BASE GASKET BLOW OUT

[monster malibu]

Hey guys, I just replaced my bikes topend and the base gasket blew out. The cylinder was tightened and checked after the breakin period. I was wondering if anyone has had this problem with Cometic gaskets. The base gasket looked real thin, but I used it anyway. I'm going to buy a Winderosa topend gasket set in the morning.

[stewart]

was the gasket all paper or metal with paper on both sides,,,,,  how thick does it mike

[monster malibu]

The gasket was all paper. I can't believe the new gasket blew out already, the bike has an hour total run time on it after getting a new topend.

[fluffy]

i just replaced my base gasket and head gasket with factory ones. no problem, other than the head gasket was 42.00 dollars and the base was 8.00. base was just hard paper.

[kaw rider]

gasket meterial is key to no having problems. i know the buttom of cylinder is not flat. I only run oem gaskets.

[monster malibu]

Are the oem gaskets metal/paper combo, or are they just made of paper? Anybody using Moose gaskets, or Vesrah gaskets with any luck?

[FactoryPhil]

The OEM gaskets are paper only. In my experience they are less flimsy or flexible than most aftermarket ones. Honestly, I have used Cometic gaskets with great success in the past. You   might want to check your cylinder and crankcase mating surfaces very carefully next time you replace the gasket. It is possible there could be some old gasket left or maybe a gouge from scraping that caused the failure.

[kaw rider]

oem are paper base gasket.

[BDI]

Cometic makes base gaskets that are aluminum with foam rubber on each side. These gaskets will not blow out sideways because of the metal in them.  The foam rubber makes them seal much like O-rings would, plus when you have to take your engine apart they come right off with zero clean up, no gasket scraping means no scratches and no future sealing problems. If your base gasket leaks around the transfer area it is very likely that the base of you cylinder is not flat. This is usually caused by over torquing of the base nuts. You should check the bottom of the cylinder for flatness and have it machined accordingly then torque the base nuts using a crows foot to 25 foot pounds. You should first torqe them to ten then twenty then twenty five In a criss cross patern. Cometic makes the best gaskets I have ever used and this Is not my first rodeo. If you order your gaskets from a after market supplier you will get what they have on the shelve. If you order from www.cometic.com you will get what you specify. They even have stainless steal gaskets the are rubber coated but they are expensive. If a gasket blowes It Is generally not the gaskets fault.  You must figure out why It blew and fix the problem.

[FactoryPhil]

If a gasket blowes It Is generally not the gaskets fault.  You must figure out why It blew and fix the problem.

Bingo!

[monster malibu]

I checked out cometic.com and they list a topend gasket set for my 87 kx500. My bike has the stock bore 86mm, cometic lists a 88mm for my bike, will it work?

[gowen]

Cometic makes base gaskets that are aluminum with foam rubber on each side. These gaskets will not blow out sideways because of the metal in them.  The foam rubber makes them seal much like O-rings would, plus when you have to take your engine apart they come right off with zero clean up, no gasket scraping means no scratches and no future sealing problems. If your base gasket leaks around the transfer area it is very likely that the base of you cylinder is not flat. This is usually caused by over torquing of the base nuts. You should check the bottom of the cylinder for flatness and have it machined accordingly then torque the base nuts using a crows foot to 25 foot pounds. You should first torqe them to ten then twenty then twenty five In a criss cross patern. Cometic makes the best gaskets I have ever used and this Is not my first rodeo. If you order your gaskets from a after market supplier you will get what they have on the shelve. If you order from www.cometic.com you will get what you specify. They even have stainless steal gaskets the are rubber coated but they are expensive. If a gasket blowes It Is generally not the gaskets fault.  You must figure out why It blew and fix the problem.

Correct. I have run Cometic for years and years without issue on every single bike I've owned.. I have also used Moose with success on my KX (Eric Gorr had a thick one designed for my KX or something like that).. Everything else had Cometic. I'd guess it was warped too.

[KXcam22]

Regardless of the gasket brand, I like to glue my base gaskets with some type of form-a-gasket.  Once rebuilt, the 500 tends to stay together for quite a while so I don't mind the extra effort to scrape/clean off the glued gasket during the next rebuild.  However, I have had to do at least one rebuild because an unglued base gasket blew out (un noticed) and sucked dirt into the engine, ruining a out of town riding adventure.  My K5 one (OEM) is nicely cemented in place with the last of my Kawibond. Cam.

[hughes]

I agree. I use yamabond 4.

[BDI]

Maybe I'm crazy but anything that works better and makes my life easier, Im all about It. A gasket that doe's not need to be glued In place and never blows out and comes off cleen when your done with It. How could you not want that I rate scraping gaskets right there with spooning tires,cleaning air filters and smashing my finger with a hammer. All things I'm capable of but probably would never do again If I did not have to.