Tune or Replace?

[roli150lam]

ebay yes you could take the chance.

[Adam_Winstone]

Until the last year or so, I’d have agreed with WT about the 270 on either a PHBL or PHBH. But, I have a Casa 192 with a PHBL25 and a standard mushroomless GP200 exhaust. I think the salient point with my attempts at jetting it was the fact that it didn’t like a 40 slide, it liked a 45. I ended with 48 pilot; D29/2; AQ270: Main 100. I even went to the added expense of buying an AQ269 but, no, it ran weak at one point in the mid range.

My TS1225 runs a PHBH30 with an AV268, whilst my Stage 4 200 (PHBL25) didn’t like the 45 slide/ AQ270, it runs a 40 slide and AQ266.

One thing to note from the comments re: atomiser requirements for different carb types is that the body type and size is a variable... and to note that we're coming back with different size recommendations for each.

There are plenty of existing threads about how reed induction motors often require a slightly bigger atomiser than when using the same size/type carb on a piston port motor; e.g. AV266 (X7 needle) use is typical for a 30mm PHBH with piston port but AV268 (X13 or X2) is fairly common with the same sized reed motor. However, there seems to be little info out there re: influence of venturi size or body type.

I have been so impressed with a 24 PHBL on my iron 'Baby 200' in recent years, using it as a general 'go to' bike and the last 3 Euros + 1 x 5-Nations, that I opted to use a PHBL 25mm for my reed Rapido 225 that I built for this year's 5-Nations, with a balance of touring performance and fuel economy in mind. However, I was really surprised to find that my throttle position checks (including tests with the main jet out to ensure no restriction at partial throttle openings) was telling me that it was very weak through the mid range. I spent a lot of time testing to ensure that it was right for the 1200+ mile trip that I was about to take this new motor on and everything was pointing to the AQ266 atomiser being too weak. Thankfully the PHBL has single steps, rather than double, so I was able to source a AQ267, AQ268, AQ269 and AQ270 as well as already having a range of needles, jets and slides from setting up the 24 on other motor. Try as I might, I could not use a richer slide and leaner atomiser, found that a 45 slide and AQ268 was useable but still lean mid range, ending up on an AQ270 with 50 slide giving good test returns at all throttle positions. This bike then covered 1200+ miles without issue and not having the plug out once (plenty of checks done prior to leaving).

Interestingly, whilst my pre-5-Nations testing had led me to my own 'richer atomiser required' conclusion, this was not being reflected in the returns that I was getting from searching the web for PHBL setups... HOWEVER, that was until I stumbled across an older thread by a respected dealer of the day stating that they had found that the reed smallblock kits that they were a main agent for needed an AQ270 (perhaps AQ268) to stop the recommended 25 PHBL from running lean through the mid-range. This totally reflected my independent testing!

LambrettaMarky - please excuse me for talking PHBL, which doesn't relate to your PHBH requirement, but it continues a topic that others have introduced.

Other Dellorto models - I have experienced PHBH, VHSA, VHSB and VHSH Dellortos running atomisers as small as 260 diameter (but ranging up to 270), even when using the same 2.5mm diameter needles, so wonder how much the efficiency of model, speed of air flow through the carb (even different slide design influence for same size) or other factors may be influencing atomiser size requirement?

LambrettaMarky - You are doing the right thing by starting rich and working leaner, testing along the way.

Good luck and keep the thread going as those responding have a wealth of experience.

[Storkfoot]

ebay yes you could take the chance.

Mark, I’ll vouch for Wasp that they sell genuine Dell’orto parts. Avoid eBay unless you have to, in my opinion.

https://www.wasp-performance.co.uk/dell ... av268.html

[LambrettaMarky]

ebay yes you could take the chance.

Was in a rush work wise this morning so ordered this quickly: https://www.ebay.co.uk/itm/125449167438 ... media=COPY

[LambrettaMarky]

ebay yes you could take the chance.

Mark, I’ll vouch for Wasp that they sell genuine Dell’orto parts. Avoid eBay unless you have to, in my opinion.

https://www.wasp-performance.co.uk/dell ... av268.html

Thanks Paul - hopefully I’ve not bought one that’s made of soft cheese!

[roli150lam]

wasp had genuine stock when i checked earlier. today.

[LambrettaMarky]

Until the last year or so, I’d have agreed with WT about the 270 on either a PHBL or PHBH. But, I have a Casa 192 with a PHBL25 and a standard mushroomless GP200 exhaust. I think the salient point with my attempts at jetting it was the fact that it didn’t like a 40 slide, it liked a 45. I ended with 48 pilot; D29/2; AQ270: Main 100. I even went to the added expense of buying an AQ269 but, no, it ran weak at one point in the mid range.

My TS1225 runs a PHBH30 with an AV268, whilst my Stage 4 200 (PHBL25) didn’t like the 45 slide/ AQ270, it runs a 40 slide and AQ266.

