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Message started by gdrseeker on 10/30/12 at 09:36:50

Title: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 09:36:50

Just put in a new Carb rebuilt from Lancer. I have no torque at the higher RPMS like I did before. Is it just a matter of fine tuning what main and pilot jets to use and the correct turns out on the air mix screw.

This is what Lancer sent me

I installed a #52.5 pilot with the pilot screw set at 1.5 turns out as a starting point for you.
The white spacer was replaced by 3 washers.
A #152.5 main jet is installed.
The carb was totally disassembled and cleaned and checked.
I also included extra jets: #50 & 55 pilot as well as #147.5, 150 & 155 main jets.

I believe you said you had a Jardine muffler, and if so then you may need to go up on the pilot and /or main jet, but you won't know until you get it together and test it,

Just holler if you need help with tuning

Michael

Title: Re: No torque at higher RPMS
Post by justin_o_guy2 on 10/30/12 at 09:39:52

I believe you said you had a Jardine muffler,

Do you?

and if so then you may need to go up on the pilot and /or main jet, but you won't know until you get it together and test it,

Have you?

Title: Re: No torque at higher RPMS
Post by Dave on 10/30/12 at 09:50:48

The mixture screw has almost no effect on high rpm power - it sets the idle mixture and has little effect beyond 1/8th throttle. The Pilot Jet has an affect from about 1/8th throttle to 1/4th, the Needle has affect from about 1/8th throttle to 3/4 throttle, and the main has an affect from 3/4 or more. There is a bit of an overlap from one jet to another......but generally that is the way it works for me.

Have you checked to see that the throttle cable is attached correctly and opening the carb butterfly properly?

What kind of elevation (MSL) do you live and ride at?

When you notice the power drop.....is the engine surging and running uneven (lean)....or does the engine still run smooth?

Why was your carb rebuilt and rejetted? Was it because of the muffler change?

Did you contact Lancer for the help he offered in jetting?

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 10:37:10

I have not gone up on the pilot jet or the main jet yet. That was my plan but I wanted to get feedback as to which one to change or both??

Ran fine with the stock muffler at 145 main and 52.5 Pilot.

Yes I have the Jardine muffler now.
I started to make adjustments after I put on the Jardine.

I got the rebuilt carb because the fuel / air mix screw was messed up and when I tried to remove to replace it I screwed it up so bad it was toast.

I live at 5000 Feet.

The engine seems to run smooth each gear at the lower portion of the throttle, as I throttle up it just doesn't seem to get any power, it seems to continue smooth but just raises the RPMS and not the speed / torque .

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 10:39:22

I am going to change out to the 155 Main and see how it feels.

Title: Re: No torque at higher RPMS
Post by Dave on 10/30/12 at 11:30:24

6360767761616F6176040 wrote:

I am going to change out to the 155 Main and see how it feels.

Because of your altitude....I believe you are already too rich. The thinner air requires less fuel at altitude and you need to drop the jet sizes. I would drop to the 150 first and see how that works. If you do install the 155 and things stay the same or get worse......at least you will know where to go next.

I am between 500 and 800 feet where I ride, and I have a #50 Pilot, a 150 Main, 2 washers on top of the needle, and I have a Dyna Muffler and a stock air filter. I had 3 washers on top of the jet needle at first, then found I had a lean stumble just off idle - it was corrected when I took one more washer out.

Title: Re: No torque at higher RPMS
Post by verslagen1 on 10/30/12 at 11:32:11

2320363721212F2136440 wrote:

The engine seems to run smooth each gear at the lower portion of the throttle, as I throttle up it just doesn't seem to get any power, it seems to continue smooth but just raises the RPMS and not the speed / torque .

As in rpms pick up but speed doesn't?

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 11:36:51

Correct RPMS go up but bike doesn't get the surge or torque it did before it picks up speed slowly just not responsive.

Just put in the 155 I will see what happens going for a ride around the block.

Title: Re: No torque at higher RPMS
Post by Serowbot on 10/30/12 at 11:36:56

Dave's gotcha'... he's giving good advice...
#155 is a lot of jet for 5k elevation...
Try the #150...

Take it away Dave... ;)...

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 12:05:50

155 was worse ......

Trying the 150 now.

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 12:54:09

Tried 150 then 147.5 and now 145 got better with each.

I now am at 145 main and 52.5 Pilot, three washers on the needle, and 1 turn out on the air/fuel mix screw. Only minor pops on deceleration.

Things seem good but not as much power / torque as I had before.

Not sure if I should change the pilot. or mess with the needle?

Going for a ride out of town and back for a total of 100 miles I will see how she acts.

