Gasket cement Verboten!

[vmx1963]

G'day again,

Following my usual practice of not reading instructions until afterwards, I was browsing through the Penton manual on engine reconstruction and read the recommendation not to use gasket cement. Now I'm assuming the term 'cement' refers to what I know as 'sealant' or Silastic silicone rubber.  

Sniffing the sinus-clearing, eye-watering aroma of my freshly-joined cases sporting their carefully applied gasket sealant, I felt a sensation that more sensitive people would call guilt but I refer to as the "aww crap" sensation.  Given the clarity of the Penton manual on this issue, I'm half expecting the door to be broken down at 3am by the gasket cement police.

So before the weight of guilt becomes crushing and drives me to evaluate my choice of career, wife and superannuation plan, I'd be interested in the division of opinion on this issue - to sealant or not-to-sealant gaskets.  Through the fog of forgetfulness I can distinctly recall putting Husky cases back together (sans sealant) and having them leak oil almost immediately - thus began my lifelong association with gasket sealant.  Yes, I've gone through the learning curve of only putting the merest film of sealant on the gasket to fill any irregularities or pores and not over-indulging until goop hangs from the underneath like bunches of plump-ripe grapes.

So hands up who abides by the 'grease only' school or who is inclined to dabble in the silicone when it comes to joining things together (get your minds out of the gutter, I am still talking about gaskets! ]).  And why one or the other?

Cheers


VMX1963
Western Australia
VMX KTM

[DKWRACER]

Seems reasonable to use what works....I have been using H20 to first soften the gasket material, then liberal amounts of grease....have disassembled many engines 5 years later and found the gasket to be in good shape, and easily removable...etc....so water and grease works fine for me....Adios!!!!

[Kip Kern]

Ditto, I go the water and grease route too.  I always have nice words for the engines that I get which are "glued" together with the Permatex or Silicone.  Those engines, and dirty ones get the "extra" charge;)  If you have to use a gasket sealer,  try Gas Ga Cinch (sp) , it is a light rubber cement that will wipe off after drying, lasts for years and wipes off gaskets after many years use.  I use this on all seal OD's to aid in installation and sealing.
Never use silicone on Magnesium, it retains moisture and rots the cases.

[Gavin Housh]

I too am using Gasgacinch (available at auto parts stores) with good luck on my 125 center case gaskit and cases. Side covers I use blue silicone on one side, and a thin film of transmision oil on the other side. Thinking is that when you put the two togeather and let it dry the silicone only sticks to one side. This allows you to take the cover off repeatedly without having to do anything except take the screws out and put them back in. You need to make sure that if you don't use a gasket on the clutch cover that you shim your shift selector shaft flush with the engine case. Having the selector shaft shimed properly will help the shift mechanism to shift the same as it did when you adjusted your transmission using your special Penton transmission adjusting casting. If you don't have one of these tools then find someone that does. I digress. Why is it that when I start to talk about 125 Pentons I always get around to talking about how to improve shifting? For those of you that are wondering why your shifting does not stay adjusted it's because of not being able to adequately tighten the cam bolt on the two piece selector arm. For more info on how to perform this stunt of Sachs trickery give me a little prodding and when I have time I may write an entire article on all the things that need to happen for your transmission to work right. Gavin

[john durrill]

VMX,
 If you do use silicon sealant , make sure its the kind that is safe for electrical connections. If its not  it contains an acid ( smells a bit like vinegar). The vapor from that type of selant will rust the crank on the mag side and cause damage  to any metal parts there in.
It can ruin the crank where the main seal rides. It might not be good for the magnizeum on KTM engines for that reason also.
 We use the kind that says its safe for sensors ( LIKE O2 sensors).
I did , years ago, sell more than one mag flywheel and point set to folks that used the other type of sealer on their bikes. It ruined the point cam and damaged the crank.
 Hope this is some help.
John D.

[vmx1963]

Thanks folks, I've just ordered some Gasgacinch and will give it a try.

VMX1963
Western Australia
VMX KTM

[lksseven]

DKW,

how long do you soak the gasket in water before installing?

Larry Seale
I choose to ride

[desmond197]

Use of gasket sealer is determined by the motor. I do not use it on Sach and Zundapp motors.

Bultaco and Montesa motors it is a must. Use the stuff that is OK to use with O2 sensors.

I soak my gaskets in warm water for about 10-15 min. and use grease to hold it in place.

[lksseven]

10-15 minutes - thanks, Des!!!

Larry Seale
I choose to ride

[fasmith]

Rod Bush told me one time ... "only use grease on a gasket" and he told me if I bring a bike into the shop with gasket sealant on the motor, he would hold me down and burn me with his cigerette.   One other famous quote I got from him was this..."You never need more motor than a 125."  He said.. and I quote.. "Hold the throttle wide open, shift up to go faster, shift down to go slower and never touch the brakes."  

So I have only used grease for years and never had a problem.

And in an enduro long ago, I was ten rows ahead of the AA riders and he was the first one to pass me on a KTM 125 about a mile pass the 3 mile mark and made me look like I was tied to a tree. BTW, I was on a KTM 390 and this was on a big hill on a power line up in Greenville, SC.

Freddie

[dkwkid]

I have used Yamabond on all my sealing surfaces for 15 years now and have had not a single leak(fluid or air).Comes apart rather nicely too.Grease and paper works but is it the best tool for the job?Plus you won't have to fight it out on U-PAY for obsolete gaskets for motors out of production for 30 years.

[tomale]

As a rule unless there is a reason to I only use grease or gear lube. I have yet to have a problem with that and the cases come apart real nice.
I have a question, I can see the need to maybe use a sealant on the ignition case, especially if the surfaces are abit rough but I am wondering about, the use of sealants on the center cases, wouldn't that cause a possible problem with too much side play on the transmission shafts?
years ago when I rode a Maico I broke a transmission because I had too much side play. I did that three times before I got ride of the bike, That was expensive! The guy that bought the bike from me, shimmed it right and that was the last time it broke.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
75' GS400 (project bike)
72'sixday (project bike)