Looking for Teikei Y27PV Secodary Main Jets

[xtzrick]

If you're looking to fit larger than standard it might be easier to drill out the old jets.


Then fine tune with the primary main which are still available. My local parts supplier calls them "standard" jets, also known as "280 style" jets, they are not specific to teikei.

Getting an equal mixture down each port is guess work, the main thing is the right mixture getting to the spark plug.

Rick

[manco]

If you're looking to fit larger than standard it might be easier to drill out the old jets.


Then fine tune with the primary main which are still available. My local parts supplier calls them "standard" jets, also known as "280 style" jets, they are not specific to teikei.

Getting an equal mixture down each port is guess work, the main thing is the right mixture getting to the spark plug.

Rick

Thanks for the tips. Crazy thing about thing about the drilling tip is just yesterday used a micro drill bit set to open up the pilot jet on one of my XTs. Talk about coincidence. Here is a link to my current XT600 build thread on a riding club forum for my area. One of my last posts talks about drilling the pilot jet. http://www.meetup.com/Front-Range-Dual- ... d/38618492 There may be some TT vs XT errors in the thread I am finding out as some of the info I gathered during the build was based on hear say. I will be correcting this info soon.

As for the secondary jets I am after, larger jets are not what I am looking for actually. What I need is smaller then normal secondary jets. I live in the Rocky Mountains, Denver Colorado to be precise. Denver isn't known as the Mile High City for nothing. My house sits at 5200' of elevation. When I go riding I generally ride between 8000' & 11,000' with pass crossings possibly as high as 12,000 - 13,000 feet & can max out my rides as high as 14,000' if I ride up Mt Evans, Pike's Peak or close equivalents on other various routes. Because standard elevation is so high I really need to find the smallest secondary main jets I can find so my carbs can be leaned out to deal with the high elevation of my local terrain. If need be I may have to solder closed & drill secondary jets to what I am after.

I had heard that set of Mikuni jets would work for the primary mains. I didn't know that they were standardized & known as 280 jets. Last weekend while studying to find more jet options I reversed engineered Yamaha's parts numbering to discover what jets Yamaha offered that would fit these carbs. I found that over the past 40 years or so many various Yamaha motorcycles used the XT600 primary jet style. I compiled a list of Yamaha part numbers for jets during the study. Many jets were no longer available. Now knowing what you have said about the Mikuni jets opens up a whole world of jets. I wish I would have looked into all this sooner. I just blew a wad of cash buying 3 obsolete OEM Yamaha jets. I am guessing could have gotten twice as many jets for that amount had I have known to look for Mikuni jets instead.

Now I am trying to sort this Mikuni/Teikei jet equivalent out. The reference to "280" & Mikuni doesn't seem to bring up consistent results. "280" may not be a standard parts reference is my guess. The results that do come up on google when Mikuni 280 is searched don't seem to be a proper match for the TK primaries. If someone can lend a hand on sorting this please do. Below is what I have found so far. The links under each section lead to pages where I got the info.

Jets R Us says the specifications on XT600 primary jets are:

OVERALL LENGTH = 8.0 mm
DISTANCE ACROSS FLATS= 7.0 mm
DIAMETER OF THREAD = 4.9 mm

This coincides with measurements that I have taken of my XT primary jets using a caliper. Jets R Us is not showing a thread pitch unfortunately. I don't have a thread gauge either. When I can I will bring a jet into the hardware store & see what pitch the jets are in the nut & bolt section.

UPDATE: None of the below Mikuni jets listed will work. See my below posts for more info on Keihin jets that will work.

Jets R Us XT600 jets with specifications: http://www.jetsrus.com/a_jet_kit_dirt/y ... XT600.html

The closest Mikuni equivalent to this is the Mikuni Large Round main jet series N100.604 which are

OVERALL LENGTH = 9mm
HEAD DIAMETER = 8mm
THREAD DIAMETER = 4.9mm
THREAD PITCH = 5.0 x 0.7

Jets R Us N100.604 jets with specifications: http://www.jetsrus.com/a_jets_by_carbur ... _round.htm

Jets R Us is also showing that the Mikuni N102.221 series of jets may work though the head diameter is one millimeter smaller. Here are the Mikuni N102.221 specs:

OVERALL LENGTH = 9mm
HEAD DIAMETER = 6mm
THREAD DIAMETER = 4.9mm
THREAD PITCH = 5.0 x 0.7

Jets R Us N102.221 jets http://www.jetsrus.com/a_jets_by_carbur ... _round.htm

When I look up Mikuni 280 google doesn't have much however consistently Mikuni 280 does bring up the Mikuni 4/042 series which are

OVERALL LENGTH = 11.5mm
THREAD DIAMETER = 5.2mm
THREAD PITCH = 5.25 x 0.9

Because of the thread diameter these 4/042 series will not fit in the XT600 carbs I would assume. The thread pitch may not be right & the length is also too long. Whether or not the length matters I am not sure.

Jets R Us 4/042 jets http://www.jetsrus.com/a_jets_by_carbur ... in_Hex.htm

SIP Scooter Shop sells Mikuni 4/042 jets & refers to them as the 280 series of Mikuni jets

http://www.sip-scootershop.com/en/produ ... +_40702800

Here is a list of all Mikuni jet series on Jets R Us

http://www.jetsrus.com/a_jets_by_carbur ... ection.htm

From this info I would imagine that the Mikuni N100.604 series would be the match to the Teikei primary main jets for XT600s. How the 280 series plays into this I am not sure. Maybe the 280 number just got mixed in by mistake? Who knows. Whatever the case hopefully this mystery can be resolved. It would be nice to have a standard jet series code for the Mikuni jets that will work. Maybe this thread can sort it out. Does anyone have definitive info on the Mikuni main jet series equivalent?

UPDATE: None of the Mikuni jets listed above will work. See my below posts for more info on Keihin jets that will work.

If anyone is interested in the original Yamaha part numbers for jets that will work with XT600 Teikei carbs here is everything I have found that has ever been sold by Yamaha that will work in the XT600 carbs. Part numbers in bold are currently available new from any Yamaha parts distributor. Parts that are italicized are no longer in production. When years of production are referred to below it is from the perspective of the USA market. So some years & corresponding models of XT will vary for the European market. Overall though the information contained below applies for all years of XT600s as regardless of year of model all XT600s use either the Y27PV or Y26PV carburetor. As for the XT600z, XT660 or whatever other model didn't sell in the USA market so long as the carbs are the equivalent the following part numbers will be compatible. Here is a link to a chart detailing what years of XT600 used which of the two Teikei carbs for more info. http://www.xt600.de/xt_werkstatt/_techn ... _xt600.htm


