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General Category >> Rubber Side Down! >> Seat & idle screw/carb rejet issues -- again.
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Message started by Karen627 on 07/24/05 at 22:33:13

Title: Seat & idle screw/carb rejet issues -- again.
Post by Karen627 on 07/24/05 at 22:33:13

Sorry -- I know this has been covered to death here. :P

I put another 250 miles on the bike this weekend, and my tailbone's not at all happy. I just did a search and I may have missed it, but I didn't see if anyone has any experience with the S40 gel seat (either the pillow or the classic)...? So... um... does anyone have experience with the S40 gel seat?

And: re-jetting and the idle mixture screw. I know it adds to power and performance; but does it affect the gas mileage? (I get about 60 mpg now.)

(If it doesn't hurt the mileage, then I'm going to have to get a Clymer manual and learn what "re-jetting" is. ;D )

Thanks.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Hammy211 on 07/25/05 at 02:10:38

Cylmer manual will help you get everything apart and back together. You can find what you want to change on this site. You can also find a seat altercation that you should try before buying a new seat.

I put in a new filter, new muffler and rejetted with great results and for $100 total. I was getting around 48 mpg before and I am actually getting better now not to mention the much noticed and needed power increase. You do not normally rejet unless you are making intake/exhaust changes.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by lancer on 07/25/05 at 05:35:54

Excellent "Newbie" advice. You are learning quickly and well. The intake/exhaust rejetting changes makes the Savage "MORE EFFICIENT", which yields more good usable power.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Karen627 on 07/26/05 at 23:43:51

Hammy211 wrote:

You do not normally rejet unless you are making intake/exhaust changes.

Okay, then, never mind about re-jetting. :P :D

The idle mixture screw and white spacer mods, on the other hand, don't sound quite so complicated. Just to confirm: I can do those two things without having to do anything else, correct?

And regarding the seat: is anyone familiar with these seat pads? http://www.crossgel.com/files/products4.html

Thanks.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/27/05 at 00:44:33

Karen627 wrote:

Okay, then, never mind about re-jetting.

The idle mixture screw and white spacer mods, on the other hand, don't sound quite so complicated. Just to confirm: I can do those two things without having to do anything else, correct?

Hi Karen. Rejetting consists of:

1. the white spacer mod.
2. drilling out and pulling the cover over the slow mixture screw and adjusting it richer.
3. replacing the main jet with a larger one.

The hardest part is 1 & 2. Changing the main jet is quite easy. I would think doing the spacer mod and slow mixture screw would be worthwhile on a stock bike. These bikes are very lean from the factory. Unfortunately it's not real easy for a novice mechanic. It can be done, but it's far from easy.

I did a Supertrapp muffler, 1/2 white spacer, and the slow mixture screw and it's like a different bike. It hauls butt ;D Gas mileage is still good (52 combined) and driveability is way better.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Savage_Rob on 07/27/05 at 07:01:12

As noted above, you normally rejet when you modify the intake and/or exhaust. However, jetting can be modified while still using stock intake and exhaust. If you decide to do this, I would only recommend going to the 150 main jet without an exhaust mod though. Otherwise, I think you'll probably be too rich.

Improving the intake is as easy as getting a K&N direct replacement for the air filter. It will improve your airflow.

Changing the jets is very easy and involves removing the float bowl from the bottom of the carb (4 screws) and replacing the main jet. I was able to get a few different size jets for $3 each at a local HD shop. A couple of hints for this procedure:

1) Place a rag, tarp, paper or something over the starter area below your work area. Dropped screws and such often go under the starter and require you to remove it to retreive them. Though it's pretty simple to remove it, it still better to avoid it.

2) First drain the float bowl into a can or baby food jar, etc. using the drain on the bottom.

3) Have an offset screwdriver for removal of the screws and then replace them with stainless allen screws and lockwashers when you reassemble. I was able to get these at my local Ace Hardware. This will make subsequent removals a snap.

