Carb driving me crazy....

[TexasTiger01]

Hey guys,

Long time reader, first time poster looking fro some advice. I bought my son a 2001 Blaster for Christmas. FMF gold pipe and air box lid delete. It ran ok besides the carb leaking. SOOO, I rebuilt the stock carb (.230 main jet) and finally got the float set to stop the overflow leak. It ran good for a few weeks, never idled great...As usual, not being able to let well enough alone... I ordered a new carb off of ebay and jet kit. I also ordered a pryamid reed block. Long story short and 4 cheapy carbs later, multiple jet changes I have the stock carb back on with original jetting. The problem has been a midlrange pop (seems lean to me) with all configurations. Cannot get to WOT it is so bad. Bottom end is ok.

I have done a crankcase pressure test, 6PSI for 8 minutes, no leaks. I even went back to the stock reed block, same problem. Original main jet is .230, 32.5 pilot, and needle in 3rd clip. I have went all the way up to .340 main with no real change. Compression is 100psi.

Any advice before I send this thing to the Yamaha shop and waste alot of money??

Also, I'm in Houston Texas. Pretty much sea level.

Thanks guys!!!

 

[TexasTiger01]

Hey guys,
Long time reader, first time poster looking fro some advice. I bought my son a 2001 Blaster for Christmas. FMF gold pipe and air box lid delete. It ran ok besides the carb leaking. SOOO, I rebuilt the stock carb (.230 main jet) and finally got the float set to stop the overflow leak. It ran good for a few weeks, never idled great...As usual, not being able to let well enough alone... I ordered a new carb off of ebay and jet kit. I also ordered a pryamid reed block. Long story short and 4 cheapy carbs later, multiple jet changes I have the stock carb back on with original jetting. The problem has been a midlrange pop (seems lean to me) with all configurations. Cannot get to WOT it is so bad. Bottom end is ok.

I have done a crankcase pressure test, 6PSI for 8 minutes, no leaks. I even went back to the stock reed block, same problem. Original main jet is .230, 32.5 pilot, and needle in 3rd clip. I have went all the way up to .340 main with no real change.

Any advice before I send this thing to the Yamaha shop and waste alot of money??

Also, I'm in Houston Texas. Pretty much sea level.

Thanks guys!!!

 

[Slydog]

What's your compression at now after running a way lean 200 main and multiple Chinese carbs with the fmf and lid off??? Stock needle
Is #5j22 check number on yours.thats the one that should have originaly been in carb. That is the one you need in the stock carb. If it doesn't have that # the taper is wrong.instal 5j22

 

[TexasTiger01]

What's your compression at now after running a way lean 200 main and multiple Chinese carbs with the fmf and lid off??? Stock needle
Is #5j22 check number on yours.thats the one that should have originaly been in carb. That is the one you need in the stock carb. If it doesn't have that # the taper is wrong.instal 5j22

Ok, I verified the needle to be a #5J22. It is set on the third notch.

Verified the original main jet to be .230, not a .200 as stated before. ( been dealing with may to many jet sizes in the past weeks lol).

Compression is 100PSI. It cranks first kick and performs well in low range, as soon as it hits mid range it spits, pops, and sputters.

Should I move the needle position? It's currently set on the 3rd notch...


it's blowing my mind because this exact setup worked fine when i first got the bike

Also, just verified the main jet washer is in place and pilot jet is 32.5

 

[TexasTiger01]

 

[Awk08]

"adjusted the needle to stop the leaking" <<<< does that mean you just kept adjusting it until the leak stopped or actually adjusted it per specs to 20 - 21.5mm ?

https://www.blasterforum.com/threads/float-heights-and-how-to-adjust-them.50565/

needle clip in the middle slot
genuine mikuni jets ?
completely disassembled carb to get to and clean the tiny holes in the needle jet under the main ?
that's the sole purpose of the brass washer under the main jet, it holds the needle jet down in, pushing it up into the carb with light taps on a wood dowel or correct size 1/4 drive deep socket, gets it out to clean.

 

[TexasTiger01]

"adjusted the needle to stop the leaking" <<<< does that mean you just kept adjusting it until the leak stopped or actually adjusted it per specs to 20 - 21.5mm ?

https://www.blasterforum.com/threads/float-heights-and-how-to-adjust-them.50565/

needle clip in the middle slot
genuine mikuni jets ?
completely disassembled carb to get to and clean the tiny holes in the needle jet under the main ?
that's the sole purpose of the brass washer under the main jet, it holds the needle jet down in, pushing it up into the carb with light taps on a wood dowel or correct size 1/4 drive deep socket, gets it out to clean.

Thanks!!!!! The needle jet was dirty, cleaned it and verified the float and she is running as good as when I bought her. (which is still not great IMO) My son is stoked!!

My next question; in your opinion is my .230 main jet too small. I have deleted oil injection, FMF Gold Pipe, and Airbox lid delete with K&N type filter. I have always suspected from everything I have read on this site that with these mods I should be running a .300-.340 in my area (Houston,Texas) which is pretty much sea level.

I'm gonna do a plug chop in the A.M, but I suspect to find it lean due to the engine still not running as good as I would expect it to and the warmer the engine gets, the worse she sounds.... Or maybe it's just been too long since I've rode a 2 stroke

Thanks for the help!!!!!!

 

[Slydog]

Ok, I verified the needle to be a #5J22. It is set on the third notch.

Verified the original main jet to be .230, not a .200 as stated before. ( been dealing with may to many jet sizes in the past weeks lol).

Compression is 100PSI. It cranks first kick and performs well in low range, as soon as it hits mid range it spits, pops, and sputters.

Should I move the needle position? It's currently set on the 3rd notch...


it's blowing my mind because this exact setup worked fine when i first got the bike

Also, just verified the main jet washer is in place and pilot jet is 32.5

At 100 on compression. Thats low. What main jet is in it now? 230 is not going to work with the fmf pipe. Need jets around 280-310 usually for that pipe

 

[TexasTiger01]

At 100 on compression. Thats low. What main jet is in it now? 230 is not going to work with the fmf pipe. Need jets around 280-310 usually for that pipe

Thanks man, probably do a new top end in the near future.. Maybe a big bore kit.

.230 main jet is what is in it now, that's what it had in it when I bought it with mods. This is what the plug looked like after I did a pull. LEAN

The smallest jet in my jet kit is a .340. Any suggestions on where to get individual jets? I'll try to find a site sponsor....

 

[Slydog]

View attachment 34572

Thanks man, probably do a new top end in the near future.. Maybe a big bore kit.

.230 main jet is what is in it now, that's what it had in it when I bought it with mods. This is what the plug looked like after I did a pull. LEAN

The smallest jet in my jet kit is a .340. Any suggestions on where to get individual jets? I'll try to find a site sponsor....

I get all

View attachment 34572

Thanks man, probably do a new top end in the near future.. Maybe a big bore kit.

.230 main jet is what is in it now, that's what it had in it when I bought it with mods. This is what the plug looked like after I did a pull. LEAN

The smallest jet in my jet kit is a .340. Any suggestions on where to get individual jets? I'll try to find a site sponsor....

Jetsrus. And some others have all the genuine carb parts you could ever need.do not use aftermarket jets. Is your float set right as mentioned above. That has to be right before you can go any further.Buy a 4 pack or more of plugs. Get the jets mentioned. Start big an do plug chops to confirm what main jet you need. That couldn't have been a new plug?

 

[TexasTiger01]

I get all

Jetsrus. And some others have all the genuine carb parts you could ever need.do not use aftermarket jets. Is your float set right as mentioned above. That has to be right before you can go any further.Buy a 4 pack or more of plugs. Get the jets mentioned. Start big an do plug chops to confirm what main jet you need. That couldn't have been a new plug?

Plug had about an hour run time on it. I just ordered a pile of plugs

I put a .290 main jet in it yesterday. The bike lags midrange and doesn’t like WOT. 3/4 throttle and it performs fairly well. Would a .35 pilot help the low/midrange performance?

Thanks again for all of the help!!!

 

[Slydog]

Plug had about an hour run time on it. I just ordered a pile of plugs

I put a .290 main jet in it yesterday. The bike lags midrange and doesn’t like WOT. 3/4 throttle and it performs fairly well. Would a .35 pilot help the low/midrange performance?

Thanks again for all of the help!!!

Assuming the carb is cleaned good like awk mentioned?The stock pilot works on almost all pipes and mods.there is a sequence that must be followed. If one is off it throws everything off. Float set 20-21.5. flooding issues fixed? Then set air screw adjustment to achieve highest idle. Which is explained if you look up tuning or jetting
Did you change the stock slide by chance?

 

[Slydog]

This will give you a general understanding of throttle positions and what circuits are involved

hope this helps

 

[TexasTiger01]

Thanks for the help guys. I got it running now with a .290 main.