Acceleration stutter. Full throttle denial. Ghetto rigged carbs.

[650Skull]

Jasidok, I;m not a carb guru by any sense of the word. If the floats were to much to sort out on a set of CV carbs especially with the experience on this site i cannot help to wounder how your going to solve the problems with these Klein carbs................ We have 2 of the most experienced carb guys on the site who do and will work through any problems when working with CV carbs............ Just about any one else who has learnt to get the CV Carbs working right has either learnt directly from these 2 members or learnt from reading the Carb Guide or others who have learnt from these 2 members or the guide......... . This was written by Grizld1 and 5twins and they have posted this information free for all of the XS650 community to use and learn from.

On the Kein PWK carbs there are a couple of threads, (the thread where you were posting), and another, ( i will post up both links). Start at the beginning on both threads, especially the first page of the first link and make sure to go through at least 8 pages of the second............

http://www.xs650.com/threads/keihin-flatslide-pwk-carburetor-oppinions-issues.6592/
http://www.xs650.com/threads/mikes-keihin-carb-kit.3446/

The second thread gives all the information regarding the vacuum barb and Vacuum petcocks and using the barbs to equalize the carbs..........may be different now because Mikes may have changed things around...............I honestly don't know how your going to solve problems on these carbs that don't have a good reputation and a very small knowledge base, (basically there is no one who has posted any information in the last few years on how to set up and run these successfully. If they have they have not posted up up here)

i do wish you luck, i don't have any thing to add. Except, how to go about, (procedure), setting up CV carbs, may not work on cable pull carbs.

 

[mrtwowheel]

You gave up on the stock carbs because the floats were messed up? You should try again.

Scott

Edit, yeah, what Skull said.

 

[jasidok]

Oh man. I mean. Skull, and mrtwo. You guys are making incredibly valid points. And I believe you both. I will absolutely read those threads in a few here and put a more dignified response up. I just want to say that I mean, I’m down! I’m down for the challenge and the headache and the failure and laughter. Hopefully it works out. But I’ll have fun doing it. These bikes are so cool man. I love my XS. And these carbs are definitely intriguing. More later.

 

[peanut]

The Keihin flat or semi-flat slide carb is an excellent carb and has been used extensively and successfully for racing both 4 and 2 stroke. They are used on bikes scooters quads power boats snowmobiles etc etc I believe I read somewhere that Keihin is the carb officially adopted by Yamaha so they can't be that bad can they !? despite the rubbish skull posted about them.

you have made the decision to buy and fit the PWK so it would make sense to persevere with them. Personally I don't think you will find much to help you in the 'carb guide' which is mostly relevant to the CV constant velocity type carbs . I feel the guide is really hard work to read through for the novice and needs a lot of stuff cutting out, lots of punctuation and paragraphing and a complete reorganisation but thats just my opinion.

 

[650Skull]

Oh man. I mean. Skull, and mrtwo. You guys are making incredibly valid points. And I believe you both. I will absolutely read those threads in a few here and put a more dignified response up. I just want to say that I mean, I’m down! I’m down for the challenge and the headache and the failure and laughter. Hopefully it works out. But I’ll have fun doing it. These bikes are so cool man. I love my XS. And these carbs are definitely intriguing. More later.

You have been nothing but dignified. If your confident on being able to sort these carbs then good for you. Please document any findings and procedures that relate to an outcome for others and to add to the site base....... In the Kein carb thread there were 2 guys who said they ran them successfully but wouldn't help answer your questions with specific answers.....

The Keihin flat or semi-flat slide carb is an excellent carb and has been used extensively and successfully for racing both 4 and 2 stroke. They are used on bikes scooters quads power boats snowmobiles etc etc I believe I read somewhere that Keihin is the carb officially adopted by Yamaha so they can't be that bad can they !? despite the rubbish skull posted about them.

you have made the decision to buy and fit the PWK so it would make sense to persevere with them. Personally I don't think you will find much to help you in the 'carb guide' which is mostly relevant to the CV constant velocity type carbs . I feel the guide is really hard work to read through for the novice and needs a lot of stuff cutting out, lots of punctuation and paragraphing and a complete reorganisation but thats just my opinion.

Please read what has been written properly.......learn about the history of Mikes Kein carbs.........Grizld1, especially and 5twins have repeatedly told the history of the PWK carbs and their intended use as a 2 stroke specific carb that is being used as a 4 stroke carb now........