Pilot Air Screws for Teikei Y27PV & Y26PV Carburetors

50M-14105-00 1989 & older XT600s & 1983-1986 TT600s

51Y-14105-00 1990 & newer XT600s


Pilot Jets for Teikei Y27PV or Y26PV Carburetors

#40 43F-14342-20

#42 43F-14342-21

#46 43F-14342-23

#48 43F-14342-24

#50 43F-14342-25

#52 43F-14342-26

#54 43F-14342-27


Primary Main Jets for Teikei Y27PV or Y26PV Carburetors

#66 288-14343-33

#68 288-14343-34

#70 288-14343-35

#72 288-14343-36

#74 288-14343-37

#76 288-14343-38

#78 288-14343-39

#80 288-14343-40

#82 288-14343-41

#84 288-14343-42

#86 288-14343-43

#88 288-14343-44

#90 288-14343-45

#92 288-14343-46

#94 288-14343-47

#96 288-14343-48

#98 288-14343-49

#100 288-14343-50

#102 288-14343-51

#104 288-14343-52

#106 288-14343-53

#108 288-14343-54

#110 288-14343-55

#112 288-14343-56

#114 288-14343-57

#116 288-14343-58

#118 288-14343-59

#120 288-14343-60

#122 288-14343-61

#124 288-14343-62

#125 288-14343-63

#128 288-14343-64

#130 288-14343-65

#132.5 288-14343-66

#134 288-14343-67

#135 288-14343-68

#138 288-14343-69

#140 288-14343-70

No record of 288-14343-71 or 288-14343-72

#146 288-14343-73

#148 288-14343-74

#150 288-14343-75

#152 288-14343-76

#155 288-14343-77

#156 288-14343-78

No record of 288-14343-79

#160 288-14343-80

No record of 288-14343-82

#166 288-14343-83

No record of 288-14343-84

#170 288-14343-85

No record of 288-14343-86 or 288-14343-87

#176 288-14343-88

#180 288-14343-90


Pre-1990 XT600 Secondary Main Jets for Teikei Y27PV Carburetors

#120 5Y1-14343-60

#125 5Y1-14343-63

#130 5Y1-14343-65

#136 5Y1-14343-68


1990 & Newer XT600 Secondary Main Jets for Teikei Y26PV Carburetors

#80 30X-14343-40

No Record of 30X-14343-41

#84 30X-14343-42

#86 30X-14343-43

#88 30X-14343-44

#92 30X-14343-45

No Record of 30X-14343-46

#94 30X-14343-47 (Maybe it exists)

#96 30X-14343-48

No Record of 30X-14343-49

#100 30X-14343-50

#102 30X-14343-51

#104 30X-14343-52

#106 30X-14343-53

#108 30X-14343-54

#110 30X-14343-55

No Record of 30X-14343-56 or 30X-14343-57

#116 30X-14343-58

#118 30X-14343-59 (Maybe it exists)

#120 30X-14343-60

No Record of 30X-14343-61 or 30X-14343-62

#125 30X-14343-63

No Record of 30X-14343-64

#130 30X-14343-65

No Record of 30X-14343-66 or 30X-14343-67

#136 30X-14343-68

No Record of 30X-14343-69 or 30X-14343-70 or 30X-14343-71 or 30X-14343-72

#145 30X-14343-73

No Record of 30X-14343-74 or 30X-14343-75 or 30X-14343-76 or 30X-14343-77

#155 30X-14343-78

No Record of 30X-14343-79

#160 30X-14343-80

[manco]

So some of what I posted guessing about Mikuni jets above may be worthless. I did find a Keihin jet that worked. I am about the town. Gonna go check thread pitches on jets. I'll post more when I am back on my PC. For now I justed wanted to note that the above my not be relevant.

[xtzrick]

Looking at that list I've probably got it wrong

288 series jet not 280 (it's been a few years)

Bare in mind different jets are calibrated in different ways, some by diameter some by flow rate.
Sticking to the same style jet if you can keeps things even.

Rick

[manco]

I did some more digging on compatible primary jets for the TK YDIS carbs. What I found is that the Keihin 393 series main jets will work in place of the OEM Yamaha jets for these carbs. There is a Mikuni jet that "looks" like a Keihin 393 but the threads are not correct.

How I found all this out is this: I took a TK YDIS carb to a shop. I tried all the Mikuni jets. None would fit. I then tried all the Keihin jets sure enough one style fit. I asked what the series was & the shop said it was the Keihin "Small Round Slot" main jets. Then the person at the shop said something like, "Yah there are two types of these Keihin jets. Sound have a band around up high on the head & some have a band down low. The two types have different threads though." I noted this as interesting, bought a Keihin jet & left.

I then took both the Keihin jet & a OEM Yamaha jet for the TK YDISs to a hardware store. There I found that both the OEM Yamaha jet & the Keihin jet had a thread pitch of M5 x .08 which is also known as 5mm x .8 .

I took all the info I gained today & pumped it into the all mighty Google oracle to see what came up. This is what I came up with:

The Keihin main jet that will fit a TK YDIS is known as the Keihin "393 Series Main Jets.

I cannot find any reference to a Mikuni jet that is a M5 x .08 or 5mm x .8mm thread. The closest Mikuni gets is 5mm x 0.7mm which is a M5 x .07.

"Small Round Slot" refers a series of Mikuni jets

Interestingly enough I also find a site that said the Mikuni N102.221 series is Known as the Small Round Slot & "Looks a lot like a Keihin 393 series jet, but the threads are slightly different"

My guess is either there is a M5 x .08 Mikuni jet somewhere I haven't found OR maybe the supposed Mikuni jets that fit the TK YDIS are actually Keihin 393 main jets that have been mistaken for Mikuni jets by accident. I think the person that helped at the shop may have been making a similar mistake when they said they thought there were two types of Keihin jets with different threads. Chances are they were actually referring mistakenly to a Mikuni "Small Round Slot " jet that had different threads.

