No top end/mid end

[ptnov]

Hi,

So i just put on UFO exhaust with morley jetkit. I have the air corrector, modified airbox and PCV connected and read on http://www.vmaxoutlaw.com/tech/cv_carb_tuning.htm that you begin with tuning the top end with main jet sizes.

The problem is that I can't even get to the top end before the engine begins to slow down. Around 5k-5.5k RPMs it slows down considerably. By the time the vboost kicks the power is already so low that I can't feel it anymore. The very bottom end also sucks but at 1.5k - 4k i runs relatively good. My bike's now like a cruiser lol.

where do I start? should I start with the mains even though I can't reach 7.5k.

 

[sdt354]

I'd start with basic stuff. Carbs fully seated into good rubbers and tight, carbs sync'd, floats set correctly. Needle clip position? Needles installed right with the little teet in the hole in the slide. Diaphram condition and installation? A 155-157 main should be fine to start with. A/F set at 2 3/4 from seated is a good starting point.

 

[ptnov]

I'd start with basic stuff. Carbs fully seated into good rubbers and tight, carbs sync'd, floats set correctly. Needle clip position? Needles installed right with the little teet in the hole in the slide. Diaphram condition and installation? A 155-157 main should be fine to start with. A/F set at 2 3/4 from seated is a good starting point.

Yeah did do the basics, Carbs are synced, floats are synced using pics from Seans website. Still using stock needle setup. Diaphrams are good and installed correctly. I'm currently using 157.5 mains and A/F mixture screws are all at 2 1/2 turns.

One thing though. The rubber around carb 4 is cracked, and I've ordered new. I did try this with stock mains and stock exhaust. That worked perfectly fine...

could the rubber and new exhaust affect performance this much?

I'm almost at sealevel btw.

 

[one2dmax]

Stock Needles need much larger mains.

 

[ptnov]

Stock Needles need much larger mains.

Right! So it's possible to do it two different ways.
Is there any difference between using dj needles and smaller mains vs using stock needles and larger mains? What would you recommend? What size would you say would be good to start with for mains if I use stock needles?

Thanks btw!

 

[one2dmax]

Our original kits used the stock needles and larger mains and worked well. Some had difficulty tuning in the midrange and thus the optional needles became standard. You can get excellent fuel mileage if you can get it tuned in with the stock needles. Start with the biggest in the kit (165) and see if that doesn't help get it pulling hard up top.

 

[ptnov]

Our original kits used the stock needles and larger mains and worked well. Some had difficulty tuning in the midrange and thus the optional needles became standard. You can get excellent fuel mileage if you can get it tuned in with the stock needles. Start with the biggest in the kit (165) and see if that doesn't help get it pulling hard up top.

Thank you I'll try and tell how it went!

 

[Rusty McNeil]

Right! So it's possible to do it two different ways.
Is there any difference between using dj needles and smaller mains vs using stock needles and larger mains? What would you recommend? What size would you say would be good to start with for mains if I use stock needles?

Thanks btw!

I don't know zip about tuning Morely muscle kit, but;

Just my two cents but the correct mains are the correct mains, period, since the mains should be sized for WOT "on the main only" which is generally around 7000 up at WOT.
At this point the needles aren't in the picture.

Yes, at other rpm's and throttle openings the mains and the needles work together so if your not working toward optimum WOT on the main only performance, there probably are multiple combinations of needle and main that would work to get good results in cruise, mid, and high mid areas.
But if the main isn't picked for high RPM only with the needles out of the picture then its never going to be right in this area.

From what your describing I would guess your extremely rich at the point where its bogging and refusing to accelerate, since lean will usually rev to the moon before something det's

Besides jetting its also possible for the slides to open too early as well. What springs are you running?

When it bogs is it doing it when your trying to
1. creep up slowly from a lower RPM to WOT?
2. Cruising steady state and then brisk acceleration to WOT?
Or
3. starting from 3000 or so and going WOT till redline?

When I was trying to sort my stage 7 out on a new big motor it would easily accelerate (with a soft spot) WOT past your bog point till redline if doing it from low rpm and staying WOT straight to redline, but creeping up on it was causing it to do what your describing.

Mine turned out to be too much needle and too much main both, combined with too high a float level.

