What the hell kind of carb kit is this?

[warbeast]

So I got my max almost a month ago. First thing I notice is that it sucks the gas down like no tomorrow. I take the vacuum diaphragms out and notice that the pilot air jets under there are labeled "150". no other marks or indicators of brand. So I take the needles out and drop them a notch and a half and it's running "okay", but not as peppy as I would expect, however my mpg has gone up a little.

To try and determine which mysterious carb kit was installed on my bike I progress to taking the airbox cover off. I already know that the needles are stage 1 needles, but this needle came in the cobra kit and the dynojet stage 1 kit. To tell the difference between the two kits without tearing the complete carbs apart is to look at the other PAJ in the carb mouth which if it is a cobra kit should be DJ080, and if it is the dynijet stage 1 kit should be mikuni 90. I get the cover and find a jet that has what resembles "Q 150" or "(Bullet symbol) 150". Sorry, I don't feel like taking time to figure out how to type a bullet symbol right now.

I'm like "WTF?!?! :damn angry: that is almost twice what it is supposed to be!" So I proceed to remove the carbs from the engine and drain them and take the main jet access screw off and find that the mains are the same jets as the PAJ in the carb mouth. :bang head:

What do you think about that one guys? :hmmm: I'm not sure how I should jet this now... I live at at or below 1000 ft and I have cobra slash cuts with a k&n stock replacement filter. Should I just order the actual jets for the cobra kit since the slides are already drilled and I wasn't given any of the original stuff when I bought it? :th_help:

Mark had mentioned that I put all stock Jets back in. This was before I knew that all of the jets were the same number, but would the slides being drilled have any negative affects over the cobra kit jets? I'm not trying to second guess you or anything Mark, I just want some more opinions or experiences before I move forward. I don't want to have to be tearing this beast apart like this again anytime soon.

 

[warbeast]

I guess I just want some opinions on whether I should go with all mikuni jets 90/170 for PAJ and a 147.5 for the main... or with the dynojet 80/150 for PAJ and DJ155 for the main. I do not have the stock needles and have no intention of buying them at this point. Any suggestions?

 

[maleko89]

I think DJ 080/150 for the idle is too rich for Cobras. If anything, the kit should have leaned that out not richened it up. I would go back to stock PAJ1 and PA2 and start with 147.5's for the mains. Then, set you floats and make sure they are all the same...either 16 mm or 17 mm. Then, run the bike hard from 7500 to red line and see how it pulls. You can either shut down quick after testing to pull a plug to see how it looks.

Next, do the needle tests as outlined in the Carb section. Finally, adjust your mixture screws one at a time and sync your carbs.

Good luck!

Mark
#1098

 

[warbeast]

Is it easier to set the floats dry while its off the bike or with fuel on the bike? And if they are adjusted correctly already and I just had the carbs synched a week ago, would I really need it done again? It's kinda pricey.

 

[maleko89]

If you have to change the floats, you need to at least break the carbs in pairs....but first just check the level. I set them dry...when you turn the carb upside down you measure the distance with a caliper. It should be around 1.10 inches. There's a picture in the Carb section on setting the dry float level. Then, use an auxilliary fuel tank to check the wet level.

Anytime you remove the carbs from the rack you need to check the sync because usually it changes. You can always try leaving the main jet you have and see how it runs. Then, if your floats are good you won't have to remove the carbs at all....just change PAJ1 and PAJ2.

Mark
#1098

 

[warbeast]

So are the PAJ's the same head and thread style as the main jet for the stock jets? I don't have anything stock and the dealer is asking me. Apparently it makes a huge difference in price.

And how do you check the float levels with fuel do you hook clear tubes up where the float vent tube is? and where do you measure from?

 

[shawn kloker]

So I got my max almost a month ago. First thing I notice is that it sucks the gas down like no tomorrow. I take the vacuum diaphragms out and notice that the pilot air jets under there are labeled "150". no other marks or indicators of brand. So I take the needles out and drop them a notch and a half and it's running "okay", but not as peppy as I would expect, however my mpg has gone up a little.

To try and determine which mysterious carb kit was installed on my bike I progress to taking the airbox cover off. I already know that the needles are stage 1 needles, but this needle came in the cobra kit and the dynojet stage 1 kit. To tell the difference between the two kits without tearing the complete carbs apart is to look at the other PAJ in the carb mouth which if it is a cobra kit should be DJ080, and if it is the dynijet stage 1 kit should be mikuni 90. I get the cover and find a jet that has what resembles "Q 150" or "(Bullet symbol) 150". Sorry, I don't feel like taking time to figure out how to type a bullet symbol right now.

I'm like "WTF?!?! :damn angry: that is almost twice what it is supposed to be!" So I proceed to remove the carbs from the engine and drain them and take the main jet access screw off and find that the mains are the same jets as the PAJ in the carb mouth. :bang head:

What do you think about that one guys? :hmmm: I'm not sure how I should jet this now... I live at at or below 1000 ft and I have cobra slash cuts with a k&n stock replacement filter. Should I just order the actual jets for the cobra kit since the slides are already drilled and I wasn't given any of the original stuff when I bought it? :th_help:

Mark had mentioned that I put all stock Jets back in. This was before I knew that all of the jets were the same number, but would the slides being drilled have any negative affects over the cobra kit jets? I'm not trying to second guess you or anything Mark, I just want some more opinions or experiences before I move forward. I don't want to have to be tearing this beast apart like this again anytime soon.