Title: Re: No torque at higher RPMS
Post by Dave on 10/30/12 at 13:12:27

I would drop the Pilot as well.......and keep dropping it until you can't make the idle too rich at 3 turns out. If you can make the engine too rich at idle with something less than 3 turns....the pilot is probably fine.

You may also be too rich on the needle with 3 washers.....you are up in the clouds and don't need as much fuel as us 'bottom feeders".

Title: Re: No torque at higher RPMS
Post by heroicseven on 10/30/12 at 13:37:40

Clutch springs?

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 14:13:58

Got on the highway and no power past 45 mph. No get up and go to pull out in traffic. Can't ride to my appointment like the. I will drop to lower pilot and change the needle washers when I get home. Thanks for the input so far.

Title: Re: No torque at higher RPMS
Post by verslagen1 on 10/30/12 at 14:50:47

You got the slider out with your greasy mits.
Did you clean it before you put it back in?

Slide is very sensitive to dirt, I hope you're not. ;D

Title: Re: No torque at higher RPMS
Post by Dave on 10/30/12 at 15:29:59

When in doubt....put things back the way they used to be ....then start over by just changing one thing at a time. If you put the jets back to what you had originally....it should run the same. (Don't change the exchaust). Then you can change one at a time and see if things get better.....or worse with that change.

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 16:01:04

I put it in straight from the box from Lancer. I haven't messed with the slider.....not sure what you are referring to.

I have only messed with the jets so far.

I have to check my old carb and see what the needle setup was. As for now I have it back to the jets that were in the old carb but it is still running poorly no power / torque.

Title: Re: No torque at higher RPMS
Post by justin_o_guy2 on 10/30/12 at 17:10:21

If an engine picks up rpm & the speedo doesnt show more MPH, the clutch is slipping, so, no, you wont feel any torque.

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 17:35:47

WOO HOO

I think I got it mostly fixed.

I have POWER and TORQUE now!!!!!!

I swapped old carb diaphragm which I assume is stock washer on the needle, because I couldn't get it apart one of the small brass screws was very tight and I didn't want to strip the head, so I just swapped them.

I am sitting at a stock 145 and 52.5 with what I believe to be a stock needle spacer. at 2.5 turns on the air mix screw I still have some popping on deceleration but not much. at 3 turns it is better. I don't want to ride at 3 turns out so I am going to drop the pilot to 50.

Again THANKS for all the help, I think I understand the carb tuning better now.

Title: Re: No torque at higher RPMS
Post by gdrseeker on 10/30/12 at 18:25:00

So i got to thinking as I was replacing the pilot screw shouldn't I go to a 55 instead of the other way to 50. If I am getting pops and backfire on deceleration it is too lean on the lower portion of the throttle correct?

I tried both the 50 and the 55. The 50 was worse. I changed out to the 55 and sure enough I am now 1.5 turns out on the Air Mix screw and I couldn't get it to pop or backfire at all, and I have more Power and Torque than I ever had.....or it could be my imagination because it has been screwed up for almost a month.

FIXED

I wanted to make sure I got that all squared away before I started messing with something else.

So

Now on to the next project..........

Verslagen1 I will be tearing down my Cam Chain adjuster soon. I ordered all the parts to replace gaskets and Oil filter while I am in there.

Then the fork seals and dust seals on my forks.

Title: Re: No torque at higher RPMS
Post by Serowbot on 10/30/12 at 18:34:55

Rich can cause popping, too...
Bikes very often pop in the mountains because of this...
In the old days,.. people in cars used to turn their air filter covers upside-down, to lean them out in the mountains....

If it's running good, and not doing gunshot backfires,... just mellow pops and blats,... I'd leave it alone...

Title: Re: No torque at higher RPMS
Post by Dave on 10/31/12 at 05:21:18

My method for choosing the correct Pilot jet is the setting on the mixture screw. You want as small of a Pilot Jet as you can that allows the engine to run smoothly. With the engine warm and idling, turn the screw in until the engine RPM's begin to drop....then turn the screw out until the engine runs smoothly.....then continue to turn it out until the engine rpms drop and the engine begins to run rich. If you cannot turn the screw out enough to make the engine run rich....then the pilot jet is too small. If you can turn the mixture screw out 3 turns without the engine beginning to run too rich....the next size bigger pilot jet is probably needed.

Once you find the correct pilot jet that allows you to find the settings that will make the engine run lean and rich......you set the mixture screw between those two limits. Then ride the bike and see how the bike firing is......and you can open the mixture screw a little bit and see if that cuts the backfiring down any. You will never be able to eliminate it completely......big singles and those big V-twins backfire and there is no way to elininate it (maybe Fuel Injection systems can).