|
|
Post by turnerman on May 16, 2012 0:21:46 GMT -5
forgive me if this has been discussed; I couldn't find an exact answer while searching..
I just bought an '81 xs650.. thing turns right over with the choke on, and will idle great with or without the choke. It revs up great, however when I take it to the road it falls on its face.. bogs way down.
I am at altitude, around 7,000 ft, and am assuming it is running rich.
The '81 does not have an idle mixture screw, and the jet needle is also non adjustable.
I will be running pod filters with open pipes, and cannot find an answer to what size jets I need.
Also, I noticed the carbs have two main jets? Should these two jets be the same size?
any help would be great,
turner
|
|
|
|
Post by 5twins on May 16, 2012 0:43:03 GMT -5
Your carbs do have mixture screws but they were capped over at the factory so you couldn't mess with them. You need to remove the plugs to be able to adjust them. Your carbs only have one main jet.
No one can say exactly what jetting will be best for your bike. These bikes all react a little differently to mods. Best place to start would probably be one up on the pilots and about 2 up on the mains. Set the mix screws to 3 turns out. And don't buy cheap pods. You'll never get it tuned correctly if you do.
|
|
|
|
Post by turnerman on May 16, 2012 1:06:21 GMT -5
Your carbs do have mixture screws but they were capped over at the factory so you couldn't mess with them. You need to remove the plugs to be able to adjust them. Your carbs only have one main jet. No one can say exactly what jetting will be best for your bike. These bikes all react a little differently to mods. Best place to start would probably be one up on the pilots and about 2 up on the mains. Set the mix screws to 3 turns out. And don't buy cheap pods. You'll never get it tuned correctly if you do. thanks for the quick reply, I have a clymers manual and it shows two mains, I have the carbs off now and they are both there.. one with a smaller flanger than the other. Also, I'm a bit confused. if I were looking to lean the mixture out wouldn't I get smaller jets? And how do I get the plugs over the mixture screw off, just pry it? One last question, how are the pods from mixes xs? Should I just go K&N? thanks again, turner |
|
|
|
Post by grizld1 on May 16, 2012 7:58:32 GMT -5
I see. You can't find the Carb Guide that 5twins and I wrote a few years back, to which links are posted on every XS650 board on the web; you don't know how to clean or adjust your carburetors; you figure that nonoperation without the choke is a rich symptom (?!); but you know for sure that you want to rip off the mufflers and air box. Yessir, gotta get that style going!
|
|
|
|
Post by 5twins on May 16, 2012 10:43:20 GMT -5
The mix screws are covered with a brass plug about 3/16" thick. Using a 1/8" drill bit, start drilling into the plug. Check the hole depth frequently - you want to stop just before breaking through the plug. If you go through the plug, you run the risk of damaging the screw slot on top of the mix screw. Look at the plug top before drilling. You'll notice a small hole through the center. Note that hole size as you check hole depth. As soon as it starts getting larger, stop drilling - you're nearly through the plug. Find a small sheet metal screw to fit the hole you've just drilled and grind the point flat .....  Screw it into the hole until it bottoms out and then keep turning until the plug begins to spin. Grab the screw head with vice grips and twist/pull the plug out .....  You have one main jet located on the bottom of the carb body between the float "bulbs" .....  If that other jet with the smaller flange you're referring to is located around the lip of the intake bell, it's an air jet. A small round main jet is used for it but it flows air in this application, not fuel. That means making it smaller will reduce air flow and richen your mix. |
|
|
|
Post by turnerman on May 16, 2012 12:02:56 GMT -5
I see. You can't find the Carb Guide that 5twins and I wrote a few years back, to which links are posted on every XS650 board on the web; you don't know how to clean or adjust your carburetors; you figure that nonoperation without the choke is a rich symptom (?!); but you know for sure that you want to rip off the mufflers and air box. Yessir, gotta get that style going! what's the point of even posting this? thanks for being a total creep !! and if you read my post more carefully it says the bike revs great with the choke on or off, so who said non-operation without the choke? its my first project bike that isn't a super sport and I'd like to get it running properly while learning some things, thanks for being a total dick though! The mix screws are covered with a brass plug about 3/16" thick. Using a 1/8" drill bit, start drilling into the plug. Check the hole depth frequently - you want to stop just before breaking through the plug. If you go through the plug, you run the risk of damaging the screw slot on top of the mix screw. Look at the plug top before drilling. You'll notice a small hole through the center. Note that hole size as you check hole depth. As soon as it starts getting larger, stop drilling - you're nearly through the plug. Find a small sheet metal screw to fit the hole you've just drilled and grind the point flat ..... Screw it into the hole until it bottoms out and then keep turning until the plug begins to spin. Grab the screw head with vice grips and twist/pull the plug out ..... You have one main jet located on the bottom of the carb body between the float "bulbs" ..... If that other jet with the smaller flange you're referring to is located around the lip of the intake bell, it's an air jet. A small round main jet is used for it but it flows air in this application, not fuel. That means making it smaller will reduce air flow and richen your mix. thank you very much for the tutorial, I will search for your carb tuning post... the second main jet i was reffering to is in fact the air jet you explained.. my clymers manual calls it a main jet hence my confusion.. thanks again, turner |
|
|
|
Post by grizld1 on May 16, 2012 14:31:36 GMT -5
The points--which you didn't take--are that it gets old writing the same information over and over for guys who are too good do their homework, and that you need to learn the basics before you decide tear things up.
