VR vs VMax Cam

Here is a photo comparing the stock 1987 VR cam lobe with a VMax.

The lift is either the same or very, very close.

The duration is way different!

I can't wait to get this baby up and running!

Good bit of difference.

So are the valves the same in the VR and VMax?

The valves and springs are different.

O.D. of intake valves is 1.197" on Vmax compared to 1.138" on Venture

O.D. of exhaust valves is 0.980" intake on Vmax compared to 0.941" on Venture

The stem is .2156" on Vmax compared to 0.2352" on Venture, allowing a slightly larger air flow path.

Springs are stiffer on Vmax, helping allow higher rpm redline.

Gary

Yes, as has been said, the VMax valves are a little larger across the face (about 1mm) and they have slightly smaller stems (different seals - VMax seals are cheaper). The valve springs are stiffer allowing another 1000 rpm before red line.

I figure the 1300cc engine will perk up (30HP?) with just the cams.

I would've liked to put the VMax valve springs in . . . didn't have the funds.

I have an extra set of Vmax springs if you are interested.

I think 30 HP more with cams is a little much.

1200 cc Vmax with Vboost, carbs and heads is 145 HP.

Gary

I am replacing my 1985 1200cc engine with a 1987 1300cc engine.

The 1200cc VMax is rated at 145HP at the crank versus the 1200cc VR at 92 - 97HP.

It is my opinion the biggest HP difference is due to the cams.

My Frankenstein is 100cc more engine with Vmax cams.

I think 30HP more than my 1985 1200cc VR is within reach . . .

And yes, I would love to have your VMax valve springs!

Will the earlier VMax cams go into the RSV??

I am replacing my 1985 1200cc engine with a 1987 1300cc engine.

The 1200cc VMax is rated at 145HP at the crank versus the 1200cc VR at 92 - 97HP.

It is my opinion the biggest HP difference is due to the cams.

My Frankenstein is 100cc more engine with Vmax cams.

I think 30HP more than my 1985 1200cc VR is within reach . . .

 

And yes, I would love to have your VMax valve springs!

Have you re jetted carbs ?

I used my 1200 - 83 bank of carbs and rejetted main jet to a 140 vs 125 in stock 1300 venture. 117.5 in stock 1200.

Plugged air inlet port above throttle plate on #2 carb.

I am going to use a venture TCI from an 86 initially.

Haven't ridden it yet though.

PM me about springs if you want them.

I got them to put into a set of 1300 heads, but then I got a set of Vmax heads from a 1997 bike with low miles for it.

Gary

http://i1007.photobucket.com/albums/af193/gdingy101/PICT5587s.jpg

You guys are ruining my keyboard!!! Drool will short it out!! I haven't been into a engine like that for 30+ yrs.

But all these parts I got...

The tag on the new Vmax I saw a few weeks ago at the dealer said it has about 197hp!

I am jealous. That motor is beautiful!

How did you decide on the jet size?

There is a thread here that talks about leaning out the stock set-up and improving mpg.

This seems to say that the stock jetting is rich.

I was going to run my stock '85 carbs and monitor the plugs before making a jet decision.

I have two sets of carb boots and was also thinking about adding a tube between the 1-2 and 3-4 carb boots ala VBoost. There will need to be a method of blocking it off to sync the carbs, but others have claimed to successfully run VBoost full-time.

Another off-the-wall thought was to make a sheet metal intake and install one of my extra Q-Jet carbs. If I separated the left/right sides of the manifold, one Q-Jet primary would feed 1-2 and the other would feed 3-4. The Q-Jet primaries are 35mm vs 34mm for the stock VR carbs. The Q-Jet primaries operate with a power valve and the secondaries are vacuum actuated. The Q-Jet should meter fuel on demand and supply more air like VBoost.

GaryZ

Have you re jetted carbs ?

 

I used my 1200 - 83 bank of carbs and rejetted main jet to a 140 vs 125 in stock 1300 venture. 117.5 in stock 1200.

 

Plugged air inlet port above throttle plate on #2 carb.

 

I am going to use a venture TCI from an 86 initially.

 

Haven't ridden it yet though.

 

PM me about springs if you want them.

 

I got them to put into a set of 1300 heads, but then I got a set of Vmax heads from a 1997 bike with low miles for it.

 

Gary

 

http://i1007.photobucket.com/albums/af193/gdingy101/PICT5587s.jpg

Squeeze gave me a suggestion of 140 to start with.

Gary

How did you decide on the jet size?

There is a thread here that talks about leaning out the stock set-up and improving mpg.

This seems to say that the stock jetting is rich.

Remember that mains meter heavy throttle, hi rpm, while the needles meter most of the mid-range. So the max HP will depend on the mains, while MPG is tied much more to the needles.

Jeremy

I am jealous. That motor is beautiful!

How did you decide on the jet size?

There is a thread here that talks about leaning out the stock set-up and improving mpg.

This seems to say that the stock jetting is rich.

I was going to run my stock '85 carbs and monitor the plugs before making a jet decision.

GaryZ

I would have to admit that getting maximum MPG's is not real high on my priority list.

35 to 40 MPG and I will be happy.

Gary

Remember that mains meter heavy throttle, hi rpm, while the needles meter most of the mid-range. So the max HP will depend on the mains, while MPG is tied much more to the needles.

 

Jeremy

Good input

Thanks!

I would have to admit that getting maximum MPG's is not real high on my priority list.

 

35 to 40 MPG and I will be happy.

 

 

Gary

You make a good point

GaryZ

I would have to admit that getting maximum MPG's is not real high on my priority list.

 

35 to 40 MPG and I will be happy.

 

 

Gary

Building it just for Show huh???:rotfl:

Just for GO :thumbsup2:

Show is the Icing on the Cake ...

btw ... here's News for V4 addicted ...

http://www.starvmax.com/news/1-v-max-news/191-iconic-wins-show-finals

will the earlier vmax cams go into the rsv??

yes they will !