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Post by hitch007 on Oct 2, 2012 21:04:04 GMT -5
After reading the manual, trying to fix this dead spot when opening the throttle rapidly, I performed the accelerator pump check. After taking off the intake manifold and propping open the secondary throttle valve, I gave the throttle a good ole twist. I could see the mechanism moving ok but there was no squirting of fuel into the secondary throat. I'm starting to think that my hesitation is due to fuel not getting past the check valves. More evidence about this fault showed itself when as I manually actuated the acc pump, fuel was squeezing around the diaphragm indicating a blocked circuit. Has anyone out there pulled the check valves before? Is there an easy fix to get the acc pump working again? Any and all musings appreciated. Gareth  |
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Post by glankford on Oct 3, 2012 22:45:55 GMT -5
Hello Gareth, I had a problem with my accelerator pump, and it turned out to be a blockage in the little brass tube down to the secondary. I'd make sue that's clear as well.
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Post by hitch007 on Oct 4, 2012 15:20:57 GMT -5
Cheers, as part of me trying to fix this problem, I'm give the carb an overhaul so will check it out when I break it apart.
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Post by HGH 770N on Oct 4, 2012 16:13:50 GMT -5
The flow from the Acc pump is up through the 1st of the smaller jets on the left of the two together then passes between the passage under the gasket of the Chamber top and then down through the needle jet on the right of the two and squerts out the single hole Nozzle into the secondary bore. Check your needle in the jet on the right is free and squerts into bore.( clean using carb cleaner). also check your gasket is not restricting this needle from movement . You can check the pump with the top of and fuel inside bowl and the activate pump and it should squert up out of the left jet of the two. The Acceleration pump circuit is on page 57 6-2 Be cearful, the Needle jet DOSE NOT uncrew Its a Push fit and not designed to be removed because it is set so the single hole squerts in the rite place. Good Look Rog Attachments:
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Post by hitch007 on Oct 4, 2012 23:02:46 GMT -5
Hey Rog, thanks for the advise. I took the carb apart as much as I could without removing it from the engine and took a look. Yes mine does squirt fuel and it wan's blocked from the top. I also removed the acc pump from the bottom to see if the diaphram was split (it didn't apear to be) and reassembled it(after losing the damn spring!!) I was wondering if there is some way of priming the acc circuit after reassembly as it seemed to be sucking air and still no show in the secondary throat.
Would i damage anything if I put compressed air down the needle part of the jet (after it is removed of course).
Cheers
Gareth
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Post by HGH 770N on Oct 5, 2012 5:32:04 GMT -5
Gareth
I have seen and stripped down and rebuilt a few of these carbs, some of them in very bad condition,
Has your carb any signs of been messed with ?
Please understand there is only a single miniscule jet at the end of the tube that is directed down the carb throat .
this tube is difficult to remove and as seen in this photo the jet has been twisted out of alignment and damaged the slot heads.
I would advise you to use carb cleaner before you try and remove the jet. Remove Needle first.
Rog
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Post by tom93gts on Oct 5, 2012 16:47:35 GMT -5
I don't mean to hijack this thred, but what happens if the jet is missing the needle? I don't think my carb has that needle in the jet. It still runs great but if the needle is missing could this be a source of my bad fuel economy? Of course the needle could be in there but I really don't remember seeing it.
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Post by hitch007 on Oct 5, 2012 18:16:07 GMT -5
Would you think a length of .032 lock wire would go down that tube? It feels like a blockage of some sorts as when I actuate the pump it feels like it is hydraulicing somewhat. It feels blocked even if the needle is removed, I even trimmed the gasket over the top of the needle incase it was blocking it somehow. Still blocked.... Also, which particular hole is the fuel supposed to come out of? There is a brass post with no visible holes, a hole just behind that and another hole at the top of the butterfly just visible when the valve is fully closed. |
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Post by hitch007 on Oct 5, 2012 19:12:35 GMT -5
Well finally, a breakthrough. I wasn't sure about where the nozzle was for the jet so I carefully inserted a screwdriver into the jet and turned it 180 deg so I could see it from the outside. What a tiny little bugger of a hole!! Luckily for me I have some dentist picks and mirrors handy so I gently inserted a straight pick into the hole and actuated the lever. After some sputters and wonky spraying (all over me as I was looking into it!) it ended up being a nice even spray. I turned the jet back to the right way and am about to go for a wee burn around the block. I'm hoping my flat spot will be gone. I'll post the results when I get back. Wish me luck!
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Post by hitch007 on Oct 5, 2012 20:01:36 GMT -5
Success! The bike accelerates nice and smoothly now through the gears.
Very happy now!
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Post by hitch007 on Oct 7, 2012 2:54:03 GMT -5
I don't mean to hijack this thred, but what happens if the jet is missing the needle? I don't think my carb has that needle in the jet. It still runs great but if the needle is missing could this be a source of my bad fuel economy? Of course the needle could be in there but I really don't remember seeing it. After all the mucking about with this problem, I can guess that the needle is for reducing the volume in the pipe, hence accelerating the fuel through the pipe due to the reduced volume, producing a big fat spray of fuel through the nozzle. Do you have a flat spot when opening the throttle? If you do, it mat be due to not enough pressure to produce the spray required. When I cleared the blockage in mine, the fuel squirted at least a couple of feet, enough to wet me next to the bike that is! Cheers Gareth |
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Post by HGH 770N on Oct 8, 2012 6:47:32 GMT -5
Glad all is ok and no expencive fix needed,
keep the old things on the road
Best
Rog
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Post by tom93gts on Oct 9, 2012 9:20:15 GMT -5
Do you have a flat spot when opening the throttle? If you do, it mat be due to not enough pressure to produce the spray required. When I cleared the blockage in mine, the fuel squirted at least a couple of feet, enough to wet me next to the bike that is! Cheers Gareth No flat spot at all, runs perfect! But I wonder if it gets overly rich when I give it throttle and could maybe be a little quicker and a little better fuel economy as a result. I should check for that needle jet I suppose. |
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