Personally, I would only adjust the idle mixture and do the spacer mod unless I replaced the air filter. Then I would go to the 150 main. I would not use a larger jet with the stock exhaust.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Karen627 on 07/28/05 at 07:34:12

Ah.... ya know, I thought I was starting to understand this stuff, and I got up the courage to ask about doing all of this to my bike; so of course, even more questions arise to remind me of how little I actually know. I'll get better, though. I promise. ::)

Hammy, Lancer: thanks for the overview. It's good to know it'll improve the bike's efficiency, and it's not a horribly expensive project.

Dynobob, Rob: Thanks for all of the details. I just started reading the Essential Guide to Motorcycle Maintenance, and I'm going to print out this thread and go over it to make sure I fully understand it before I attempt anything. (It'll happen. It may be a while, but it'll happen.) :D

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Savage_Rob on 07/28/05 at 11:00:49

I'm learning as I go. That's one reason I love this bike; it's so very basic. If it had points/condenser instead of an igniter unit, it'd be perfect.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/28/05 at 17:16:13

Karen627 wrote:

I just started reading the Essential Guide to Motorcycle Maintenance, and I'm going to print out this thread and go over it to make sure I fully understand it before I attempt anything. (It'll happen. It may be a while, but it'll happen.) :D

Let us know when you do. I know all the pitfalls, as I just did my bike a little while ago ( using jetting info from this site :) ). There's a few tricks. Let us know before you tackle it and I will share them with you. My first bit of advice would be to buy very nice quality tools (screwdrivers in particular). Cheap tools will only cause you misery.

Bob

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by milesb on 07/29/05 at 16:42:37

Savage_Rob wrote:

Changing the jets is very easy and involves removing the float bowl from the bottom of the carb (4 screws) and replacing the main jet. I was able to get a few different size jets for $3 each at a local HD shop. A couple of hints for this procedure:

1) Place a rag, tarp, paper or something over the starter area below your work area. Dropped screws and such often go under the starter and require you to remove it to retreive them. Though it's pretty simple to remove it, it still better to avoid it.

2) First drain the float bowl into a can or baby food jar, etc. using the drain on the bottom.

3) Have an offset screwdriver for removal of the screws and then replace them with stainless allen screws and lockwashers when you reassemble. I was able to get these at my local Ace Hardware. This will make subsequent removals a snap.

Personally, I would only adjust the idle mixture and do the spacer mod unless I replaced the air filter. Then I would go to the 150 main. I would not use a larger jet with the stock exhaust.

I'm a little leary of toying with the carb, but rejetting and adjusting the mixture seems easy enough if as described. I have a couple of questions:

I've read the posts in the tech section on removing the plug over the mixture screw. Is the plug threaded? I've read to use a drill bit about 3/4 the size of the plug - do I just back it out?

Also, is the main jet threaded or does it simply "slide" onto the needle?

Thanks in advance,

Miles

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/29/05 at 17:08:48

milesb wrote:

I've read the posts in the tech section on removing the plug over the mixture screw. Is the plug threaded? I've read to use a drill bit about 3/4 the size of the plug - do I just back it out?

Also, is the main jet threaded or does it simply "slide" onto the needle?

Hi Miles.

The plug over the slow mixture screw is pressed in. No threads. You want to use a 5/32" drill bit. Drill very very slowly a little at a time as it's very easy to break through and hit the mixture screw with the drill bit. Once you're all the way through, screw a sheet metal screw into the hole and grap it with a pair of pliers and pull. Not too hard really but drill slow slow slow.

All the jets are threaded into the bottom of the carb. Use a flathead screwdriver of the correct size and they'll come right out. You should have no problem there.

One thing I did that helped alot was to remove the petc0ck entirely. Much easier to remove the tank and you won't scratch up your frame or carb.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by milesb on 07/29/05 at 17:44:58

Earlier in this thread...

"Changing the jets is very easy and involves removing the float bowl from the bottom of the carb (4 screws) and replacing the main jet. I was able to get a few different size jets for $3 each at a local HD shop. A couple of hints for this procedure:

1) Place a rag, tarp, paper ...." rest deleted

As in this post, I was hoping to get to the jet without removing the tank. I'll assume the jet is screwed into the carb "over" the needle?

