Ts1 carb ?

[Dazts1]

I've just ran to york at the weekend and I think my 35 tmx is knackered. I've ran at 70mph for 50mile but covered around 57 mile in total and used 9 litres of fuel. I run a 330 main jet and 56 needle. It used to run nearly 10m to the litre but now it's getting exsesive. I think I need a new carb I run with a stainless devtour , not everybody's favourite pipe but the bike goes well without issue. I have a 39mm dellorto spare on the shelf. Bit large I know but I do know people running similar size carbs. Do I just replace with a new tmx. Or change altogether ?

Thanks daz

[Knowledge]

I am a bit surprised that when you say that the fuel consumption has become excessive, that you would consider fitting an even bigger carb.

I know that Darryl Taylor has got some amazing power figures out of an existing kit whilst only using a 27mm Mikuni carb. If you don't want to migrate to Dell'orto, then this might be worth investigating.

[bike grim]

I've got an all most new (8 miles old) 30mm TMX powerjet carb that you can have for £95 plus postage or I can bring to Derby 150? I bought it on a whim off a mate and I'm not going to use it.

[ian i.o.w]

I've just ran to york at the weekend and I think my 35 tmx is knackered. I've ran at 70mph for 50mile but covered around 57 mile in total and used 9 litres of fuel. I run a 330 main jet and 56 needle. It used to run nearly 10m to the litre but now it's getting exsesive. I think I need a new carb I run with a stainless devtour , not everybody's favourite pipe but the bike goes well without issue. I have a 39mm dellorto spare on the shelf. Bit large I know but I do know people running similar size carbs. Do I just replace with a new tmx. Or change altogether ?

Thanks daz

I get 8 miles per litre on my ts1 tmx 35 mm doing 50 to 65 mph ,I am about as areodamaic as as bus and loaded up with camping gear etc run a super tourer exhaust changed my carb begging of year for a new 35 mm tmx not noticed any difference in fuel economy

[Warkton Tornado No.1]

I've just ran to york at the weekend and I think my 35 tmx is knackered. I've ran at 70mph for 50mile but covered around 57 mile in total and used 9 litres of fuel. I run a 330 main jet and 56 needle. It used to run nearly 10m to the litre but now it's getting exsesive. I think I need a new carb I run with a stainless devtour , not everybody's favourite pipe but the bike goes well without issue. I have a 39mm dellorto spare on the shelf. Bit large I know but I do know people running similar size carbs. Do I just replace with a new tmx. Or change altogether ?

Thanks daz

Dependent upon the rest of the engine set-up & if you have the correct 'ball park' slide, you must surely be intrigued enough to want to try the Dell’Orto VH(?) because, as they go, they can be dialed in with the mass of parts & knowledge around them. It is also a much better carburettor than, say, the PH range. Dell’Orto must be rubbing their hands with glee @ the loyalty toward that particular product, says me that has two PHBH’s (not in use!) sitting in my garage

Yes, Ø39 mm is large, but although it may not be as responsive as a smaller carburettor, that doesn’t entirely equate to thirsty. A lot of the carburettor settings Posted on Forums often strike me as rich & that tends to be a common habit within Lambretta ownership IMHO.

[Dazts1]

thanks for your replys.
As warkton says bigger doesn't always mean more thirsty. A couple of lcgb mile munching boys confirmed at the weekend. Running 38or 39mm carbs. I know the trend at the moment seems to be 30mm when talking to a lot of people. To be honest I dont really have any complaints, or haven't in the past with the tmx 35. I had noticed last year I was starting to use more than my mate on the same setup. But only a litre or so between fill ups. My trip to York at the weekend confirmed what I was starting to think the carb is about worn out.
Obviously which ever way i go if I can save fuel that would be a bonus but I'm happy with 10m to the litre.

[MickYork]

The carb' may be the issue but I wouldn't rule some wear at the top end (rings, reed valve, etc) or a slipping clutch......or maybe a bit of everything ?

[Dazts1]

The motor has only done 3000 mile. Maybe the rings are worth checking reeds are only 1500 mile old Yamaha but the carb has probably done around 10000 mile as it was on a previous build. I noticed fuel coming out of the pipe at the joints which it never used to do. Maybe a new main jet and needle may help.

[MickYork]

what's your plug colour like ? if you're running a tad rich it may be worth re-jetting.

[Dazts1]

I know what your saying but it's only just started running rich. I've ran 2500 mile with this jetting without issue. Time to strip and investigate I think.

[gaz_powell]

My Delly VHSB did this, (I know they are greedy!) so I rebuilt it with a new needle, atomiser, slide and float valve - there was a noticable difference, but it's amazing how different fuel economy is on different rides depending on wind, road types, speed, riding style etc. Some days it seems shite and others okay. Recently rode with a mate with exactly the same set up to cleethorpes and IOW (something I don't often do! ) and they were well matched on fuel.
Think this is a problem with mikuni as they do have an atomiser that can replaced it's an integral part of the carb, so once worn it's goosed, was talking to someone who said allens were working on drilling them out and sleeving them

[Warkton Tornado No.1]

Any carburettor fitted to an over-square two stroke with an undersized crankshaft (with little mass damping) is going to have a tough time of it, despite rubber mounting! Wear is exasperated by the vibration & often by an unfiltered air supply that has the needle, atomiser, slide & main body as the most affected victims, probably in that order...

Race machines do very few miles comparatively to a tuned road machine but the atomiser & needle wear is quite dramatic IMO.

Keihin carburettors have removable atomisers but I understand that Mikuni are often chosen for their compact nature.

[Dazts1]

I forgot to add the mikuni has spent its used life with a ramair filter in place.

[Warkton Tornado No.1]

I forgot to add the mikuni has spent its used life with a ramair filter in place.

That's to the good, no doubt, but shows, if anything, how the Mikuni might not be the best choice from the aspect of longevity

I'm being a lazy sod here as it's in 'Wanted', but did you get the packer you require? My son might have an 'old school' type that was made by somebody cutting a slice from a crankcase cover (though I can't remember thickness! Probably 10 mm) & know the remnants of the oil filler hole was not plugged up by welding. Though Martin @ ChiselSpeed used to stock 'proper' steel packers.

I hope that all helps.