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Which Compression Tester?

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I want to purchase a compression tester. Is this a no-brainer? Any possible reason why the Motion Pro would be worth the moolah besides that its a "moto" brand and comes with a lil red lunchbox?

Motion Pro ~$85 (I already have their leakdown tester)

http://www.amazon.com/Motion-Pro-08-0188-Compression-Tester/dp/B000GV1UFM

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Innova ~$25

http://www.amazon.com/INNOVA-3612-Compression-Tester-Piece/dp/B000EVU89I/

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Another $12 and these adapters include a 10mm for small motors which comes standard with the Motion Pro

http://www.amazon.com/INNOVA-3618-Adapters-Compression-Tester/dp/B001QUHFQA/

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Thanks in advance everybody. I'm going to be put it to the test soon then I'd be happy to let friendly SDAR members use it.

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I got the motion pro, had it for years. Well made, worth the cost. Can test any vehicle or bike.

If the amazon stuff gets good ratings, its probably fine also. I would be mildly concerned about having 2 sets of threads on this one. Thevadapter could potentially come loose deep inside the spark plug tunnel and be a pain to pull out but most likely they have that sorted.

Both are probably made in china. Not sure about the motion pro but it *may be made in USA.

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You might want to consider a leak down tester instead. I have the Total Seal Tester. Not cheap, but good quality. The Jegs version is great bang for the buck. About the same price as the Motion Pro Compression tester.

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I have one just like the Inova above. It does the job, and as you can see, at a much lower price. I've used it on everything from my car, bikes, and tractor...works perfect.

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the harbor frieght tester actually works really well. have used it on about 50 -60 different bikes ..withstands commercial use.. still accurate... the case is flat.. thats nice when throwing it to the back of a tool box .but i have to agree with AATA .. leak down tester is more accurate for diagnosis.

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Thanks for the replies guys. I ordered the Innova and will post back with my impressions of it.

I already have the Motion Pro leakdown tester and will be using both tools to try and diagnose what might have gone awry with my DRZ motor on my last ride (if that is even the cause of my issue). I think both tools have their place and that the leakdown tester can be a great tool in the correct hands.

Not to hijack my own thread but.. I'm trying to figure out how my intake valves got tight suddenly. I had the valves, compression and leakdown tested not many rides before this trip and after two days, the bike wouldn't start even though I rode it into camp the previous night. I just discovered that my NoToil air filter oil chewed up my UNI air filter. The inside of the filter looked clean and it looked to be stopping dirt from getting through but Day 1 was quite dusty. I wonder if the filter was pourous due to the incapatability of the NoToil and Uni filter (I've now read that NoToil and Uni are not recommended together)?!? The filter sat oiled for months before this trip and it might have started to breakdown the filter. Once the valves are appropriately shimmed, then it's time to try the Innova Compression Tester and Motion Pro Leakdown tester!

When you're a half clueless mechanical hack like myself, having diagnostic tools (and bitchen SDAR friends) can be quite helpful :good:

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ive found that motorcycle valves normally wear towards being too tight ... (receeding valve).

its strange that it happened seemingly overnight.

also ive seen the valve seat just give in (crack or fall out). with out anything to sit on the valve will rest on the rocker assembly causing poor start or no start.

if the valves are worn slightly they are shimmable or adjustable. although a receeding valve wont stop receeding. it slowly gets out of adjustment by receeding more as you ride it.

its like my hair line ... keeeps going up and up and up. ..

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I'm not familiar with the DRZ head. Are the intakes Ti? If so once the hard facing on a Ti valve fails the clearance will go away very quickly. You can reshim but it won't last very long. The only solution is to replace the valves. On my '07 450 EXC I had this problem at 100 hours. I replaced the intakes with Kibblewhite SS intakes. They've been rock solid for over 150 hours since. One question I have is how do you do a compression test on the DRZ? Doesn't it have an autodecomp? If so won't you need to disable it somehow to get an accurate compression reading?

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Heck, I'd start with the leakdown tester you already own, and has been tested by one of The Finest Mechanics on SDAR. I think a leakdown is better than a compression test anyway.

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The valves are stainless steel on the DRZ400. The limit is .10-.20, one intake was .06 and the other I couldn't measure because the smallest feeler gauge i have is .05

We will check compression once the valves are set properly It seemed to be kicking through pretty easily and I suspect low compression. I've never kick started a DRZ400 before, but it seemed too easy for my calibrated kick start leg.

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So I'm going to assume that a DRZ has an automatic decompression release if it doesn't have a manual one. If that's the case then a compression check will be pretty meaningless won't it? Not trying to be a smart ass. Just wondering how you would do one that was valid? Is there a way?

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Rent one from http://www.oreillyauto.com/site/c/RentalTools.oap for free. Or borrow one from any of the guys above this post. Definitely don't buy one unless you like collecting obscure tools you'll rarely use. Like me...

That's funny because I actually have a drawer in my roll-away that is designated to obscure tools I rarely use, including my compression tester. Surprisingly enough, I often find myself going to the drawer for something. :smile_anim:

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Probably right, I think it may have an auto-decompression cam even though it also has a manual decompression. I'll check that out, if so a compression reading will be useless.

Tight intake valves will make a motorcycle difficult to start. Been there, done that before. Hoping a few valve shims will get it going again.

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Btw: the auto decomp (at least on the KTM) does not eliminate compression- it reduces it. Obviously one would not get an accurate compression reading, but one can determine if there is none.

I still think the leak down is the better test.

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Always causing trouble. You need to heal up quick.

; )

You ain't kidding! On that front I MIGHT sneak back on the bike by Thanksgiving. Woohoo :thumbsup_anim:

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Pretty bad readings from the leak down test, air coming from the crank case. Looks like piston/rings.

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how about giving it a wet test?

if you put motor oil into the cylinder(thru the spark plug hole) ...only a little bit, quarter cup......the compression will come back up . if so then its definitly time for the upgrade .... if not then your looking at valves or something in the top end because oil goes downward (gravity)...

normally compression comes right back up around 150 with a wet test .unless its a valve issue

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normally compression comes right back up around 150 with a wet test .unless its a valve issue

Or something more piston/cylinder catastrophic, like, say, a cracked piston?

Go ahead, ask Vacman how he knows...

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