New RS38's, what main jet to start?

[Billy Ricks]

I just read where you stated that if you open it up it sputters. Don't worry about this too much when your just cruising along you can't just grab a handful of throttle with these carbs. They'll take a big gulp of air and a big squirt of fuel from the A/P and you lose your intake velocity. Then you have to partially close the throttle until the engine breaths right again. Without downshifting you have to roll the throttle to keep from bogging it. That lets you take the most advantage of the pump anyway. Once you get some rpm up you can keep them pegged.

 

[7981GS]

He has stated that he disabled the pumps.

Eric

 

[Billy Ricks]

He has stated that he disabled the pumps.

Eric

Still, whacking RS flatslides open at cruising speed just bogs the engine. You have the slides lifted completely instead of vacuum lifting them with CVs. No velocity equals no power.

 

[gearhead13]

I have opened it up at anywhere from 4-7k rpm same effect.
Are you running a single outlet with a T?
I would like to get one with reserve, dont like the idea of running out of gas and having to walk
Found a non-reserve dual outlet on sale, and a dual with reserve for $30 more

 

[Billy Ricks]

I have opened it up at anywhere from 4-7k rpm same effect.
Are you running a single outlet with a T?
I would like to get one with reserve, dont like the idea of running out of gas and having to walk
Found a non-reserve dual outlet on sale, and a dual with reserve for $30 more

I run a single outlet with a T and it does have reserve.

Even at 7k and steady throttle the slides aren't that far up, probably about 1/3 throttle if that. That still leaves a lot of slide lift when you whack it open and velocity goes to hell. Just for grins see how much throttle you're at when you are at 6 or 7k, probably not much.

 

[Guest]

Just an observation. At 3000 rpm, in 3rd gear,pointed srtraight ahead,I can go full throttle with no bog. Of course I am looking at nothing but blue sky, so panic sents in and I have to shut it off. I looked at the build sheet and I think my carbs are not 38's. I think they are 33's or 36's. maybe thats why I have bigger jets in the mains. I submit the video below to give you an idea how it runs at the track... The video starts slow but it gets better. Times are 10.30's to 10'40's with a trap speed of 125...
Curt

http://www.youtube.com/watch?v=lByQl1w-QtM

 

[7981GS]

http://www.youtube.com/watch?v=lByQl1w-QtM

That track looks slick!
Who keeps breaking out? I see a lot of red lights at the start.

Eric

 

[Guest]

If you are running solo, the other lane shows red. And the slickness is due to a 5 inch tire and a bad rider...But I am learning...
Curt

 

[7981GS]

I don't think so much of the slickness is a bad rider as much as it is bad track prep.

Eric

 

[gearhead13]

Well, I pulled the carbs last night, reset the floats to 18mm, same 130 main, dropped the needle 1 notch and tossed my inline fuel filter She pulled ok wide open, and 14-15-1 a/f at 1/4 to 3/4 throttle. Checked a plug and looked too lean. Less than 10% of the time wide open so the plug color due to the needle I think. Theres no way I can look down at the gauge wide open, have to hook up the laptop and go for a ride.
I will be ordering a pingel when I can.

 

[posplayr]

Well, I pulled the carbs last night, reset the floats to 18mm, same 130 main, dropped the needle 1 notch and tossed my inline fuel filter She pulled ok wide open, and 14-15-1 a/f at 1/4 to 3/4 throttle. Checked a plug and looked too lean. Less than 10% of the time wide open so the plug color due to the needle I think. Theres no way I can look down at the gauge wide open, have to hook up the laptop and go for a ride.
I will be ordering a pingel when I can.

I was able to tune my bike real well and with 1166cc have 135 mains (up from 137.5 DJ) only because of my 4:2:1, I would think you should be in the 145-155 range with 1327cc

Read at the top my compare between the 4:1 and 4:2:1. At 4:1 I needed 140's. I have a selection of brand new Mikini jets at 145-155 if you woud like them cheap. I will not need them.

http://www.thegsresources.com/_forum/showthread.php?t=164565&highlight=AFR

14-15 is real lean, you dont want to psuh that baby.

You need to find a long hill and measure AFR at fixed throttle settings

1/4, 1/2, 3/4 and WOT. Things are changing too fast if you try that on the flat.

