Very stiff choke control

[Pefkias]

My TA is fitted with an XPAG engine with what appears to be a fairly standard TC carb set up but the choke control is much too stiff.

From the carb numbers they are probably TD period and have the slow running linked to the choke control rather than the TA/TC separate control. Other than that they seem the same as TC spec.

I have done the obvious things like backing of the non standard slow running screw completely, cleaning the pull cable, cleaning and checking the choke tubes and their seals, making sure the cable moves easily when disconnected etc. I now wonder if the actual choke springs are incorrect and too stiff. Has anyone ever measured the correct spring pull? Were different springs used for the twin carb setup from the single carbs? Any clues to help me check if my springs are correct would be much appreciated.

Thanks
Cliff (Still in Skopelos Greece)

[Tom Lange, MGT Repair]

Cliff - there are really only a few places that things can be binding - the cable, or the jet assembly. I see that you have done some things already, but I would detach the cable from the carbs, and see from the dash if it moves freely. The cable is spiral-wound, so you can run oil all along the length of the outside of the cable, and it will work its way inside. I also VERY slowly feed a drop of oil at a time into the choke cable where it enters the dash, and that usually clears up any rubbing. Like the speedo and tach cables, the angle of the cable impacts the pull.

With the cable detached check the action of the jets and enrichener levers and linkage; if there is any binding or stiffness that obviously needs to be addressed. It's usually the gland washers in the jet holders that cause friction there; sometimes just putting a drop of oil on the jets helps them slide more smoothly. The mechanism should move completely freely, and the springs (there is only one type) should return the jets to their full and upright position, without any help or urging.

There is always disucssion on the Boards about the use of Teflon o-rings to replace the cork gaaskets which can leak when old, and which seem to grip the jets a bit more snugly. Other than these things, there really isn't anything else. If you still have stiffness in the jet assembly I would suggest a complete, professional re-manufacture of the carbs, which also addresses any loose throttle shaft issue.

As always, a few pictures would be a big help. Sorry if I am re-stating the obvious.

Tom Lange
MGT Repair

A picture

[frenchblatter]

Cliff, Tom has dealt with the issue for you. My experience has been the small clamp on the air cleaner bracket can squeeze the outer cable tight against the inner cable and make it hard to pull out. I remove the clamp completely and use a small bolt to reshape the clamp to being round again. It does need to grip the outer cable but not squash it.

[searunner]

[quote="Tom Lange, MGT Repair"]Cliff - about the use of Teflon o-rings to replace the cork gaskets which can leak when old, and which seem to grip the jets a bit more snugly. Other than these things, there really isn't anything else. If you still have stiffness in the jet assembly I would suggest a complete, professional rebuild/quote]

I agree with Tom suggestion
I have same problems with O-RINGS, stiffness was horrible and jets NOT return completely in position when the cable was pulled and pushed again in rest position- luckly my engine start without the use of coke cable in summer time -and engine in this situation run very well

[Pefkias]

Hi
Thanks to everyone that replied.

Tom's assurance that only one spring type was used was useful and I can eliminate incorrect springs as the cause.

I think I have found the solution to my problem. The angle between my pull cable and the choke lever was about 30 deg. Adjusting it to about 75 deg improved the leverage considerably. I compared some pictures of TA, TB and TC choke linkages from Clausanger's book. TA and TC angle is about 75 deg. The TB pictured is almost as bad as mine. My conclusion is that when the XPAG choke arrangement is mated to the TA bulkhead and cable then the cable routing and operating angle needs to be optimised carefully. Also I have noticed that there seem to be several differing variations of the brackets attached to the carb flange that restrains the cable outer sheath.

I will probably make a new bracket to optimise that angle.
Thanks again
Clifford Knight

[Duncan M]

If switching to the teflon o-rings the jet they slide against should be polished, with special attention to the openings (holes) in the jet tubes. Otherwise the choke will not operate smoothly.

[Franz Tenbrock]

Hallo
please make some pictures

I have also a TA but a XPAG engine
my choke works fine, but iw oukld like to see what you mean

Regards
Franz