Thanks,

Miles

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Savage_Rob on 07/29/05 at 19:25:06

milesb wrote:

The jet is accessible from the bottom of the carb. You only need to remove four screws. To access the needle and do the white spacer mod, you have to remove the tank and open the top of the carb by removing four screws there.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/29/05 at 19:35:39

milesb wrote:

As in this post, I was hoping to get to the jet without removing the tank. I'll assume the jet is screwed into the carb "over" the needle?

You can change the main jet without taking the tank off if the screws will come lose. The main jet is screwed in from the bottom. Loosen the clamps securing the carb and rotate it a bit. With a short phillips head screwdriver remove the float bowl. The main jet will be right there.

You are aware that the main jet only affects 3/4 -> full throttle. The white spacer and needle affects the midrange where you spend most of your time.

BTW, it is a very good idea to replace the bowl screws (as well as the diaphram cover screws) with stainless allen head screws. The OEM screws are pretty soft and the slots strip easily.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by milesb on 07/29/05 at 20:34:43

Dynobob wrote:

Thanks guys. The spacer was removed by the previous owner but I don't think he rejetted the carb.

I also saw the earlier post about replacing the bowl screws with allen heads - that makes a lot of sense. I have an offset phillips, so maybe that'll make it a little easier to get the bowl screws out.

Between the advice given here and the carb photos/diagrams in the tech section, this should be pretty easy.

One last thought, are the jets specific to the carb model? I have a Suzi dealer not too far away, so I'll assume they should have them - planning on getting at least a few sizes (150, 152.5 and 155).

Again, thanks for the info.

Miles

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Reelthing on 07/29/05 at 20:58:22

The stock screws are pretty soft - if you have an offset phillips that fits properly you may be ok a few times -

These carbs use the Large round jet for main but the small round will fit.

I can not count on the dealers - the ones here just do not stock main jets except for the oem size - had a dealer try to tell me $7 was good deal as he should be asking $15 for it - about $5 is more reasonable, so I ordered quite a sack full from an internet dealer.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/29/05 at 21:54:21

milesb wrote:

One last thought, are the jets specific to the carb model? I have a Suzi dealer not too far away, so I'll assume they should have them - planning on getting at least a few sizes (150, 152.5 and 155).

Not specific to the carb. Standard Mikuni large jets. I had to special order mine through a local dealer. He found them in an aftermarket catalogue. Some have reported getting them at a Harley dealer.

You should consider adding a 1/2 spacer. Removing the entire spacer makes the bike too rich in the midrange. 1/2 spacer in mine is perfect. I took a stock spacer and sanded it down with some 220 sandpaper. I used a micrometer to measure it.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by milesb on 07/30/05 at 05:39:48

Dynobob wrote:

I have an email into the former owner of the bike to see if he replaced the spacer with anything like #4 washers, etc.

If I have no spacer, I'm not getting any appreciable backfire, the bike seems to idle and run well, and I have slightly increased the airflow by drilling the baffle, should I just stick with the stock main jet? I guess what I'm asking is does drilling the baffle "balance" the effect of removing the spacer?

Again, I really appreciate the indulgence of the folks in this group. I've gotten a lot of great advice on D-I-Y maintenance and mods.

Miles

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Savage_Rob on 07/30/05 at 07:16:34

Yup, just Mikuni large round jets. In fact, I was able to get them for $3 each (already in stock) at a local HD dealer.

Title: Re: Seat & idle screw/carb rejet issues -- aga
Post by Dynobob on 07/30/05 at 15:28:04

milesb wrote:

I guess what I'm asking is does drilling the baffle "balance" the effect of removing the spacer?

Yes it does. The freer flowing your exhaust is, the richer you need your jetting to be. I would think going up a size or 2 from stock (145?) on the main jet would be a good idea. The best way to determine if your main jet is correct is by reading the plugs after doing a full throttle shut down.

http://www.motorcyclecarbs.com/jetting/plugreadings.htm