[Homer]

Don't have one, I would like to buy one to keep handy with my future addition of restoring mini bikes (z50's at the moment). But i also want one I can use on regular car motors. Something with adapters I'm assuming.

Do they all work pretty well (even cheap harbor freight ones) or are there any decent ones out there people recommend getting?

 

[Charper732]

I have a snap-on and a HF comp set. They both do the same task. Just make sure the Schrader valve in the end of the hose is a good one and you are good to go.

 

[sh0rtlife]

i second that..good valve and it really doesnt matter what brand it is..but like you said get one with the adaptors...i got mine at shucks/orielys back in the 90s still works like a charm

 

[Dan Z50]

Whatever you do, don't rent one, for two reasons:

1. If you need a tool once, you'll need it twice, buy what you use.

2. When I went to purchase mine from a local auto parts store, the guy mistakenly thought I wanted to rent it not buy it because they do rent a lot of tools out at this location. So he had rung me up at the rental price, I clarified i'm buying a new one, so he got a new identical one and rerung it...SAME PRICE! So don't get burned renting something when you could have purchased it!

Clearly you plan to use yours on other stuff too, but for guys who are one time users, don't forget another route is to buy the tool, use it, then resell it to your buddies for just slightly less than what you paid. You get your use out of it, most of your money back, and they get a great price on an almost new tool, and YOU can always borrow it back from them later for free!

I've known guys to do this with big items too like M.I.G. welders and plasma cutters.

 

[sh0rtlife]

allot of parts houses like autozone and oreilys both rent most tools these days...the system they use is briliant..charge you the price of the tool incase you keep it..but give you a FULL refund when you bring it back....


but really if your planning on using a few times imo its still better to buy "most" tools....scan tools are a whole nother can of worms

 

[tmas]

I like the Snap On one.
tmas

 

[Homer]

just went and grabbed the cheapy harbor freight version.. hooked her up and got 80 psi, DOH. guess ill check valve clearances, will hook up the leakdown as well.

funny thing is, it starts 1st kick. is there some math to be applied to compression that indicates how much power is lost per pound of psi or ballpark? just curious if anyone reading happens to know.

 

[Matthonda86]

you sure your to TDCC, 80% leakdown is basically missing parts.

 

[Homer]

for compression dont you just hook her up, kick a few times and see the max psi? tdcc would be for leakdown testing, right?

 

[Matthonda86]

Yay your right i thought you got a leakdown...carry on

 

[spiz5]

Throttle needs to be wide open when kicking

 

[Homer]

following up for others, thanks for the tips and help as well to those in this thread.

leakdown - 15%
compression - 100 (using cheapy harbor freight tester)

dont forget to run the motor and warm her up first. throttle open as well (as spiz5 pointed out)

 

[sh0rtlife]

for a "valve" leak down if my memory serves me..pull the plug put some oil in the cyl and kick over SLOWLY a few times with the plug still out..this is to coat the cyl wall with oil...put the tester in and kick it over to TDC twice leaving it the second time....this is your leakdown test of the TOP END..this will tell you how the head gasket and valves are doing...without oil adds in ring pressure loss

 

[MatthewMCRepair]

Here is the one I use, about $40:

Motorcycle Compression Tester

Don't use the HF one! The Schraeder valve is not located at spark plug location so the long hose adds to cylinder head volume and you will get lower results. Ask me how I know.

 

[MatthewMCRepair]

Here is a vid I put together some time ago: