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Post by Tommy on Jan 21, 2012 17:41:49 GMT
Just tried to fit a AV266 atomiser to a 28mm Dellorto PHBH RD carb i have as recommended in an earlier thread but it won't fit anyone any ideas? Atomiser in carb already is a T266
SET up in carb at the moment-
40 slide
60 choke
45 idle
125 main
T266 atomiser
X5 needle
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Post by amazombi on Jan 21, 2012 19:57:13 GMT
The single letter before the number hints at a fourstroke carb. Does your atomiser have tiny holes in it? If so, it's fourstroke. Not very good on a twostroke engine.
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Post by Tommy on Jan 21, 2012 22:03:11 GMT
Yes the adomiser has little holes in it thanks amazombi
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Post by Tommy on Jan 22, 2012 11:20:57 GMT
Would it be possible to remove the 4stroke adomiser bush and replace it with a 2stroke adomiser bush? If possible has anyone done this before and any tips on how to do it ? Is this all i have to change to make this carb ok for a 2stroke motor
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Post by amazombi on Jan 22, 2012 18:36:27 GMT
Theoretically you can get two-stroke atomisers with the thread in the right place to work with a fourstroke carb. Those were available every now and then in the 90ies, no idea where to get them these days though. Changing the carb body itself is not really practical, I think. Buying a second hand twostroke Dellorto would definitely be less hassle, and quite possibly it would also be cheaper.
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Post by Tommy on Jan 22, 2012 19:17:19 GMT
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Post by smallyshane on Jan 22, 2012 20:47:47 GMT
yes. Done it to my vhst. Its a pig to get out if i remember right, but really can't think how i did right now.. Its about 15quid for the bush too..
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Post by jonnysnatchsniffer on Jan 23, 2012 16:56:21 GMT
sell the carb on ebay to some cunt with a lardy210 or lammy and buy the proper 28/30mm carb you need, its a bit of fucking around to change it and imo not worth the hassle unless the carb cost you fuck all
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Post by Tommy on Jan 23, 2012 19:28:04 GMT
The carb cost me about 15euro jonny might just give it a shot a change the bush think its 10pound for the bush
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Post by knowledge on Jan 23, 2012 23:57:04 GMT
The bush (also known as the primary choke) is a part readily available from better dealers or Dell'orto concessionaires. It is about £8 plus postage.
To remove the 4-stroke bush by stripping the carb of the bowl and slide, and placing a drift into the bottom of the apeture for the atomiser and place it all in the jaws of a vice so that as the jaws of the vice are closed up, the bush is forced out (gently). It comes out quite easily.
The two-stroke bush can be pushed back in in a similar fashion. You may need to drill-out one of the feeds from the front of the carb to the top of the atomiser: there is often a restrictor in this feed which is not required for a two-stroke conversion.
As to four stroke carbs on two strokes, they do work. I point you towards the Honda NSR125 as manufactured in Italy. They were fitted with four stroke carbs even though they were two stroke engines. There are other examples of this from major manufacturers.
I have always reasoned that if an engine has an inlet valve, it can use a four stroke carb, be it a four-stroke or a reed valve two stroke.
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Post by amazombi on Jan 24, 2012 6:19:05 GMT
A twostroke sucks in much more air at the same rpm (it does so every revolution, not every other), and it requires a slightly richer mixture than a fourstroke. You can use a fourstroke carb on a twostroke, it's hardly ideal and in the case of the Honda you mention it was done to lean off mixture at mid rpm to comply with European emission regulations. "Hardly ideal" may mean anything from running ok-ish to running pretty shit, or even to failure of bearings/engine due to lack of cooling and lubrication.
A valve is something that opens or closes a passage, a piston closing a port is a valve of sorts, as is a rotary inlet doing the same thing. Differentiation between the different types of inlet design does not seem plausible to me at least.
I wasn't aware that the bush was that cheap, and that it can be changed so easily. Since that doesn't seem to be a problem that's the way I'd go.
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Post by Tommy on Jan 25, 2012 13:31:28 GMT
Thanks for everyones input on this just removed the 4stroke bush today pretty straight forward job to do took about 5mins Just have to order a 2stroke bush from dellorto now and carb should be good to go
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Post by jonnysnatchsniffer on Jan 25, 2012 16:47:26 GMT
a 2 stroke bush ;D ;D ;D
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Post by arnaud on Dec 4, 2016 16:37:48 GMT
yes. Done it to my vhst. Its a pig to get out if i remember right, but really can't think how i did right now.. Its about 15quid for the bush too.. I have trouble getting one, doesn anyone know a part nr of it? |
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Post by jbcollier on Dec 4, 2016 19:28:43 GMT
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Post by jbcollier on Dec 4, 2016 19:30:59 GMT
... and don't forget to drill out the air bleed!
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Post by wacker on Dec 6, 2016 17:48:24 GMT
I seem to remember having to drill the atomiser stop deeper in the carb body as the AV wouldn't screw into the bush.
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