Blown base gasket?

NightBiker07 · Post by **NightBiker07** » November 6th, 2011, 5:30 pm

I blew the base gasket on the CR5 today. the left side, right in the middle of the cylinder.

I almost caught it too late, luckily I got her shut down before she seized.

Since riding season is almost over, I will order the top end gasket kit, and send the head to Roosty when I can.

I guess my question is, What would cause this to happen? or is it just dumb bad luck?

Gmbond · Post by **Gmbond** » November 6th, 2011, 5:50 pm

Number of factors I'd say

Over or under torqued base nuts or studs.
Non factory gasket
Warped cases or cylinder base

Maybe get Roosty to check and flatten the base of the cylinder too?

I've also heard a smear of motoseal RTV on the side thin contact surfaces can assist too.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » November 6th, 2011, 5:55 pm

i've had to trim the base of cylinders before, It wouldnt take much but it can't be done unless you are boring the cylinder also.
Use the cometic base gasket with the steel in it

Post by **AlisoBob** » November 6th, 2011, 6:24 pm

Roostius_Maximus wrote:Use the cometic base gasket with the steel in it

X 491

NightBiker07 · Post by **NightBiker07** » November 7th, 2011, 6:32 am

Roostius_Maximus wrote:i've had to trim the base of cylinders before, It wouldnt take much but it can't be done unless you are boring the cylinder also.
Use the cometic base gasket with the steel in it

Thats the one I had planned to order. Short of setting it up on a Mill and using a Dial Indicator on the thing, is there an easier way to check for warping? I know you cant do it with glass, like you can the head because of the sleeve.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » November 7th, 2011, 7:27 am

just stand a ruler on its edge, it should show. If you can clean the surface perfect then use a sharpie to color all the gasket surface. with the ruler on its edge ( a good stiff ruler) drag it across the surface and it'll show any low spots.
poor mans machinist dye

NightBiker07 · Post by **NightBiker07** » November 7th, 2011, 12:32 pm

Roostius_Maximus wrote:just stand a ruler on its edge, it should show. If you can clean the surface perfect then use a sharpie to color all the gasket surface. with the ruler on its edge ( a good stiff ruler) drag it across the surface and it'll show any low spots.
poor mans machinist dye

Cool man, thanks! I believe I have some layout dye somewhere, but I dont want to look for it lol

STUCK IN 500 LAND · November 7th, 2011, 12:44 pm

If you don't have layout dye, a good scale (ruler) or anything you can find that will lay flat (on edge), you can then try and slip a feeler gauge under it. I think .004" is the max in the honda manual but its been awhile since I looked it up. Also, I wouldn't use rtv. I think that shit acts like lube and helps it suck in faster. Learned that the hard way (twice).

Post by **AlisoBob** » November 7th, 2011, 2:41 pm

STUCK IN 500 LAND wrote:I think that shit acts like lube and helps it suck in faster. Learned that the hard way (twice).

Steel shim Cometics dont suck in....

STUCK IN 500 LAND · November 7th, 2011, 10:11 pm

AlisoBob wrote:
STUCK IN 500 LAND wrote:I think that shit acts like lube and helps it suck in faster. Learned that the hard way (twice).
Steel shim Cometics dont suck in....

Yep, Thats what I learned the hard way. Cometic is the only way to go.

Gravel Scratcher · November 7th, 2011, 10:13 pm

gee are you saying they are better than oem

STUCK IN 500 LAND · November 7th, 2011, 10:21 pm

Gravel Scratcher wrote:gee are you saying they are better than oem

I think I whatched an oem suck in right before my eyes, at an idle, warming it up. It might have been a verash (cheapy), I can't remember, it was over 10 years ago. But they both suck! cometic is it.

100hp honda · Post by **100hp honda** » November 7th, 2011, 10:28 pm

shit fools i stacked 2 honda ones with rtv on all sides

. probly want to know my secret eh

Post by **AlisoBob** » November 7th, 2011, 11:07 pm

Gravel Scratcher wrote:gee are you saying they are better than oem

I know.... surprizing....

johnnytheswede · Post by **johnnytheswede** » November 8th, 2011, 3:07 am

My friend who rode the 500 World championship in the 90;s did a "gasket thing" on my cases. He took a " metalspike"(i don,t know the name) and made three hits with a small hammer on the cases where the gasket area is smallest. This makes the gasket grip in the "dimples". Is that right pronounced? Neither his or mine gaskets fail at all. We use factory gaskets. I got a little worried when i saw it first, but it works.

Johnny

gregrobo · Post by **gregrobo** » November 8th, 2011, 6:08 am

a centre punch

NightBiker07 · Post by **NightBiker07** » November 8th, 2011, 9:04 am

this one didnt suck in, it actually pushed out.

And yes, the clowns did use a touch of silicone on this gasket.

The bike started idling high, didnt think much of it. adjusted the air screw, it brought the idle back down. went for another lap, and it started making a horrid noise

didnt blow the top end, wont know if I hurt any bearings until I pull the cylinder off.

On a side note, I cant believe how cool these motors run. I can touch the radiators no problem after its been ridden for an hour.

johnnytheswede · Post by **johnnytheswede** » November 8th, 2011, 12:31 pm

gregrobo wrote:a centre punch

=)! Thanks! Now i learned something again=)!

Post by **AlisoBob** » November 8th, 2011, 12:42 pm

johnnytheswede wrote: This makes the gasket grip in the "dimples".

I knew a girl once.... who had dimpled gaskets....

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » November 8th, 2011, 1:05 pm

are we talking speed dimples or traction aid? I'm a little concerned here.

Post by **AlisoBob** » November 8th, 2011, 2:15 pm

Roostius_Maximus wrote:are we talking speed dimples or traction aid? I'm a little concerned here.

WET dimples = Speed

DRY dimples = Traction

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » November 8th, 2011, 2:26 pm

100hp honda · Post by **100hp honda** » November 8th, 2011, 4:50 pm

from my own experience if you use a sealer especially something like hondabond most likely youll have pushout issues unless you punch the mating surface. dont need to do both sides but atleast one. then you got that shit spooged into the trans tunnels. that cometic gasket sounds like the easier less messy way for sure. probly pick me up one

gregrobo · Post by **gregrobo** » November 8th, 2011, 6:15 pm

we use a product called threebond its a gasket glue never had a failure on any bikes i have worked on
http://www.threebond.com.au/default.htm

100hp honda · Post by **100hp honda** » November 9th, 2011, 12:04 am

avoid hondabond

BannedCR500Riders.com

Blown base gasket?

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