Krazy Katana
- Thread starter CALfeRacer
- Start date
CALfeRacer
Fat man on a little bike
Yet you still probably know many, many times more about them than mecrazypj said:
CALfeRacer
Fat man on a little bike
Quick question on buying jets.
For the BS carbs it looks like there are 2 different main jet sizes. There is a "large" with an 8mm diameter head and a "small" with a 6mm diameter head. Other than that, dimensions are the same with both (9mm length, 4.9mm thread diameter, 5.0x0.7 thread pitch). Jetsrus has the 600 carbs listed as using the small size, and the 750 using the large size. I measured the 120s that were in my old set of carbs and they are the large size. They fit fine, doesn't look like the jet holder was modified either. I'm not sure what head diameter the 112.5s in the set on the bike are, but I'm pretty sure I remember swapping the 120s onto that set to check if they'd fit and they did... can't remember for sure though.
Anyways, just wondering if it really matters which head size I end up using, provided both will fit in the carbs. I can get a set of four 115s in the large size from bikebandit for $12.95 (instead of $6.39 each through jetsrus) and a set of four 117.5s in the small size from bikebandit for $11.95 (instead of $6.39 each). I assume the head diameter won't make any difference on how the jet itself performs but I figured I'd check real quick.
For the BS carbs it looks like there are 2 different main jet sizes. There is a "large" with an 8mm diameter head and a "small" with a 6mm diameter head. Other than that, dimensions are the same with both (9mm length, 4.9mm thread diameter, 5.0x0.7 thread pitch). Jetsrus has the 600 carbs listed as using the small size, and the 750 using the large size. I measured the 120s that were in my old set of carbs and they are the large size. They fit fine, doesn't look like the jet holder was modified either. I'm not sure what head diameter the 112.5s in the set on the bike are, but I'm pretty sure I remember swapping the 120s onto that set to check if they'd fit and they did... can't remember for sure though.
Anyways, just wondering if it really matters which head size I end up using, provided both will fit in the carbs. I can get a set of four 115s in the large size from bikebandit for $12.95 (instead of $6.39 each through jetsrus) and a set of four 117.5s in the small size from bikebandit for $11.95 (instead of $6.39 each). I assume the head diameter won't make any difference on how the jet itself performs but I figured I'd check real quick.
CALfeRacer
Fat man on a little bike
There's supposed to be a washer?? 
crazypj
Split personality, I fake being smart
Emulsion tube slides in from the top (after removing slide, needle, etc)
There is usually a brass washer underneath in float bowl, main jet goes through washer and into emulsion tube.
I don't remember Suzuki removing washers and using large head jets but it's possible but either size main jet head will work if you have washers under jets.
Small head jets can fit through the emulsion tube hole and the emulsion tube rises up into throttle bore, causes some real strange engine behavior (happened a few times when I worked at MMI)
There is usually a brass washer underneath in float bowl, main jet goes through washer and into emulsion tube.
I don't remember Suzuki removing washers and using large head jets but it's possible but either size main jet head will work if you have washers under jets.
Small head jets can fit through the emulsion tube hole and the emulsion tube rises up into throttle bore, causes some real strange engine behavior (happened a few times when I worked at MMI)
CALfeRacer
Fat man on a little bike
This is what mine look like (with the big head 120).
I've never seen an emulsion tube set-up that DOESN'T have washers underneath the main jet.
Not sure if that's going to affect your fueling without them - the main jet will sit about 2mm higher up in the bowl.
But as long as the jet snugs the emulsion tube home you'll probably be OK.
Not sure if that's going to affect your fueling without them - the main jet will sit about 2mm higher up in the bowl.
But as long as the jet snugs the emulsion tube home you'll probably be OK.
CALfeRacer
Fat man on a little bike
Honestly with a washer there I'm not sure how well it would even engage the threads in the bottom of the tube. The threads don't go all the way up to the "top" in that pic. Seems like a washer would space it out too much.
CALfeRacer
Fat man on a little bike
Totally should've just checked cmsnl haha. This is what I got for mine. 17 is main, no washer.
CALfeRacer
Fat man on a little bike
Also had an interesting problem earlier, when I noticed my #2 carb was dumping has as I came to a stop to park. I turned it off and looked down to see the drain screw on the bowl was MIA. Luckily I have a spare set of carbs to steal parts from!
I guess you just need to work out if the jet threads pull the emulsion tube in enough so it doesn't move about.
Like I said it probably wont matter if the jet is a mm or 2 higher in the bowl.
Definitely looks like it should have the washer though - you can see the recess is larger than the head of the jet.
Like I said it probably wont matter if the jet is a mm or 2 higher in the bowl.
Definitely looks like it should have the washer though - you can see the recess is larger than the head of the jet.
crazypj
Split personality, I fake being smart
CALfeRacer said:
This is what mine look like (with the big head 120).
Now I can see it I know that type of carb doesn't use a washer. You have to use 'big head' jets though
Washer is needed when you can see the bottom of emulsion tube.
Drain screw fell out, kinda common when you do carbs a lot. I can tell you it will never happen a second time
CALfeRacer
Fat man on a little bike
Honestly I was a relieved when it was just the drain screw. Confused, but relieved. At first I looked down and just saw liquid pouring onto the pavement from under the bike and thought something let go and I was having a massive oil leak haha. Once I realized it was gas I was then afraid that I lost a bowl or blew a fuel line or something. So just losing the drain screw wasn't too bad!
As far as the jetting, I'm going to order a set of the 115s through bikebandit and see how those are. If it still seems lean I'll order the 117.5s through jetsrus. Hopefully I don't end up with the 117.5s being lean and using the 120s I already had
PJ, I assume the 120s were too rich, especially if you're a bit rich with the 117.5s in Florida (assuming close to sea level). I forget, what intake/exhaust set up do you have on your Katana?
As far as the jetting, I'm going to order a set of the 115s through bikebandit and see how those are. If it still seems lean I'll order the 117.5s through jetsrus. Hopefully I don't end up with the 117.5s being lean and using the 120s I already had
PJ, I assume the 120s were too rich, especially if you're a bit rich with the 117.5s in Florida (assuming close to sea level). I forget, what intake/exhaust set up do you have on your Katana?
CALfeRacer
Fat man on a little bike
Ok. I've got the Vance & Hines as well (or maybe a knock off... Who knows) and airbox with K&N drop in. So hopefully 115 will work.
I'm at 100-150ft as well so we should be similar in that sense, right?
I'm at 100-150ft as well so we should be similar in that sense, right?
