vitos 421 won't rev on top end

[IDAHOSHEE]

Update.......... Ok, so I found the cause of the cutting out, air gap was fine (.018) so I started checking coil, plug wires and so on. Found loose connection in left cylinder plug wire connector. Repaired that and the cutting out is gone, now just falls flat so I will mess with the jetting alittle more. Yes it pulls real hard until it falls flat. So just down to alittle more tuning at this point I think. Thanks again for all the ideas and help.

[IDAHOSHEE]

Is this you Jason?

 

I had the same problem when I built my 4 mil, it was the pick up coil gap like mentioned above, and make sure the screw on caps on top of your spark plugs are tight, they rattle loose after time.

You nailed it, left plug wire cap conection was loose. Thanks

[bigborebanshee]

Does she pull pretty hard?? i have a similar set up to yours. Im just waiting for some jets to come in.

 

With a T-5 or Dmc pipe it makes good broad power across the rpm with a violent hit when it gets on the pipe.Have Cpi on it now and the peakyness is gone.

 

If your running these cylinders on stock bore banshee pipes other than CPI or Shearer,your handicapping yourself,get the right pipes and carbs.

[EvilBanshee]

With a T-5 or Dmc pipe it makes good broad power across the rpm with a violent hit when it gets on the pipe.Have Cpi on it now and the peakyness is gone.

 

If your running these cylinders on stock bore banshee pipes other than CPI or Shearer,your handicapping yourself,get the right pipes and carbs.

 

I have the FMF Gold Series FAtty's. their actually not that big compared to other brands i have seen. But it worked good on my old motor. so we shall see.

Also what kinda compression are you running?? i have the the 22cc domes, makes 185psi . I would have thought the 22cc's would have made like 150 psi or something.

Edited August 19, 2010 by EvilBanshee

[shanYE west]

I have the FMF Gold Series FAtty's. their actually not that big compared to other brands i have seen. But it worked good on my old motor. so we shall see.

Also what kinda compression are you running?? i have the the 22cc domes, makes 185psi . I would have thought the 22cc's would have made like 150 psi or something.

 

 

either you got a inaccurate gage or your squish is off.

 

Or... your 2k-3000ft below sea lvl.

[EvilBanshee]

either you got a inaccurate gage or your squish is off.

 

Or... your 2k-3000ft below sea lvl.

 

No we CC'd it. 16.6 cc 's of oil it took to fill the 1 cyclinder at top center, it worked out to 14:1 for compression ratio. Unless vito's messed up with marking the domes. Their suppose to be 22cc. I live near London Ontario. Not sure the sea level. i think like 650 above??

[bigborebanshee]

I have the FMF Gold Series FAtty's. their actually not that big compared to other brands i have seen. But it worked good on my old motor. so we shall see.

Also what kinda compression are you running?? i have the the 22cc domes, makes 185psi . I would have thought the 22cc's would have made like 150 psi or something.

 

I think your gauge is off.My 421 vitos with 22 cc domes made about 145psi max and that was with.039 squish.Im running 18 cc domes now and it makes 160psi.It would be hard to get more than that considering the exhaust port heightis barely 26mm

[EvilBanshee]

I think your gauge is off.My 421 vitos with 22 cc domes made about 145psi max and that was with.039 squish.Im running 18 cc domes now and it makes 160psi.It would be hard to get more than that considering the exhaust port heightis barely 26mm

 

Hmmm.. ill have to have a little chat with mr snapp on in the morning.

[shanYE west]

Hmmm.. ill have to have a little chat with mr snapp on in the morning.

 

 

have you checked your squish??

 

and the elevation thing was a joke.. I wasn't serious.

[EvilBanshee]

have you checked your squish??

 

and the elevation thing was a joke.. I wasn't serious.

 

Ya my squish is the 0.039 as well. I do think my gauge is off, im gunna get a friends and put it on , see what it reads

[shanYE west]

Ya my squish is the 0.039 as well. I do think my gauge is off, im gunna get a friends and put it on , see what it reads

 

 

how wide was the band?

[rdzbangshee]

Looking for some help, just built a Vito's 421, 20cc domes, 160 lbs compression,shearer in frams, 155 main jets in new 39mm kein pwk's. runs great until it reaches higher rpm's then seems to cut out and sputter, falls flat on it's face. Have tried going both directions with jetting does not change the cutting out. Have tried timing from 0 to 7 deg advanced, does not change the problem. Any advice at this point would sure help.

i have my timing set @ +10 now and it has good top end still wrenching wile i ride.and wating for my big bore cpi's to show up.i have the older power pistons wich are lighter than there new one's dont want to crack them running +12 on the timing,good luck tuning.

[EvilBanshee]

Looking for some help, just built a Vito's 421, 20cc domes, 160 lbs compression,shearer in frams, 155 main jets in new 39mm kein pwk's. runs great until it reaches higher rpm's then seems to cut out and sputter, falls flat on it's face. Have tried going both directions with jetting does not change the cutting out. Have tried timing from 0 to 7 deg advanced, does not change the problem. Any advice at this point would sure help.

 

I finally got mine running. Mine does the same thing in 6th gear about 75% reved out it will fall on its face. Im still waiting on different jets. The thing wont idol.

[bigborebanshee]

I finally got mine running. Mine does the same thing in 6th gear about 75% reved out it will fall on its face. Im still waiting on different jets. The thing wont idol.

 

What mains did you try? what pilot are you running?If your running a keihn carb,you should be between 48-52 on pilot depending on airbox setup and needle.I started on with 160 main and worked my way down to a 150 before it would revv clean.Also the compression you are running will make a difference on your main jet choice.The higher I went on compression,the more i had to drop the main jet.

[EvilBanshee]

What mains did you try? what pilot are you running?If your running a keihn carb,you should be between 48-52 on pilot depending on airbox setup and needle.I started on with 160 main and worked my way down to a 150 before it would revv clean.Also the compression you are running will make a difference on your main jet choice.The higher I went on compression,the more i had to drop the main jet.

 

Well im still waiting on more jets now. But i have in it right now 155 mains, 52 pilot. I have the 22cc domes (145 psi) . Like the thing will pull pretty decent through 1-5th gear, and even 6th gear until its about 75% reved out then it will fall on its face. The thing is grossly rich. It wont idol. You can see the fuel comming out back through the carbs. Im gunna Try a 40 pilot. oh maby a 35 even.