I still haven't for mine perfect tho'

 

[Rusty McNeil]

Factory pro's CV tuning guide is a great reference source as well as the 'carb bible sticky" and the "everything you wanted to know about CV carbs sticky"

 

[jwood]

Make sure you don't have a carburetor slide stuck in the open position! I just went through that dilemma...

Sent from my Galaxy Nexus using Tapatalk 2

 

[Rusty McNeil]

Make sure you don't have a carburetor slide stuck in the open position! I just went through that dilemma...

Sent from my Galaxy Nexus using Tapatalk 2

+1, been there too, and it refuses to accelerate big time.

 

[ptnov]

I don't know zip about tuning Morely muscle kit, but;

Just my two cents but the correct mains are the correct mains, period, since the mains should be sized for WOT "on the main only" which is generally around 7000 up at WOT.
At this point the needles aren't in the picture.

Yes, at other rpm's and throttle openings the mains and the needles work together so if your not working toward optimum WOT on the main only performance, there probably are multiple combinations of needle and main that would work to get good results in cruise, mid, and high mid areas.
But if the main isn't picked for high RPM only with the needles out of the picture then its never going to be right in this area.

From what your describing I would guess your extremely rich at the point where its bogging and refusing to accelerate, since lean will usually rev to the moon before something det's

Besides jetting its also possible for the slides to open too early as well. What springs are you running?

When it bogs is it doing it when your trying to
1. creep up slowly from a lower RPM to WOT?
2. Cruising steady state and then brisk acceleration to WOT?
Or
3. starting from 3000 or so and going WOT till redline?

When I was trying to sort my stage 7 out on a new big motor it would easily accelerate (with a soft spot) WOT past your bog point till redline if doing it from low rpm and staying WOT straight to redline, but creeping up on it was causing it to do what your describing.

Mine turned out to be too much needle and too much main both, combined with too high a float level.

I still haven't for mine perfect tho'

I haven't thought about when it's slowing down. But I'll keep that in mind next time I'm riding. Thanks!

 

[ptnov]

Make sure you don't have a carburetor slide stuck in the open position! I just went through that dilemma...

Sent from my Galaxy Nexus using Tapatalk 2

How do I know if it's stuck in the open and how did you clean it?

 

[tugla]

With air filter or box off and bike off look down top of carb and you can moved the slide by hand and it should snap back closed . Also when idling they don't move and then rev it up a bit and you should see all four slides move in close unison to each other. If sticking take slide cover off(watch don't drop little oring) and take the slide out clean with wd40 and reinstall, make sure not to pinch the slide in the cover as that can make it stick also. Hope that helps

 

[ptnov]

Don't think there's a problem with the slides. I did change the main jets to 165 and the top end power seem to be fine as long as i WOT. Does pop at exhaust not. Still need tweakig but seems to be going right now

thanks!

 

[veebooster]

Listen to Sean. I have his kit, HMF exhaust (very similar to UFO), stock needles. Always test with your air box cover on, make sure your vent tubing is routed right, cracked joints will mess it up, you'll need big mains. It took me awhile to get her right.
I had to shim the needles a bit and ended at 170 mains, 177.5 PAJ2.

If your float level isn't right every thing is messed up!

Dale #2592

 

[tugla]

How do I know if it's stuck in the open and how did you clean it?

Don't think there's a problem with the slides. I did change the main jets to 165 and the top end power seem to be fine as long as i WOT. Does pop at exhaust not. Still need tweakig but seems to be going right now

thanks!

Oh so you checked it out and found it all good.....cool

 

[ptnov]

Listen to Sean. I have his kit, HMF exhaust (very similar to UFO), stock needles. Always test with your air box cover on, make sure your vent tubing is routed right, cracked joints will mess it up, you'll need big mains. It took me awhile to get her right.
I had to shim the needles a bit and ended at 170 mains, 177.5 PAJ2.

If your float level isn't right every thing is messed up!

Dale #2592

where did you get the 170 mains? Morley jetkit only supplies you with 165.

 

[tugla]

I'm sure Sean can hook u up with some.....or any jet dealer online like jets r us.

 

[veebooster]

where did you get the 170 mains? Morley jetkit only supplies you with 165.

I got them from a local shop. If I remember right the PAJ2 are 170 stock. I used 177.5 in there so I ended up with extra 170s.

Dale #2592