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Post by derrick on Jun 14, 2015 10:32:41 GMT
Back to trying to sort out the carbs - clearly I will get my mate to help me strip them again as we now know we missed the jets under the rubber - but another thing that is possible amiss and could someone please advise is whether there should be a spring loaded diaphragm arrangement in the side mounted " enricher / air damper" located by two small phillips screws on the left side of each carburettor as bike faces forward.
If there should be what is the effect of them not being there - someone has said they were fitted to some models but not all and there only purpose was to stop backfire on the overun..........could someone please help!
Derrick
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Post by wazzbo on Jun 14, 2015 12:46:18 GMT
Not on the 250 Derrick ,only the 400 has the air cut off diaphragm fitted
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Post by wazzbo on Jun 14, 2015 12:47:53 GMT
Some people block the off on the 400s as they can give problems. I think it was only fitted as you say to stop backfires on the overrun as the bikes were set up to run lean for the USA market to get round their emissions rules.
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Post by derrick on Jun 14, 2015 16:04:35 GMT
Thanks for that info I thought the rubbers were missing so was about to bid on some carbs - it seems therefore that the most likely cause of running problems are solely down to weak mixture so will need to strip them down again and this time ensure we clean the hidden jets under the rubber within piston assembly, and if the needle is a fixture and cannot be raised I guess the only other area would be the rubber carb to manifold inlets or the carb to air filter letting by?
Currently air screws are 1 1/2 turns out so I guess I could also try screwing them in further but to what extent - Haynes suggest they should be two turns out.
Will try and study the honda link suggested after dinner.
Sorry if I am driving you all round the bend with these questions but I really want to get her running before spending another £150.00 on tyres - us poor old pensioners....but still getting my free TV licence!
Derrick
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Post by bojer on Jun 14, 2015 16:15:41 GMT
The screws under the carbs control the amount of fuel not air - try setting them at the 2 turns out initially - 1/2 a turn will not make much difference but in the right direction ! General rule is if adjuster screw is on engine side of carb slide it adjusts the fuel , filter side it adjusts air . Probably worth cleaning the secondary and main jets again in case debris has got into them from the tank . You've seen this ? honda-superdream.co.uk/thread/5271/new-superdream-carb-section
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Post by wazzbo on Jun 14, 2015 16:34:45 GMT
yes bojer is right about muck in the tank,I thought I`d got mine clean but am still getting bits in the carbs even through the filter in the tank.
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Post by marktrower on Jun 15, 2015 9:12:23 GMT
Love the pics derrick that panther is one of the bikes on my wish list enjoy the superdream
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Post by derrick on Jun 15, 2015 9:22:51 GMT
Tried connecting to link suggested by bojer but eep getting " you do not have permission to view / access this" - WHY?
Derrick
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Post by derrick on Jun 15, 2015 9:27:00 GMT
Ref the Panther one of 4 in our little club the green one is a 120 of 650cc the rarest one is a rather unique twin throttle - left throttle controls the dip mechanism on the twin headlight - East Northants Classic MCC do have a very eclectic mix of machines - including of course my Superdream(s) and a milatary superdream / gs special.
Derrick
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terryc
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Post by terryc on Jun 15, 2015 9:44:51 GMT
Tried connecting to link suggested by bojer but eep getting " you do not have permission to view / access this" - WHY? Derrick You need twenty posts to access that thread Derrick so post another and you're in
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Post by derrick on Jun 26, 2015 10:09:00 GMT
Hi Guys,
Been away for a few days so not had chance to sort the CB250n although did get new rear tyre and she passed MOT, which is something.
Have now managed to access carb thread (made more than 20 posts - thanks for info on that) re- stripped carbs thoroughly and and used mates air compressor throughout .......two questions please please 1) early info said air screw was in fact a petrol flow jet therefore more screwed out the greater fuel flow - whereas various other references state it is an air screw which as you screw out allows more air therefore weakens mixture so I am confused?
2) The two jets top and bottom of the rubber plug opening do not have any size stamped on them - I assume one is main the other idle but to the eye even using jewellers loop they appear to be the same size - can you please advise the correct size jets, which goes where and most importantly where I can obtain new jets.
I guess if they are different size and they are in the wrong place this might be the answer to why it idles well but starves when you try and open and needs choke pulling out?
Derrick
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Post by bojer on Jun 26, 2015 18:32:25 GMT
If you look at the carb info it confirms what I said in my post that the screw controls the fuel not the air - in the pics the fuel is shown in red and the air in blue - honda-superdream.co.uk/thread/5271/new-superdream-carb-sectionIf the screw is on the engine side of the slide it is always a "fuel control" screw afaik - Haynes call it an air screw ......... The jets should be marked with their size the main jet being the 78 and the secondary the 112 - the secondary jet screwing into the emulsion tube - or needle jet holder in the Haynes book
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Post by derrick on Jun 26, 2015 23:51:52 GMT
Brilliant thanks for that info - as no markings whatsoever and can't really see a difference in jet size I will buy new jets - are they special to the carb type or can I buy amal jets. if carb matched where can I get new jets.
This bike will run properly sometime (soon I hope).
Derrick
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Post by bojer on Jun 27, 2015 6:33:18 GMT
Think these are the same size - check against yours , not got any to hand to compare with www.ebay.co.uk/itm/Brass-main-jet-Keihin-carburettors-8mm-short-type-99101-393-range-of-sizes-/360796082517?pt=LH_DefaultDomain_3&var=&hash=item54011f5155Have used Amal jets in the Mikuni carbs but of course they are sized in "flow" rather than hole sized so open up a whole new can of worms - physically different too. Be warned that you might yet need to go through the carb cleaning again , I bought an ultrasonic tank after I had "cleaned" mine with spray etc with no big improvement - it took the U/S and another clean before they were somewhere near Not original but I put allen screws in to replace the float bowl screws which means it is relatively easy to remove the bowls with the carbs still fitted . Good luck .
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