Thinning the head gasket

jrfan

jrfan

New member
Joined
Dec 19, 2008
Messages
51
Location
Saskatoon Saskatchewan Canada
well I see thinning the head gasket seems to be a popular and safe mod, I was wondering If anyone could give me the procedure to do this or point me in the direction of where to buy, can I get from dealer?

how thin does one go?
(98 VMax 600 twin) is what I am working on.


thanks you in advance!!
 
Try searching should be lots on info on how to do this mod,i would avoid it IMO you'll need to run premium fuel afterwords and with todays crappy @ss gas detonation is likely with the increased comp.

$.02
 
thanks for the input guys, my mechanic already talked me out of it, he also said it is risky on the 600, so I guess she gets a stock rebuild and some V force reeds...........and stretched to 136" lol
 
I'd do it again in a heart beat. At least take one layer out. Keep the money in your pocket on the v-force reeds.

Mechanic? Who needs those? Get a Yamaha service manual for it and grab a set of metric wrenches.
 
FuzzButt said:
I'd do it again in a heart beat. At least take one layer out. Keep the money in your pocket on the v-force reeds.

Mechanic? Who needs those? Get a Yamaha service manual for it and grab a set of metric wrenches.
Click to expand...

I take it you don't like V force reeds? any reason why?? this is all new to me so I like people's input ;)!
 
FuzzButt said:
I'd do it again in a heart beat. At least take one layer out. Keep the money in your pocket on the v-force reeds.

Mechanic? Who needs those? Get a Yamaha service manual for it and grab a set of metric wrenches.
Click to expand...

Did you have a noticeable difference peeling one layer off?
 
jrfan said:
I take it you don't like V force reeds? any reason why?? this is all new to me so I like people's input ;)!
Click to expand...
In a stock trail ridden sled there not worth the big coin because you really don't see much of a difference vs OEM,maybe....a little better bottom end throttle response but that's it, is it worth the high price for these reeds?

OEM reeds are hard to beat
 
daman said:
In a stock trail ridden sled there not worth the big coin because you really don't see much of a difference vs OEM,maybe....a little better bottom end throttle response but that's it, is it worth the high price for these reeds?

OEM reeds are hard to beat
Click to expand...
so Daman what would you recommend? my original plan was thin the head gaskets, reeds and a can just to loose some weight (12lb savings).

Oh ya and I am stretching it to 136 1 1/4 ripsaw, using a Hartman extension kit I picked up.

I guess I should explain that this sled was good for a 100mph top end and could pull the skis off the ground and hooks hard, out of the group we ride in I can take a 670 formula 3, mxz 583, polaris 700 all off the line (hard pack) till about 75-80mph then she is a slow climb till 100 mph.
I weigh 330lbs so I figure this is pretty good, pisses them all off,lol

long tracking it to be better in the deep snow, figure it will work well with the Viper mountain ski's I have on it now, they made a huge diff this year keeping my front end up!
 
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jrfan said:
so Daman what would you recommend? my original plan was thin the head gaskets, reeds and a can just to loose some weight (12lb savings).

Oh ya and I am stretching it to 136 1 1/4 ripsaw, using a Hartman extension kit I picked up.
Click to expand...
I don't know what kind of money you want to throw at this? but your not going get a power house outa this twin should have bought a trip if thats what your looking for,streaching it out would be fine,may need to regear after.

Stock Yamaha reeds are good reeds cant go wrong with them,clutch it to rev 7800 on top,get jetting dialed in, get track deflection right, yea loose some weight would help and you'll have a nice relyable good powered twin.

im more of a stock kinda guy i'd rather be accually out riding relyable and enjoying my self vs a wrench in my hand all the time fixing burn downs. $.02
 
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I like my little twin,lol enough power to hurt me ;)! I think after all the input and reading up on the subject I will kep it stock, and enjoy the reliability.


thanks again...........
 
I have a 97 twin and when I re-built with wiseco pro lites I also peeled the gasket, put v-force 3 reeds in and clutched to 8,000. I also have a Bender helix on, but I don't remember the numbers. Just went 136" and dropped a tooth on the drivers. Now I'm consistantly running neck and neck with stock yammie 700's till I run out of top end at about 90 (on the speedo). I ride with a few different 700's so it's not just his sled either.
 
Sorry about my delay in replying. Life seems to get in the way every time I sit down to respond.

