82 450E Jetting Help Needed - Don't match what's available?

[pete]

Just a quick one here, I did my valve clearance checks and only had to change one, but I've put the 22.5 pilots in and put the mixture screws 2 turns out ready for whenever I get to kick it in the guts again.

[GsRocket]

Pete, have you figured out your jetting yet? I have a 1981 GS 450 ive been working on for the past year or so with moderate success. I'm also currently working on carb/jetting and have ended up with a 22.5 pilot, 144 main, float height is at 23mm, needle with 2 shims, and my air screws seem to need to be at different turns out(right at 1 1/4and left at 2). I have K&N pod filters and stock exhaust.
Currently i can get it to start and it seems to run fine(better and smoother than ever actually) at all throttle positions. then abrutly will stall after a minute or two... Also seems to take a few seconds to actually start up and get to idle.
i have 138 and 142 jet sizes for main, another shim for the needle, and my stock pilot. any advice would be appreciated i'm planning on tearing the carbs down this weekend
Right spark plug shows lean, left shows rich. also my mixture screw is an air screw not fuel.

[pete]

Pete, have you figured out your jetting yet? I have a 1981 GS 450 ive been working on for the past year or so with moderate success. I'm also currently working on carb/jetting and have ended up with a 22.5 pilot, 144 main, float height is at 23mm, needle with 2 shims, and my air screws seem to need to be at different turns out(right at 1 1/4and left at 2). I have K&N pod filters and stock exhaust.
Currently i can get it to start and it seems to run fine(better and smoother than ever actually) at all throttle positions. then abrutly will stall after a minute or two... Also seems to take a few seconds to actually start up and get to idle.
i have 138 and 142 jet sizes for main, another shim for the needle, and my stock pilot. any advice would be appreciated i'm planning on tearing the carbs down this weekend
Right spark plug shows lean, left shows rich. also my mixture screw is an air screw not fuel.

Hey mate unfortunately not yet. I'm currently getting her ready for the safety certificate which means I'll be able to get her registered and on the road, so I should know how it's jetted in the next few weeks.

If you have the stock exhaust and K&N's, I'm really surprised you've had to go up in pilot sizes as everything I've seen and read indicates you should only need to play with the mixture screws in that scenario.

Have you done a full carb dip and clean and replaced all the O rings from www.cycleorings.com? If you haven't, I'd highly recommend it as it sounds to me like you may be working around some blocked or partially blocked fuel passages.

Also, with the stalling, if you take the fuel cap off does it solve the problem? If so, it's likely the little breather hole in the filler neck is blocked.

Just some thoughts from what I've seen along the way anyway...

I'll definitely update this thread with how my jetting is looking once I get her on the road again and start tuning.

Oh, and also, I'd highly recommend chucking an introduction thread into the GS Owners forum so everyone can say hi and BassCliff can you give you your mega welcome. And feel free to chuck some pic's in there too because we all like pic's

[GsRocket]

Tried the gas cap removed with no change
Dipped my carbs before i started jetting about a month ago, but i'm cleaning them again today and checking all the passages.
Initially before i did jetting i had the K&N's taped up(restricted) and it ran but was far from peak performance, with it untaped it wouldnt even start so i started changing jets. first i did the main and needle, but my idle was still extremely rough, and also it would occasionally stall after a minute or so at 3/4 throttle, seemed like lack of gas and spark plugs confirmed this
So i decided to up the pilot(for the idle) and the main(for the high end throttle). The kit i got from 6sigma initially didnt have a pilot, but after review he said i would probably need it and sent a 22.5 and also the larger 144 main(both for free.)
From what i've been reading though i'm thinking my pilot should probably be like a 20 and my main should be a size or two higher still. We'll see if the stock pilot will suffice for now though.

BTW got some pics up in the intro thread, check 'em out

[pete]

Wow ok... no rust in your tank or anything like that? Or a restrictive inline fuel filter maybe? It just sounds unusual to have to do any of that with just the K&N's... the needle doesn't surprise me though as I believe they're quite lean "out of the box".

And did you do the O rings? They're rather critical...

Just thinkin' anyways...

And yeah saw your pic's, looks like a good start there

[GsRocket]

Wow ok... no rust in your tank or anything like that? Or a restrictive inline fuel filter maybe? It just sounds unusual to have to do any of that with just the K&N's... the needle doesn't surprise me though as I believe they're quite lean "out of the box".

And did you do the O rings? They're rather critical...

Just thinkin' anyways...

