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Post by motomartin on Dec 4, 2016 20:48:52 GMT -5
My RE5A starts easily and idles nicely, but is slow to pull away and will not rev higher than around 4K. I'm guessing that the secondary throttle valve is not opening. I noticed on another thread that the vacuum hoses were arranged in the photo below: I have the vacuum hoses around the other way with the secondary valve diaphragm attached to the lower of the two air jet outlets. If I arrange them as shown the bike will rev uncontrollably, and later the plug will be fouled/ bike flooded. The port valve seems to be opening correctly. I'm thinking the secondary diaphragm is not working correctly, is that still available? Is it re-buildable? My pump nozzle needle is also missing.
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Post by h2e Al In Aus on Dec 5, 2016 16:21:52 GMT -5
I just checked my carby hoses they are same as Photo ,there was someone on the site making new needles , or Jess might have them, as the carby Diapham as well ,good luck with the Carby
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Post by motomartin on Dec 5, 2016 17:16:01 GMT -5
Thanks for the reply. The next time I get a chance I will swap the valve diaphragm hose over but leave the enrichment one off for now, as that seems to flood the bike when I hook it up differently. I'll have to adjust the idle way down.
Cheers
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Post by redbug2 on Dec 5, 2016 18:34:28 GMT -5
I had a similar problem with the bike not revving up. It was the main jet, too small. One bike I bought a jet kit and used jet size 100. The second bike I used small drills and kept opening the hole diameter until the bike started running right.
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Post by h2e Al In Aus on Dec 5, 2016 21:26:35 GMT -5
If you have to run big jets there is a problem , one of my bikes came with 98 main , once carby cleaned and sorted correct port valve carby timing ,etc , got it back to standard jetting ,and running perfect no flat spots ,
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Post by motomartin on Dec 5, 2016 22:00:11 GMT -5
I installed the 100 primary main this weekend, which helped with the 3k-4k rev range, but I need help pulling away and going up hill.
What size should the secondary main jet be?
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Post by wayne on Dec 6, 2016 16:21:18 GMT -5
The secondary main is normally 180. I have experimented with them but have not had much luck. A 190 caused the bike to quit 200 metres up the road and would not restart until the 180 was returned. I tried 185, 182.5 with varying combinations of Primary. Overall, I don't think there was any positive contribution from changing the secondary away from the stock 180.
However, these bikes can be very individual so feel free to try.
While I fully endorse the use of a larger Primary main jet to stop anyone flinging themselves off a cliff over the hesitation, I reiterate and second Al that these bikes can be made to run perfectly with the standard 87.5 or 90 PMJ and 180 SMJ. If you need to change jets, then there are other problems with the carby but I'm well aware of hard it can be to diagnose.
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Post by motomartin on Dec 6, 2016 16:38:16 GMT -5
Yep, I have a 180 secondary main jet.
Wayne, when I route the hoses as shown in your photo above, my bike revs like crazy and later will not start. What do you think causes that? With the hoses routed the opposite way around it starts easily and idles nicely but the secondary valve does not open (I think).
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Post by h2e Al In Aus on Dec 6, 2016 16:50:24 GMT -5
I installed the 100 primary main this weekend, which helped with the 3k-4k rev range, but I need help pulling away and going up hill. What size should the secondary main jet be? primary main jet 87.5 2ndary main 180 ,
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Post by wayne on Dec 7, 2016 4:48:27 GMT -5
Martin, with the hoses around the wrong way I'm not surprised that the bike will start and idle nicely but the secondary is not opening.
Basically by putting the hoses around the wrong way, you're not really affecting the primary circuit. But you will probably be preventing the secondary from opening. I suspect the vacuum available to the enrichment is pretty minor and is not going to drive the secondary's actuator. Also, from memory, that enrichment valve comes in somewhere higher in the rev range. It's effect is very subtle. If you disconnect the enrichment valve it's hard to pick the difference. I once rigged it with a manual actuator to try and pinpoint just what effect it gives (not much).
As to why the bike revs like crazy when the hoses are correct..............I'm not sure. I was thinking that the bell housing has vacuum as it should have but it's opening the secondary too early. There is a mechanism that prevents movement of the bell housing actuator arm before 41 degrees of Primary butterfly movement. However, if that mechanism has been modified ?
Connect up the hoses correctly, take the air horn off, start the bike and observe what happens to the secondary. If it is opening even with the primary butterfly closed, then this would explain the rpm runaway. I would then suspect that someone has modified the mechanism that stops the arm from moving the secondary until at least 41 degrees. It may be acting on the secondary even at idle speeds. Previous owners do some crazy things to try and get the carby sorted.
Have a look at this video, it shows the mechanism. It's a slotted plate which blocks the bell housing arm from moving and opening the secondary until a pair of metal tabs come into contact (different to the Accelerator Pump touch tabs) and start to rotate the slotted plate unblocking movement of the Bell Housing arm. Is this mechanism still on your carby as shown in the video ? Has the little arm that connects the secondary butterfly to the limiter plate been removed ?
The mechanism is shown from 30 seconds into the video and again from 2:02 to about 2:30 into the video.
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Post by motomartin on Dec 8, 2016 17:00:06 GMT -5
Thanks Wayne, I'll try what you have suggested this weekend.
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Post by pmcburney on Dec 8, 2016 18:40:43 GMT -5
You can, fairly easily, isolate the vacuum system and get the secondary to open mechanically: It's a bit hard to see, but (circled) is where I installed a screw and nut into the slot in the secondary butterfly actuating arm. When the primary opens its set distance it physically pulls the secondary open because of the screw hitting hard against it. I tried it on my bike to see if it was part of my hesitation issue, but it didn't make any difference to that for me. It doesn't make the opening of the secondary any different, apart from it being mechanical and not reliant on the vacuum actuator at all.
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Post by motomartin on Dec 9, 2016 0:39:21 GMT -5
That's a great tip. I'm optimistic that I'll get this sorted out soon.
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Post by motomartin on Dec 11, 2016 0:49:37 GMT -5
Yeeeeeeeeeeeeeessss! I added a nut and bolt to the secondary valve arm, and removed the diaphragm as suggested. The bike is now running as it should, what a difference. The bike pulls strong like a 750 from that period and is great fun to ride - likes to be revved. I still want to change the gearing, around town the 41 sprocket seems too high, I want to change to the stock 43. Thanks to all that helped. Now I feel compelled to buy some shiny parts for it. Cheers, Martin
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Post by goandy on Dec 11, 2016 6:46:03 GMT -5
Not sure if it's related... the free revving may indicate an air leak- possibly the secondaries diaphragm has a small hole in it?
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