Carb Problem

Howardr · Post by **Howardr** » Sun Sep 08, 2013 7:47 pm

So, I am trying to put the top of my carb back together and can't remember the correct order.

There is a spring, the pin and a "tripod" looking plastic piece. How do these go back together? I tried a couple of variations but once it's all back together, the bike starts fine and idles fine, but it won't accelerate past about 1/4 to 1/3 throttle.

Ideas? Suggestions?

Howard

PeteH · Post by **PeteH** » Sun Sep 08, 2013 8:34 pm

Here's an assploded diagram for the 125 carb. Don't know if it matches what you have on Iron Buddy:

http://www.scooterloungeonline.com/buddy125carburetor

Howardr · Post by **Howardr** » Sun Sep 08, 2013 9:35 pm

Well drat! I got it back together the right way and it still won't go over 1/4 throttle or so. This started right after I adjusted the valves for the first time. What else might I have screwed up?

PeteH · Post by **PeteH** » Sun Sep 08, 2013 10:30 pm

Is .08mm the correct cold clearance for the Big Valve head (as it is on stock), or does that head and valve train call for anything different?

No damage or misalignment to the carb diaphragm, since you had the topside of the carb open? I hear that's pretty easy to dork up. Were you chasing another problem which caused you to start carb surgery? Just trying to understand the sequence of unfortunate events: was it valve adjustment leading to bad performance, or something carby in between?

You -did- adjust the valves with the engine stone, dead cold, yes? And properly at TDC? Just asking the obvious, forgive me.

Howardr · Post by **Howardr** » Mon Sep 09, 2013 12:40 am

Coincidence. I developed some valve clatter since returning from Amerivespa. My shop had adjusted the needle in the carbon to compensate for riding down in San Diego. Specifically, he placed a couple of spacers under the needle. I opened the carbon and removed the spacers. Since then I get no more than about 1/3 throttle. The diaphragm looks okay. Anything specific I should look for? I'm not much of a mechanic. If there's a boneheaded thing that can be done, I probably did it.

Howardr · Post by **Howardr** » Mon Sep 09, 2013 12:42 am

Oh, and yes engine was cold and TDC when valves were adjusted

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 12:52 am

my guess.. for what is is worth. Was the seal on the diaphragm in good shape?.. it relies on vacuum to raise and lower so if it is not in the carb correctly it will go go over 1/4 to 1/2 just like you are describing.

If torn = new one
If not torn was it in the little grove around the metal of the carb? i use some vaseline " just a small amount" to make sure the diaphragm stays in the channel

Howardr · Post by **Howardr** » Mon Sep 09, 2013 2:03 am

@Throwback - I read your post, grabbed the vaseline and ran outside. I examined the diaphragm and I cannot see any tears or holes. I put a light coating on the rim of the carb and some along the lip of the diaphragm.

Nada! No change at all.

Should I look for something interfering with the travel of the needle?

Howard

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 2:23 am

See if the carb does this

http://www.youtube.com/watch?v=L4knwjlNC1o

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 2:24 am

Also what does the scoot do after 1/4 to 1/3 throttle ?

Howardr · Post by **Howardr** » Mon Sep 09, 2013 2:39 am

Throwback7R wrote:See if the carb does this

http://www.youtube.com/watch?v=L4knwjlNC1o

Would that require taking the carb off? I don't see how I could do that.

The bike starts, idles and starts off normally. However, once I hit 15-20mph, nothing else happens. I can roll the throttle all the way and there is zero change. No funny noise, it doesn't bog down. It just gets to about 20 and there's nothing else.

I've never had anything like it happen before.

Howard

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 2:52 am

you can leave the carb on .. just take the air intake off - air filter side!

What else did you do to the scooter?

Does the engine rev up more if you give it more throttle?

I would pull the carb just to see if the Slide is working correctly..

From the information I have " Currently" it points to the slide not working correctly. It would act as a restriction to the carb causing only a little bit of air to get through.

Just to make sure you have it installed correctly as well..

Black plastic cap, Spring, white thing should fit around the needle, needle

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 3:08 am

here is the order

Also make sure this is in the correct spot.

Just recapping for others in the future.

Howardr · Post by **Howardr** » Mon Sep 09, 2013 3:18 am

Nothing else has been done to the bike other than what has been described above. Well, at least not in a couple of years.

If the bike is one the centrr stand, it still won't Rev more than enough to go more than 20mph or so.

Looks like I need to pull the carbon. That will be first.

Howardr · Post by **Howardr** » Mon Sep 09, 2013 3:22 am

Throwback7R wrote:here is the order

Also make sure this is in the correct spot.

Just recapping for others in the future.

Thanks for the pica. I'll check it when I get some light. I don't know that my plastic piece is up inside the spring. Would that cause my problems?

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 3:35 am

Yes that would cause the spring to be a lot heavier and not open with the correct vacuum.

Howardr · Post by **Howardr** » Mon Sep 09, 2013 3:53 am

Couldn't stand waiting, so I put on my headlamp and went outside, in the rain. I made my spring look just like the pic.

also, no real change. Initially, it sounded like it may go higher, but it didn't.
After looking at your second pic, I do wonder if the diaphragm is seated correctly. I guess I'll order a new one and see what happens.

Howard

Thanks for the help.

Throwback7R · Post by **Throwback7R** » Mon Sep 09, 2013 12:18 pm

you should not need a new one as long as it has no tears in it.

try putting some vaseline in the metal part to hold it in place.

What else did you do to the scooter before this happened?

Howardr · Post by **Howardr** » Mon Sep 09, 2013 2:16 pm

When prepping the bike for Amerivespa, the shop added 2 small washers under the needle. They also turned to idle out half a turn.

As mentioned, after the rally, the vales were making a lot of noise so a friend was teaching me how to adjust the valves. While we were there, we decided to remove the washers under the needle because it was running very rich.

It the past, I had a 62mm piston done with a big valve head, however, no change was made to the carb. It is bone stock.

Howard

Throwback7R · Post by **Throwback7R** » Tue Sep 10, 2013 2:58 am

You did not install a different main jet?

Howardr · Post by **Howardr** » Tue Sep 10, 2013 2:43 pm

The work was done at my local dealer a couple of years ago. Now that you mention it, I think he may have increased the the main jet, but I wouldn't swear to it.

Howardr · Post by **Howardr** » Sat Sep 14, 2013 2:47 am

Just ordered the new part with the diaphragm off of scooter lounge. They have a 2 week delivery time. Ugh!

I can't see anything wrong with the current diaphragm but it sure acts like there is some kind of vacuum issue.

Any other ideas?

Howard

Throwback7R · Post by **Throwback7R** » Sat Sep 14, 2013 12:28 pm

did you pull the carb out and check to see if the slide " when lifted" goes back slowly?

Howardr · Post by **Howardr** » Sat Sep 14, 2013 6:49 pm

Unfortunately, I think pulling the carb off may be a little outside my skill set. That will have to wait until I completely give up and decide to take the bike back into the shop.

For what it's worth, if I rev the motor and keep the throttle wide open, the motor will gradually increase RPM's to close to full. However, if I am riding, it still won't go over about 20mph.

Howard

Throwback7R · Post by **Throwback7R** » Sun Sep 15, 2013 4:26 am

If you just disconnect the front hose clamp and the rear hose clamp and leave the gas line connected and the throttle cable connected it just comes right off " much like a coolant line in a car"

Also doing what your saying leads me to think it is vacuum

Too bad your not closer I would totally help ya out.

Howardr · Post by **Howardr** » Tue Sep 17, 2013 6:42 pm

okay, I made a short video. It shows me taking the top of the card off and looks at the way the parts are assembled inside. Please check it out and tell me if anything looks wrong.

http://youtu.be/YbCZgJc8GVo

Howard

charlie55 · Post by **charlie55** » Tue Sep 17, 2013 7:35 pm

In your case, I don't know if the plastic piece at the end of the spring (spring seat) has a hole through the center of it. If it does, then are you absolutely sure that the needle is below the piece and not through it? That was the problem I had when I did some work on my Blur a few years ago. Take a look at my post in the following thread for a diagram and description:

viewtopic.php?p=192739&highlight=