At any rate the Keihin 393 series main jets do indeed fit in the TK YDIS.

Here are links to some info:

Keihin 393 series main jet specifications & for sale http://www.mickhone.com.au/find/part/S.15507

More Keihin 393 series main jet specifications & for sale http://www.factorypro.com/products/Jets ... %20buy.htm

Jets R Us Keihin 393 series main jet specifications & for sale http://www.jetsrus.com/a_jets_by_carbur ... 28-xxx.htm

The Mikuni N102221 "Commonly known as: "Small, round, slotted Looks a lot like a Keihin 393 series jet, but the threads are slightly different" http://www.factorypro.com/products/Jets, Mikuni, buy.htm#main_jets

Jets R Us Keihin 393 series main jet specifications & for sale http://www.jetsrus.com/a_jets_by_carbur ... 28-xxx.htm


I will get some pictures of the Keihin 393 jet & the OEM Yamaha jet up in a coming post.

[manco]

Looking at that list I've probably got it wrong

288 series jet not 280 (it's been a few years)

Bare in mind different jets are calibrated in different ways, some by diameter some by flow rate.
Sticking to the same style jet if you can keeps things even.

Rick

No worries on the 280, 288 or whatever it may be.

You brought up a good point about jet sizing. It has been on my mind the past few days actually as I did the pilot jet drilling & looked for compatible jets to the TK YDIS primaries. There are two ways to measure jets that I know of. One is in mm so that a #36 jet is .36mm or a #120 jet is a 1.2mm. The other way to measure a jet is by rate of liquid flowing through it under certain conditions & then assigning a number to how much liquid can flow however it does. As to which companies use which method I am beginning to research. I will not guess as to which company does what at this time. I do know that from what I have done so far with the TK YDIS jets that I believe they are measured in mm. I say this because when I drilled the pilot out yesterday I thought about how it could be measured & started with a .4064mm drill bit which slipped right through. I then tried a .4572mm drill bit which met resistance. When I drilled through with the .4572 there was little resistance when the bit went through. Then I drilled through with a .5080mm drill bit which took a little more effort to go through when it did. I would surmise because of the bits sizes I used that the pilot on the TK YDIS carb is in mm.

I want to look into how these Keihin jets are rated. I have a suspicion they too are in mm but I want to do more research before I make any statements.

One thing to when when switching brands, shapes or using compatible jets as we are talking about now is that even if the hole size is measured the same, when switching to other brands or shapes the flow may change anyway so revisiting the tune is a must as jets are chosen.

I would love to ramble more but my mates & I are about to head out to the movie, Why We Ride. Should be a hoot.

http://whyweridefilm.com/

https://www.youtube.com/watch?v=AxGNI4jpzL4

[manco]

I want to look into how these Keihin jets are rated. I have a suspicion they too are in mm but I want to do more research before I make any statements.

My hunch was fairly close enough. Check my next post for more info.

One thing to when when switching brands, shapes or using compatible jets as we are talking about now is that even if the hole size is measured the same, when switching to other brands or shapes the flow may change anyway so revisiting the tune is a must as jets are chosen.

I was right on the money with this statement. Check my next post for more info.

I would love to ramble more but my mates & I are about to head out to the movie, Why We Ride. Should be a hoot.

http://whyweridefilm.com/

https://www.youtube.com/watch?v=AxGNI4jpzL4

Erm yah. The movie should have been called "Why Early Middle Aged Men & Their Families Ride." or better yet "Why Early Middle Aged Men & Their Families Buy Motorcycles & Why You Should Too." Typical American consumerism & propaganda. I am not saying it was utter tripe however I if I want to watch a movie that comes close to why I ride I think I will stick to the quintessential classic "On Any Given Sunday." I would have to say the best part of the movie was learning who Ted Simon was. He is the fellow that motorcycled around the world twice & wrote the books Jupiter's Travels & Dreaming of Jupiter.

[manco]

So I did some digging into jet measurements. This is what I have found. Teikei& DynoJet measure in mm & Keihin probably does. Teikei & DynoJet are essentially right on the mm & Keihin are slightly smaller per jet number and the amount smaller gets larger as the jets numbers increase possibly. Below is a link to a Ninja 250 article that puts the Keihin #s larger then actual mm. I also found a forum post that puts that difference between Keihin jet # and actual mm as a larger gap though too.

