Jump to content

Carb Issues ... the saga continues


Recommended Posts

Hold the presses ... springs are RED by the way...

 

So to reinvent the wheel I go backwards yet again and start at the source - the fuel cell - shined a light in the tank and despite it being brand new and previously blowing all the lines out I find this crap on the bottom:

 

GasTank_zpsv9jz8v8d.jpg

 

and this in the catch

 

PumpCatch_zpsaks3zz0v.jpg

 

What in the world is going on?

 

So, now I got to figure out where and the easiest way to drain 10 gallons of gas and remove the tank to rinse (I assume). More importantly, is there more of this in my lines now and what's the best to get rid of the same? Any suggestions? Thought about buying a 12v fuel pump, hooking my inverter to it, and circulating it for an hour or so with a fresh filter, but not sure if this will catch everything, let alone what may be lurking in my lines now.

Link to post
Share on other sites

That doesn't look to be enough to cause problems. Drop the float bowls off the carbs, put a container underneath, and turn the engine over on the starter, with the plugs out and the LT lead to the distributor disconnected. That'll flush out the crud that has got past the filter in the fuel pump.

 

Pete

Link to post
Share on other sites

That doesn't look to be enough to cause problems. Drop the float bowls off the carbs, put a container underneath, and turn the engine over on the starter, with the plugs out and the LT lead to the distributor disconnected. That'll flush out the crud that has got past the filter in the fuel pump.

 

Pete

The good news is I have another in line filter b/w the pump and the carbs, so there shouldn't much to the carbs. Bigger question is what the heck do I do about the crap? Wonder how bad it is affecting fuel flow to the carbs at throttle. Kind of hard to dial in A/F when the fuel is not flowing normally. At least the catch worked for the big stuff. Bigger wonder is why would a new tank create this mess and/or was this mess just in the lines despite my attempts to blow it out?

Link to post
Share on other sites

I Think Yellow is the preferred Spring to use with the Richer Needles.

Take Petrol Pipe supply to the Filter Off,insert Compressed Air Line and blow all back into Tank,Remove Tank and Clean Out.

PS,remove Filler Cap before above.

Link to post
Share on other sites

I Think Yellow is the preferred Spring to use with the Richer Needles.

Take Petrol Pipe supply to the Filter Off,insert Compressed Air Line and blow all back into Tank,Remove Tank and Clean Out.

PS,remove Filler Cap before above.

Actually ordered a set of TW (Standard) needles this week. So hopefully with the new reds they will work well - but first another flush apparently.

Link to post
Share on other sites

I had an issue with intermittent rough running and the rear 2 plugs fouling and it really baffled me. Finally tracked it to the jet in rear carb being loose! You could push the whole jet up and down by about 10-15 MM. This was causing what could only be described as "variable mixture control" NOT good. Check it by grabbing the jet body (black tube under the carb) and try moving it up and down. It should not move, (it should only move when the choke is used). If it does then the carb needs to be stripped and the jet re-assembled. Not difficult. It was just after I had stripped and rebuilt the carbs so it was all down to my shoddy workmanship!

 

I bought a carb balancing devise recently. I am really impressed and my carbs are really nicely set up now. A point to remember, but easily overlooked. is the "freeplay" between the central linkage and the individual throttle spindles. I adjust mine so both have zero movement. with the throttle at idle, but equally you could adjust both to have maximum freeplay It does not matter as long as both are the same. It is easy to forget this little adjustment. When the carbs are loosened on the linkage and then reconnected, if one nut is tightened up with the peg in the upper position and the other in the down position there will be different responses from the carbs when the accelerator is pressed and all your time and effort in balancing the carbs will have been wasted.

 

I have seen people adjust their idle speed by turning just one of the carb idle screws with the carbs linked. Not a good practice to have balanced carbs as we all know.

 

I know some people curse the SU's but if you understand them they are quite easy to keep in tune. I have owned my TR since 1975 so I have spent many an evening tweaking (AKA swearing and cursing) and tuning. I am not an expert but a lot of practice does help! The SU's are really quite simple devices and once set up should be good for thousands of miles without touching them.

 

Cheers

 

Simon

Link to post
Share on other sites

Thanks Simon. The rear carb, when I pull on the end of the black choke does move maybe 1/8"+. Front is solid. Guess I'll have to order two jet kits and replace them both while I have them off the manifold.

Link to post
Share on other sites

Not necessarily.

4A SU's

 

1/Check that the small philips screw that attaches the jet (the black tube) to the choke spindle (via a bracket) If loose then tighten and your woes are over, This screw often loose because it is difficult to access as your screw driver hits the filter bowl, If loose the jet will not return fully to off after use causing mixture mayhem.

