I have searched several places trying to find a compression gauge that will fit the small 12mm threads common to ATV's to no avail. Any ideas? I was attempting to take your advice and make sure the used unit I got has good compression. Eventually, I will have a trailer and can get a mechanic to look at it but for now, I am trying to do as much maintenance as I can, myself. Starting with compression would be great place to start but has proven difficult.

 

Two possibilities:

1) The El Cheap-o conical, rubber, one-size-fits-all compression gauge.

2) Adapters that snap onto a hose; Snap-On makes one, for example; you get a gauge, hose with connector, and adapters to fit all spark plug hole threads. Costs plenty! Flag down the next Snap-On Tools truck you see; the driver will be GLAD to sell you one.

You might ask the boys who work in the dealership service department what they use and recommend; if they're decent folk, they'll give you some worthwhile tips.

Diogenes

 

Mityvac..part#5500..sorry no phone# on package it came in.Address is 6952 Fairgrounds Parkway,San Antonia texas,78238-1280.Was about $50.00 bucks, comes with two adapters,14&18mms,can buy other sizes.It has a real nice long S.S. hose& quick-disconnect guage.
Maybe less expensive than Snap-on,not sure.

 

I bought a decent compression tester at Sears Hardware. It is the screw in type.It has been working great for years.

 

I purchased mine from Sears too. Got it several years ago but it has the std 14 and 18mm threads. The ATV has 12mm threads and I have found it very difficult to find the adaptor. In fact, I have not been able to find one. I am going to borrow a trailer and have it checked professionally. It looks like i need serious carb help anyway.