One thing to note from the comments re: atomiser requirements for different carb types is that the body type and size is a variable... and to note that we're coming back with different size recommendations for each.

There are plenty of existing threads about how reed induction motors often require a slightly bigger atomiser than when using the same size/type carb on a piston port motor; e.g. AV266 (X7 needle) use is typical for a 30mm PHBH with piston port but AV268 (X13 or X2) is fairly common with the same sized reed motor. However, there seems to be little info out there re: influence of venturi size or body type.

I have been so impressed with a 24 PHBL on my iron 'Baby 200' in recent years, using it as a general 'go to' bike and the last 3 Euros + 1 x 5-Nations, that I opted to use a PHBL 25mm for my reed Rapido 225 that I built for this year's 5-Nations, with a balance of touring performance and fuel economy in mind. However, I was really surprised to find that my throttle position checks (including tests with the main jet out to ensure no restriction at partial throttle openings) was telling me that it was very weak through the mid range. I spent a lot of time testing to ensure that it was right for the 1200+ mile trip that I was about to take this new motor on and everything was pointing to the AQ266 atomiser being too weak. Thankfully the PHBL has single steps, rather than double, so I was able to source a AQ267, AQ268, AQ269 and AQ270 as well as already having a range of needles, jets and slides from setting up the 24 on other motor. Try as I might, I could not use a richer slide and leaner atomiser, found that a 45 slide and AQ268 was useable but still lean mid range, ending up on an AQ270 with 50 slide giving good test returns at all throttle positions. This bike then covered 1200+ miles without issue and not having the plug out once (plenty of checks done prior to leaving).

Interestingly, whilst my pre-5-Nations testing had led me to my own 'richer atomiser required' conclusion, this was not being reflected in the returns that I was getting from searching the web for PHBL setups... HOWEVER, that was until I stumbled across an older thread by a respected dealer of the day stating that they had found that the reed smallblock kits that they were a main agent for needed an AQ270 (perhaps AQ268) to stop the recommended 25 PHBL from running lean through the mid-range. This totally reflected my independent testing!

LambrettaMarky - please excuse me for talking PHBL, which doesn't relate to your PHBH requirement, but it continues a topic that others have introduced.

Other Dellorto models - I have experienced PHBH, VHSA, VHSB and VHSH Dellortos running atomisers as small as 260 diameter (but ranging up to 270), even when using the same 2.5mm diameter needles, so wonder how much the efficiency of model, speed of air flow through the carb (even different slide design influence for same size) or other factors may be influencing atomiser size requirement?

LambrettaMarky - You are doing the right thing by starting rich and working leaner, testing along the way.

Good luck and keep the thread going as those responding have a wealth of experience.

Thanks again Adam.

I’m definitely keen to be on the safe side so will be doing plenty of plug chops as i get this going.. All part of the fun!

[coaster]

Chrikey you dont hang about Mark Good choice with the 30 PHBH and loads of good advice so far. I probably mentioned that I also have a GT240 as well as the GT200 version I was riding to Marlow. JL3 will suit the 240, I had one on a TS1225 and Ron Moss Avanti but neither would rev past 6.5k RPM. I have a BGM Clumman on the 240 which suits its tall gearing but I fitted a Franspeed Race to the 200 and also tried an ADS3 both of which were brilliant, very slight loss of torque at low revs but bags of torque where you need it for overtaking.

Someone mentioned 'trenching' for the GT240 but it just requires a minimal amount of metal to be removed from the casingusing a dremel or die grinder. 1mm deep and 10mm approx. I did mine in about 10 minutes using an angle drinder through the mag housing side but that was a bit brutal tbh

[LambrettaMarky]

Chrikey you dont hang about Mark Good choice with the 30 PHBH and loads of good advice so far. I probably mentioned that I also have a GT240 as well as the GT200 version I was riding to Marlow. JL3 will suit the 240, I had one on a TS1225 and Ron Moss Avanti but neither would rev past 6.5k RPM. I have a BGM Clumman on the 240 which suits its tall gearing but I fitted a Franspeed Race to the 200 and also tried an ADS3 both of which were brilliant, very slight loss of torque at low revs but bags of torque where you need it for overtaking.

Someone mentioned 'trenching' for the GT240 but it just requires a minimal amount of metal to be removed from the casingusing a dremel or die grinder. 1mm deep and 10mm approx. I did mine in about 10 minutes using an angle drinder through the mag housing side but that was a bit brutal tbh

I hadn't actually considered a half way house really Colin, so when the idea was made on here just thought I'd go get the bits and try it.

It was you that suggested the cast iron kits and for good reason, so the GT240 will be where I go next if I don't get what I want from the carb & exhaust.

Cheers

Mark

[LambrettaMarky]

..gotta love a designer with a sense of humour putting M7 X 1.0 threads in the barrel!

Little did they know I already have a set of taps & die plus nuts etc as the case bolts on my Montesa Cota was designed by a family member perhaps..