And yeah saw your pic's, looks like a good start there

Well there are a few rust spots visible inside the tank, and as far as inline fule filter you mean the petcock? i seem to be getting plenty of gas from the tank to the carbs.
And by orings you are referring to the mixture screws? i can't think of any others ive seen.

Speaking of mixture screws the OEM diagram shows an air screw, and then the "mixture screws" are just simply listed as a screw. Would i also need to adjust the air screw? and do you have any idea(or pics) where its located because the OEM pic is not real clear.
Also the mixture screws would be controlling fuel flow at idle correct? so if i had mine 3 turns out and the plugs are still white i would think i need the 20 or 22.5 pilot and the stock is just too small

I put everything back together with stock pilots and it did not want to run yesterday, throttle was sluggish and nonresponsive. but today it started right up and ran amazing. i road it(hauled ass) around my neighborhood for about 15 minutes to make sure it would stay running. There were some pops now and again which i think is because of excess fuel? but after tuning the mix screws in a little more it went away. So i decided to hit the open road and give it some truly open throttle. however about a mile or two out there was a loud pop out the exhaust the the bike stalled everytime i pulled the clutch in until i stopped. It wouldnt start again after that

I'm sure i'm doing something wrong but i can't figure out what. No one else seems to have this issue with jetting, where it runs fine and then you get it out there and it dies on you. I would think its too lean because of the plugs but i thought the super loud pops were from a rich mix

Might need to start a new thread soon....

[pete]

Well there are a few rust spots visible inside the tank, and as far as inline fule filter you mean the petcock? i seem to be getting plenty of gas from the tank to the carbs.
And by orings you are referring to the mixture screws? i can't think of any others ive seen.

Speaking of mixture screws the OEM diagram shows an air screw, and then the "mixture screws" are just simply listed as a screw. Would i also need to adjust the air screw? and do you have any idea(or pics) where its located because the OEM pic is not real clear.
Also the mixture screws would be controlling fuel flow at idle correct? so if i had mine 3 turns out and the plugs are still white i would think i need the 20 or 22.5 pilot and the stock is just too small

I put everything back together with stock pilots and it did not want to run yesterday, throttle was sluggish and nonresponsive. but today it started right up and ran amazing. i road it(hauled ass) around my neighborhood for about 15 minutes to make sure it would stay running. There were some pops now and again which i think is because of excess fuel? but after tuning the mix screws in a little more it went away. So i decided to hit the open road and give it some truly open throttle. however about a mile or two out there was a loud pop out the exhaust the the bike stalled everytime i pulled the clutch in until i stopped. It wouldnt start again after that

I'm sure i'm doing something wrong but i can't figure out what. No one else seems to have this issue with jetting, where it runs fine and then you get it out there and it dies on you. I would think its too lean because of the plugs but i thought the super loud pops were from a rich mix

Might need to start a new thread soon....

Hmmm... ok I'm definitely seeing why you're getting confused... I'm not exactly a guru at this but I can definitely see some weirdness there...

If the plugs are white, I'd agree it's lean.

Is the popping during acceleration or deceleration? I thought popping on deceleration was a lean condition.

The 80 - 82 450 carbs don't have an air screw that I'm aware of, just the mixture screw. Winding it in (clockwise) makes it leaner, out (anti-clockwise) makes it richer. So, when you say you wound it in and it ran better, that actually made it leaner...

However, when you say you're giving it some throttle etc., that mixture screw is irrelevant, that's all needle or main depending how open the throttle really is.

Very generally speaking, closed to quarter throttle is pilot jet + mixture screw, quarter to three quarter throttle is needle jet and jet needle, and three quarter to full throttle is main jet. Of course they all influence each other as well but that's the simplest way of looking at it.

By an inline filter I meant in addition to your fuel tap's filter, but if you seem to be getting plenty of fuel then I guess that's not the issue...

Here's a couple of references I'm using in addition to all the stuff on BassCliff's site:

http://www.motorcyclecarbs.com/Jetting_Rules_of_Thumb_W43C551.cfm

http://www.motorcyclecarbs.com/Throttle_Chop_Method_W328C551.cfm

The other thing here is you may be chasing two different issues... perhaps you have an ignition issue along with a fueling issue?

My best suggestion right now is to start a new thread so you can hopefully get some more experienced heads in the mix...

