LCGB Forums

Hi, Just put a new Mugello V4 225 on my GP. Always ran the V1 open mouthed but decided to add a breathe sweet filter with this kit. Runs and starts fine but floods nearly every time I stop and switch off then try starting again. I get the chugging at full throttle until it clears it then revs cleanly. Had this lots with Jetex but this is a 30mm phbh which I have run for years. Only running a 52 pilot, tried switching fuel off and letting it tickover a while before switching off but always the same result. Any ideas but please don't suggest reed valve as I don't want to go down that route. Might return to open mouthed if I can't cure it.

Rich'

I have experienced the same issue with a remote filter on a piston ported kit & in my own current set-up, it seems to get better, the further away the filter can be located. Currently, my DIY foam filter is nestling under the air scoop with a 60 mm flexible tube between the two silicone elbows, one to carb, the other to filter. Very 'Deja vu' of my early Lambretta ownership but I know for a fact that the standard air filter box, & particuarly the bellows, simply cannot cope with the demands of an engine modified to deliver something like twice the OEM performance.

The problem is exasperated by the amount of inlet timing, IMHO, which is difficult to resolve with the Mugello (or Rapido)

On 'the other Forum' you will have it suggested that a drain hole in the elbow/bellows will cure it, but I would only advocate that to be applied if in conjunction with a OWV (One-Way-Valve) & tubing or with a filtered breather located downhill from the carburettor. Just like Innocenti used to do.....

TBH, when I have looked @ the amount of 'flooding' there may be after stopping the engine, @ most there may be a fuel 'mist' on the walls of the elbow, but I guess that may be all it takes to significantly richer up the fuel/air charge to cause the starting issue.

That is probably the next step that I will personally try as such items are so cheap on the auction site that it has to be worth a shot. I reckon a 2 mm OWV would be large & 'sensitive' enough to do the job, if, in fact, it is down to 'flooding'

(I must concede, that despite what may appear as cynicism my engine will start after loads of kicking over with the fuel off to clear what must be an overcharged mix)

If you do try it yourself, please let us know how you get on.....

Thanks WT1, food for thought there. Mine actually starts fine every time but just will not rev until it clears with the fuel off.

I had the same problem on my Rt195 running sweet breath filter and could never get rid of the chugging until I turned off the fuel and removed the filter. Binned the filter and put on a mb panel filter which cured it no end. I say that’s it’s the lack of air that’s stopping it from clearing its throat if you know what I mean.

I noticed on my Avanti the issue was worse when the Breathsweet was vertical, it was better when horizontal but did not cure it fully (but worth a try).


I finally "cured" it by fitting a Chiselspeed panel filter (not sure how effective the filter is but better than open mouthed).

MickYork wrote:I noticed on my Avanti the issue was worse when the Breathsweet was vertical, it was better when horizontal but did not cure it fully (but worth a try).


I finally "cured" it by fitting a Chiselspeed panel filter (not sure how effective the filter is but better than open mouthed).

Got one of those to try so that's my next move.

Rich'

i,m having same problem with my avanti.....been using casa filter horizontally due to long range tank.... it doesnt doit all the time ..but very frustrating .....
i have just got the chiselspeed filter to test as well.....

philcasino1973 wrote:i,m having same problem with my avanti.....been using casa filter horizontally due to long range tank.... it doesnt doit all the time ..but very frustrating .....
i have just got the chiselspeed filter to test as well.....

Fitting the Chiselspeed filter on mine seems to have worked, time will tell.

Rich'