Jump to content

1980 720 carb problems


hatch

Recommended Posts

  • Replies 9
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Need more info. '80 720 should have an Hitachi 340 carburetor. Putting anything but a factory installed or California smog approved carb will not pass. Visually or emissions. The '80 carb has many emission connections that a weber simply doesn't have.

 

Fix your carb. The Hitachi venturies (I assume this is what you are referring to) are non removable. Non California are held in by screws on the back side of the carb.

 

A picture would sure help.

 

101_0101.jpg

  • Like 1
Link to comment

hatch - I suspect you have the same problem I've tried to describe in post #12 of this thread:

 

http://community.ratsun.net/topic/67183-have-2-dch340s-which-one-for-74-l18-620/

 

I don't know if my long rambling post there will clear things up for you or just confuse you. The important things if you have a loose small venturi holder is these are held tight in the carb body by a set screw pushing against the venturi holder from one end. The set screw is staked into the carb body and may not be easy to tighten or loosen. Between the venturi holder and tip of the set screw there should be a small flat spacer piece that may be missing if your holder is loose. On the opposite end of the venturi holder from the set screw, there should be a tiny O-ring where the fuel passage comes from the carb body. Not all carb kits include these O-rings although generic O rings may be available from a good auto parts store.

 

As I said in my post on the other thread, I chose to give up on the Hitachi with this style venturi holder, but that may not work for you in Cali. I also suspect a Weber may not be an option for you due to your smog testing there but someone from Cali will have a better idea on that than I do.

 

Len

  • Like 1
Link to comment

A couple of questions on this subject:

 

Does a 1/2 hour soak in carb cleaner damage the hidden O-rings on the ends of the small venturi holders (since they are not easily removable)? I know carb cleaner can damage some plastics, but I don't know about O-rings.

 

Can the staked set screws which hold the venturi holders in place be unscrewed without somehow grinding out the staking in the body? I thought of using something like a dental burr in a Dremel tool to grind out the staking, but don't know if it is necessary. I put quite a lot of force on a screw driver trying to loosen one of the screws but quit rather than damage the screw slot. I didn't have the carb body in a vise though (yes I would protect the carb body from the jaws with wood or plastic); I was just hand holding it. Probably PB Blaster on the screw might help too.

 

Len

  • Like 1
Link to comment

Yeah, I think they had to make it safe n sane for guys like me. :lol:  I've lost count of the number of times I've shot spray carb cleaner down a hole and had it blow back into my eye! The first time it happened it really scared me, but then I realized the cleaner just barely stings when it gets in the eyes. I do still go rinse my eyes with water when it happens, but maybe don't even need to do that. Pretty weak for a dangerous chemical.

 

Maybe the soak-a-carb stuff that comes in a bucket is more dangerous. I've yet to splash it in my eyes, but no doubt that will happen one of these days and I can give a full report (unless I'm blind of course).

 

Len

  • Like 1
Link to comment

i rebuilt it on thanksgiving , wish i would have gotten a better carb kit , the venturi o rings were not in the cheap ass kit i got . i was able to find a few and make them work , the venturi screws were a s.o.b. to get lose or out completely being 35 yrs old and pinned by the factory .. it works alot better now and i'll try to pass smog tomorrow.

thanks datzenmike and LenRobertson

Link to comment
  • 2 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

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...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.