1982 Yamaha Seca 650 (Project)

don't go down that road
if it acted better with pods and breaks up with a air box the jets might be setup for pods, so now your running rich. take the filter out of the box and see what it does. the idle goes high because it needs a running sync
but if you're not going to go through the carbs completely you might as well go watch cartoons

 

Carbs are next.

What I haven't made note of yet in this is that the breakup I'm experiencing happened when the pods were on the bike. That behavior has not changed. And this is now after I've changed to new plugs and caps and confirmed healthy coils.

What has mostly changed is the hanging idle.

Carbs are coming off this weekend to give them a look over to see if anything has been changed.

 

Ok .. pulled carbs this weekend and dove into them and here is what I found..

The top needle? Didn't think these bikes had needle adjustments? Also the washer I know is an old trick as a spacer but on a bike with an adjustable needle?

The top jets are 50/205 but it seems stock should be closer to 50/195? Assume the 205 is making it run a bit richer.

With the bottom though this is where things are weird... I see the #43 marking which for Canada is normal, but I'm not seeing markings on the other too?

Thoughts?

Top - Needle


Top - Jets - 50/205


Bottom - The only one with a marking says #43 which is stock for this bike

 

That is an aftermarket jet needle.
The air jets are the correct size, and in the correct positons.
The main jet is probably aftermarket too. Do you have a set of jet drills, or wire gauges?

 

Yeah got no tools for that.. will see what I can find. I know of the jet drills.. .but wire gauges?

 

Jet gauge tool. It's a set of precision-gauged wires for measuring jet sizes.
The name escaped me earlier. The closer it gets to move day the more things I have to remember. Moving sucks.

 

So I found a set of numbered drill bits and it seems like a #56 fits into the main jet which from what I can see falls into a 120 jet size.

Being that its a 120 jet that means its +10 over the stock number which means its running a whole lot richer than it originally was lol.

So far carb wise even though pods were put onto it not much was changed except for the main jet.

Should note.. I am running a UNI filter so I don't think the 120 main will be a problem.

Also figure I'll drop the needle a spot or two and see if that helps fatten it up a bit.

 

So going over the carbs I have discovered that 3 of the 4 cinch rings for the rubber diaphragms are broken.

Anyone know if this is an issue or nothing to worry about. Could it cause a air leak?

 

split is not an issue

http://xjbikes.wikidot.com/carb-specs

 

Here is a picture.. Its not like just a split.. they are full on missing a good chunk. When I pushing the slides up and down in the bores 1,3,4 and sounded like a whoopie cushion going pffft where #2 did not.

https://i.imgur.com/8FFIFWm.jpg

 

that could be from someone removing them you have to split them .normal

 

So got the proper TCI for the bike (just cause) and also got some proper clamps for the air box boots.

Figured since I have adjustable needles on this bike I'd experiment with them but unfortunately I think I went the wrong way. I initially thought dropping the needle (richen) would help but it seems that maybe since I have a 120 main jet over the 110 that I think is stock I think I need to lean this bike out.

I have an order of new float bowl screws showing up tomorrow so I'll rip out the carbs and lean out the needles and see if that helps.

I remember why I hate carbs so much

 

Dropping the needle (raising the clip) leans the mix out.

 

Yeah I'm running into the bogging down low now.. around the 3-4k range where before it was in the 5-6k range.

From all the reading I've done this signifies a rich mixture and I have the screw at 2.5 turns out right now.

So I want to see if I might be able to get the slides out without pulling the carbs and if not.. well out they come again!

 

look at the hole in the bottom of the slide, does it look original?

 

Yeah slides are original.. Needle is different as I'm thinking someone tried to change it out for when they were running pods.

So I discovered you CAN remove the slides with the carbs still installed so I pulled them out tonight and move the clip up a few spots and now at idle when you try to accelerate it goes POP POP out the exhaust so this is now a sign of being lean.

I went to hook up my aux tank so I could play around with the adjustment screws but I apparently used the hose for something and so will need to pick up some before I go adjusting the air screws.

 

the slide would be original but some of the jet kits that were for running pods came with adjustable needles and a drill bit to enlarge that hole in the bottom of the slide
once that's done everything changes

 

are you still running 50 and 205 air jets? 50 and 195 are stock



50 and 205 are for maxim 650


changing needle height does not affect the pilot jet circuit

 

Hrm... Maybe I'll pick up the used carb set I found and then can do some comparisions.

Yeah just trying to get this thing running with what I have first

Also adjusting the needle has made a difference in how the idle to 1/4 throttle responds.

 

is your bike a Canadian bike or US bike?