TBR7 & Mikuni - Access Fuel/Air Screw

Nehrke · 03-16-2024, 07:42 PM

Hi All! Hoping someone can help. I have a 2020 TBR7 and I swapped out the stock carb with a Hwbnde VM26 Mikuni clone. I got a jet kit and can't remember exactly what I have in there.....but I am in Denver and looked at a bunch of the charts listed and went with that setup.

Long story short - bike runs well at slower speeds, but once you get up to like 45-50 it cuts out. Not sure what is up. I thought it might not be breathing, so I added a Uni foam air filer, set the idle, but I can't get to the damn fuel/air screw on the bottom of the carb! I just took it out hoping it might be good with the new air filter.....but hope is not a strategy and it is doing the same.

I would like to get to the fuel/air screw to make sure that it is dialed in....but there is not a lot of room and a lot of things that want to burn me, even in gloves! I tried a Z-shaped screwdriver....I tried putting a small screwdriver head in a socket.....I tried my mini screwdriver - I just can't get on it.

Is there a trick? Can anybody share? I'd love to be able to sort this myself, as it literally only has like 55 miles on it and all I want to use it for is to run shuttle when we go rafting......but I need it to run. Appreciate any help or suggestions. Thanks - Nehrke

Bill Hilly · 03-16-2024, 08:15 PM

The two methods that I found best are to take a flat bit, and small socket taped together so if dropped it stays together. I know you tried that, but the way I learned to do it is, basically trial, and error. Assuming that you have it pretty close now, you could do like I have did in the past, which is to wait till the motor is cool enough not to burn yourself, and give it about a quarter turn in a chosen direction, before even starting the bike,and ride the bike, and see if it's better, or worse. If better, then the next time you ride it give it another quarter turn i in the same direction . If worse go the other way a quarter turn past were you started. I remember using a finger of my left hand to push the bit in position, and turning a little with my right hand. It's awkward, but can be done. That being said, I later discovered that I had a tool that made it a breeze to adjust, aside from not being able to accurately count the turns. It was a small flat squeeze ratchet type thing. It doesn't have a square ratchet drive, but rather a hex shaped opening, and if I remember right you just turn it over to reverse it. I had it for years, and that's all I ever used it for. I'm sure you can still get them, but don't know what they cost . I bought mine, along with another small tool set at a flea market type sale that a local Church was having. Unless you really like that carb, it probably would make more sense to buy a Nibbi PE28FL, or a Nibbi PEZ, which is the same as the PE28FL, except it has a little smaller inlet on the breather side. I will try to find a similar tool , and post a link, or picture.
https://www.amazon.com/CRL-Piece-Squ...4aAhNaEALw_wcB

I am surprised that they are so expensive. I got mine, and another small set of tools for $5.00, if I remember right. I did see that eBay had several sets used for much lower, but honestly, unless I am missing something, I have never had any use for them, except for the time, or possibly two that I used it on the mixture screw

Nehrke · 03-16-2024, 10:30 PM

Reminds me of a book that has never been penned….a song that has never been sung. Thinking there has to be an easier way! Please help!!

Nehrke · 03-17-2024, 01:05 PM

Update! I dug into a few more things this morning and didn't really come up with much. Took it for a ride to see how it was doing.....same old - got the RPMs and the speed up and it started bogging down and then dying. Funny thing is I noticed (finally) that when I went to restart it the choke lever had slid up approaching the clod start position. Starting to make sense!

Ran home and tightened the screw that holds it and took it back out - running well again! Can't believe it took me this long to figure it out....but all seems to be realtively well in my world again. Hooray!

dirtbkr188 · 03-17-2024, 01:14 PM

One of THESE makes life (and fine tuning) easier when the fuel screw is mounted in front of the float bowl.

