Sputters at about 1/4 throttle

[Post edited]




Good Fortune!

Patton, that drawing is misleading. It shows the service level up to the edge of the carb body, but area 4 should start 2.5mm below the edge of the carb body. Si?

Alan

Haybus wrote: Patton, that drawing is misleading. It shows the service level up to the edge of the carb body, but area 4 should start 2.5mm below the edge of the carb body. Si?

Alan

Many thanks for the heads-up!

Will make the correction, and edit the post.

Good Fortune!

Ok. That is the way I did it. I measured from the visual transition between the bowl and the body (the edge), and I am at about 3 mm for each carb. Maybe I should check again just to be sure.

Thanks for the images, Patton.

I will go bleed my brakes and then think about what I will try next.

The image below shows the exhaust that I have on the bike. The headers are a bit old and banged up and leak a bit at the engine. Is it possible that this exhaust requires a rejet?



I will be getting a different exhaust at some point, but that exhaust is all I have for now.

I would think it's quite likely that you need a rejet. If your stock secondary main is 125 ( I need a magnifying glass to see ) then I would suggest changing that one to 130. They are cheap - $1.75 each from Z1 Enterprises. www.z1enterprises.com/ListItems.aspx?pag...e=20&keywords=keihin
The shipping would cost you more than the jets. I have 4 plastic or some kinda gas resistant 135 jets which you are welcome to FOC if you want to try them.... they may be to big but with that exhaust hard to tell. Just PM me with an address if you want and I'll pop then in the mail tomorrow.
Your carbs same as mine and there are no slots for needle clips so needles not adjustable

When checking the fuel level in the bowl I have found that it's best to actually measure with a ruler and the clear tube held against the carb body. You can hold the tube for carb 2 against carb 1 and that works. Spec is 4 +/- 1mm according to the Haynes manual.

Looks like silver bodywork. It will be nice to see a pic with side panels and tank when you ger er going.
Good luck

Thanks, JR. I will send you my details shortly. I will also check with my local dealer to see what they have (but they normally don't stock many jets).

From what I can see (using a magnifying glass as well), it is indeed a 125 jet. The pilot looks to be a 35 and the other jet is a 62 (but the 125 is the only one I am sure of).

For the fuel level, I used a marker to make two lines. One line was lined up with the edge of the carb body, while the second line represented the 3mm. Since the marker lines were think, it isn't the most accurate. I will use a ruler and try to be more precise.

You are correct about the needles not being adjustable. I see that some people shim them, but I don't want to mess with that until all other avenues have been tried.

Yep. The bodywork is silver. It is in fairly decent shape for the year, so I will most likely leave it as is. I will certainly post a pic once she is up and running.

Thanks again for your help.

Peter

Your method of measuring sounds pretty good and I'm sure its fine. I used to do eyeball but found I was way out when I actually measured.
I did check the Haynes manual and corrected my post above as the spec for fuel level 4mm +/- 1 mm, Getting the fuel level right in spec was the single biggest improvement I made to how my bike runs

Thanks again, JR. Those jets made a big difference! It still stumbles a bit, but nothing like before. If nothing else, it shows me that it is most likely carb setup and not electrical that is causing the issues.

I didn't do a proper plug chop, but the plugs are light grey to white. It also pops a small bit when I give it a good rev in neutral (but doesn't seem to pop on deceleration).

So, it seems to be a little lean (I think that is what it means). Would that mean I should go up a little more on the jet (I am now running 135 jets)?

Almost there!!!

I'm glad those jets are a help.
Plugs light grey to white could be normal to a tad lean.
Have you played with the air mix screws on the top front of the carbs? I think stock setting is 2 turns out from lightly seated and if you feel you need to rich things up a bit you could try unscrew each a quarter turn at a time before going to a larger jet. I've had those screws set at anything up to 3.5 turns out at times. I find it hard to imagine needing even larger secondary mains for just an exhaust but I guess anything is possible.
Regarding the small popping I'd probably be looking at vacuum caps and carb holders. I have had small popping in the past and found I needed Permatex #1 between the carb holders and the engine.
When you went through the carbs did you remove those air mix screws and clean? There should be the screw a spring a washer and an O ring - long shot
Edit
Just re read above and see you have some small exhaust leaks so possible reason for the popping there and might be something you have to live with until you eventually replace

I went around all the boots with carb spray and the rpm didn't change. Regardless, I will be buying new holders and boots just so I know they are fine.

I did clean out the mixture screws, but I used the old o-rings. I will be replacing those as well. I currently have them all set at two turns out, so I will start adjusting them out a bit to see what happens.

Maybe I will have it ready for next spring (stupid winter!!).

Finally, I will see if I can get a new exhaust system during the winter. The header I have is the type that uses springs to keep it tight. I just can't get it to seal properly. I am hoping a system with the collars will allow me to seal it up properly. I am thinking of the Vance and Hines 4 into 1.

Turning the mixture screw out 1/4 turn on each carb seems to have solved my issues. I can probably dial it in even more, but I am happy now that I am seeing some progress.

The 135 jets don't seem to be overkill, and I am not noticing any bogging. Once I get the bike set up properly and have it certified, I will be able to do some more intensive testing.

This thing can really pull when it is dialed in. I thought I was going to lift the front up a few times!

Thanks for all the help and suggestions. I have lots to learn, but you are all great teachers.

Peter