4 mil Serval Jetting

[lotuseater]

I just got my motor together last week and I am trying to figure out a close jetting quickly before a race this weekend. I am curious how many others have dialed in a setup similar to this and where they ended up on jetting.

 

The current specs are:

Serval Cub Cylinder

HotRods 4mm Crank

Fast NOSS Head

22cc Cub Domes

Shearer Inframe Small Bore Pipes

35mm PWKs

+4 timing

 

It passed the leakdown test last week and my squish is around .047"-.048". Left cylinder compression is around 162 psi and the right at 165 psi.

 

I am currently using stock reeds, but hope to upgrade to some vForce 3's soon. My jetting right now is at 170 mains and 48 pilots for break-in, with CEL needle middle clip. It doesn't seem too far off on jetting as is, but it is hard to tell as my riding area around the house is pretty limited. Most of the smoke goes away after the bike warms up, but there does seem to be just a very slight bog when getting back into it from a low RPM. I am tempted to put the 165 mains in it to try for this weekend. I realize doing a plug chop is the best way, but I am just limited on time. I will attempt to do that eventually.

Edited April 6, 2011 by lotuseater

[gizmoman]

I just got my motor together last week and I am trying to figure out a close jetting quickly before a race this weekend. I am curious how many others have dialed in a setup similar to this and where they ended up on jetting.

 

The current specs are:

Serval Cub Cylinder

HotRods 4mm Crank

Fast NOSS Head

22cc Cub Domes

Shearer Inframe Small Bore Pipes

35mm PWKs

+4 timing

 

It passed the leakdown test last week and my squish is around .047"-.048". Left cylinder compression is around 162 psi and the right at 165 psi.

 

I am currently using stock reeds, but hope to upgrade to some vForce 3's soon. My jetting right now is at 170 mains and 48 pilots for break-in, with CEL needle middle clip. It doesn't seem too far off on jetting as is, but it is hard to tell as my riding area around the house is pretty limited. Most of the smoke goes away after the bike warms up, but there does seem to be just a very slight bog when getting back into it from a low RPM. I am tempted to put the 165 mains in it to try for this weekend. I realize doing a plug chop is the best way, but I am just limited on time. I will attempt to do that eventually.

 

My setup is about the same as yours except with 39pwks and i'm running 175 mains,50pilot,cel middle clip.

[gotta_goatsfast]

Its really stupid to go out racing without properly dialing your carbs in. Anyway, I'm running the same carbs as you are and found this to be my best setup (while being safe)

 

48 pilot, air screw 1-3/4 out

CEL needle middle clip

158 main jet.

 

I could throw in a 155 for a little more out of it but I feel safe with what I have.

 

Also, I'm at 800' above sea level and jetted for 60-70 degrees.

 

I think the reason gizmo has a 175 main is because the signal strength across his carburetor is less than my 35mm venturi. I wonder where the smaller carbs will jet in at with these?

[lotuseater]

Its really stupid to go out racing without properly dialing your carbs in. Anyway, I'm running the same carbs as you are and found this to be my best setup (while being safe)

 

I understand what you are saying. I feel that I should be on the rich side with where I am at. This thread was meant more as using for a comparison. As I said above, I will be doing a plug chop test as soon as possible.

Edited April 6, 2011 by lotuseater

[gotta_goatsfast]

Start with a 50 pilot and 165 main. Plug Chop your way to happyness.

[gizmoman]

Its really stupid to go out racing without properly dialing your carbs in. Anyway, I'm running the same carbs as you are and found this to be my best setup (while being safe)

 

48 pilot, air screw 1-3/4 out

CEL needle middle clip

158 main jet.

 

I could throw in a 155 for a little more out of it but I feel safe with what I have.

 

Also, I'm at 800' above sea level and jetted for 60-70 degrees.

 

I think the reason gizmo has a 175 main is because the signal strength across his carburetor is less than my 35mm venturi. I wonder where the smaller carbs will jet in at with these?

 

I'm running rich on top with the 175s but my bottom and mid range is great.

[gotta_goatsfast]

I started with a 175 not knowing where to begin with. Once well into the powerband it ran (rich) but if I opened the throttle up all the way at say 5000rpm it would drown out and sputter until it revved up to around 7500 then it would launch. Now when I hold the throttle all the way open it pulls, unless you open it all the way down way low like 2500 then it hesitates lol.

[gizmoman]

I started with a 175 not knowing where to begin with. Once well into the powerband it ran (rich) but if I opened the throttle up all the way at say 5000rpm it would drown out and sputter until it revved up to around 7500 then it would launch. Now when I hold the throttle all the way open it pulls, unless you open it all the way down way low like 2500 then it hesitates lol.

 

If I'm just cruising at say 1/4-1/2 throttle and then peg it, it hesitates just a little then builds rpm really slow. I'm probably missing out on alot of power should probably be at a 162-165 main.

[bebetekbanshee358]

If I'm just cruising at say 1/4-1/2 throttle and then peg it, it hesitates just a little then builds rpm really slow. I'm probably missing out on alot of power should probably be at a 162-165 main.

 

 

im in the same boat as u but i have 35 pwks shearers v3s . im running a 165 and it seems a bit rich on top.. i have a 162 im thinking lof trying tommorow.. im also thinking of trying some 30mm carbs also.

[figjam]

Hi guys I also need some input on this please!! Going 421 serval with 35mm carbs, vf3 reeds, pods and either cpi's or shearers. I'm at sea level. What would you recommend for the jetting??

 

Thanks!

[robert.b.west]

Hi guys I also need some input on this please!! Going 421 serval with 35mm carbs, vf3 reeds, pods and either cpi's or shearers. I'm at sea level. What would you recommend for the jetting??

 

Thanks!

 

I have the same setup except 33mm pwk's and I have 165 mains. The 35mm should be about the same.