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Rapide Carburetor overhaul

aaronabutt

Forum Website User
Non-VOC Member
Hi to all!

In the process of trying to start my 49 Rapide after 20 odd years of sitting around, I put some oil in the orifices and some gas in the tank and gave her a few kicks. I couldnt change the oil that had been inside due to a stripped crank nut that is surrounded by the engine plate. I didn't have the tools to mess with that so I jsut thought I'd give it a try with the old crap inside. What a bad idea! ( I only saw this bike for a few weeks a year, which is why I was unprepared with no tools). Well it started to turn over but it was very hard, and it sputtered a few times over the course of a half hour of kicking, and kept shooting blackened oil all over my door from the overflow hose. Then, upon checking why gas wasnt flowing, I saw that the tank sludge had now gathered and had clogged my gas filter and gone into the carburetor. Hence the questions:
1. Are my carbs gummed up throughout now, or is it just the float chamber that can be cleaned. I've cleaned Triumph carbs but these look a little more complicated.
2. Is there anything I should be careful of when rebuilding these carbs if I have to go deeper than the float chamber?
 

Albervin

Well Known and Active Forum Website User
VOC Member
I would more concerned that you have induced hydraulic lock from all the oil in the crankcase. Can you remove the oil filter? Replace if possible. If the crankcase drain plug is stripped how come it is staying in place? You could remove the big end quill to reduce crankcase pressure when kicking the bike over.
At the very least your main jet and needle jet will be partially blocked so I guess you should pull the carbs to bits, place in a bath of environmentally sound solvent and agitate. Dry off then place all bits in an ultrasonic cleaner full of a dilute water based surfactant. Dry off using high pressure air. If you remove the jet block be gentle, do not use a hammer. It should come out with gentle heat such as immersing in nearly boiling water for a couple of minutes. To refit, make sure you put it back right way round, put jet block in the freezer for a few minutes and it should just drop into the carb body.
Clean your petrol tank using fresh petrol or methylated spirits. Good luck.
 

aaronabutt

Forum Website User
Non-VOC Member
Thanks for your excellent advice and methods.Can you tell me more about what hydraulic lock is? How can I know if the lock you mention is present? I will remove that drain plug when I get back to the bike in late July. Sorry, I meant to say the head of the bolt was stripped, not exactly stripped, just a big notch in one side that effectively prevents the use of a slim socket to take it off without removing the right side engine plate. I will remove the oil filter as well as drain all the oil from the crank. This should make it easier to kick. I will drain the oil and clean the tanks, but I'm a bit worried about all the 'bits of carburetor'. Must I remove the jet block to get at the jet?
Ive never messed with the big end quill either, what will happen if the bike starts without that in place? OH, are all these old amal carbs whitworth as well?

Many thanks for your help with what must seem trivial to users of this forum! We young owners have a lot to learn and there is only one place to learn and that's from experienced owners. I am in the unfortunate position of being nowhere near anyone who knows anything about Vincents.
 

Albervin

Well Known and Active Forum Website User
VOC Member
Aaron, you need to get your hand on some books. Join the club and soak up all the info. One of the laws of physics states a liquid cannot be compressed. In this case the liquid is oil; if a large volume of oil is trapped beneath or above a piston then movement of the piston may lead to damage of an expensive nature. In your case the piston rings are probably stuck and so minimise that event. There are some sockets available that can deal with rounded heads, I use the Metrinch brand but there are others. Take out the spark plugs and squirt some upper cylinder lubricant in to loosen the rings. Removing the quill will achieve 2 things, you can clean it and check that it is not damaged. You only need to remove the carb jet block if there is a lot of muck in there. Carbs have various threads, without my books at hand I think they are all BSF and BA. I know there is a long term owner not too far from you so you are not alone.
 

greg brillus

Well Known and Active Forum Website User
VOC Member
Hi there, an easy fix for your rounded drain plug is to drill a 1/8 th pilot hole right through the center of it , put a drain tray under first, as you will most likely end up with the entire contents of the oil tank in the sump after all this time...could be as much as 3.5 to 4 litres....anyway open the hole in the plug out to no more than 3/8 ths of an inch in diameter and screw in stud removal tool of the type that bites in as you turn it anti clockwise, and this will remove your damaged plug. New plug part no A26 and sealing washer part no A27 readily available from the VOC spares co or other suppliers found on this forum. Cheers for now....Greg.
 

stumpy lord

Well Known and Active Forum Website User
VOC Member
Hi,
Be ware the tool I beleave that Greg is talking about is what we call an easy out, these tools are quit effective but care must be used when using them as they are britlle and very hard, a broken one can be the very devil to remove. so dont be to heavy handed on the easy out. Snap on do a set of screw extractors that are very good and not prone to breaking, but off course are expensive . stumpy lord.
 

greg brillus

Well Known and Active Forum Website User
VOC Member
Hi again, Yes Stumpy is correct, and thinking back when i did it the extractor set i used was indead a Snap On set. But if you use a larger sized one it should remove the plug without breaking....what's an easier alternative ??? remember that it's a relatively small plug with not a huge surface area on the washer, and provided that it hasn't been tightened up enough to hold the entire crankcase together.....famous last words.......Greg.
 

aaronabutt

Forum Website User
Non-VOC Member
Thanks to all
I will only need to sand the nick in the bolt and it should be ok
Have the beast ordered!
I really dont want to pull the head though
I take it will be evident if the rings are stuck as it will....

Ride on
 
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