2/ The choke return spring either has not fallen off/exists/or is still stiff

3/ spray some WD40 on the jet return springs. These are nasty little springs that sit each end of the choke connect shaft. Unfortunately these springs are pretty important

to ensure the choke returns to fully zero when choke pushed in.

 

IMO most carb problems are due to wrong choke adjustments. If jet mixture is a few flats off the best mixture it will not matter too much. MOST PROBLEMS HAVE A SIMPLE ANSWER

 

Cheers

Simon

 

really advise you all check that tiny Philips screw is tight

Link to post
Share on other sites

'hits the filter bowl' That was a typo I meant to say float chamber. Anyway, difficult to access this little screw, especially the rear carb, hence often the rear jet assembly loose.

 

Simon

Link to post
Share on other sites

'hits the filter bowl' That was a typo I meant to say float chamber. Anyway, difficult to access this little screw, especially the rear carb, hence often the rear jet assembly loose.

 

Simon

You mean impossible to to access .. lol

Is that the only screw that secures it from being lose?

Link to post
Share on other sites

Hi

This little screw attaches the choke link lever to the base of the jet. If it comes out or loose then the jet will not return to its proper position after the choke has been used. So if rough running is experienced after choke use it is well worth checking this screw. The choke link lever goes to the choke link rod. At each end of the choke link rod is a spring that puts the correct tension on the link lever so there is 'closing' pressure on the jet assembly when the choke is not in use. These springs are important and often miss-assembled (I have done it) after a carb overhaul. There is a 'tang' on the spring that is supposed to be to the correct side of the link lever so as to pre-tension the link lever. If this tang has not been correctly positioned there will be no natural pressure on the link lever and so no pressure on the jet assembly to slide shut after choke use.

Am I making sense? It is difficult to explain.

In a word Yes. This little screw is vital in securing the jet assembly. Use the smallest ratchet with the smallest phillips socket to tighten it. or take the carb off and do it on the bench!) As I said the float chamber gets in the way of the screw driver. No screw or loose screw = no upwards pressure on the jet assembly. Of course, if the screw is missing the choke will not operate in the first place as the link lever is operated by the choke cable,

 

The little springs mentioned above are of quite complex engineering design, not 10p items. I think the cost of new ones is around £8.00 so they must be important!

This is the set up on the 4A with SU's. It is slightly different on the 4 but the theory is the same.

 

Cheers

 

Simon

TR4A

Link to post
Share on other sites

Carb removal and jet rebuild week - any tips or things I should look for that aren't obvious? I want to do this one time and correctly on the first try ... :D

 

On the screw on the bottom that seems to loosens, would a drop of Loc-tite be advisable? At least the vibrations shouldn't wiggle it free.

 

Thanks,

 

Don

Link to post
Share on other sites

NO! Do not use loc-tite. Get an SU carb re-build kit. They are not expensive. Comes with all the gaskets, jets, needles etc. Also comes with new butterflies but I have found they are not needed unless your throttle spindles are worn and need changing. Get a can of aerosol carb cleaner and lots of clean lint and thread free rags. Also a can of compressed air and lithium grease useful

Try and get a jet centring tool as it is important the jet is 100% centred and this tool saves a lot of hit and miss adjustment. There is a huge amount of information on the web as to how to do this job together with videos and u-tube postings. EVERY TR owner has had to do this job once in a while so it definitely not rocket science.

Once you have overhauled the carbs (around 2 hours a carb first time around) make sure you assemble the throttle and choke linkages correctly. Hint. DO NOT remove the jets return springs from the choke stub spindles unless you have taken loads of pictures from all angles so you can remember how to re-assemble. These springs are not the ones at the bottom of the black jet.

Once you have re-built the carbs tune carefully, There is also volumes written on tuning SU carbs available for you to download.

 

What's the weather like in Florida at the moment? Turned cold in England so could pop over this weekend on a cheapy flight and sort it out with you. Trouble is your beer a bit like p...s

 

Cheers

 

Simon

Link to post
Share on other sites

90F and sunny ... and no, I always have a good keg in hand (currently Sam Adams Boston Lager) ... especially when working on the TR4. I can't drink the piss either #BudLight, #MillerLIte, #CoorsLight ... :D

Link to post
Share on other sites

First hurdle passed with decent beer. I am probably needing to go to Florida in early May, either Orlando or F/Lauderdale. Where are you?

 

Simon

Link to post
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.   Restore formatting

  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

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.