding, new valve job and new valves).... LOTS of FUN!

MAJOR DIFFERENCE!!!!!....:D :D :D :D :D
 

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kdan311 said:
Pulled the plugs, they're sooty and black. Can they be cleaned up and reused or should I just go buy new ones? ......
Typically, yes, they can be if they are cleaned correctly and have not been abused/damaged. A little brake cleaner and a towel will not necessarily do the trick though. As always, the correct tool is always helpful. I picked up this handy dandy spark plug cleaner many moons ago when I used to race two strokes (MX and Desert mostly). It's a sand blaster and air blaster in one. The bag contains the media and you put the lever in blast. Hooked up to an air compressor you pull the trigger and move the plug around on the rubber seal. After a few seconds of blasting, you throw the lever to air only and blow away the grit. It actually works pretty well but, with today's engines, I haven't pulled it out of it's hiding place in many years.

 

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Discussion Starter #9
on the subject of a good pressure gauge, can anyone recommend one and where to get it? Online or locally? Like advanced auto parts or autozone? If I buy one can it also be used on lawn mowers and cars?
 

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Sensei
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I got a set at Sears with the gauge and a variety of adaptors and hoses for different size/pitch plug holes.... I think it was about $40... Should work on mowers and cars as well....
 

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WOZERD said:
I have found that spark plugs can be cleaned -- and sometimes they can't. A shot of brake clean, wipe electrode with a cloth, maybe a few scrapes between the electrode and the groundy thing with sand paper, and check for spark. No spark? Try again. No spark? Pitch em. B8ES spark plugs are a Buck-99 at Advance Auto.
Don't wire brush them!!
Also--
Steve,
Maybe I have a bad compression guage but-- now I have three 450's. One with 23K, one with 13K and one with just under 7K.
Warm engine, open throttle, crank over with starter until needle stops climbing.
All right at 100PSI. Both cylinders. The two that are rideable run great! Rip right to red line in all gears. The one with stock gearing struggles in 5TH and can't quite make red line (like all my bikes used to). The one geared lower hit's it no problem.
Wondering how many of us here get my readings or the 180 + PSI readings.
Maybe I need a new guage?
funny you should say that.......i had low compression readings also. i used a sears craftsman gage....brand new or rather its rarely been used. My bike starts right up and runs great. When i had the head off recently and replaced it with one with no torsion bars i inspected the rings and they were fine. I tested the compress. after installation and got around 125psi. I just knew that had to be wrong....maybe its one of those little airvalves in the hoses of the compress. gage that is faulty....or like was mentioned ...the gage itself.
 
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