 

[gearhead13]

I was able to tune my bike real well and with 1166cc have 135 mains (up from 137.5 DJ) only because of my 4:2:1, I would think you should be in the 145-155 range with 1327cc

Read at the top my compare between the 4:1 and 4:2:1. At 4:1 I needed 140's. I have a selection of brand new Mikini jets at 145-155 if you woud like them cheap. I will not need them.

http://www.thegsresources.com/_forum/showthread.php?t=164565&highlight=AFR

14-15 is real lean, you dont want to psuh that baby.

You need to find a long hill and measure AFR at fixed throttle settings

1/4, 1/2, 3/4 and WOT. Things are changing too fast if you try that on the flat.

Ya, when I saw how lean it was I backed off, it does 12-13 at cruise on the highway. Idle is about 11.5-12.
I was running about a 150 with my bs36's, but these are a much different beast.
Do you think my a/f gauge is still accurate? I did recalibrate it, when I pulled the sniffer out it was all sooty.
Thanks for the offer, but I have every mikuni from 130 to 152.5, and some pilots but these pilots are different.
For right now I have an oil leak after running high rpm that I have to fix, it never ends............

 

[Billy Ricks]

Just an observation. At 3000 rpm, in 3rd gear,pointed srtraight ahead,I can go full throttle with no bog. Of course I am looking at nothing but blue sky, so panic sents in and I have to shut it off. I looked at the build sheet and I think my carbs are not 38's. I think they are 33's or 36's. maybe thats why I have bigger jets in the mains. I submit the video below to give you an idea how it runs at the track... The video starts slow but it gets better. Times are 10.30's to 10'40's with a trap speed of 125...
Curt

http://www.youtube.com/watch?v=lByQl1w-QtM

The smaller carbs would be less likely to have any bog snapping the throttle open, especially 33s. It sounds like gearhead is about where he needs to be. I know I have my 700 over-carbed with 34s and a basically stock engine. The rush up top is unreal but if I'm just cruising along I do have to roll the throttle if I don't downshift and make it sing. It's easy to over-rev because it doesn't fall on its nose until well beyond redline, 3k beyond.

 

[gearhead13]

Looking for reasons the bike wasnt running right. I had the top end off just before mounting the carbs and redegreed the intake cam. I cleaned and reoiled the pods, then rememebered how tired I was when I was degreeing the cams so I checked them and the intake was at 109.5, so I set the intake to 106 and ex to 108, checked my plug gap and it was tighter than a .026 gauge. I set the gap to .028. Went for a ride, much better, takes full throttle ok, probably on the lean side with the 130's in there.
The thing that bugs me about these RS carbs is the rattling noise they make, bike sounds like a rattle trap. They make good power, but what a racket
Part throttle 2nd gear power wheelies Yippee!

 

[7981GS]

Back up to 135's+ we go, eh?

Eric

 

[Billy Ricks]

Looking for reasons the bike wasnt running right. I had the top end off just before mounting the carbs and redegreed the intake cam. I cleaned and reoiled the pods, then rememebered how tired I was when I was degreeing the cams so I checked them and the intake was at 109.5, so I set the intake to 106 and ex to 108, checked my plug gap and it was tighter than a .026 gauge. I set the gap to .028. Went for a ride, much better, takes full throttle ok, probably on the lean side with the 130's in there.
The thing that bugs me about these RS carbs is the rattling noise they make, bike sounds like a rattle trap. They make good power, but what a racket
Part throttle 2nd gear power wheelies Yippee!

Makes you think you have a head full of loose valves with the rattle.

 

[gearhead13]

Back up to 135's+ we go, eh?

Eric

Ya, have to start over with the main, sounded kind of 'dry' on the top end. Still waiting for my pingel.
Amazing how much difference 3.5 deg of cam timing can make

 

[gearhead13]

Makes you think you have a head full of loose valves with the rattle.

Ya, hard to hear the regular rattle the engine usually makes.

 

[4cyl h2]

RS 38 Main Jet

RS 38 Main Jet

I have a 1327...track 160, street with baffle is 155...

do your 38s have a main air jet?? those jets seem really big