Venus 50 (Now 96cc!)

[2strokd]

Some 90cc ones may be restricted that way too John, you know how these lil motors can very, ride to ride :scared: :help:

[dude]

Help me understand I am part dyslexic. Wouldnt you want the 8.83 gears for cruising or top end? If so would the 90cc be strong enough to pull that gear? Or are you after a wheel scoot 11.08?

[90GTVert]

The 8.83 gears would be better for speed. 11.08 is better for take off. The 90 would pull the 8.83 gears pretty well I think, although my weight would probably keep me from going too fast short of a hill or something in nearly stock form. I absolutely want to do wheelies. It still might not happen, but that's why I want the deep gears from the 50cc engine.

[90GTVert]

I didn't have much time to mess with it today, but I did get to do a little checking on a few things.

52mm Bore x 42mm Stroke (89.2cc)



The piston sits about 1.9mm below deck on the stock setup.



It also comes pretty far from clearing the ports at BDC.



Port durations with the stock setup are :

Exhaust : 178
Boost : 114
Transfers : 120

I still have the 52mm cylinder that I tried to put on T2 long ago, so I figured I might as well see what it's like. I had it milled too much on the deck (3mm IIRC). I forgot a pic, but the piston sita about 1mm above deck with it. I used to correct with multiple head gaskets without any issues. When I was messing with it, I really had no idea what I was doing with 2 strokes yet. It's pretty much new.

The piston comes pretty close to clearing the ports with this one.



Durations are :
Exhaust : 189
Boost : 123
Transfers : 133
Secondary Transfers : 123

Then I decided to try both cylinders with 2 base gaskets and see what happens.

The piston is still way off clearing the ports at BDC with 2 base gaskets and the stock cylinder.



Duration with 2 base gaskets are :
Exhaust : 182
Boost : 120
Transfer : 124

The piston is about flush with the port at BDC using the aftermarket 52mm cylinder and 2 base gaskets.



Port durations with 2 base gaskets are :
Exhaust : 192
Boost : 131
Transfers : 136
Secondary Transfers : 131

I haven't even paid attention to any of the numbers yet. Takes long enough to get 'em and post the details. lol

On top of looking those over, I need to decide which pipe I'm going to try. I think the only ones that will fit are the modified stock Triton exhaust (bottom left), the Leo Vince SP3 (mid left), or the MRP (bottom right). I have the stock Venus pipe too, but it's got emissions crap and a smaller header. I think the MRP is out because of a small stinger. I had overheating problems using it on the Triton's 90cc.

[190mech]

Ya only got that funky head?The stocker cyl looks mild with low compression,if ya pick up the cyl,then ya loose more compression..The other jug looks OK with 1 gasket if you can adjust the squish properly.The MRP looks like a good bet if you increase the stinger/muffler size.Hack the one off the pipe I built ya,its 19.5mm ID,should be good for that size motor,or you can hunt around and find some bent tube(bicycle handlebar,lawnmower handle,etc)and build your own,if ya like I can scrounge around here and try to find something and mail it to ya.Remember this needs to be a tame machine as the Old Man is gonna ride it!!

[190mech]

My pipe calculator states stinger diameters(ID);
70cc=18mm
80cc=19.5mm
90cc=21mm
103cc=24mm
Dont think these numbers are "set in stone" though..

[90GTVert]

I have 2 stock 52mm heads and then I've got 3 different 54mm heads around. Both stock heads are the same with the less than ideal cc design. All the 54mm heads are squish style.

I kinda wanna leave the MRP alone and keep it around as a good 70cc pipe anyway. I like the way it acts with all the 70s I've had. As far as being mild for my father to ride it... I was kinda thinking stock pipe for that reason. It should have more power down low, but it won't hit. If it's not at all what I want, I might consider modding the MRP. Really don't want to though. I was coming to the same conclusion on the aftermarket cylinder with 1 base gasket and maybe filing just a touch off the piston where it meets the exhaust port. My only concern there is whether the port timings are too high for something with a stock pipe to run well. I think it should be OK though.

[190mech]

Since its a bolt on,try both cyls.I think either will work fine.Wish I could get an idea of the head pipe crooks,then maybe I could come up with a better pipe from this and that...

[stepthrutuner]

I think you should go with the 'extended timings' cylinder and the pipe most appropriate for the timings and displacement and tame it down with heavy rollers. Then the street race challenge machine is only a roller change away. The stinger can always be re-swapped later :2cents:

[2strokd]

I like the jug you already had...The one with more timing.
Good advice Reg! Thats kinda what i was doing with Skeedr before.
I would try your 54mm head too, just for the hell of it.

[90GTVert]

I dunno what I wanna do anymore. lol This was supposed to be a very simple project. lol

[190mech]

Bolt it back together stock with the stock muffler and see what ya got..

[drawkward]

Aug 9, 2010 13:54:58 GMT -5 190mech said:

Bolt it back together stock with the stock muffler and see what ya got..

Agreed.Test it out the way it is. The whole point, I thought, was to have a simple bolt on 90cc engine in the first place. Everything looks in order on initial inspection. Fire 'er up and let us know how the stock-swap works out before you start moddin'. Will also give you a good baseline to start from.

[90GTVert]

I know it's the wrong way to go, but I'm looking for a "leave in" more than a baseline. The problem is, once I saw how far off some things are stock, it bugged me and now I'm having a hard time wanting to leave it alone. I just feel like I would be putting it back together wrong so to speak.

[190mech]

Ive got 183 EX and 130Tran and it has a very smooth powerband,so a few mods should still make a nice machine.Heck,I couldnt leave it stock if the truth is known!!!