These things have been posted many times before: First, if you hack off the mufflers and run the headers straight, you will make a lot of noise, but you'll wind up with primaries that reduce power below an engine speed that's far beyond redline. And second, vacuum carburetors function much better with a still air box than they can with pod filters. Sure, you can make the bike run with that stuff; but don't be surprised when some guy with a whisper-quiet stocker blows your doors off.
|
|
|
|
Post by XS Rod on May 17, 2012 12:48:14 GMT -5
Stock twin wall headers with no mufflers... performance mod or rat bike? Should we take a poll? I'll go first... rat bike "Dick"... we already got yours... 5Twins... nice post bro  |
|
|
|
Post by turnerman on May 17, 2012 13:09:56 GMT -5
The points--which you didn't take--are that it gets old writing the same information over and over for guys who are too good do their homework, and that you need to learn the basics before you decide tear things up. These things have been posted many times before: First, if you hack off the mufflers and run the headers straight, you will make a lot of noise, but you'll wind up with primaries that reduce power below an engine speed that's far beyond redline. And second, vacuum carburetors function much better with a still air box than they can with pod filters. Sure, you can make the bike run with that stuff; but don't be surprised when some guy with a whisper-quiet stocker blows your doors off. you're right, sorry for wasting precious bandwith !! I found the carb guide, after googling since the search option on this forum is a joke.. and to be completely honest after reading the entire carb guide twice I still cannot figure out why it falls on its headlight in any gear and any amount of throttle.. xsrod is right...I'm building a hardtail bar hopper out of this bike.. I don't need it to be super fast.. I don't plan on racing a bike with a 130 rear tire  .. that's what the GSXR is for |
|
|
|
Post by XS Rod on May 17, 2012 13:41:14 GMT -5
I haven't run stock carbs in a long time... but I think you have to tear down and rebuild your carbs using the guide bro... it's pretty dry reading without a carbbie in your hand.
Honestly in my opinion you shouldn't run the stock headers w/o something to firm up the back pressure... they are too short. They should be about 31-32 inches as I recall...
What Griz is telling you is that by running headers that short you will move the power-band into a higher RPM than your motor is capable of running at for a sustained period... you'll be well into redline bro.
it's a balance... and you ain't gonna get respect here by running stock twin walled headers that are too short...
|
|
|
|
Post by turnerman on May 17, 2012 14:30:46 GMT -5
I haven't run stock carbs in a long time... but I think you have to tear down and rebuild your carbs using the guide bro... it's pretty dry reading without a carbbie in your hand. Honestly in my opinion you shouldn't run the stock headers w/o something to firm up the back pressure... they are too short. They should be about 31-32 inches as I recall... What Griz is telling you is that by running headers that short you will move the power-band into a higher RPM than your motor is capable of running at for a sustained period... you'll be well into redline bro. it's a balance... and you ain't gonna get respect here by running stock twin walled headers that are too short... fair enough! thank you for breaking it down for me.. and the carb guide was a great read.. very informative I definitely learned a lot. It just did not mention altitude as far as jetting, and I'd just like to get a good place to start before I spend a bunch of unnecessary money on shipping and jets.. I'm a starving student !! I don't care about the bike being loud, I just love the look of open pipes... |
|
|
|
Post by XS Rod on May 17, 2012 14:43:41 GMT -5
Bro... l i s t e n ...
open pipes are ok with me bro... but here's the revelation bro... size really does matter... and the stock ones don't hit the spot...
Get yourself some longer straight pipes... 650 Central or Mike's
Rod... over and out
|
|
|
|
Post by G Man on May 17, 2012 20:57:54 GMT -5
Turnerman... just a note here. This is not some sportbike or similar forum where it is commonplace and expected to act like someone sans any sort of manners or forum etiquette to speak of. The fellas above who have been answering your thread are some of the most knowledgeable guys on the planet on the subject of all things XS650. They've all been at it for decades. Irregardless of what you may think of anyone or the replies, one more word from you disparaging anyone or my forum....  You get the idea?  Now ask 'em nicely and you will get the God's honest truth on absolutely anything to do with the XS. G Man Admin |
|
.. that's what the GSXR is for