December 22 by KTM Marky, on Flickr

[LambrettaMarky]

Excellent service from Scooter Infinity as the Atomizer has arrived before I'm ready to install it and run the motor.

[LambrettaMarky]

Well it's assembled & running. Some fettling with the exhaust mount and cylinder shroud, but overall seems OK. I've used a new exhaust gasket & some sealer on the stub mount.

The choke mechanism is the same so that's good to keep the little lever thing as is. Runs just @ tick over with the idle screw all the way in & revs well. I forgot to change the atomiser over after all that & need to make a bird cage tool for the 1.2mm cable so I can make a proper throttle cable with a solid nipple using my solder pot at the twist grip end as I really do not like the look of the device that comes with the mega long cable from Cam Lam that uses a grub screw. I'll use a new outer I think to get the right length and bend closer to the carb.

The exhaust note is so much better than the clubman & I really like the look too..

JL3 LHS by KTM Marky, on Flickr

JL3 RHS by KTM Marky, on Flickr

JL3 Silencer by KTM Marky, on Flickr

I think the little punched Lambretta plate on the stand will need to go before I try to take the stand up!

[Adam_Winstone]

If you bike has the correct GP plastic / nylon throttle wheel in the headset then a worthwhile modification is to drill or melt a suitably small hole through the back of it, along the cable's direction of travel so that the long 'universal' inner cable can run through, then cut and soldered to stop strand fraying. The benefit is that it is easy to source and replace cable inner as/when necessary.

[LambrettaMarky]

If you bike has the correct GP plastic / nylon throttle wheel in the headset then a worthwhile modification is to drill or melt a suitably small hole through the back of it, along the cable's direction of travel so that the long 'universal' inner cable can run through, then cut and soldered to stop strand fraying. The benefit is that it is easy to source and replace cable inner as/when necessary.

I'm on the throttle cable tomorrow Adam & will take a look at your suggestion - Thank You.

I've a Venhill cable kit that I use for my trials bike builds so will make up a spare while I'm at it..

Just been running the motor again and it's such a lot better than the previous set up.. Sounds and looks mint so that's 10 mph straight away!!

[LambrettaMarky]

Blimey.. Leg shields etc off to replace the throttle cable. Popped along to Cam Lam for some new control wheels too. What a faff....

[LambrettaMarky]

New throttle cable made:
PHBH Cable by KTM Marky, on Flickr

Throttle cable bend radius increased:
PHBH Cable Routing by KTM Marky, on Flickr

New throttle pull cam (significanly better quality moulding than the SIL one):
New Throttle Pull Thru Hole 2 by KTM Marky, on Flickr
New Throttle Pull Thru Hole 1 by KTM Marky, on Flickr

Thanks for the tip with this as I carry spare cable inners, so making a temporary spare with this hole should be OK..

[Adam_Winstone]

Yep, that's exactly the throttle modification that I was trying to put into words (lol). I'm glad it made sense.

[LambrettaMarky]

Yep, that's exactly the throttle modification that I was trying to put into words (lol). I'm glad it made sense.

Crystal clear - Thx.

[LambrettaMarky]

One thing has led to the other & while I'm in around the headset, decided to replace the clutch cable wheel for the new 'better' moulding from Cam Lam. I also want to improve the throttle return which once the wider diameter reverse pull cable has gone in has been poor. So I pulled the whole cowl off as you can see.

I've opened up the clearance where the brake cable enters the casting to give the cable clearance which it didn't really have before, milled the window a bit too to help get the headlight/horn wires in and fed through. Fettled the general fit of the front brake lever assembly too.

Brake cable clearance by KTM Marky, on Flickr

I've new brake pads that hopefully will improve slowing down & dressed the disc 4 thou a side just to de-glaze and have a fresh face. I'm undecided if the whole inboard front wheel assembly is a piece of design genius or just a PITA, either way I'm getting better as working on it all. Had to scrap the thicker cable inner & outer so will go get another tomorrow.

Skimmed disc by KTM Marky, on Flickr

Disc Skim by KTM Marky, on Flickr

While I'm at it, will pull the forks out and just grease the head bearings so I know how much is in there..

[LambrettaMarky]

..well of course one thing leads to another and after a chat @ Cam Lam yesterday I decided to strip & service the forks also to upgrade the stops/spring etc from the standard' SIL stuff - this is ahead of fitting some BGM dampers.

Fork 1 by KTM Marky, on Flickr

Fork 2 by KTM Marky, on Flickr

An interesting design that is a right faff to get disassembled, but once apart the Indian Molasses type lubrication was quite something:

Indian Spring by KTM Marky, on Flickr

Careful use of a 27mm spanner & tie down helped too:

Stop Removal by KTM Marky, on Flickr

Finally a tip was to increase the ball diameter so I've ordered some SS 9mm to replace the 8mm ones in my unit:

8mm Balls by KTM Marky, on Flickr

Be up and running again in no time....

10.11.24 by KTM Marky, on Flickr

It needs to be as I need to ramp to go get some new tyres on another bike.