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MG Midget and Sprite Technical - Seeking the SU Guru

OK before I start going further than I have to I thought I would see if anybody may have some direction for my.
I have a 1973 1275. Car has done 18,000 miles. Smog equipment has been plugged and air pump removed.
After the Headgasket was replaced, got everything back together. With nice clean head, I decided to degrease engine and cleaned a lot of grease off Carb. Had an issue with leak in manifold causing high idle which I resolved. Ran Car over weekend but after starting, choke was sticking and with choke fully in I had to push the return on the choke linkage. Car ran well for 70 miles over weekend. The throttle was not returning during gear changes and cars tacho showed 2500 rpm during gear changes. If clutch was held in, revs would drop. My first thought was the return springs for the Choke and the Carbs, but I just want to be sure (Original return springs). Not that I don't want to waste $10.50 I thought I would get everything I needed or if there is something else I need to look at. I am guessing at only 18,000 carbs should be ok.
Thanks
Allan
Allan Jacks

Sure you have the springs in the right places? Accelerator cable action smooth?
If the revs are dropping with the clutch pedal down, it sounds like an issue with the crank thrust bearings; better check them out soon.
David "waiting for Godot" Lieb
David Lieb

I will check the springs to make sure I dont have one out of place.
Regarding the gear changes, the revs increase as soon as I engage the clutch, they drop down a little if you hold the clutch in. Like the carb is taking a while to return. Maybe I should change the accelerator cable also.
Allan Jacks

Did you check that the over flow vent is clear (on top of the fuel bowl where the fuel shoots out and on to the hot manifold when float needle gets clogged and you have to bang on the side of the fuel bowl to clear it so it will stop shooting gas all over the place...."that vent" It can get cloged up and will cause the engine to run around 3000 rpm at idle.

Sure the linkage isnt binding up somewhere I had a nasty little problem a year ago with the choke JUUUuuust barely hanging on the back carb and causing all kinds of back fireing problems, never could find it till I tore it down,,, the little spikey lock washer wasnt fully closed and thats what was catching on the linkage touch it with a light finger and it would snap right into place

Does the gas pedal work smoothly, back and forth, no hang ups, no flat spots, you press it in its smooth, you let off and it comes back with no vibration, hesitation or noise, sometimes a bad cable take 300 miles to make itself known...and boy do they wear out...about 1 every 2 years...have one custom made at a bike shop with high end cables they will last around 20xxx with no problem....or maybe thats just me. But the point is they can stick at higher revs and slowly release them selves.

Prop
Prop

If you do, the best source for an accelerator cable is the local bicycle shop. Buy the sweetest braided stainless steel cable with teflon-lined sheath and it will still be cheaper than a trashy accelerator cable from any of the usual suspects.

You miight still want to have someone push down the clutch pedal (engine OFF) while you pry back on the crank pulley and check for movement front to back of the crankshaft. Not as common with the A-Series as with the 1500, but still can happen.
David "it is the best way to find out..." Lieb
David Lieb

Wow, I haven't replaced either Choke or accelerator cable so they are at lease 3 years old. No it doesnt come back very smoothly but I thought that maybe due to spring tension. Even looking at the Carb Cable surround, I wonder if PO got wrong length as I have alwasys had to play with cluch by pulling out slightly and then back in quickly to disengage.

Prop I still have the head, just been busy in not sending. Sorry and thanks for the advice to get a complete head, it worked out great.

Allan
Allan Jacks

Thanks David. Can you replace the Carb cable with a bike cable or is it connected to the T Cable Pull.
Also is it better to get metal or plastic casing for cable.
Thanks,
Allan
Allan Jacks

hold up on the head, I hope to find out how its going to work in the next few weeks plus I hope to be building the engine late next week, I just finally got this last head ported out over the weekend, It appears to have turned out really good from the looks, alot better from the 1st one I did this last winter, I cant wait to see how it does in real life....its a mad dash to get the engine done now. If the head works like I hope, Ill certianly help you out,,,btw, dont remove the valve guilds if you havnt done so...the porting goes alot easier with them in, then replace the guilds after the porting is done.

On the accel. cable....

open the carb throttle completely open and jam a huge screw driver down between the linkage and the heat shield to hold the linkage open then crawl in the driver hole and pull the accel pedal all the way up, that will release the tension on the cable the little noddie fits into the vary eend of the peddle linkage work it out then unbolt from likage at the carb...take the cable to a high end custom bike shop....not kmart, or sears, but high end and have one custome made like david makes note of...

(Buy the sweetest braided stainless steel cable with teflon-lined sheath)

Prop
Prop

Allan,
The choke cable is different. I have heard of people using a lawnmower throttle cable for this and grafting it to the handle, but I would be inclined to use a new one. No real need to replace the housing on it usually (unless it is kinked), just cut off the carb end and pull out the old one, spray some silicon lube (or whatever you favor) down the housing, then slide the new core into place.

As far as the housing for the accelerator cable, most of them are a wound metal with a plastic coating. The good ones are teflon lined inside. Work carefully installing it to avoid ANY kinking of the cable near the carb end as this will cause hangups. When you cut the cable to length, it can be helpful to run a little silver solder into the cable where you are going to cut it so that you can eliminate the fraying before it starts.
David "the cable slows down the bike and speeds up the Spridget???" Lieb
David Lieb

Allan

Just a thought, and probably a red-herring, but I assume you have had the air cleaners off to check the carbs are returning properly. An anonymous midget owner had a fast and poor-running problem. Several "experts" embarased themselves with wrong ideas, then we found this.......

Andy C


(It's one of the air-cleaner spacers. The bolts should go THROUGH them!)


Andy Pie-Crust

Andy,
That made me laugh but totally believable. I did have the air cleaners off. I would guess this has happened to more than one person.
Allan
Allan Jacks

This thread was discussed between 30/04/2009 and 01/05/2009

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