Doesn't have the punch it should

[nick20555]

As some of you have seen, I've been working on my build for about 6 months now and I've finally zoned in on the jetting. You guys have approved my plug chops and everything. I've finally put about 2 tanks through it and I'm ready to GIVE IT HELL!!!!..........but..........it just wasn't there. When doing my plug chops, the thing nearly threw me off the back but now I'm just not feeling it. Not sure if its just that I had never ridden it full throttle before so I was just imagining that I was going fast or if it really was throwing me off and now its not.

I went on one ride with my friend on a predator and my dad on his lesser built blaster now that I had my jetting completed. I grew up on my dad's blaster and rode it up until I finished my blaster. We never lined them up but I'm not too sure I would have beat either of them.

My dad's blaster has .050 bored over with head machined a bit, no porting, stock carb, toomey pipe with air box vents, and a reed spacer. So my 240 with +3 crank KOR ported and 170 psi head, 35mm carb, lightened flywheel, vito's pipe, cfm airbox with foam filter should LEAVE HIM LIKE HES STANDING STILL. I just don't feel the punch it should have. It isn't slow but I keep expecting it to kick in but it never does.

What do you guys think could be the issue? the plug chops look great with jetting close to similar build. So I'm lost. I'm running 32:1 with half race fuel and half 93 pump gas like I was told.

 

[Awk08]

whats your jetting again ?

altitude-
pilot-
needle-
clip position-
main jet-

reeds condition ?
try new plug ?

 

[nick20555]

whats your jetting again ?

altitude-
pilot-
needle-
clip position-
main jet-

reeds condition ?
try new plug ?

altitude-400ft
pilot-50
needle-CEL
clip position-bottom clip position
main jet-162

reeds condition ? brand new vforce 4
try new plug ? New plug put in after plug chopping, just before the one ride I went on

 

[nick20555]

I'd really hate to tear it apart again since I've done it about a billion times in the last month only to get about 45 minutes of disappointing ride time. Kinda lost motivation with the disappointing results. I did everything I was told on the build. No corners cut, no expense spared.

I really wanna throw some rooster tails at the atv drags at our county fair in a week. With the turnout last time, I'd probably be the only 2 stroke there except maybe a banshee will show up this time. I'd really like to stomp the 400s and give the 450s a run for their money.

 

[Awk08]

I'd say that needle clip setting is too rich, try raising it one notch at a time and give it one quick blast for each setting to see if it gets better.or you could do 1/2 throttle plug chops also to confirm each clip setting.

 

[nick20555]

I'd say that needle clip setting is too rich, try raising it one notch at a time and give it one quick blast for each setting to see if it gets better.or you could do 1/2 throttle plug chops also to confirm each clip setting.

I did half throttle chops. Here were the results I posted. The first one is of bottom clip with brake held during pull

half throttle plug chop

• nick20555
• May 31, 2015

Half throttle plug chop on bottom clip position

This was a redo without using the brake. The half throttle is on the right

half and full plug chops

• nick20555
• Jun 12, 2015

Half throttle plug chop on bottom clip position (right) full throttle plug chop with 160 main (left)

 

[MURPH]

Float height 16mm?
Exhaust and intake from airbox free flowing?

 

[jus_me]

Did you advance the timing? if so than go back to stock.


Spark is nice and blue?

 

[nick20555]

Float height 16mm?
Exhaust and intake from airbox free flowing?

Float was good. Exhaust and intake are good. It would throw off the jetting if it wasn't free flowing.

Did you advance the timing? if so than go back to stock.


Spark is nice and blue?

No timing changes were done. I haven't checked the spark. Didn't think about that. I'll check that when I get time

 

[MURPH]

Float was good. Exhaust and intake are good. It would throw off the jetting if it wasn't free flowing.

So your jetting is correct?

 

[nick20555]

As long as those plug chops above look good. I went up a size on the main from that picture with the 2 plugs

 

[Awk08]

I still say the CEL needle on the bottom clip is too rich.
raise the clip one position and do a pull to see if it gets better,
one pull won't hurt anything, it's like doing a plug chop and finding you need to bump up a size or 2.

 

[nick20555]

I still say the CEL needle on the bottom clip is too rich.
raise the clip one position and do a pull to see if it gets better,
one pull won't hurt anything, it's like doing a plug chop and finding you need to bump up a size or 2.

I can try that. I was wondering myself if the bottom was too rich. Would it be safe to bump the main up one while I'm at it or just keep it where it's at?

 

[Awk08]

when jetting............ start at the bottom and work your way up.
1. float height
2. pilot/airscrew
3. needle
4. main jet

no sense to work on jetting needle or main if the float height or pilot hasn't been perfectly tuned yet, ect.
when you go back and adjust a lower jetting range, (float height, smaller/bigger pilot, needle clip position, different needle) all ranges above should be re-checked/tuned

 

[speedyslyder]

maybe your carb slide is not opening fully?
did you ever post up close pics of yur setup?
not that we need to see it but it is interesting lol

 

[nick20555]

maybe your carb slide is not opening fully?
did you ever post up close pics of yur setup?
not that we need to see it but it is interesting lol

Here is both sides until I can work on the jetting and check the spark

left side motor

• nick20555
• Jun 30, 2015

Close up of left side motor

right side motor

• nick20555
• Jun 30, 2015
• 3

Close up of right side motor

 

[nick20555]

Let me know if anything stands out. This thing was bought in pieces in a box and most pieces were missing. I have not put the final zip ties and tuck on the wires yet so please don't hate the temporary spaghetti mess I have going on. I just didn't want to clean it up just to have to tear it apart so I am waiting till all is well to put the final details. But if there are any problems let me know.

 

[bansheedave]

That's a keihin carb not a mikuni so the jetting will be completely different than a stock carb.

 

[bansheedave]

Unless of course that's already been discussed...lol

 

[bansheedave]

I would put the needle clip in the middle position and I would think the 50 pilot is way to big for that motor. You should be between a 42 and 45 with the air/fuel screw 1 and a half turns out. The black screw is the idle adjust screw.