Base gasket still leaking after replacement - video!1!1!

Did the top end, had the jug sleeved ect. ect. We originally took the bike apart to replace the base gasket then just ended up doing a top end anyways. If I hadn't seen the coolant at the base here, I never would of known. Im to the point where I might just get some copper sealer sealant and paste it on both sides of the gasket and see what happens.

The bike rips with the new top end btw.

After sitting and looking at the bike for a moment, I realized that it may have at some point been in fairly big wreck. For the life of me I could not get the top engine mount back on after taking it off the first time, or the second time today. I had to drill out holes on the mounting bracket. Then I realized that the mounting point for the engine mount was right above the area that was leaking on the bike. Correlation? Hard to say... But definitely worth noting. Unless somebody else has a plausible reason as to why this would happen...

But in some hi temp copper seal and Im keeping my fingers crossed.

my 03 that i had was a pain to get the top head stay bolts on.. i found, just loosen up the engine mounting bolts then put everything in place, then torque it all down. seemed to help it a lot.

with aligning the head stay bolts i mean. about the leaking base gasket. the cylinder base or cases must be damaged or warped. maybe try using hondabond? but i dont know how long it will last.

I wonder how long it will hold : / I used a copper sealant that is high temp. Ive heard pretty good things about it. Ordered another head gaseket. I didn't check to see if the bottom of the jug was true when I took it off dang it. I should of.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By ashfmxuk
      So Been rebuilding my bike and the rubber mallet just "wouldn't cut it"!!!!
      I had to pry managed to sand down it all looked flat but this seems a bit gappy.

      This is only on the outer edge but I can help worry this is going to leak or get shit into the engine.
      Any help or advice would be awesome thanks

    • By Kaito Sutton
      Hey guys, so cant find much online about cr 250r enduro conversions (nothing recent) so im wondering if it is an option or not. I currently have a crf 250x 2009 and a XR 650r. If i want a 2 stroke enduro but want to stick with the honda line up, is a 2007 or 2005 honda cr 250r a good option. and if so what would need to be done to it to get it up to spec for trail and enduro riding. Thanks very much
    • By dirtbikesrule
      If you own a 2 stroke dirtbike,please reply once. Im just wondering how many people on this site have them.
    • By skipn8r
      Note: This specifically applies to the '92 - '01 CR250 engine, but it should be adaptable to any 2-stroke. The basic idea is to pull the carb and exhaust, plug one and pressurize the engine through the other to look for leaks.
      It's very important to pressure test a 2-stroke after it's assembled. The reason is that a 2-stroke gets it's lube through the pre-mix. An air leak means your engine can run lean. Lean means too little fuel. Too little fuel means too little lube. Too little lube means death to your engine. So here we go.
      First, you need to pull the seat, tank, shock, carb and pipe. Everything you need (other than a tire pump) is shown below.

      The assembly below is basically a 1-3/4" PVC plug (same OD as the intake pipe ID) that is transitioned down to a 0-15 psi gauge, a shut-off valve and a Schrader valve (to connect a tire pump). The 1-3/4" PVC plug is a tight fit in the intake pipe, but it'll fit with enough persuasion. I used yellow heavy duty pipe tape (made for gas systems) to put everything together. I don't have all the technical names for everything, but if you take the pictures to a hardware store, they should be able to help you piece it together.

      The item below is an adjustable rubber freeze plug. They are available at automotive parts stores in various sizes, but the closest one I could make work was a 1-3/4" version. You tighten the nut which squeezes two metal plates together which squeezes and expands the rubber piece between the plates. You have to tighten it a lot, but it makes a good seal in the exhaust port.

      Before you install everything, make sure that the piston is at BDC (so that all the ports are open), the spark plug is installed and all other components are properly tightened. Below, you can see the gauge/valve assembly installed in the intake pipe. Make sure to tighten your intake pipe hose clamp tightly as the pressure will tend to push the assembly out.

      Below, you can see the freeze plug installed in the exhaust port.

      Once you have everything installed as shown, use a tire pump to pressurize the engine to 6 - 8 psi, then close the valve and watch the gauge for any pressure drop over a 5 - 10 minute period. A well sealed engine will hold pressure with no observable pressure drop for 10 minutes easily.
      One common "leak" in a healthy '92 - '01 CR250 engine (and probably other types) is through the powervalve linkage. It probably doesn't affect performance, but it'll sure throw your leak measurements off. To avoid leaks, make sure the powervalve linkage is correctly lubed (per the Service Manual) with grease and Moly 60 Paste during assembly.
      If your engine holds pressure with no observable drop for 10 minutes, you're good to go. If the pressure drops 2 - 3 psi or more over 10 minutes, spray soapy water all around the pressure test parts first to check for leaks there. If you find none on the test setup, start spraying the soapy water around the base gasket, head gasket, center gasket etc. Any pressure drop of less than 2 psi over 10 minutes is your call, but I'd definitely fix it.
      I've had really good results by using Permatex Copper Gasket Sealant on the base gasket, PV cover gasket and reed cage gasket. I don't use anything on the head gasket.
    • By ulmanb
      What value would you say a 1986 cr250 with a freshly plated cylinder and new top end, newer tires, newer chain & sprockets, in overall very good condition?
      I picked up the bike (cheap) a month or so ago in need of cylinder replating & top end. Apparently the headgasket blew internally scouring the cylinder. The crank feels good and the bike is very clean/good condition.
      I havent put the bike together yet (too busy to ship cylinder and order parts), but figure I would have a total of $600 (including bike cost) to get it into good running cond.
      A friend wants to buy it as-is for his 15 yr old 200# kid. What value wouldyou put on it in As-is condition vs with a fresh engine?