ADVrider (
-   Thumpers (
-   -   Aaarrrrgggg!!! damn base gaskets.... (

laramie LC4 09-29-2006 04:25 PM

Aaarrrrgggg!!! damn base gaskets....
well, i've been kinda dragging my feet the last 2 days with replacing my base gasket due to me freaking about other issues (should i replace the rings? what about the cam bearing? ......) but decided to take a look at it again this afternoon to decide which one of the 3 base gaskets i'm going to use.

well, you would think it would be easy but, each one has some issues that make me want to rip my hair out!!!! <!--emo&:frustrated:--><!--endemo-->

lets start with the Cometic gaskets.

the Cometic gasket, although made of very nice material, doesn't fit for SH--!!! there are gaps the entire way around the cylinder and especially around the timing chain slot. to say the least i'm a little upset about the "high" quality of this gasket. you'd think they would at least make it fit right.... one show the area around the cylinder and timing chain.

and here is a closer one of the timing chain area.

now for the OEM gaskets from KTM. start with the metal one, part number 58630035200.

this one must be for the 625 or newer LC4's, because it doesn't fit either. well, let me clarify that, the gasket fits well, but doesn't have the proper holes for the metal dowels that hold the cylinder into the cases.

this is the one that i had planned on using but now obviously i cant unless i modify it myself. has anyone ever had luck with doing something like this? can i just take a drill bit that is the right size and punch out those holes to match? or am i just inviting more doom and gloom?

now for the paper OEM, part number 58030030100.

actually, the only bad thing i have to say about this one is the fact that it is paper!!! it has the best fit of all of them and looks to be of MUCH better quality than the OEM green gasket that i had put in last time. remember this one is listed at 0.7mm, which is just a little thicker than the green which is 0.5mm

so, what do i do here guys? what would you do?

i cant believe that i have 3 different gaskets and not a one of them is what i need and want!!! typical KTM for ya..... <!--emo&:frustrated:--><!--endemo-->

i'm going to drink a beer and think about my options, maybe ill just set it on fire and push it into my landlords house and claim it was an accident. he's on my SH-- list anyways and it would at least make me smile.... <!--emo&:hihi:--><!--endemo-->


laramie <!--emo&:cheers:--><!--endemo-->

christian 09-29-2006 04:33 PM

can you push it in my back yard with all the parts and title in a box ? :ear

Cogswell 09-29-2006 05:11 PM

I would use the cometic gasket in the first picture with a very thin coating of hondabond (the grey colored case sealer) on it. It will help seal in the thin area, and is not prone to leaking at all if used properly.


PackMule 09-29-2006 06:30 PM


Oh, and I ain't got a clue which one to use...

Cactus Dave 09-29-2006 06:32 PM

The paper is the easiest and the reduction in compression will be negligible. However, if your confident of your ability to modify, I'd use the metal KTM gasket and carefully drill out and then trim with a rat tail file the locater holes. Be sure to put a wood block behind the gasket, and I'd put a wood block with a pilot hole of the proper size on top and clamp the blocks together with the gasket in between. The gasket may have a tendency to grab the flutes on the bit and ride up the bit while your drilling thereby effectively bending and ruining the gasket (wanna know how I know this?). Clamping the wood blocks stabilizes the metal gasket. The Cometic gasket is probably the best quality - they do make good stuff - but you're asking for a leak with the mismatched surfaces. Maybe not, but you won't know 'till you try, and it leaks. While the Hondabond or Yamabond or high temp silicone sealers work well (I use 'em in lieu of gaskets), they are not intended to fill the large gaps created by the Cometic mismatch. And by the time you goop that much on, you're asking for a lot to ooze into the cam chain tunnel and ultimately find its way into your oiling system thereby probably plugging something (wanna know how I know that as well?). Smart thing taking a break to contemplate over a beer. Good luck.

laramie LC4 09-30-2006 09:12 AM

after speaking with a few other guys who have use the Cometic gasket i guess i got a bad one. figures huh? :huh anyways, i guess ill contact cometic on monday and send them the pics and ask them to either refund my money or send me a new gasket. hopefully they wont give me any shit cause im not in the mood....

ill keep you posted.


laramie :cheers:

laramie LC4 10-02-2006 10:09 AM

spoke to Cometic gasket company this morning and they were very helpful, no shit what so ever. i sent them the photo's of the gasket along with an explanation of what i thought was wrong with it. they called me back within a short time and said that they agreed and that they had a different base gasket that might be better. it is supposedly for "older" lc4's but he said that it would match up to my cylinder. hopefully this one will work. ill post some pics and a part number when i get it.


laramie :beer

laramie LC4 10-06-2006 06:57 PM

you guys ever get the feeling that things just weren't ment to be....??????


just got my gasket from Cometic and guess what ?????

come on, take a wild guess......







