VITO VS STOCK

[stroking]

I have a set of vito 68mm triple port cylinder here,but after comparing them to the stock cylinders the tranfers are alot smaller on the vitos,now i'm wondering if i should port them before install......take a look below and tell me what you think.

 

its going on a 4 mil longrod vito crank.

 

does anyone on here run them for drag racing,if so how are they?

 

[banshee(911)]

I have a set of vito 68mm triple port cylinder here,but after comparing them to the stock cylinders the tranfers are alot smaller on the vitos,now i'm wondering if i should port them before install......take a look below and tell me what you think.

 

its going on a 4 mil longrod vito crank.

 

does anyone on here run them for drag racing,if so how are they?

 

well ive herd that their is allot to cut away on a vitos cylinder to get them to run good..and they dont look lke tripple port cylinders

[BANSHEE HP]

^^^^you must not be looking at the exhaust port in the first and third pic, the reason they are smaller is because they're 68mm bore and ur stock cylinders are not, stock cylinders with big bore sleeves will have smaller transfer port area because the sleeve has a larger o.d.(as well as i.d.)

[shanYE west]

no mistake about it.. them are trip ports.

 

Transfers are the biggest problem with the 68mm bore on stockers.. Thats the first time i've seen the vito's cylinders.. Definately alot of work needed in those things.

 

 

[stroking]

does anyone run them on here?

[AWR]

i've done two sets in the last 2 months.both sets had way too much exhaust duration for me(203-204) and seemed poorly cast but you can't beat the price.tranfers are really small towards the bottom but easily fixable.used 4 mil cranks in both.one hauls ass the other is'nt set up right-i tell him one thing he does another(he's on his own).seem very picky about jetting and not much lowend

Edited June 15, 2010 by AWR

[stroking]

well this is the motor im having trouble with....it has a bog on take off and it bogs between gears on a full override

 

its on alky,after i went from a 58 pilot to a 48 the take off bog got better but it still doesn't feel right when going threw the gears.

 

ive built stronger stock cylinder 4mil

[camatv]

might need to degree it and really get into it as far as tuning...

 

i jetted one a guy put together and no matter what i did it just didnt have much bottom end but had a noticeable overrev and hp pull on top. was fun in a straight line but needed help. i would really like to get ahold of a set and set them up on a 10 mill or a 4 mill. see what can be done with them. i think they have great potential.

[stroking]

i had the timing at +12 the whole time i was tuning it,maybe vito's dont like that much timing.....being that it was bogging off the line i figured dropping the timing would only make it worst.

[rb0804]

I could never figure out why they took the time to cast their own cylinders with tripple exhaust ports but they never bothered to 'beef up' the intake side where you would be cutting the Boyseen ports. Seems like the exhaust duration is a little much also. The mismatch of pipes and that high of duration could be the root of some of the problems that I have seen listed such as being jetting sensitive, bogging, etc.

[RadarRacing]

Overall I was excited to see these $599 kits with pistons etc but they are not very good kits for a 4 mil seing as how they are really ported for a 54mm stroke.

 

 

If it were me , I would do this. Mind you do at your own risk and be sure not to cut into the water jackets etc.

 

#1 use a thinner base gasket if possible but still not get the bottom of the exhaust port below the top of the piston at BDC.

I would shoot for a 194-198 exhaust duration.

 

#2You'll then need to call Dave Noss at Noss Machine and tell him you need special domes cut ($80 set approx.) I would use probably a 19cc dome with less "STEP" in the dome than what you had. Do the math to get your squish to approx .042

 

#3 I'd port the tops of the transfers up to get it to the 128-130 range for transfer duration. NOT JUST THE TOP OF THE PORT but port back to the bend where the tunnel starts aiming down. KEEP THE ROOF ANGLE THE SAME

 

#4 Cut the bottom of the sleeve just a bit more on the side closest to the exhaust, probably cut it to where the bridge between the tunnels is.

 

#5 Get a cub base gasket and port the transfer tunnels to match the gasket and port the cases to match. You would need to have enough room to cut the tunnel all the way up and keep it from bottlenecking anywhere. The smallest point in the tunnel is the size the rest needs to be up till the bend when the charge is compressed smaller at the bend.