Daman mentioned the reasons that I was going to use on the reed upgrade. The Yamaha reeds are perfectly fine in these twins. Yes there are some motors that may perform better with different reeds but you are not going to see an improvement that is related to the money you are going to spend on the reeds. If you have worn out ones then by all means replace the petals.

As far as the head gasket mod. Well I got a thinner gasket and modified the reed stopper when I replaced a cylinder and both pistons. It was all at the same time. I cannot say the gasket or stopper mod individually was related to the things I noticed afterwards. I also have a helix that is progressive, not the 47* OEM piece.

I have excellent throttle response. Warm idle all the way to WOT above 7000.

The 600 is what it is though. You are not going to get any huge numbers out of it without drastically changing something. You need it to pump more air to get more power.

I am and will likely always be a "long haul" "reliability over power" kind of rider. Being stranded or worse without a machine at all some where deep in the woods is not fun. I want to simply put gas and oil in it and ride. Wrenching on it out on the trail sucks. I've done it on my sled in the past and I would rather not even have to worry about it.

Oh and about the V-force reeds in particular. I was thinking about a set for my Johnson outboard so I am not putting them down as a whole. Though I am also looking at a set from Chris Carson as well. See http://www.chriscarsonmarine.com/reed-valves.htm they are a lot like the Yamaha reeds. I don't think he makes sled reeds though.
 
JRFAN- Thoutht I'd add my .02. I have the same sled as Fuzzbutt. When i did the piston upgrade I went with a thinner head gasket also and kept the stock clutching. The difference in bottom end response was night and day, with the added bonus of an increase in gas mileage. The original gasket was .14mm thick, replacements were .10,.08, & .06. I went with .08 because a Yamaha dealer said I could still run regular gas with it, but I don't. I've run it for 2000 miles with no issues. I feel it has the reliability that Daman looks for along with a noticable performance increase that Fuzzbutt and I appreciate. I'd do it again, for sure.
 
It works just fine call hauck.

I put the .06 gasket on mine and it does make a huge difference, I've held mine WOT for more than a minute several times just ripping during riding with buds, What more do U want, Yes I do put 92 or higher in when I refuel but I'm not sure I even need it, I checked my piston to head clearance and it's 73 thousants even with .06 gasket I talked to Pat Hauke about it and he seemed to think that 65 to 70 thousants is the cut off point for reliabilty on any two stroke, Unless U run airplane fuel, I'm 3 over and safe, Just call Pat he's done right by me.
 
Go with at least the .08

You'll love it in the end and considering U're weight is up there go with 8ab weights no rivotst(Bushings are what stock ? May need to fiddle, They can help U) and whatever spring and shims(Combo) gets U close to target RPM of 7900, Test only after U get Turks idea on a helix and get it set right, Then test, Get it as close to what U want use shims if it warrents, And of course rollers play their part in getting to 8100 to start( Hopefully get it close without adding rivot weight 8000 to 8100 This leaves U room to dial it in later when U can, U can mess with the shims for engagement but it affects shift too I think, Before trying to add rivot weight depending ? And get on here and say right away where U're @ after U're test, Plus run a green sec spring @ 60 maybe 70 cause U do way a little bit LOL, Turk can make U're clutching pull U just fine, Get a hold of him about a helix, The stocky on my 97 was 45 single, I'm geared up one tooth and run a 50/44, The mod made this possiable, I only weight 160 wet though and I'm still clutching it I will never stop
 
Bottem line !

Get it as close to target without adding rivot weight til U get it close, 1 hundy over is good( When U have to finalize it by adding weight rivot amounts by all means do it and have fun with U're little rocket, Adding heavier tip rivot will bring target down (7900), Mid really don't help( Mid rivot depends on U're helix angle and sec spring tention, Less tention or more angle on helix will make it shift too fast U'll notice it gets kind of groggy, Not enough angle on helix or too much spring tention then it will not pull at all U'll notice, Stock feels that way to a true techi
 
Thanks a lot for the info guys!! I really appreciate it, turns out another member on here lives in my city and he put me on to a Yamaha nut,lol his suggestion's are the same as most have mentioned.
Re-gear, re-clutch, thinner head gasket and enjoy!


thanks again everyone ;)!
 
Best thing you could do while you're spending $ is replace the twin with a triple. The twins are time bombs.
 
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