Forum

[PeteF]

I recently cured a problem with a flooding Monobloc and thought the fix might be of use to someone here. Write up is here. http://www.whfolk.co.uk/REOCHUMBER/Arti ... nobloc.htm

[Craig]

Thank's Peter, Very interesting.... As a New Comer to the MonoBlock I find any additional info helpful......("Some swear by Them,Some swear at them":AMAL)....Thank You..Craig

[Alan R]

Hi Guys----have just read the article indicated. I think that the amounts removed should be shown as }---- 0.010" ie 10 "thou"... As printed it is showing a removal of 0.0010" ie 1 "thou" and using a wood-turning lathe ???? For those not used to these dimensions------ the thickness of a line on an engineers rule is about 10 "thou". If you can find an old one with 1/100's shown ( ie 10 thou) then you will notice that the width of the lines is approx. that of the gaps between them. Useful when hand-fitting using a rule & calliper only. Now you can work down to + or - 0.005" by eyeball !! We had to and regularly at that.

[PeteF]

Oooops! Quite right Alan, I'll put that right.

[apparently lucky eddie]

I've had a running rich/flooding problem with my tiger 90 and when I've just checked there's the washer on the monobloc that should n't be there. Hopefully problem solved. Nice one, thankyou.

[Dennis C]

Hi Pete, When you know these carbs you forget that these are now being used far less and people using them now just don't know them as we did, being shown by my Dad many years ago I take it for granted how and why they work and what to do if they don't. -------- I hope you won't mind me saying that an easier way to make the adjustment, if the copper/brass float is fitted is to put a spot of solder on the tab which can be dressed back to gain the exact level, or on the plastic float cut a strip of thin metal and wrap it over the tab using a thickness to suit the required adjustment.

[Les H]

Hi Pete. Nice article again. I recently had the same dilemma as to fit the washer or not. As you say, the washer was not an original fitment but it now comes in the gasket sets. I fitted it and there was a tendency for the carb to flood so I removed it and all was well. As you also say, it really doesn't need to be used as the fuel level should be below the joint and the valve body extends passed the washer too. I did not realise the dot on the side of the float bowl cover was the fuel height level but I have noticed the old original carbs have it slightly higher than the modern carbs. Don't overlook though that the VITON float needle valve is available which is very good at sealing. BTW Dennis all the Monoblocs I've had lately even oldish ones have nylon floats, in fact it is so long ago that I've seen a copper float, I cannot remember if they ever existed in the Monobloc? I simply cannot remember now. I was going to suggest that your idea could be altered to use a blob of modern resin on the nylon float but that damn methanol in petrol seems to attack nearly every substance known to man, including brass and copper.

[Howard 612]

Nicely written and illustrated article Pete. It does underline the fact that you can do just about all measurements and adjustments on the Monoblock whilst leaving it in situ. The only time you need to take it off is to change the slide or needle position. Only drawback is the limited size of throat, with only the Concentric being available in larger sizes more suitable for a tuned engine.

Sorry to wander off topic a little bit.

[Dennis C]

Hi Les, Yes if you have an old original it would have been fitted with a copper float, the current ones are a plastic/nylon type material but the ones I have seen have a slight recess at both sides of the flat which contacts the needle, just deep enough to wrap a thin metal cover and tuck in to hold it in place. the pre monobloc of course had a bendable tab to make the adjustment with, Hmm resin and ethanol not sure on that one. --------- As I have said previously, in a past life I spent a lot of my time tuning engines for racing, these where mostly run on a mixture of Avgas, Methyl Alcohol and Nitromethane as the principle ingredients and I have to say that Methyl Alcohol (now Ethanol I understand) never caused any problems with metal parts in the carbs or the tanks.

[Les H]

Hi Dennis, after giving it some more thought, the mists of time have cleared and I can remember the originals having copper floats, quite often with a dent in them by careless handling. I agree with you that the warnings of methanol seem to be exaggerated, and I have never seen any metals inside carbs attacked, otherwise the brass jets would be damaged and I have brass floats in other carbs that look ok. I once suggested copper plating inside petrol tanks as a more solid form of tank lining rather than plastic compounds but I was told the methanol would eat the copper away and had to accept what was said as supposedly this is true. I reckon it would have been a good idea though. However "some" plastics and rubber are subject to methanol damage.