[GsRocket]

So as an update i had it running again with good throttle response at all positions. however occasionally on decel it would make one very loud pop, not constant popping on decel like a lean mix makes. i rode it around for awhile like this before i started messing with the mix screws again and then it wouldnt run. i'm starting to think that this pop is essentially harmless(at least that it has nothing to do with jetting) and is due to the fact that my exhaust has two nice sized holes rusted out on the bottom. any thoughts?
Iv'e read a few others like this and i might get the mac 2-1 a little sooner than i thought if this is the case

[pete]

So as an update i had it running again with good throttle response at all positions. however occasionally on decel it would make one very loud pop, not constant popping on decel like a lean mix makes. i rode it around for awhile like this before i started messing with the mix screws again and then it wouldnt run. i'm starting to think that this pop is essentially harmless(at least that it has nothing to do with jetting) and is due to the fact that my exhaust has two nice sized holes rusted out on the bottom. any thoughts?
Iv'e read a few others like this and i might get the mac 2-1 a little sooner than i thought if this is the case

Aaaaaah! I reckon you could be onto something there!

Those holes will have a definite impact. Not sure if they will cause the popping or not but I suspect they would at least contribute to it.

If I was you I'd be doing something about that to make sure your whole air/fuel system is in a known state before trying to perfect the fueling. As those holes get larger it will put your AFR out more and more...

[GsRocket]

Ok, here is my final solution.
My jetting is pretty close to where it needs to be, i could probably still go up one or two on the main. The real culprit was my dam manifold orings. They were completely flattened and stiff as a rock so i was leaking air through the manifolds the whole time. Also contributing was my petcock that was flowing at probably 60%. now that i have those two fixed it runs like a beast. If you can pull it off jetting is definately worth it. I'm positive my 0-60 went down by 2-3 seconds from where it was before and even my top end is higher(not sure how much since it stops at 85 but its very noticeable)
Thanks for the advice and if anyone every has rich jets but lean conditions ask them about the manifold o-rings it will save alot of headaches

[pete]

Ok, here is my final solution.
My jetting is pretty close to where it needs to be, i could probably still go up one or two on the main. The real culprit was my dam manifold orings. They were completely flattened and stiff as a rock so i was leaking air through the manifolds the whole time. Also contributing was my petcock that was flowing at probably 60%. now that i have those two fixed it runs like a beast. If you can pull it off jetting is definately worth it. I'm positive my 0-60 went down by 2-3 seconds from where it was before and even my top end is higher(not sure how much since it stops at 85 but its very noticeable)
Thanks for the advice and if anyone every has rich jets but lean conditions ask them about the manifold o-rings it will save alot of headaches

Aaaah nicely done!

I didn't even think of the O rings... they're one of the first things on the hit list along with intake boots and so forth too! Mine are new along with my intake boots so I'll have other issues no doubt

Glad to hear you got her running well!

What size pilots and mains did you end up with and what did you end up doing with the needle?

[GsRocket]

Pilot is stock 17.5, mix screws 3 turns out, needle is at 2 spacers(about one clip for needles with clips) main is 144. pilot and needle are perfect for now but i'm going to up the main because full throttle is what struggles and my plugs are still white... can't wait till i see brown plugs again its been almost half a year.

Still, a huge improvement from before(not running). As soon as i put the new orings in it started right up.
when i get a high flow exhaust or go straight pipes i'm sure the pilot will have to go to the next size.

[pete]

Excellent, so I suspect I'll be close with my pilots, but I'm probably going to still be way too lean on the mains at a guess.

Time will tell once I get her registered and rolling...

Keep at it with the tuning and let us know how you end up

My dream is to have both a Morgan Carbtune and Colourtune so I can balance the carbs perfectly and have them jetted as close as I can across the entire throttle range...

[pete]

Time to revive this thread for me too I feel

She's still quite lean with the pilots two sizes up, and I have no idea how the mains or needles are yet but I suspect it will still be lean all around.

This is how she's running now, sounding great, but hesitating before coming back down to idle:



And the plugs are a bit on the white side:



I ordered some more jets today and am getting them express posted to me. 27.5 pilots and 137.5 mains.

I'm getting a guy in tomorrow to give it the safety certificate inspection, but I don't expect to have the jets in early enough to be able to make it come back down to idle properly, but he doesn't see that that will be an issue.

Once that's done I can get her registered and then start tuning in earnest

[Suzuki_Don]

Keep going pete

Keep at it pete. There is light at the end of the tunnel -- albeit a very small light. You will make much more progress when you are able to ride it on the road and get some decent plug readings (colour) and feel whether it is pulling strongly in the different throttle positions. Don't forget to mark your twist grip at the mandatory, 1/8, 1/4, 1/2, and full throttle positions.

Good luck, I'm watching with interest.