03-16-2024, 07:42 PM	#1
Nehrke Join Date: May 2020 Posts: 14	TBR7 & Mikuni - Access Fuel/Air Screw Hi All! Hoping someone can help. I have a 2020 TBR7 and I swapped out the stock carb with a Hwbnde VM26 Mikuni clone. I got a jet kit and can't remember exactly what I have in there.....but I am in Denver and looked at a bunch of the charts listed and went with that setup. Long story short - bike runs well at slower speeds, but once you get up to like 45-50 it cuts out. Not sure what is up. I thought it might not be breathing, so I added a Uni foam air filer, set the idle, but I can't get to the damn fuel/air screw on the bottom of the carb! I just took it out hoping it might be good with the new air filter.....but hope is not a strategy and it is doing the same. I would like to get to the fuel/air screw to make sure that it is dialed in....but there is not a lot of room and a lot of things that want to burn me, even in gloves! I tried a Z-shaped screwdriver....I tried putting a small screwdriver head in a socket.....I tried my mini screwdriver - I just can't get on it. Is there a trick? Can anybody share? I'd love to be able to sort this myself, as it literally only has like 55 miles on it and all I want to use it for is to run shuttle when we go rafting......but I need it to run. Appreciate any help or suggestions. Thanks - Nehrke
	1

03-16-2024, 08:15 PM	#2
Bill Hilly Join Date: Feb 2021 Posts: 929	The two methods that I found best are to take a flat bit, and small socket taped together so if dropped it stays together. I know you tried that, but the way I learned to do it is, basically trial, and error. Assuming that you have it pretty close now, you could do like I have did in the past, which is to wait till the motor is cool enough not to burn yourself, and give it about a quarter turn in a chosen direction, before even starting the bike,and ride the bike, and see if it's better, or worse. If better, then the next time you ride it give it another quarter turn i in the same direction . If worse go the other way a quarter turn past were you started. I remember using a finger of my left hand to push the bit in position, and turning a little with my right hand. It's awkward, but can be done. That being said, I later discovered that I had a tool that made it a breeze to adjust, aside from not being able to accurately count the turns. It was a small flat squeeze ratchet type thing. It doesn't have a square ratchet drive, but rather a hex shaped opening, and if I remember right you just turn it over to reverse it. I had it for years, and that's all I ever used it for. I'm sure you can still get them, but don't know what they cost . I bought mine, along with another small tool set at a flea market type sale that a local Church was having. Unless you really like that carb, it probably would make more sense to buy a Nibbi PE28FL, or a Nibbi PEZ, which is the same as the PE28FL, except it has a little smaller inlet on the breather side. I will try to find a similar tool , and post a link, or picture. https://www.amazon.com/CRL-Piece-Squ...4aAhNaEALw_wcB I am surprised that they are so expensive. I got mine, and another small set of tools for $5.00, if I remember right. I did see that eBay had several sets used for much lower, but honestly, unless I am missing something, I have never had any use for them, except for the time, or possibly two that I used it on the mixture screw Last edited by Bill Hilly; 03-16-2024 at 08:21 PM. Reason: Linking tool
	0

03-16-2024, 10:30 PM	#3
Nehrke Join Date: May 2020 Posts: 14	Reminds me of a book that has never been penned….a song that has never been sung. Thinking there has to be an easier way! Please help!!
	0

03-17-2024, 01:05 PM	#4
Nehrke Join Date: May 2020 Posts: 14	Update! I dug into a few more things this morning and didn't really come up with much. Took it for a ride to see how it was doing.....same old - got the RPMs and the speed up and it started bogging down and then dying. Funny thing is I noticed (finally) that when I went to restart it the choke lever had slid up approaching the clod start position. Starting to make sense! Ran home and tightened the screw that holds it and took it back out - running well again! Can't believe it took me this long to figure it out....but all seems to be realtively well in my world again. Hooray!
	0

03-17-2024, 01:14 PM	#5
dirtbkr188 Join Date: Aug 2009 Posts: 496	One of *THESE* makes life (and fine tuning) easier when the fuel screw is mounted in front of the float bowl.
	1