So if Teikei that is #120 is 120mm. A Keihin that is a #120 is probably around a 117mm or so. Regardless of the exact mm even if the jet orifice does measure the same the jets shape & placement of the hole in the jet will effect how a jet flows fuel. Because of this what xtzrick is very much correct when he stated above:

Sticking to the same style jet if you can keeps things even.

I would go so far as to say, "Sticking to the same style jet is the ONLY way you can keeps things even."

What this means is if a bike is tuned with say Teikei jets & then it will be switched to Keihin jets the process of tuning will need to start all over somewhat to find the proper jet. Once the proper jet is found if the carb needs to be tuned again the best way to do it is to stick with the Keihin jets so you know how to richen or lean the jetting without having to guess again what another brand of jet will be like. So if you have a Teikei #120 main jet that measures 120mm & you need to go richer & you want to switch to Keihin you can neither assume that #122 Keihin is the right jet because the # number is bigger nor can you assume a Keihin with a 122mm orifice is gonna flow more fuel because the shape of the jet is gonna effect flow. What needs to be done then in this example to switch from Teikei to Keihin jets would be to buy a few Keihin jets that have orifices close to the Teikei say maybe #120 #122.5 & #125, #127.5, try them out & see how the bike runs. Once you find how the bike is running on the Keihin jets then the Keihin jet sizes become relevant for tuning in the usual manner of jets.

A few other things to note that I found is the Keihin 393 jets run in increments of 2.5. ...#115, #117.5, #120, #122.5, ect

Since the charts I have seen are inconsistant maybe Keihins are #s do not coincide with mm???

Mikuni jets are measured in flow of cc per minute.

Mikuni jets even though measured in cc per minute tune the same as any other jets. To convert to Mikuni would be the same process I described above.

Some people have been known to cram Mikuni jets into Teikei or Keihin carbs. (This may be how some are saying Mikuni jets will work in the TK YDIS carbs. I am still looking for Mikunis that will actually fit.)

Here are some links to info on measuring, switching brand of, & comparing different jet brands:

This is an article about switching jet brands in a Teikei carb that is different then the YDIS. Its a good article up till it recommends a power drill to drill out jets. I am sure a power drill will work but a hand drill will be much more acurate & forging I would think. Meh whatever. Do what you like. http://home.comcast.net/~loudgpz/GPZweb ... rills.html

Mikuni vs Dynojet comparison http://vmaxoutlaw.com/tech/dyno-mikuni.htm

DynoJet - Mikuni -Keihin comparison for the Ninja 250. This is a good article. Its too bad the chart on the page is so incomplete. http://faq.ninja250.org/wiki/Dynojet_-_ ... conversion The page has a great letter from DynoJet about changing jet brands that states "We are often asked for a "cross reference" sheet that compares our main jets to Mikuni or Keihin. The fact is you cannot directly interchange the jets for a given size. Many things affect fuel flow through a jet of the same orifice size. The entry and exit tapers of our main jets differ from those of other companies. Due to this, the fuel flow changes as a function of velocity through the carburetor venturie. This means that two jets of equal orifice size will have a different fuel flow curve relative to intake air speed. At a certain speed the two may flow equally, but a change in velocity changes the flow characteristics. The Dynojet main jet hole size is measured in millimeters. For example, a DJ142 has a 1.42mm hole."

A forum thread talking about switching brands. Some of what is in this thread is pretty good. Some of it, well, lets just say its the usual forum banter. The chart in this thread is pretty sweet if it is accurate. Note that in the chart because DynoJets jets are measured mm the DynoJet #s should be the mm measurement of the corresponding jets from other brands. Remember when looking at this chart though just because the mm sizes line up does not mean the flow is gonna match. Shape & design will still effect flow rate. http://www.hawkgtforum.com/forum/forum/ ... sion-chart

[manco]

Here are the pics of the OEM Yamaha/Teikei Main Jet vs the Keihin 393 Main Jet I picked up today.

[ActionManMelb]

I was thinking of getting a local firm with cnc machine to make a 100 jets, either undrilled or drilled to the smallest jet size and user could drill to own size.

What do we all think?