Scooterotica

my old dragster had 24 BHP without any tuning to the barrel, all bolt on and standard crank, Ryann Saxilby got well over 30 with a bit of work done to them,

lifes a drag wrote:my old dragster had 24 BHP without any tuning to the barrel, all bolt on and standard crank, Ryann Saxilby got well over 30 with a bit of work done to them,

So Ryan did enlarge the transfers in this case, is that what you mean?

i would like to see a cylinder for Lambretta with no restrictions from the studs. For getting good power out of a TS1 you have to use silly transfer timings that are way out of the rev range our engines work. Next, you need enough blowdown time area. If we say 70% of bore is a safe width if you maintain your piston and rings regulary, you still end up with 30-33 degrees blowdown as example. Top ex-port shape plays an important role, square would be nice to gain area but makes powerband tight, so you´ll loose time area again. Exhausts with a longer tuned length bring the power/torque down to usable revs. It´s all a case of bodging around small transfer widths. That´s why i am so surprised to see kit after kit arrive that doesn´t fulfil one of the simplest two stroke principles: port width before port height.

yes Ryan did enlarge them but if you read my other post on page 5 it explains that you can have them too large,

i imagine he did more than transfer ports to get well over 30 BHP though,

my old dragster was all bolt on and he did no other work on mine apart from build it right, the big suprise was from 20 to 24 BHP by just fitting a bigger carb, the first time i rode it i had to shut the throttle off as it suprised me so mutch ,,, ha ha

Darrell Taylor wrote:

drunkmunkey6969 wrote: Bigger crankcase transfers would certainly make a BIG difference, but in context to the rest of the tune and what you are trying to achieve. Its not something you would simply do on its own with no thought to the rest of the motor.

thats a bold statement to make ,have you conducted a singular test to evaluate these results std transfers v enlarged transfers if not it would make for an interesting comparison

Yes, we did it on an RB20 motor that a customer is running round on, and it worked for that application, as you know....having your own dyno gives you the luxury of testing whatever you want and PROVING what works and what doesn't. On this motor, larger transfers were beneficial, we gained a small amount of power right across the rev range. Its a slightly different example also, but if i recall correctly i think Scootering magazine did a step by step test whilst fitting a Mallossi 210 kit to see what changes were beneficial, and when enlarging the transfer ports on the casings they gained power also. This is slightly different to the Lambretta scenario, because of course on the Vespa example the Mallossi has larger transfers than a standard casing so the casing needs opening up to match the kit.....but you get my drift. Did you see the article in Scootering you may know the one i mean?

Darrell Taylor wrote: have you read my comment about transfer window size constantly changing
in my example a 20mm wide transfer at 1mm open is 20 sq mm the std duct entry is 600sqmm so the ducts entry is 30 times bigger !!
many modern race engines have larger transfer duct entrys but have you seen the ultimate 125 gp motors transfer ducts? approx 1 to 1 ratio

Fair enough, but a Lambretta is not an ultimate gp motor is it, you have to compare like for like. And presumably the cylinder transfers on the ultimate gp are larger than a Lambretta cylinder, so at 1:1 the ultimate gp will make sense.....and if we are enlarging transfer ports on the lambretta cylinder wall, then we will want a large entry to match. But i see what you mean, although surely the crankcase window size/area should at least match the cylinder transfer area when they are fully cracked open and not just when they are 1mm open??? Or can you offer further info on why this is not the case? Please explain why if so, i'm interested to learn. And lastly.......do you not find that when the piston is nearly at BDC that the transfer window in the crankcase is almost blocked/closed.....another reason why we modify pistons and transfers, let me know your experience in this case.

