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Post by toystoretom on Aug 14, 2021 12:40:17 GMT -5
I was trying to get one of my A's running for an upcoming rally and I discovered that many people had been inside the carb and had done terrible things. I do have it running now but that carb is not the best. So I am toying with the idea of converting the bike over to an SU carb. I have seen this done from time to time on the internet. Has anyone here tried to do this? What SU carb did you use? Did you start with say a 3 or 4 inch aluminum cube and just start drilling and filing?  I see cubes like that on E Bay and we have a place called Metal by the Foot and they might have something. Or possibly someone has made some and they would like to sell one? Any thoughts or ideas would be very helpful. Thanks! Tom |
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t140v
3rd Gear
Posts: 427
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Post by t140v on Aug 14, 2021 17:39:32 GMT -5
Hi Tom, I had major problems with my bike, hesitation was getting worse so I checked the carb out, and the composite float gasket carb was goosed so I made my own, big mistake bike ran like a pig and I thought it was going to destroy itself, so I bought some alloy plate and pair of SU carbs to do the conversion.
Bought a new needle for the SU that was as close to the one used in the Norton rotaries as possible, made the conversion manifold and was ready to go for it when Roger sent me a nos float bowl gasket.
That solved the problem the bike ran like never before, no hesitation no flat spot could not believe a gasket could make so much difference, I had a batch of float bowl gaskets made but made a mistake and had them made in standard petrol resistant rubber but the ethanol made them swell so had them made in Viton which seems to have solved the problem.
So before jumping in and going down the SU road make sure that its not an easy fix thats causing the problem.
Aluminium is not the soft easy stuff you think it is, its one of the hardest materials I've had to work with.
Regards Stuart.
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Post by wayne on Aug 14, 2021 17:44:07 GMT -5
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Post by toystoretom on Aug 14, 2021 17:56:34 GMT -5
I didn't mean to mislead you, the studs holding the air horn are stripped in the carb body, most of the jets are buggered up, (slots stripped and so on) , the strange mixture adjustment screw that is at a 45 degree angle on top of the carb had been installed at a bad angle and had stripped those tiny threads, and so on. it needs more help than a new float bowl gasket, however, that is good advice and I have other RE5s that probably can use that gasket.
I looked originally and didn't see that thread Wayne so I thank you. I like the comment about it running better than it ever did before. I do have it running to the point where you can ride it down the road but this might be a cool project this winter.
Thanks guys and if you have any ideas let me know!
Tom
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t140v
3rd Gear
Posts: 427
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Post by t140v on Aug 14, 2021 18:11:38 GMT -5
I have made and bought new jets, the Idle screw at 45deg can be remade and threaded oversize the threads recut at 5.5mm if the carb can take it.
When you live in the UK and have a limited budget to work to, you need to think outside of the box.
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Post by toystoretom on Aug 14, 2021 18:27:09 GMT -5
I just read through that thread quickly and the adaptor plate he made was 12 mm or about a half inch thick. I don't know why but I had envisioned something much thicker/longer almost like tubes of an intake manifold on a car. His set up is more like an adaptor plate you would find for an Edlebrock carb on an old 350 Chevy motor, but mounted vertically, not horizontally. Shoot, I probably have some aluminum stock laying around that would work. This is very interesting. I have a machine shop right down the street from where I work that could probably fab that up nicely. I think the sticky part (for me anyway) will be finding or making an o2 sensor set up, I will have to study that more and give it some thought.
Tom
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Post by toystoretom on Aug 14, 2021 18:33:15 GMT -5
Hey Stuart, I was looking at that 45 degree idle screw and it appears that it threads into a small removable adaptor that is held into the top of the carb by two small Phillips head screws and you could probably remove that as an assembly. Maybe get that out of there and clean those threads up? I'm not going to mess with it until after the rally next weekend, I'm just happy it runs right now
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Post by wayne on Aug 14, 2021 19:48:30 GMT -5
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Post by toystoretom on Aug 15, 2021 18:33:13 GMT -5
Oh wow, he needs a 80 cubic inch engine Harley carb off of something like a 80's or 90's Fat Boy or the like. Those things were actually a snowmobile carb and because the pulses from the cylinders sent such a shock backwards through the carb it looked like that carb was running backwards lol.
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I see cubes like that on E Bay and we have a place called Metal by the Foot and they might have something. Or possibly someone has made some and they would like to sell one? Any thoughts or ideas would be very helpful.
