NE0 Posted July 28, 2012 Posted July 28, 2012 I did a search through the forum, nobody seems to have asked this question before, or if they did, they put it in title with a cryptic heading like "help" or "question" or "need help" that sort of thing, I must confess these simple titles get my goat up!!! why can't they be more concise? Anyway back to the question in hand......... I'm just in the process of doing an engine rebulid on my Honda CB400/4 , I did the DTMX 175 last year!! The base gasket has leaked oil for some years, in fact shortly after i rebuilt the engine a few years ago it started...but recently its got worse and enoughs enough! i decided its time to fix it, so engine out and replace the seals and the gaskets, and whilst I'm in there I'll do the primary and cam chain (£80 for the primary chain!!!!.........'kin hell!!) I didn't replace the primary the first time around just did the shell bearings, rings and cam chain. false economy i know it was probably a lot cheaper then too!.Mind you next to no wear on the shells which i'm pleased with. However, I'm just in the process of putting it all back together, and I thought what do others do when it comes to fitting the gaskets. Back in the 70's and 80's it seemed to be common practice (in my neck of the woods) to smear the new gaskets with a thin layer of instant gasket (except for the head) just for insurance purposes, i.e make sure the bugg'r don't leak!! When i rebuilt the DT175, I must confess I put a thin film of hylomar blue on the crankcase halves along with the gasket, it didn't do it any harm, made a barely visible blue line (there wasn't so much that it made large globules of the stuff inside and out! that could have resulted in foreign matter in the workings). it doesn't leak. I recall back in the 70's and 80's old cortinas and the like with bright orange silicone in big unsightly globules all around the joint faces....they also didn't leak but looked sh*t!! What are your thoughts and recommendations fellas, Put them in dry? Use a thin film of instant gasket? Smear them with oil? smear them with butter, jam......... body fluids! or maybe Leave them out altogether? (that last one was a joke!!)
Moderator Airhead Posted July 28, 2012 Moderator Posted July 28, 2012 crypyic titles!!!I'm with you NEO, dont like them at all and useless for searches as said!! Me I just smear gaskets with silicone grease both sides it helps them not to stick, Ive had the clutch cover off my DT twice now and not replaced the gasket...it's on it's 3rd tour of duty lol
Ventura Posted July 28, 2012 Posted July 28, 2012 Im with Airhead on that one. Grease or oil on the gaskets, primarily to try and avoid them sticking, so they might be reused again, is good practice. And an easy way of avoiding frustrating and time consuming scraping off of old gasket! In saying that tho, there's little chance of a thin smear of liquid gasket doing any harm if its used for "belts and braces" sealing. Or even do both (liquid gasket one side, grease on the other) for frequently removed casings, so that the gasket stays stuck to one side only, therefore avoiding it being torn when the casing is removed. But really if the faces are in good order then its not really necessary. I'd avoid the butter or jam tho! And Im not going anywhere near the suggestion of bodily fluids!! V.
dt502001 Posted July 28, 2012 Posted July 28, 2012 I hate loose titles as well, as far as gaskets I go dry after cleaning the mating surfaces with alcohol. I figure thats the way the factory does it and new bike's rarely leak. That said if the surface has been gouged then PERMATEX THE RIGHT STUFF gasket maker part # 30874 it's black makes any gasket and needs only 1 min to set. I have put on oil pans immidatly filled with oil and never had a leak the stuff is amazing. Only just a thin film on the gasket does the trick so no messy globs ,if any squirts out wipe away imediatly and nobody will even tell you used it. Yamabond or threebond works just as well and is grey just takes 24hrs to fully set As for the base gasket leaking Did you re torque after first warm up? I have made it a practice to do it on every rebuild and haven't had a base gasket leak on any rebuild in 20 years. Nothing more frustrating than a leak right after a rebuild esp.a base gasket
NE0 Posted July 28, 2012 Author Posted July 28, 2012 I had a quick look on ebay-uk folks and DT's PERMATEX is readily available here in black as he suggests. Did you re torque after first warm up? No DT, I got a feeling I didn't, I know I was thinking about it, but for whatever reason I never did, paid for it in the end as it's leaked oil in the same place for years, just a dribble but more recently on a long run it gave up the ghost and started pissing out! which is where "blown a gasket" comes from!!! Not something i'm going to miss doing this time though! Initially I'm going to reuse the old rocker cover gasket, then after a few miles re-torque the head and then replace the old gasket with the new one.
dt502001 Posted July 28, 2012 Posted July 28, 2012 Great it's expensive but the uses are endless you can even make a o ring in a pinch, just always leave a bit hanging out of the tube so you can pull it out and not have the whole nozzel harden up. Not sure why but only the first inch or so will harden and can be pulled out of the smallest opening you make in the nozzel. Sounds like a good plan reusing the VC gasket if you wash it in alcohol it might even go another round so you can save the new for the next valve adjust. I don't even ride the bike high rpms cause pressure in the bottom end that could push oil out under the gasket ( perma leak) just warm up alow to cool to room temp and then re torque and giver shit. The only gasket I blow is my own when all shit goes wrong LOL Good luck on the re build hope all goes well
Recommended Posts