1st gen head gasket question

[dingy]

Does any one know what the stock head gasket thickness is?

I am going to pull the heads off my motor this winter & put new valve guide seals in it. I am getting a some smoke from exhaust under acceleration. Compression is near spec. on all cylinders, so I am confident rings are OK. They measured OK when I had engine apart last winter. Heads came off a 97 VMax that was supposed to only have 17,000 miles on it.

 

While I have the heads off, I want to increase the compression ratio on the motor.

 

One way to do this is to mill the heads or block. The other way is to put a thinner head gasket on. Head gaskets are available in varying thicknesses.

 

One of the VMax guys gave me the thickness for VMax gaskets, but it seems thinner than the set I put on this winter.

 

Also going to put a Vboost on while I am in there. I am going to run it from the Ignitech TCI module.

 

This work should put to rest that nasty rumor that Brown 1st gen's are the quickest that has been coming from someone in West Virginia.

 

 

Gary

Edited November 21, 2010 by dingy
spelling

[friesman]

But the Brown ones are fastest, doesnt matter if theyre in West Virgina or not....

 

Brian

[Yammer Dan]

But the Brown ones are fastest, doesnt matter if theyre in West Virgina or not....

 

Brian

 

 

 

I think that bout says it!!! Thanks for the help Brian!!:clap2:

[bkuhr]

Gary, I still have my old gaskets out in the garage, they are the 3 piece and seperated, but I will mic them tomorrow squeezing 3 three pieces as tight as possible, as well as all 3 seperate to be added together, and see if that will give you a working range.

 

Brian

[bkuhr]

Gary,

All 3 layers are magnetic. Top and bottom strongly and middle less than strongly but not weakly. Suspect top and bottom steel, and middle some steel alloy.

 

Top and bottom measure the same as follows.

material thickness=.0065", with 'glue lines' seem to measure about =.008"

 

Middle material tickness=.001" but has stamped raised parts that measure=.005"

 

All 3 stacked together measured accross glue lines and raised stamps=.029"

Math should be .008+.005+.008=.021" but I also have a lot of corrosion built up.

 

Suspect the stamped raised parts crush during torque, so I would guess an installed gasket would measure .0065+.001+.0065=.014"

 

This may give you a range of .014"-.021"

 

Hope this helps

Brian

[skydoc_17]

Hey Gary,

Having the two tone "Elegant/Birch" brown 87'VR myself with a tweak here and an adjustment there, I would have to agree with the WV gent, that the Brown VR's are the fastest. Although I must admit that I am very excited about your current project. There is so much untapped potential power in these V4 motors, it gives me "goosebumps" to see another VR.ORG member "boldly go where no man has gone before".

Perhaps we can share some hi way or track time in the up coming year?

My hat's off to ya', Gary.

Earl

[dingy]

Thanks Brian, that's what I needed to know.

 

VMax rebuilder said the stock sets were .027" for the VMaxs.

 

I can get a .010" thick copper head gasket. Which would be a decrease of .017".

 

Head gasket route would be simpler than having heads or block milled.

 

I have run the numbers in a compression ratio calculator I have and the gain in compression would be very minor from a gasket change. Milling or gasket change also induces valve timing retardation. Domed pistons would be the better way to go but cost is beyond me.

 

I may look at forcing air into the filter box by ducting air into it from the two intakes that are on the sides of the fairing. These are non-functioning now that I have removed the knee fairings. From the pictures I took last winter during the rebuild, it looks like I could run 1 1/2" flexible tubing into either side of the air box and connect this to the two front air intakes. This will help force air into the air box similar to a cowl induction system. This may help the motor breathe better. With the setup I have now, the motor is not as sensitive to the changes in air box restriction like a stock Venture is. This may help, it may not. Something else to play with. It is something that would not be verifiable with a dyno test though, due to no air flow on dyno.

 

The bike is pulling very strong up to about 8,300 to 8,500 RPM's, then it starts to flatten out. This seems to me to indicate it is starving for air flow. I have had it up to 9,500 RPM's but it is out of torque at that point.

 

I am going to mount a VBoost system and possibly a set of stock VMax carbs this winter.

 

Also considering removing exhaust collector and running 4 separate exhaust pipes out rear end. This appears doable, but I need to do more research on what if any benefit there may be. I have a local shop that can do the bending for me. I need to layout system in my CAD program to see about clearances. If nothing else it would be a unique look & sound. I would use 1 1/2" S.S. tubing. This could be polished out to a nice finish.

 

If money was no object, which it is, there is a fuel injection system for VMAX's available. Would run around $1800. FI is to costly for the modest power gains. Good for gas mileage and the environment though.

 

http://roadstercycle.com/yamaha_vmax_fuel_injector_cv_car.htm

 

Gary

 

 

Gary,

All 3 layers are magnetic. Top and bottom strongly and middle less than strongly but not weakly. Suspect top and bottom steel, and middle some steel alloy.

 

Top and bottom measure the same as follows.

material thickness=.0065", with 'glue lines' seem to measure about =.008"

 

Middle material tickness=.001" but has stamped raised parts that measure=.005"

 

All 3 stacked together measured accross glue lines and raised stamps=.029"

Math should be .008+.005+.008=.021" but I also have a lot of corrosion built up.

 

Suspect the stamped raised parts crush during torque, so I would guess an installed gasket would measure .0065+.001+.0065=.014"

 

This may give you a range of .014"-.021"

 

Hope this helps

Brian

[bkuhr]

Milling or gasket change also induces valve timing retardation.

 

May try milling slots onto cam gear bolts holes, to allow 1-2 deg adjustment of gear on cam shaft. A metal plug in the space left in the slot between the bolt and gear prevents movement and is retained by the bolt itself. Had a simular setup on race car, but cant find info right now, that had a couple of different plugs with off center hole that could be installed with offset to right or left in slot(advance/retard), and plugs with different amounts of offsets.

Let me know if you want more info.

[Grisolm1]

Vboost is allowing a Vmax to effectively breath from 2 35mm carbs at high RPM. I don't doubt your motor is going flat at high RPM without it. If you can get a Vboost setup to work then jetting will probably have to go back to Vmax specs. You are a brave man than I with this project.

 

Watch your squish area and piston/head clearance around the piston edges with thinner gaskets. Many motors (at least HDs) like to have ~30 thou here to prevent detonation.