carbs and jet sizes

[sly409]

So after successfully removing the broken mixture screw tip I'm ready to start rebuilding my carbs and upgrading the jets. Ive found that my current jet sizes are:

132.5 main jet

42.5 pilot jet

I dont think the main jet is stock size as the Haynes manual states it should be 142.5. Also I noticed my needle jet is an x-6 type as opposed to x-4 as stated in the manual. My current setup includes pods and no exhaust and its running a bit rich at the moment according to the color of my plugs. Refer to http://www.xs400.com/forum/showthread.php?t=8633

I think from reading somewhere on here its been said that I should go up jet sizes for pods and straight pipe. Is this correct? And I should go up from the actual stock size. Would something like 150 main and 45 pilot work? Are there any other jets I should change out/upgrade?

Very new to carbs and will need to play around a bit. Also I've found that mikesxs seems to be the only place selling jets. Are there any other websites you guys recommend? thanks!

 

[sly409]

Here it is, I'm followed this guide. Does it look right? Thanks!

http://www.motorcyclecarbs.com/Motorcycle_Carburetor_Jetting__W7C240.cfm

 

[drewpy]

its a good start, there is also another guide on here which says to get the top end done first and mid then lower (pre 4k)

 

[16VGTIDave]

Haynes manuals are, IMNSHO, only slightly better than toilet paper. Especially when it comes to specs and wiring diagrams. I only use their manuals as a last resort, and question everything they state.

Is your bike running rich, or is it just running cold? And I'm referring to oil temp, not head temp. It takes a decent ride to get the oil up to temp, especially in cold weather.

As a reference point, I'm currently running 150 mains and 47.5 pilots in my DOHC with pods and free flowing aftermarket mufflers that don't have the balance pipe between them. The pilots are still too small, but will do for now. I should add that I'm riding in cold weather, close to freezing.

HTH,
Dave

 

[sly409]

So I'm having trouble finding mixture screw for my carbs. They are 1979 bs34 with the plunger type choke. Any recommendations on where I can buy these? MikesXS seems to only have ones for 80-84. Also are there any places where I can buy a jet "kit" that includes several different sizes? I found a site from one of the links on this forum but its a canadian website.

http://www.siriusconinc.com/pro-detail.php?pid=&product_id=4276

I would rather order domestically if possible.

Thanks guys!

 

[drewpy]

tried Yamaha?

I got mine from Motoward in UK. they must be still listed

part # 2A2-14923-00

 

[16VGTIDave]

I probably posted their info. I deal with Sirius on a weekly basis, they are good people who >stock< parts for our bikes. I know that they sell a lot to the US. And, as with most items these days most of the parts are from "off-shore" sources, like our bikes.

I appreciate your desire to do business with a "domestic" company, but with NAFTA, Canada isn't that far removed from the US economy. In fact, we are an integral part of the US economy.

If Sirius has what you need in stock, they will ship quickly. If you drop them an email, Chris or one of the girls will put together a jet kit for you. They are good people who appreciate our bikes. I wouldn't have been able to refurbish my Maxim as quickly or easily as I did without the knowledge and support of the folks at Sirius.

Regards,
Dave
(a happy customer of a great XS supporting company)

 

[drewpy]

I even use Sirius and live across the pond!

 

[sly409]

well if you guys have had good experience with them then I'll give them a try. i noticed they have items listed on ebay also

 

[sly409]

I emailed them about mixture screws. I only saw a rebuild kit with the mixture screw but it was 32 bucks per carb ouch...

 

[xschris]

I can sell you a set for $15 shipped.

 

[sly409]

ok so I was about to pull the trigger on several different sizes of main jets from MikesXS but then noticed that it didnt say anywhere if they were compatible with my carbs (bs34 79).

Here is a link to one of the jets. Has anyone tried these yet and can verify they will fit?
http://www.mikesxs.net/product/48-0125.html

thanks

 

[xschris]

Yep those are the type.

 

[Stabler]

I found a "company" at ebay named Sigma6. They said send what mods you've done to your bike along with the correct type and year of bike and we'll send you the jets and instructions needed to get it to run right.
I gave it a shot. I have pods and high flow shorty mufflers. The kit they sent me along with the instructions on needle position and what not was spot on.
I did several plug chops to confirm and I'm golden.
Just a thought.. Maybe others haven't been as lucky.

 

[MechNewb]

I found a "company" at ebay named Sigma6. They said send what mods you've done to your bike along with the correct type and year of bike and we'll send you the jets and instructions needed to get it to run right.
I gave it a shot. I have pods and high flow shorty mufflers. The kit they sent me along with the instructions on needle position and what not was spot on.
I did several plug chops to confirm and I'm golden.
Just a thought.. Maybe others haven't been as lucky.

Do you know what size jets came in the kit? Ill be running shorty muffler snad pods as well.

 

[Scorpio1963]

I went with 150 for my mains and 45`s on the pilots,Im running open headers.Just check on your pilots and make sure you get the right ones.There is two types,Ones that have a large hole at the end and some that have a small hole that a small needle will barely fit through.

 

[Scorpio1963]

An update on my jey size I went up another 1/2 size.

 

[dnseal]

Sly, whats the overall condition of the engine? Did you do a compression test? In my dumb way of thinking, its not a good idea to upgrade anything if the engine is lower than say maybe 115 lbs or less of compression. If compression is low, better performance and reliability would be gained by getting your compression back up to specs 140 to 170. Why put a blower on an old loose chevy 400 when you'll get better performance from a tight crate 350 engine. If you get back to the 170lb range you would really feel a difference. Then you could re-jet and mod to your heart desire until the poor little 400 says enough and creates another set of problems.... smile. Doing other wise on a low compression engine would prevent a required/proper combustion; it would be more of a flash which causes all sorts of other issues such as excessive heat, wear, odd burning of oil, etc.. Just my two cents worth.

 

[Scorpio1963]

x1 dnseal

 

[dnseal]

Sly new to this forum and chat site stuff. Whats x1? hope its something good... smile