As far as I can estimate with my little bit of solder wire, the squish is about 1.3/1.4. I have retarded the ignition to 16DBTDC which is too low I feel, but still sounds like pinking.Powolotti wrote:it´s not the best head design from Casa...double check your squish clearance, I would suggest 1.3 to 1.5 on these heads. They give good bottom end / midrange but tend to pinking if set too tight.rog60 wrote:Needs to be tweaked a little on timing (currently on 18DBTDC) because of 'pinking, .
you can richen the 5899-2 by filling in a hole or two that enter the side of the atomiser with a little solder making sure not to impede the main hole through the center the 5899-1 is an atomiser I have used on a 22 on a Honda 205 but I cant remember what main jet I ran on it... Sorry..rog60 wrote:As far as I can estimate with my little bit of solder wire, the squish is about 1.3/1.4. I have retarded the ignition to 16DBTDC which is too low I feel, but still sounds like pinking.Powolotti wrote:it´s not the best head design from Casa...double check your squish clearance, I would suggest 1.3 to 1.5 on these heads. They give good bottom end / midrange but tend to pinking if set too tight.rog60 wrote:Needs to be tweaked a little on timing (currently on 18DBTDC) because of 'pinking, .
As motor is running on less than 1/4 throttle going to try bigger pilot jets and atomiser(s).
Anyone know which way the number sequence for 5899 series atomisers runs.i.e. is 5899-1richer than 5899-2 etc or is it the other way round -5 is richer (for SH2/22 Dellorto carbs)?
For infor Scootopia tell me that the cylinder head has been designed so that minimal(theoretically zero) deposits remain after combustion!
Thanks for input Sean, no cutaway on back of slide.sean brady scooters wrote:do you not think the prob is with the slides/re the cut out on the back.............venting in air.?
I now have access to a 5899-4 and 5899-5. Going to try them to see if any difference. Got 52 and 55 pilots coming in next week. I've also been told that opening out the centre drilling can be advantageous (more fuel flowing).J1MS wrote:the bigger the holes in the side the more air enters the fuel being supplied but the larger the hole in the center the more fuel that can flow through it they can be fine tuned somewhat, with a little thought put into it... But not so easy to do.. big changes for little alterations... but loads of old atomisers around and cheap if not free..!!
I tried my first attempts at this type of rejetting on a 22mm dellorto, on an old barrel that was going to be ported and rebored. So I wasnt too bothered if I holed a piston... I eventually tried this on a a 205 Honda which wouldnt jet smoothly running on a reamed 22mm carb to 24mm but as I say I cant now remember the final jetting on that one..
I filled in one middle one first then one top to see how it effected it, the tried two top then two middle opposite ones then side by side... I went through about twenty atomisers cant now remember what I actually settled on, but it ended up with a slightly modified 5899-1 which was also shortened 1mm... but its been a while since it wasd done & its now been sold to someone in Ireland...
That was the intention and to keep the costs down a bit especially as the kit is supposed to be used with existing carb/exhaust. Just to try something different...bought a set of micro drills today and measured one at .57mm, redrilled a spare .45 jet to the bigger size after carefully removing any swarf etc will try it out and see what happens. If all else fails may have to fit more modern carbjonny snatchsniffer wrote:is your choice of carb to keep it as standard as poss, if not then maybe you should try a different carb like a 25mm phbl where the range of settings are greater.
