Big Bore Kit - Help Needing Choosing Which One

Hi All,
Well after reading through these forums for the last few months i finally decided to become a member so i can join in on the discussions (and ask a few questions of my own) =)

So here goes a mate and i bought a CAG each and have mucked around with a few of the mods posted on here basically just done the reed mod (cut the middle bar out and put in carbon fibre ones bought from danny) put an s bend 3 piece pipe on (with the springs) a 2 spring clutch and ported the stock carbi (all of which has given us a fair bit extra from when they were standard).

I am now wanting a bit more power so have been looking to upgrade the carbi and put a big bore kit in BUT am not knowing which kit and carb to go with. I have done as much research as possible reading as much as possible on here and other pocket bike sites but am still a bit unsure basically i am looking at getting either a 16mm Walbro copy or a 14/14 Dellorto copy I belive the Walbro copy has more tuning required but does not require jet changing for this (correct me if i am wrong) so are swaying more towards this one as the not jet changing sounds good and like the idea of being able to tune low and top end richness.

The other thing is the big bore kit i have been looking on ebay and found some at HKS MOTOS but do not know weather to go with the 4 port or 5 port Yellow Jacket copy both come with a full circle crank the YJ sounds better BUT it says gives a compression of 17:1 which i think will not run on anything but methanol etc could i go with the 5 port and request a different dome as i belive this is what governs the compression? Also is the 5 port better than 4 port?

I am not wanting to spend the earth on it and know it is Chinese not one of the Italian beauties =) but enjoy doing the research and mods and fingers crossed getting some nice results.

Any help would be VERY much appreciated!!!

on my cag i used to run a del 14/14 rep and i was happy with it. i havnt run a walbro but i have heard they are a bitc* to tune. i also had a 3d ported head kit (1 big port rather than 4 smaller ones) and that worked extremely well. i prefer watercooled bikes so i cant be of too much help but from my experience a 3d ported head kit and a del rep work great.
good luck with it mate

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-SQ blata rep (47cc big bore kit, 19mm dellorto PHVB, Blata reeds, Blata crank, Zocchi Rep Pipe, 7mm reed spacer)
-911 rep (BZM 50cc 6 port top end, bzm bottom end, bzm 40cc pipe, BZM red crank, bzm gold head, BZM 18mm carb)
-D1 (50cc 5 port polini rep engine, 19mm del rep carb, bzm 50cc rep pipe)

Email:
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Thanks for the quick reply SIkko_X2 yeah i am not really up with what difference the ports make. Was sorta going on the principle that more is better probably not right sorta think that any head kit gotta make some difference as are increasing the cubes and from working the cars always work on the principle that nothing makes power like more cubes BUT these being 2 strokes and from what i have read on how they work it is completley different. Just didn't want to spend too much and didn't want to buy something that makes bugger all difference powerwise. But might start trying to do some reading up on the 3d port kits.

Also did your dellorto rep have any tuning adjustments the vibe i got was the dellortos are pretty much a bolt on and off you go where as the walbro is more a race carb that you can fine tune (maybe a little too much)

The other thing with the head kits i saw i have notice some have all the anidosed parts on top and some just like cast cooling fins and seems like no "dome" which i belive sets the compression. Is it a thing if you get one with a dome you can change the copmpression where as the ones with out the dome are just set to a compression and that what you get.

Thanks again for ANY help!!!!

Has anyone had any experience with a similar head kit to what I am looking at

* YELLOW JACKET COPY 5 Port with full circle crank

OR

* ADA STYLE 4 Port with full circle crank

ANY HELP would be great!!!!

Thanks Ben

Ben0350

Please dont' cross post the same question across multiple forums. One is enough. I have deleted your other threads with this same topic.

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Sorry crash dummy just wasnt sure if i had put question under the right section.

Hi All,
Still chasing some info on this if anyone has seom experience with the head kits?? I can put the links to the ebay items if it helps?

Ben, firstly the main difference between these 2 head kits are the boost porting, the Yellow Jacket has 2 x approx 8mm boost ports and the ADA has 1 x large 20 mm boost port which is also cut deeper into the cylinder wall. both head domes are very simular as so compression ratios of around 13 to 1 to 15 to 1. now what your looking at is both of these head kits are chinese copies of the original U.S. designs from P.B.U. and ADA , this is where the power difference comes into play. the chinese do give good first impressions in looks of there works but when it comes to actual machining such as boost and exhaust ports , the quality drops very rapid. i have re machined well over the hundred mark of chinese cylinders , Dazza from Ozminimotos has sent me many of his imported head kits to be correctly cleaned up so he could sell clients good quality kits that would both last and supply top power.
for the real test of power output i would go for the ADA over the Yellow jacket mainly due to the massive boost port which has more volume than the twin boost ports of the Yellow jacket. if you take a look to your right at the [ site navigation ] box , look at ADA 44MM HEAD KIT. after alot of testing both brands we now have the AUSSIE ADA HEAD KITS which are ever more powerfull than the originals.

Hey RD,
Thanks for that good to get an answer with some explanation of the ports etc... So next question where do i get one of these ADA 44mm kits and how much am i looking at? Also with the squish setting that is the only part that would concern me doing it myself am pretty cluey with it all but not sure what is involved with setting the squish? Also which carb would you recommend with that kit a dellorto 14/14 or a walbro 16? Same deal with those i was looking at rep ones or am i just buying headaches?

Thanks Ben

the rep carbs do work ok but the extra you pay for a genuine carb is well worth it in the longrun
it is one of the few parts i would advise going genuine dell/walbro 14-17mm the 18mm may be a lil on the big side for a cag

the dell carbs are easy to jet & tune the walbros are tuned by mixture screws so no jet change is needed, some find the walbros a little hard to tune but i found its usually the walbro replicas that can be fussy & hard to set up

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