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Post by dazzman64 on Jul 5, 2023 11:14:43 GMT 1
Hi guys, i Have a bit of an issue. Recently brought a second hand genuine throttle cable which as you would expect fitted perfectly. I have checked the oil pump alignment as per the diagram in the Haynes manual supplement area and it is spot on. I can see the throttle valves lifting up to the top on full throttle opening thru the windows. When I now start the bike(4th crank  )the revs shoot straight up to 6000 rpm and bike is missing and backfiring. Stopped bike immediately as engine has been fully rebuilt with less than 100 miles on it. Tried adjusting idle screws to try and bring it back down a bit on the carbs without success. Throttles valve issue/setting?Any help would be greatly appreciated. Thanks in advance. |
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Post by headcoats on Jul 5, 2023 11:22:11 GMT 1
Back the idle screws right off and see if the slides bottom out
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jimmyg
Drag-strip hero
Posts: 232
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Post by jimmyg on Jul 5, 2023 11:24:29 GMT 1
You haven’t got the slides mixed up and the wrong way round? Ie back to front
Or the balance/vacume pipe off?
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Post by linx on Jul 5, 2023 11:24:37 GMT 1
Are the cable adjusters on top of carbs right down?
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Post by stusco on Jul 5, 2023 11:35:09 GMT 1
Maybe one of the cables has popped out off the threeway junction under the tank,the slides will come right up but won’t go all the way down causing high revs
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Post by dazzman64 on Jul 5, 2023 11:49:14 GMT 1
Are the cable adjusters on top of carbs right down? Yes, as far as they can go. |
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Post by dazzman64 on Jul 5, 2023 11:54:26 GMT 1
You haven’t got the slides mixed up and the wrong way round? Ie back to front Or the balance/vacume pipe off? These only seem to go in one way with the groove on the valve facing outwards by the viewing window. How can I check if these are the wrong way round or mixed up.? I think they were put back the same way as they were removed but I will check. Balance pipe is untouched. |
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Post by dazzman64 on Jul 5, 2023 11:57:14 GMT 1
Maybe one of the cables has popped out off the threeway junction under the tank,the slides will come right up but won’t go all the way down causing high revs I can see the valves going up and down in the sight windows and the cable adjuster on top of the carbs is screwed all the way in. |
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Post by stusco on Jul 5, 2023 12:02:21 GMT 1
If the cable has popped out ,the slide wont go all the way down you can’t see that in the window ,it still goes up and down,just follow the cables with your hand you will find one of the cables is not in it’s spigot just pop it in and all will be good
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Post by dazzman64 on Jul 5, 2023 12:22:06 GMT 1
If the cable has popped out ,the slide wont go all the way down you can’t see that in the window ,it still goes up and down,just follow the cables with your hand you will find one of the cables is not in it’s spigot just pop it in and all will be good Just checked it all they way back to the three way junction under the tank and all the cables seem very tight and secure. I don’t think I could pull them out of their housing if I tried as they are very secure and under tension. I know this can happen on aftermarket ones (as I had one and sent it back) but this is a genuine cable . |
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Post by arrow on Jul 5, 2023 12:30:51 GMT 1
The correct slide for the correct carb. can't go in the wrong way round, but the other hand slide can only go in (the aforementioned carb). the wrong way round. If that makes sense.
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Post by stusco on Jul 5, 2023 12:48:53 GMT 1
Oh well thats what it usually is
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Post by midlifecrisisrd on Jul 5, 2023 13:43:39 GMT 1
Check the vacuum pipe and choke link pipe aren't off, leaking or split
Steve
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Post by dazzman64 on Jul 5, 2023 15:11:27 GMT 1
The correct slide for the correct carb. can't go in the wrong way round, but the other hand slide can only go in (the aforementioned carb). the wrong way round. If that makes sense. On each slide there is like a little dot punch mark for want of a better word. When the throttle is open fully these little marks should show up in the carb body window. Is that correct? If so then for some reason the cables are not returning to their home position resulting in the carbs being 50% fully open. When the carb tops are unscrewed but still connected to the slide and spring the cables return to their home position but when screwed down there is now no movement in the throttle whatsoever because the cables won,t return to their home position. Checked all the routing and it is straight. Think I,ve had enough for today.  |
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Post by midlifecrisisrd on Jul 5, 2023 15:22:10 GMT 1
If with the slides/springs connected to the cable it operates correctly but not when in the carb it is not the cable I'd think
Check on each slide that as well as the slide dot corresponding with the window on the body as you insert it that the angled cut out for the idle screw is in the correct place for the adjusting screw
If not the idle screw will be hitting the bottom of the slide and holding it open
Steve
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Post by dazzman64 on Jul 5, 2023 16:47:35 GMT 1
If with the slides/springs connected to the cable it operates correctly but not when in the carb it is not the cable I'd think Check on each slide that as well as the slide dot corresponding with the window on the body as you insert it that the angled cut out for the idle screw is in the correct place for the adjusting screw If not the idle screw will be hitting the bottom of the slide and holding it open Steve Hi Steve. Disconnected the whole lot again and found the issue. As Jimmy G said valves were fitted to the wrong carbs and the wrong way round. Initially slides would only go down carb bore with groove facing out without any hassle. This is why I could line the dot up on the slide with the carb window because it was on the other carb. After fiddling around managed to get them down the carb bores with the groove facing inwards. Put everything back and perfect throttle response . Just now need to play around with adjustment screws to get even tickover. Thanks guys. Rookie mistake but we got there in the end.  |
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Post by arrow on Jul 5, 2023 16:54:57 GMT 1
Sorted. The oil pump pulley adjustment is the last item you check after adjusting the carbs. 👍
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)the revs shoot straight up to 6000 rpm and bike is missing and backfiring. Stopped bike immediately as engine has been fully rebuilt with less than 100 miles on it. Tried adjusting idle screws to try and bring it back down a bit on the carbs without success. Throttles valve issue/setting?Any help would be greatly appreciated. 
