ULC Soulagent wrote:Very interesting topic going on here, I purchased two delly vhst 28 when I worked in the scooter trade( bought for peanuts) and even though they were apparently designed for the 4-stroke engine but using some of the phbl d- range needle set. I set about converting it over fully, Blue printed it and along with adding 2-stroke atomiser bush and all the internals of the phbl card range bar the floats which was two single self floating units.I initially got good results from the acceleration side and top end part sussed but when it came too cruising on the mid section setup,The carb had me baffled and after destroying my 4 top ends, 3 imola’s and a Ts1 I gave up and went back to a phbl with no issues since. I’m keen on these pwk & Oko copies from China and obviously they need work too make them right but I’m reluctant too get bit on the arse twice
Sorry if I’ve taken it off topic.
Regards
Shane
No, perfectly on topic.
I was interested to read that WT1's 34mm had the 8-hole atomiser in, which mine did not. Although the Polini website says that the 30-hole is fitted as standard to the 32 and 34mm, with the 8-hole being fitted by someone along the way, which is standard fitment for the 24-30mm.
I have been down the similar route of changing the atomiser holders over on Dellortos, changing a PHBH 'T' atomiser holder to an AV/AS longer nosed 2-stroke type. Thankfully, I didn't have any further issue with the carb. Funnily enough, a clubmate ran his iron 175 on the same type with T atomiser for years and that was both quick (for a 175) and reliable, with us doing a number of long distance rallies together. However, that also ran a needle that I'd never heard of anyone else running for Lambretta applications.
As WT1 commented above, I have no doubt that the 30-hole could be made to work, whether it transpires to be 2 or 4-stroke, but that would lead me down the path of buying a whole range of other needles to try, where shaft diameter, taper length and tip diameter could / might be able to resolve my current carburation issues, however, I have no intention to buy the world's stock of needles to determine which one might work. God knows that I've gone down that rabbit hole with other carbs! As such, I think that a swap to the 8-hole for testing is probably my best step (8, 20 and 40 on order) so that the work already put in by the majority can be put to good use, starting with those needles that I see regularly listed.
I'll keep people posted as there is very little that I can find online about atomiser use for this range of carbs and copies (Keihin, OKO, PWK, Polini). The Modern Vespa link that I posted previously is about as good as the info available gets.
Ta
Adam