I don't have anyone to operate the key so have to do the testing myself. All I know is, with the pipe on the left disconnected as shown in the photo (and I assume this is the pipe from the fuel pump via a filter) turning the key for a second or two results in a wet patch of petrol on the inlet manifold under the disconnected pipe. Because I'm turning the key, I can't see where exactly the fuel is coming from, but I assumed it's from the disconnected pipe. The seller did say he'd had the carbs off due to a "flat spot" he'd been unable to correct, however, it did run for a while after I took delivery of it so I don't see how the carbs could be on the wrong way around.
 
Landlover99 said:
I don't have anyone to operate the key so have to do the testing myself. All I know is, with the pipe on the left disconnected as shown in the photo (and I assume this is the pipe from the fuel pump via a filter) turning the key for a second or two results in a wet patch of petrol on the inlet manifold under the disconnected pipe. Because I'm turning the key, I can't see where exactly the fuel is coming from, but I assumed it's from the disconnected pipe. The seller did say he'd had the carbs off due to a "flat spot" he'd been unable to correct, however, it did run for a while after I took delivery of it so I don't see how the carbs could be on the wrong way around.
Click to expand...
If you cant see it dont "assume" it comes out of that pipe ;).
If you are on your own just tape a couple of little ziploc bags/ballons/ condoms over each end then you will know which way the fuel is flowing.

J
 
That's fair comment indeed, Marjon. But when I made that assumption I was unaware there was a return pipe. I simply assumed (yeah, that word again) that for some reason, each carb had its own fuel feed.
 
Yes, that would have saved me all sorts of time when I put the electronic ignition on it! I must get one of those; I was told you can get 'em off Ebay and I must have a look as a priority. You can't get anywhere near the solenoid on this model as it's buried right underneath the lump out of sight. :rolleyes:
 
Landlover99 said:
That's the problem with this type of carb. As you can see from the photo, the float chambers are the concentric (to the main jet) type and there's not enough clearance to remove them separately. I prefer the older design with the float mounted remotely and connected by a fuel bridge as you could further isolate the fault with those.
Click to expand...
Me too, but it looks like you are going for a strip down and clean up anyway, rather than just getting them working quickly.
I just hope that your work with taking them to bitz and ultrasonically cleaning them doesn't end up with you having to retune them too much.
 
I just thought before I did anything drastic I'd better just try just one last thing. I popped the top off one of the carbs and momentarily inserted a cocktail stick into the main jet hole. It was bone dry, save for a tiny bit of petrol right at the far end. So by that discovery, it just seemed most likely to be stuck float valves. It The engine runs with Easy Start and by clouting the carb bases a few times, spinning the engine over on Easy Start and repeating this process a few times it became apparent the engine was trying to fire after the initial squirt of Easy Start had worn off. I just kept on repeating this cycle a few more times and the engine finally roared into life. So those of you who said it was most likely float valves stuck shut can give yourselves a big pat on the back!
Thanks, guys. :vb-drink:
 
Landlover99 said:
I just thought before I did anything drastic I'd better just try just one last thing. I popped the top off one of the carbs and momentarily inserted a cocktail stick into the main jet hole. It was bone dry, save for a tiny bit of petrol right at the far end. So by that discovery, it just seemed most likely to be stuck float valves. It The engine runs with Easy Start and by clouting the carb bases a few times, spinning the engine over on Easy Start and repeating this process a few times it became apparent the engine was trying to fire after the initial squirt of Easy Start had worn off. I just kept on repeating this cycle a few more times and the engine finally roared into life. So those of you who said it was most likely float valves stuck shut can give yourselves a big pat on the back!
Thanks, guys. :vb-drink:
Click to expand...
Glad you got it sorted! :)
 
It’s normally the tips on the float stops. They are rubber type & get a ridge on them & then stuck(that’s why you give them a tap to release them)
SU do good rebuild kits probally takes longer to get the carbs off than to rebuild
 
Yes, it would doubtless be a good idea to rebuild them. I did notice when I had the offside one's top off that the needle of the main jet was off-centre. I think they're supposed to automatically snap to the centre through some springs, but that one twanged off to one side and is presumably rubbing against the inside of the jet it runs within. Not sure if that would have any effect on performance or not, but it's certainly undesirable.
 
I'm sure you're supposed to centralise them but i never never figured out how that was possible.
When the piston is fully seated, turn the screw on the needle, but the screw isn't accessible at that point!! At least not on mine
Edit: seems like you centralise the jet not the needle and the purpose is to stop it binding
 
kermit_rr said:
I'm sure you're supposed to centralise them but i never never figured out how that was possible.
When the piston is fully seated, turn the screw on the needle, but the screw isn't accessible at that point!! At least not on mine
Edit: seems like you centralise the jet not the needle and the purpose is to stop it binding
Click to expand...
Peeps haven't needed to do that for a long time. Sprung ones do rub on the jet but that isn't allegedly, a problem.
 
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