I would also recommend going back to all mikuni jets.I did this with mine and stage7.There are different jets of unknown origin made that probably do not flow the same.DJ and Mikuni jets do not with the same number.

 

[warbeast]

I've read on here how to get the main jet out without cracking open the bowl. Is this fairly easy to do? And how easy is it to screw the new main in there?

 

[maleko89]

So are the PAJ's the same head and thread style as the main jet for the stock jets? I don't have anything stock and the dealer is asking me. Apparently it makes a huge difference in price.

And how do you check the float levels with fuel do you hook clear tubes up where the float vent tube is? and where do you measure from?

They're the same. You want the small round head Mikunis.

Clear hose on black hoses coming out the side. Next, loosen drain screw and make sure distance from line on carb body to the fuel level in hose is either 16 or 17 mm. I think there's a picture in the Carb section somewhere.

 

[shawn kloker]

I've read on here how to get the main jet out without cracking open the bowl. Is this fairly easy to do? And how easy is it to screw the new main in there?

After you get it loose,jam a toothpick in it to pull it out.Use a toothpick to stick the new jet back in then tighten it up with a screwdriver.

 

[warbeast]

I don't know if the guy at the dealership is trying to screw me into buying something more expensive than what I need or what, but he just tried explaining to me that The Vmax factory mikuni jets are completely different specs than if I walked in the door and asked for a small round head mikuni 170 and 90 main jet (i.e. they jet hole is bigger on one than on the other even though they are labeled the same jet number.)


Is there any truth to this?

 

[maleko89]

Bullshit. Go get a pipe wrench and spank him with it. When done, just tell him that's for being a stupid ass.

DJ and Mikuni do rate their jets differently. DJ rates their jets by the hole size diameter. Mikuni uses flow rate. Mikuni is a much more accurate jet. I have found DJ jets with the same rating (DJ165's) and the hole size was obviously different. I trust Mikuni more.

Mark
#1098

 

[warbeast]

You guys are awesome. He was trying to tell me that I had to buy the jets that are made by mikuni for yamaha and they are $9 & $10 each. I could kinda tell that he was trying to make shit up as he goes. I already got the 147.5's from the local dealer and they are going to have the 170's and 90's in tomorrow. The Tard that was trying to tell me different was at the next nearest shop in Saint Johns, about 30 miles from my house. So at the local dealer I'm getting out of it for around $36 where as if I went to US-27 Motorsports, i would be getting raped at around $120

 

[maleko89]

Yeah, only dealer I trust is Umotors in Fargo, ND or K&N in OK City, OK. Next time, try them....jets are cheaper there.

Mark
#1098

 

[warbeast]

Ok, one final question before I head home. Is there anyway that the float bowl can be removed with cracking them apart? With like a bent screwdriver perhaps. with what I have found so far I am curious to make sure that the other jet in the bowl is the factory mikuni 37.5. Sorry for asking so many questions, I just don't want to render the bike useless and do it right the first time.

 

[maleko89]

No, you'll need to remove the carbs and then remove the four screws holding the float bowl cover on. Then, you'll need to remove the jet block. To do this remove the float from the pivot post. Nest, remove the brass flat head screw holding the needle jet on and the two Phillips screws holding the jet block on. Be careful of the jet block gasket and the o-ring that goes over the needle jet. There is also a brass washer under that flat head screw. Be careful not to damage the needle either. Take the smaller left-most rubber cap off and you can then get the pilot fuel jet out. The marking is on the side, not on the head like the other jets.

When putting the jet block back in, make sure the groove on the needle jet is at the 9:00 position. There's a small nipple inside the jet block needle bore than fits in there to ensure the outlets are positioned correctly.

I included a picture to help you for reference. You can see the float bowl pivot post, the jet block, screws, and the rubber caps.

Mark
#1098

 

[warbeast]

Thanks Mark. I'll post when I get the jets all changed to let you know how it went.

 

[warbeast]

Hey guys,
I just tried crackin the carbs off the rack and the screws won't even budge. Then I looked at the screws and none of the ones I hadn't tried to take off looked they had ever been touched. My question however is about pilot mixture screws.

By changing these jets should I even need to adjust these or not? I'm not sure if these jets that I am replacing even affect the pilot mixture or not.

I screwed them in and then back out to see where they were at and all the screws were at 2 full turns out from seated. I did get the main jets in no problem though. Thanks for the tips Mark and Shawn.

 

[maleko89]

Is it the front/rear brackets? I use an impact driver with a bigger bit. I don't use a hammer, just push down on the driver and turn a bit and it usually pops right loose. A locking pliers works too. If they've never been off then I'm sure the original loctite the factory uses is holding them tight.

Mark
#1098

 

[warbeast]

"At the least you should be able to do this by the time the engine is fully warmed up but if you are more than 1/2 way between the dot and cold on the temp gauge your pilots are plugged or too lean... (clean or reduce the PAJ2). "

This was post in the sticky about jetting and tuning as a test for pilot mixture. If the temp EVER goes more than half way between the cold and dot while running does that mean it's too rich. or are you just saying within the first to minutes?