No the Carb guide has absolutely no dog in this fight..........Again read my post and what i was referring to and the reason i was referencing the guide.........

So now your claiming every thing i have written about the Kein PWK cabs is rubbish.............here you go again Peanut...............read the links i posted. These people have had practical experience.......where is yours......belittling my comments by saying i post rubbish is up to your usual high standard............

 

[jasidok]

Alright man. That was incredible. First off it wouldn't run, i finally figured out, because over the past week i had been running that engine so rich that the spark plugs were so caked in soot that they weren't making a spark. So, out of sheer hopelessness, I started brushing the plugs with a wire brush, and then boom, starts right up. Alright so heres my set up after going around town and shopping a little.

I put in a main jet 115
Pilot Jet 40
Float level 18.6mm
I have brand new Uni air filters that i bought today. I have a PMA and E-advancer, dual coil, ignition blah blah mikesxs.
It's also Red.

So I went out on the highway to test it out. It was a little jumpy at first. It was hitting weird random flat spots for like an instant and backfired a couple times. (pulling out of my apartment complex at midnight....) By the time i got to the highway, the low rpms had kind of balanced out I think. And I was really putting my focus on the higher RPMs and WOT. I am so used to it losing power and sputtering out at WOT that when it didn't do that i was stunned. So, It wasn't like riding a ducati or anything, but man, that was so nice. It had power all the way up to about 6000 rpms. I put it up to about 80/85 easy. Unfortunately at a certain point it was starting to backfire a lot and get a little jumpy. So i backed down. That was cool though. It definetely has some issues to iron out, but i feel like it is so mich more responsive than the diaphram carb. I mean maybe it's just me. And i still need to sync them. But I really feel like it was completely at my control. sensitive to the throttle. It also sounded so much nicer. Hmmm Yea. I think everyone should try it.

 

[jasidok]

Ok so i went to go take some pics for you guys and noticed that it's leaking something for sure. It looks like it's from the top side of the engine..... ummmm....

Am I going to blow up?

 

[peanut]

Ok so i went to go take some pics for you guys and noticed that it's leaking something for sure. It looks like it's from the top side of the engine..... ummmm....

Am I going to blow up?

probably ..... nah just kiddin with ya....

Is it oil or gas ? stick your finger in it and smell and taste it like all blokes do lol. .....

Don't forget to reconnect your vacuum hose/s or you'll never get it started and running lol.

Your bike looks really good it is the same year and model as mine , I actually like the upswept exhaust ...first I've seen on an XS.

 

[gggGary]

Relevant point? Denver is at 5000 feet er 1,300 meters of altitude. You are going to find the sweet spot with leaner jetting than what "most" report.
I cringe, thinking of trying to jet with "off brand 20 for $2" jets specially on non CV carbs. Add to the mix typical 40 degree temp swings day to night in denver fall weather. Non CV carbs are fussier about correct jetting and require more finesse with throttle roll ons. Whacking open the throttle can really lean out the mix, that may be a clue.

 

[peanut]

nothing wrong with $2 jets gary so long as you use a jet guage and a vernier guage to confirm accuracy of the jets bores. There is absolutely no guarantee that expensive jets are necessarily going to be any more accurate than cheap jets . I have found several Dellorto jets that were defective recently.

jazidok reports severely sooted up spark plugs which suggests a over-rich idle mixture not a lean one. Its the slide , pilot jet , start jet and idle mixture that governs throttle pick up off of idle so my best guess is the pilot jet and mixture settings are too rich but there is clearly an issue with the vacuum petcocks too. I do not know if Keihin approve the use of vacuum petcocks with their carbs . If it were me I'd get rid of those to simplify things.

Very good point about altitude , weather and temperature swings and their effects on the stoichiometric ratio but my inclination is that these carbs have simply not been set up correctly or tuned yet . Once thats done they should perform fine

 

[jasidok]

I have installed the #120 main jets. #42 pilot jets. 2 full rotations of the mixture screw. And the idle screw all the flipppn way in. I have a Motion pro Sync Pro thingy. The non mercury tool with 4 vacuum line things. I don’t know how to use that to sync the Keihin carbs. I mean they’re separate carbs right? Any ideas?