IT DONT FIT !!!!!!!!!!!

it is the EXACT SAME as the newer, OEM Metal gasket. so im going to go out on a limb and say that ktm outsources their gasket making to Cometic now a days.

so now im back at step one again. do i dare try and use the other Cometic gasket that doesnt have very good coverage ? or do i try and modify one of these new ones to make it work ? i guess since i now have 2 of them i can afford to make at least 1 mistake.....

if i wasnt still needing other parts (rings and cam bearing) id would be extremely pissed off !!!!!

im starting to get the same feeling i had with my ex-wife....maybe its just time to part ways.


laramie <!--emo&:cheers:--><!--endemo-->

Groundhog 10-06-2006 08:08 PM

Just thinking out loud as it were but ...

Seems there have been several issues with base gaskets lately. I was trying to figure out any possible causes because I don't think there should be enough pressure in the cylinder base (crankcase) to blow gaskets. Is there a restriction in the vent? Hose kinked? Is the filter in the vent line partially plugged?

I am sure you have checked all that, but it still seems that there might be some reason that the crankcase pressure is building up. Let me know if you find something would you please?

Another way to cut holes in a gasket (will work on metal too, just a little harder) is to put the gasket in place and tap around the edge of the hole with the peen end of a ball-peen hammer. You wouldn't want to do this on your cylinder, but could use any piece of metal with the proper sized (sharp edged) hole. (drill a hole in a piece of scrap?)

Good luck on the next gasket!

meat popsicle 10-09-2006 08:45 AM


Have you looked at these P/N? Just came across this auction.

Beez 10-09-2006 12:35 PM

Enlarging the holes
I've made my own gaskets in the past (no, not base gaskets :lol3) and I used bullet shells to make the holes. My father-in-law gave me a selection of shells of different sizes. Place the gasket on a piece of wood and pound the shell with a hammer. It cuts a nice clean hole.

laramie LC4 10-09-2006 01:20 PM


Originally Posted by meat popsicle

Have you looked at these P/N? Just came across this auction.

thanks meat but that has the older, green 0.5 mm base gasket. you can see it in the pic. that gasket set is what you get if you order a complete engine rebuild set. it comes with everything, gaskets, crush washers, everything..... i got one of those for when i rebuild my engine the last time.

laramie :cheers:

PackMule 10-11-2006 07:49 PM


Originally Posted by Beez
I've made my own gaskets in the past (no, not base gaskets :lol3) and I used bullet shells to make the holes. My father-in-law gave me a selection of shells of different sizes. Place the gasket on a piece of wood and pound the shell with a hammer. It cuts a nice clean hole.

A guy from Kalifornia who now lives in Massaschusetts using shell casings to work on his dirt bike. :rofl :clap :beer

laramie LC4 11-03-2006 01:00 PM

<TABLE cellSpacing=1 cellPadding=3 width="100%" border=0><TBODY><TR><TD class=post2 vAlign=top>
</TD><TD class=post2 vAlign=top width="100%"><!-- THE POST 1596627 -->ok guys, ive been bad about not keeping up on this post. so here it goes....

i finally got sick of waiting and messing with cometic and decided to use the OEM paper gasket with some "high tack" gasket sealant. i reassembled the engine and stuck it in the bike.

as soon as i started the bike i knew thing werent right. the new gasket was leaking worse than the old one that was blown out. to say the least i was a little pissed off!!! <!--emo&:frustrated:--><!--endemo-->

from the looks of it, it was like the gasket had sucked inside the engine and was leaking all around the right side of the jug. i wasnt sure if the gasket or the sealant was to blame? i had used this sealant on many automotive applications and had never had any issues. so i wasnt sure what to think.

well, after taking the engine back apart again today i have the answer.

it wasnt the gasket sealant. in fact i had one hell of a time just getting the jug back off. the sealant was definitely working. in fact i had to rig a board to help me knock it loose.

once i finally got it off, this is what i found....

you can see where it completely missed seating on the cases and under the jug. i have no idea how this happened but thats definitely going to leak. it just seems kinda strange to me that the sealant held so solid in all but that one spot. why would it just fall in like that?

anyways, this isnt going to happen again. this time im using the "original" metal cometic gasket that i got in the first gasket set i ordered. the one that i thought didnt have enough coverage. i tried to modify the other one but was afraid that id never get it perfect and would be right back at first base again real quick. if that were to happen, i think id just loose it and drive the bike head on into traffic!!!! :baldy :baldy :baldy <!--emo&:roost:--><!--endemo-->

so cross your fingers for me and wish me luck. i know this bike wants to run, it just needs a little encouragement. <!--emo&:2thumbs:--><!--endemo-->

ill keep ya posted,


laramie <!--emo&:cheers:--><!--endemo-->

Stu 11-04-2006 06:32 AM

Don't worry too much about cutting the gasket. Beez and Cactus Dave are both right. In the, uh, old days we used to make all of our gaskets from blank material. (Remove the studs and stick the oiled surface on the gasket material to mark it.) We did not use sealers. We just put them on dry. We would purchase different thickness material to get different deck height. Sometimes the sealers will make the gasket "walk". Not always, but I found that out the hard way once before a race....

Times are GMT -7.   It's 07:32 AM.

Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2015