Darrell Taylor wrote:ive done it on a few development motors not lambretta (aprilia rs125/cobra 50 mx/derbi gpr50/minarelli am6/ktm50 and found the effort put in is not worth the results in fact the results were no different before and after so for these motors i dont bother no more
i once conducted a test on the derbi 50 of 7 different reed blocks and 5 different petals for the std reed block to find out that the standard reed block and standard reed petals gave the best results i can therefore say that on that engine spec the std reed and block provided best performance and money spent on any of the aftermarket reeds or blocks was money wasted,i passed this info to mb and you now have it in his latest reed valve conversion kits for the piston port lamby

Interesting info, which i am grateful for, but slightly off topic because its about reeds not transfers, and unfortunately Lambretta never made a TS1 kit with reedvalve......AF Rayspeed did!! lol......so whilst i understand that an aftermarket company may not be able to improve on the huge R&D investment a major motorcycle/scooter manufacturer (thus 'standard' reeds being best) i am not at all surprised that Tassinari Vforce or Yamaha Banshee/Boyesen dual stage reeds are actually better than AFs standard reeds/block. Thus in your examples of aprillia/minarelli etc the factory reeds were best, but in our tests (on my TS1 race engine) we improved power using non-standard reeds. Still, interesting that you did the test and thanks for sharing the results.

lifes a drag wrote:yes Ryan did enlarge them but if you read my other post on page 5 it explains that you can have them too large,

Yes cheers, i saw your other post, and i agree......there certainly is a point at which they can become too large, i said as much in my earlier post on the previous page: "Whilst being careful not to over-enlarge the area, thus reducing velocity into the cylinder:- everything has an upper and lower level of benefit, one figure can be too high, whilst if you go too far in the other direction the figure will be too low......both will effect the results in a negative manner and reduce performance. "

But in any case, i just wanted to check if Ryan was enlarging transfer ports above standard size when carrying out his tuning work........thanks.

Just to confirm, with the RB20 you done the testing on, were the case transfers matched to barrel on first test then enlarged and tested, or standard on first test then matched?

drunkmunkey6969 wrote:

lifes a drag wrote:yes Ryan did enlarge them but if you read my other post on page 5 it explains that you can have them too large,

Yes cheers, i saw your other post, and i agree......there certainly is a point at which they can become too large, i said as much in my earlier post on the previous page: "Whilst being careful not to over-enlarge the area, thus reducing velocity into the cylinder:- everything has an upper and lower level of benefit, one figure can be too high, whilst if you go too far in the other direction the figure will be too low......both will effect the results in a negative manner and reduce performance. "

But in any case, i just wanted to check if Ryan was enlarging transfer ports above standard size when carrying out his tuning work........thanks.

if im honest its that long ago i cant really remember what the transfers were like on the barrel
Ryann did, i just remembering the difference on the ones my mate had a go at, I do remember my mates words to me that day though ,,, he seid thats why good tuners charge what they do, as they have probably ruind lots of barrels until they know just how mutch to remove and how mutch not to remove,

wezly wrote:Just to confirm, with the RB20 you done the testing on, were the case transfers matched to barrel on first test then enlarged and tested, or standard on first test then matched?

Not sure what you mean? When I talk about enlarging transfers I mean anything above a standard factory port size....so if a kit has larger case transfers than the actual casing and you enlarge the case transfers to match.....you have still enlarged the case transfers....yes?

So what we did was bolt the kit on to standard casings and run it up, we then enlarged the casings to the max without welding (similar to Jason Frosts picture in the very first post of this thread) and matched the cylinder to that.

It worked for us on that application......others may have different experiences in different applications.

And don't forget.....you pick ten different Yamaha or Honda casings off the shelf and chances are they are all identical. You get ten different Lambo casings and chances are they all have very slightly different deck heights and transfer widths......Spanish, Indian, Italian, big block, small block etc......each has variations.

lifes a drag wrote: Ryann did, i just remembering the difference on the ones my mate had a go at, I do remember my mates words to me that day though ,,, he seid thats why good tuners charge what they do, as they have probably ruined lots of barrels until they know just how much to remove and how much not to remove,

And the 'less good' ones just keep hacking away ruining more barrels.