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xr 200 fouling plugs

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my friend called me saying his bike (83 xr200r) was fouling the plugs. it would run for 10 seconds then quit, would pull the plug and it was oily. is it just needing a top end, or is it more serious?

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Need a little more info.

Was it running fine then suddenly started doing this and now does it every time?

Did he just buy it?

Has it been running and gradually got worse and worse?

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Do a two stage compression test; the first one is dry and the second with half a teaspoon of oil added. Then check a service manual for what is acceptable. If the pressure is low it is time for a rebuild. If the second reading is much higher than the first the rings are bad, if not then the valves are leaking.

Do the tests with a warm engine and full throttle.

If the rings are bad that is where the oil is comming from. The oil could also come from failed valve stem oil seals and worn valve guides.

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ok heres the history, my buddy originally bought the bike in 1990 but the timing chain kept skipping so he sold it to another buddy of mine (mechanically inclined) who had it till 2007 untill he sold it back to him for $200 (ran fine). it needed some minor repairs which i took care of and it ran fine for me last month although it took a long to get it started but once it was warm it cranked right up evey time first kick. i did check the compression and was at 120 psi but i was using a wally world gauge. i'm guessing its the original top end. whats the compression supose to be?

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190psi, warm engine, throttle fully open. Check it again and them add a teaspoon of oil to the cylinder and test a second time to see if the problem is the rings or valves.

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thanks for the replies guys. i think i'm gonna do a top end and valve job on my budies bike just to be safe via the crank bearings are still good.:banana:

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