 

[peanut]

I have installed the #120 main jets. #42 pilot jets. 2 full rotations of the mixture screw. And the idle screw all the flipppn way in. I have a Motion pro Sync Pro thingy. The non mercury tool with 4 vacuum line things. I don’t know how to use that to sync the Keihin carbs. I mean they’re separate carbs right? Any ideas?

yes I posted a suggestion in post # 19 the simplest method is to use a small twist drill under the slide. Adjust each throttle stop until it sits snugly on the drill and that will get you very close to sync especially on new carbs . Its a tried and tested method used for over a century . i wouldn't bother to try and use the motion pro sync it will just complicate things . get the basics done first like the idle mixture

Turning the idle mixture screw out 2x turns is merely a starting point to get the engine running. Each cylinder will have slightly different requirements and so each carb idle mixture screw will need to be set seperately once the engine is warmed up.

let me have a link to the exact carbs you bought and I'll try and find a spec for tuning and rejetting .

post script ....why have you bought 42 pilot jets ? they will make things even worse ... you need to go lower not higher . You need 35 pilots to achieve a leaner idle mixture . I would order 37.5 and 35 pilot jets .

 

[jasidok]

post script ....why have you bought 42 pilot jets ? they will make things even worse ... you need to go lower not higher . You need 35 pilots to achieve a leaner idle mixture . I would order 37.5 and 35 pilot jets .

Fair enough. I’ll just switch it back out then. It felt weird like it may have been lean on the low rpm/ idle side of life. But.... I’m probably just jumping the gun here. For sure. I’ll switch it back out for the 35s. Then I’ll sync it and see how it feels. I should check things out first before I just run to switch out the jets huh!?



And the carbs.... https://www.mikesxs.net/yamaha-xs650-keihin-pwk33-carburetor.html

 

[peanut]

yes ....your plugs are sooting up which means that although the bike might be starting and running the fuel air mixture at idle is too rich.

you need to adjust the mixture screws and the idle speed screws to get the mixture right in each carb. if you have to screw the mixture screws in or out excessively then that will tell you you need to go down or up with your pilot jets. In your case it is definitely down ie lower.

The feeling of a lack of power you experience is not due to a lack of fuel at idle or on throttling up ............its actually the reverse .
further up the throttle range 1/2 ...3/4 and full throttle you will probably need to adjust your main jets , slides and jet needles etc but first things first always adjust your idle mixture first.

can you give me a URL link to where you bought your carbs

 

[gggGary]

You are going to find the sweet spot with leaner jetting than what "most" report.

jazidok reports severely sooted up spark plugs which suggests a over-rich idle mixture not a lean one.

Higher altitudes need leaner jetting than the same set up run at lower altitude.

 

[5twins]

Those carbs appear to be a new offering from Mikes so there probably isn't much info available yet on jetting them. They appear to be just a plain slide carb very similar to the tried and true Mikuni VM. Your plugs could be all black from repeated cold starts using the choke and not running down the road a few miles to burn them clean. To hook up your carb sync tool, connect it's hoses to those vacuum barbs on your manifold where the petcock vacuum line connects. You will then need to run the petcocks on the "Prime" position to get fuel flow.

 

[peanut]

Higher altitudes need leaner jetting than the same set up run at lower altitude.

when you say leaner jetting gary I take it you mean leaner idle or pilot jets yes ? which is what I said . The op had swapped his 35 pilot jets for a 42 which provide more fuel at idle ie richer mixture given the same idle air supply. He needs to go to a lower pilot jet . Our BS38 cv carbs have a fixed idle air jet but I believe these PWK have a changeable start jet which will allow you to reduce or increase the air supplied to the idle circuit so presumably you can adjust start jet, pilot jet and the idle mixture to get the idle mixture just right .

 

[650Skull]

From Mikes..........Looks like these.......
https://www.mikesxs.net/yamaha-xs650-keihin-pwk33-carburetor.html

 

[650Skull]

Hee is a link to
PJ Motorsports
http://www.pjmotorsports.com/jetting-tuning.html

Page gives a detailed explanation on how to jet for a lean or rich situation. This does not go into the differences for jetting at altitude

This is what is was hinting at earlier when i said be careful on information given about CV carbs for your carbs.........there is a different procedure for jetting Non CV cabs and CV carbs.........

 

[TwoManyXS1Bs]

... noticed that it's leaking something for sure. It looks like it's from the top side of the engine...

I'd expect a lot of oil from here: