Jump to content

Beta Rev 3 carb leaking please help.


betabell
 Share

Recommended Posts

 

  • Replies 37
  • Created
  • Last Reply

Top Posters In This Topic

Hello Dan. I am glad I am getting closer to how it should be set up. Should I have more or less travel?

I have put an new gasket on the float bowl but it did not make any difference.

Should I buy some new floats?

Edited by betabell
Spelling
Link to comment
Share on other sites

 
 
 

Two things. you never spray carb cleaner in a bike carb.( I know every one does it) So look at the gasket of the needle and seat. It will swell three times the size with carb cleaner. Also you have never shown your vent hoses. ps I only use contact cleaner on my bikes.

Link to comment
Share on other sites

 

Hello lineaway I did not know that you should not use carb cleaner in a bike carb. Having said that the float needle, the needle itself the needle gasket and the float bowl gasket where not sprayed with carb cleaner because they where all new parts. It does make me wounded about the carb drain bolt gasket, that would have had carb cleaner on it so I shall replace it. I will photograph the vents when I get a min. 

Link to comment
Share on other sites

 
On ‎5‎/‎8‎/‎2017 at 1:17 PM, betabell said:

Hello Dan. I am glad I am getting closer to how it should be set up. Should I have more or less travel?

I have put an new gasket on the float bowl but it did not make any difference.

Should I buy some new floats?

No I think you checked your floats and they were good so not the floats. Your float level is pretty good now too. Only happening at 3/4 throttle is the odd thing that still points to vibration in my mind. Possibly a casting defect. This is a tricky one. I will give you credit for being persistent and patient with this. It's the hallmark of a good mechanic.

Mikuni tang2.jpg

Link to comment
Share on other sites

 

The top arrow adjustment does not set the float travel but rather the needle seat travel.  The floats do what they want to do independently from the perpendicular tang.

If the floats go down hard from a drop off the small tang will always limit the needle travel.

Link to comment
Share on other sites

 
 
 
10 hours ago, billyt said:

The top arrow adjustment does not set the float travel but rather the needle seat travel.  The floats do what they want to do independently from the perpendicular tang.

If the floats go down hard from a drop off the small tang will always limit the needle travel.

Fair enough. Wanted to keep it simple in practice.

Link to comment
Share on other sites

 

I don't believe the Mikuni uses a stand pipe like the Keihin. If I remember correctly a bore in the float bowl lines up with a hole in the bottom of the carb body and there is an overflow hole into the top of the float chamber.

Link to comment
Share on other sites

 

Betabill

In looking in more detail at your float bowl. Specifically the part where my pen is pointing to the marks/gouge is witness mark that at some point in time there was an issue with the pin that holds the brass tangs to the float carb body.  This heavy gouge mark means that the pin was not in securely when the carb was placed back on the float bowl.  After working with this carb for many many years I had seen one of these gouges before where it put a hair line crack in one of the posts and caused all sorts of flooding issues.  

The pin can and will float about from left to right however this is not on the side but rather a mark that has been forced into the top due to poor fitment.

Can you get  take a better more detailed picture of this area on the float bowl? 

 

 

FullSizeRender.jpg

Link to comment
Share on other sites

 

Hello feetup my cab does not have an overflow standpipe. It is exactly as dan described, it is built into the castings of the carb body and float bowl.

Interesting point billyt about the mark in the float bowl. I completely missed that, well spotted. The pin has always been in place when I have taken the carb apart many times, but as you say it there has clearly been some kind of problem in the past. I will take a better photo of this, it will probably be not for a couple of days.

So I had some time yesterday so was messing around with the bike, I remember people mentioning about the floats catching on the gasket. So I had a look and noticed two things. Firstly the gasket did sick out one side a tiny amount we are talking 0.5-1mm.  So I carefully trimmed this down but it made no difference. Secondly the casting of the carb where the gasket sits was not square. I will again take a picture of it. It may just be how they are all made, I don’t know? To describe where it is - there is a cut out where the gasket has a tab on that locates into the carb. It looks a bit like someone has hit it with a hammer. By that I mean that it is punched in a tiny bit, there are no signs of damage. As I say I will take a picture of it.

The other thing I was thinking about that you guys mentioned is the whole vibration thing. Specifically about the carb hitting the exhaust.  So I removed the silencer and the middle section and ran the bike but this did not make any difference. The fuel lines on the bike do touch the cylinder wall and a bit of the exhaust. I was wondering if they are a bit old and have gone hard could this be enough to disturbed the carb? I should say that I have ran the bike with one hand on the carb to see if that stabilizes it or if in some way that dampens the carb, but again it made no difference.

I have a question about a flat piece of metal in the carb that the needle seat bolts through. What is its function and can I remove it. The reason I ask is that I have noticed that it does not sit squarely in the carb. I could take it out completely or I could try and file it down to make it sit squarely. Again I will take a photo of this.

Thanks again for all the advice guys.

Link to comment
Share on other sites

 
 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share


×
  • Create New...