Rapido

[jonno]

My TS1 is too thirsty 35 mpg,was thinking of buying a Rapido barrel and using the TS1s piston and head,and fitting an LTH inlet.Seems a straight swap?

[Meds]

I’ve a similar rapido set up and getting better than 10ml/litre

[a.lo]

will make a good engine, as above makes at least 10 mile/litre and can get 12 mile/litre as I improve the reed jetting. current spec. Rapido 225,Atomic reed (small),Bgm clubman v3, 26mm pwk carb, Wossner piston with holes cut by myself.

[CHRIS in MARGATE]

50 mpg on a run with same set up with Franspeed

[Toddy]

Might be worth checking why it’s so thirsty I run two Scotty tuned iron lined TS’s and both return at least 10 miles to the litre one with a 35mm mikuni the other a 30mm phbh both with CST3 pipes

[jonno]

I had it dynoed,but with side panels off.Ive got MB panel filter and full panel fitted and it smoked badly even at half throttle,so way too rich.Now I think my mag seals have gone so cant plug chop.The panel and filter wouldnt have made too much difference would it?

[Toddy]

I had it dynoed,but with side panels off.Ive got MB panel filter and full panel fitted and it smoked badly even at half throttle,so way too rich.Now I think my mag seals have gone so cant plug chop.The panel and filter wouldnt have made too much difference would it?

IMHO If you had it dynoed without the filter and panel on I believe it would have richened it up making it use more fuel

[Adam_Winstone]

I had it dynoed,but with side panels off.Ive got MB panel filter and full panel fitted and it smoked badly even at half throttle,so way too rich.Now I think my mag seals have gone so cant plug chop.The panel and filter wouldnt have made too much difference would it?

... could have a massive influence on airflow, jetting and performance.

[bike grim]

I’ve got a Rapido 225 with MB reed and boost port, altered piston (holes cut by Ian Frankland RIP), 28 PHBH and a v4 BGM with a varitronic in one scooter and also a DSC Scotty tuned iron lined TS1 with a 30mm PHBH and CST3, static ignition in another. Both return c.10miles per litre. Both good for touring. Guess which one I prefer to ride ?

I’d stick with the TS1 if I were you and Just iron out the glitches

[Feersum Injun]

TS1 230 - I get a around 10 miles a litre as well with 28mm PHBH and a JL3 and I'm running quite rich... I wouldn't swap!

[col68]

My TS1 is too thirsty 35 mpg,was thinking of buying a Rapido barrel and using the TS1s piston and head,and fitting an LTH inlet.Seems a straight swap?

Sounds like a step backward to me .

[jonno]

Running an open carb with a hole in the panel would replicate the dyno setup,and run better.But would it reduce the fuel usage,and not just increase the air to match the current jetting?

[holty]

it may well reduce fuel usage with a panel hole,as your filter could be richening it up, i would also consider buying a new needle and atomiser as these wear with use and allow more fuel through thus reducing your mpg, make sure to get the numbers off them and get the same ones. remember your carb mixes air and fuel to enter the engine, if the mixture is too rich your wasting fuel, correct mixture, as per your dyno setting will give best mpg .

[NorthernJordan]

Running an open carb with a hole in the panel would replicate the dyno setup,and run better.But would it reduce the fuel usage,and not just increase the air to match the current jetting?

I don't think the fact that you have put in a filter and inadvertently richened it up would actually use more fuel. At the end of the day the main jet is simply a hole in which air pulls through fuel. So surely it cannot be using more fuel?

I would suggest that you now you have a filter you might be able to reduce the main jet size and thus increase your mpg.

[Warkton Tornado No.1]

The Rapido, being a piston ported engine with such a large inlet timing, is thirsty & messy with an open carburettor.

I will admit that I do not have the actual mpg figures to hand, but my own has improved dramatically due to 'taming' it with a longer stroke (61 mm) & despite the 70.5 mm bore, it remains very torquey. Currently, it has a Pacemaker with 19 x 46 which I believe to be the same as TV 200.

In conjunction with a large (50 mm) elbow facing vertically to a large (60 mm) bellows & a homemade foam filter, any spit back is not going to waste as would be the case with an open carb. That's the theory, anyway!

The only downside has been hot starting, but recent experiments on another machine that I concocted a similar filter arrangement for, included a 3 mm bore vent flexible pipe that had a wire mesh filter bung in it's end. That seemed the cure to the problem of any fuel mist causing the hot start problem so I will be doing the same modification to my own machine.

I am aware that there are now similar bellows available from BGM but I have seen no feedback on them. They may be adequate for your engine, but, TBH, I have found that the bigger the connection to the carburettor, the better with my own set-up.

I consider what I have achieved to be the 'poor man's fuel catcher' & not quite the equivalent to a reed valve, but it will do nicely for now....

[CHRIS in MARGATE]

I converted my Rapido to reed block and the result was very impressive. I used to have a filthy engine. Clean as a whistle now and improved from 38 mpg to somewhere between 45-50 mpg measured accurately.
Best thing I ever did.

[jonno]

Not getting anywhere with carb settings even getting a new one set up for my set up .Either far too smokey or a white /grey plug on half throttle if I even drop the needle jet one notch.

[holty]

i think a dyno session with your chosen filter and panel fitted will be the best solution, i had my 290 done by martin at chiselspeed and the mpg is almost as good as my mates 175, pays for itself over time with the fuel you will save and you wont have to worry about a siezure, other things might help too, making sure your squish is 1.2 and running the lowest gear ratio that your engine will pull, i would also do a leak down test, an air leak plays havoc with jetting , sorry if im suggesting stuff you already know or have done.

[jonno]

Ive done a leak test and theres s leak somewhere but I cant find it anywhere.The is always fuel/oil under the sparkplug,outside the head, but it never shows any bubbles on the test.Have taken engine out for thourough check.Wasnt dynoed with panels on as couldnt be strapped down,although not a problem before.Time to go elswhere.So annoying.
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[Scooterdude]

Ive done a leak test and theres s leak somewhere but I cant find it anywhere.The is always fuel/oil under the sparkplug,outside the head, but it never shows any bubbles on the test.Have taken engine out for thourough check.Wasnt dynoed with panels on as couldnt be strapped down,although not a problem before.Time to go elswhere.So annoying.
,

I wouldent mind betting its leaking from drive side oil seal. Once you get the side case off remove the front sprocket assembly and slap a load of soapy water around it with a small brush.