if you wanted to arrange it to go to a shop, commit to the assessment invoice, and pay me for the time to be inconvenienced then game on. Otherwise thanks for asking, i'll wait for an educated buyer to call.
Compression Test when Buying Bike
- Thread starter spray____
- Start date
that .01 was for friends that i know will take the bike
I had a kid come take a look at my bike once and he asks me "Is this thing hard to ride? I just got my m1 today" :?
kruzuki
Well-known member
Or a vertical twin, like a GS500.
PhatBastard
Well-known member
how many motorcycle engines have a compression relief valve? compression test would be rather useless on one of those engines unless you were aware of the procedure.
Very, very few outside of dirtbikes
A compression test requires the removal and installation of the tester. A ham-fisted person can easily cross-thread the tester and render the bike unsellable.
Only kick-start bikes have compression relief valves.
There are press-in compression testers that are not threaded.
There are two cases here: vintage bike, where this is legitimate concern, and a compression test is easy and trivial.
Modern bike, don't bother. Unless the bike has hundreds of thousands of kms, the bores and valves will not be worn. If there is a compression fail, it's likely from a needed valve adjustment, which you should do any way. Modern water-cooled engines are very reliable, and any major issue should be obvious ( listen to it, look for fluid leaks).
You can tell if a bike has had an abused life by looking outside the engine. Most modern Japanese used bikes do not have engine issues, it's the suspension, transmission and brakes that need to be looked at, as many bikes have never changed fork oil and monoshocks are typically garbage after 20,000km.
But SVs don't have a reason to be concerned about this. Research will tell you what to look for on a used bike -Motorcycle News collates all this. SV engines are reliable, but they do have crap shocks that fail early.
Engines are not the big money risk on modern bikes. You need to check the brake discs for abuse, the steering head bearings for play, the tranny should click into each gear, the fork seals and dampening. The rear swingarm for play, the suspension linkage for play, the sprocket, chain. All of that can be done on a centre stand. Check for fluid leaks, and check every single electrical device on the bike, because that is a sure-fire indication of a crashed or abused bike. Many people ride bikes with dead shocks. You can spin the wheels and do a quick check for trueness, use a line to check for alignment, which could uncover a bent frame.
Any engine trouble should be obvious by listening and looking at all the case gaskets for leaks. Make sure you feel the exhaust headers for temp before the first start by the seller. many pre-heat the engine knowing someone is looking at the bike. Once hot, reving the engine slowly to 3000, then cracking the throttle will reveal issues if you see blue smoke.
I've been told a leakdown check is more important. Or maybe that was just for my specific issues.
Dyno run paid by the buyer, most guys won't mind their bike going on the dyno, if the sale does not go through, at least they got a free dyno run on their bike.
Just a suggestion
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Better than nothing, but without a baseline would it tell you much?
It will tell you if the tranny works, and the power output should be near the OEM specs. It will tell you if the carbs are jetted properly. I doubt anyone will want to sell a bike that badly to do this however. I don't think someone would care about dyno data from a bike they are selling.
tonymorgan
Well-known member
Nope. Suzuki Savage 650 comes to mind right away, and there's more than a few of those running around. My Royal Enfield also has a compression relief valve, but it's electric, and kick start. My Enfield is also the proof that I use for idiots who say you can't "bump" start an EFI bike.
It's good to know many ways to start a dead Enfield.
PhatBastard
Well-known member
my 1500 vulcan has one and only electric start