 

#6 Clean up the exhaust and auxillary exhaust ports where they are really rough. I would also square the aux ports up just a bit at the top outer edge farthest away from the main exh port.

 

#7 I'd watch the timing not many cubs like or want to run at +12

 

#8 If I were running DRAG type pipes CPI , SHEARER etc I'd flatten the exh port roof just a bit by bacically squaring up the outer top portion or "shoulders" if you will.

If you are running a pipe with more range like T-5s or FMF I'd leave the main exh port roof shape alone.

 

#9 I would check the angle of the front transfer closest to the exhaust and for high RPM power make sure that front trans is aimed to intersect the other front transfer at exactly the middle of the bore. If it is aimed towards the middle of the intake I'd change it to middle of the bore for whats called loop scavenging at high rpms. My guess is its going to aim at the middle of the bore.

 

You didnt show the intake any but it's probably SOMEWHAT fixed over stock. What a bunch of bull crap these things run like they do and have to be fixed.

I dont know what CAMATV did to fix his but probably something similar.

Edited June 19, 2010 by RadarRacing

[mercury65]

Overall I was excited to see these $599 kits with pistons etc but they are not very good kits for a 4 mil seing as how they are really ported for a 54mm stroke.

 

 

If it were me , I would do this. Mind you do at your own risk and be sure not to cut into the water jackets etc.

 

#1 use a thinner base gasket if possible but still not get the bottom of the exhaust port below the top of the piston at BDC.

I would shoot for a 194-198 exhaust duration.

 

#2You'll then need to call Dave Noss at Noss Machine and tell him you need special domes cut ($80 set approx.) I would use probably a 19cc dome with less "STEP" in the dome than what you had. Do the math to get your squish to approx .042

 

#3 I'd port the tops of the transfers up to get it to the 128-130 range for transfer duration. NOT JUST THE TOP OF THE PORT but port back to the bend where the tunnel starts aiming down. KEEP THE ROOF ANGLE THE SAME

 

#4 Cut the bottom of the sleeve just a bit more on the side closest to the exhaust, probably cut it to where the bridge between the tunnels is.

 

#5 Get a cub base gasket and port the transfer tunnels to match the gasket and port the cases to match. You would need to have enough room to cut the tunnel all the way up and keep it from bottlenecking anywhere. The smallest point in the tunnel is the size the rest needs to be up till the bend when the charge is compressed smaller at the bend.

 

#6 Clean up the exhaust and auxillary exhaust ports where they are really rough. I would also square the aux ports up just a bit at the top outer edge farthest away from the main exh port.

 

#7 I'd watch the timing not many cubs like or want to run at +12

 

#8 If I were running DRAG type pipes CPI , SHEARER etc I'd flatten the exh port roof just a bit by bacically squaring up the outer top portion or "shoulders" if you will.

If you are running a pipe with more range like T-5s or FMF I'd leave the main exh port roof shape alone.

 

#9 I would check the angle of the front transfer closest to the exhaust and for high RPM power make sure that front trans is aimed to intersect the other front transfer at exactly the middle of the bore. If it is aimed towards the middle of the intake I'd change it to middle of the bore for whats called loop scavenging at high rpms. My guess is its going to aim at the middle of the bore.

 

You didnt show the intake any but it's probably SOMEWHAT fixed over stock. What a bunch of bull crap these things run like they do and have to be fixed.

I dont know what CAMATV did to fix his but probably something similar.

i new they needed work but dam. maybe that is why the quit selling them.

[RZBansheeMan]

Maybe if I had the cash.......

 

I would send a set to Jim at Passion and have him work a set over with his 12 port conversion that he does. It would be interesting to see the outcome, it would be cool to see it have a lot of torque broad mid and excellent top.

[stroking]

#7 I'd watch the timing not many cubs like or want to run at +12

 

 

well the cub i have here now runs at its best at +12 .... we tried lowering it at the track and it slowed the bike down.

 

the two things that most say NOT to do (timing and compression) is the very thing that makes use down here at sea level faster.

 

the more we throw at it the faster they get......oh and its only pavement racing for us also.

[stroking]

sounds like the vitos need alot of work

 

guess i better get busy!