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Showing results for tags 'coil over plug'.
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1993 VR with stock TCI, I switched to Coil Over Plugs (COP). A few days ago I noticed a lot of decel popping on the right muffler. My "Mark's" collector sends the right front and left rear cylinder exhaust to the right muffler. Feeling the exhaust headers I noticed that the left rear one was remaining cool until heat from the right rear one conducted over through their common shield and the where the manifold was joined. I decided to switch the front and rear COP coils on the left so that I could verify whether the problem moved with the coil or stayed where it was. I sat on a short stool while pulling the coils which gave me a view of the vacuum ports (carb sync) and noticed that the end of the port cover for that rear one was laying next to the twinkie leaving the port open on that cylinder and so I replaced it. I did the coil switch as well and now all of the headers get hot pretty quickly after starting the bike. So, no coils were actually found to be bad, my wiring is as it should be, etc. Could having an open vacuum port on a cylinder cause it to not fire? I assume that the slide would not rise in carb for the cylinder that didn't have vacuum but the idle circuit should have been working and heating the pipe. Tell me your theories, or if you really know how this should work, please share the knowledge with me? On my way home last night before fixing this the engine was actually shaking the bike while sitting at a stop light, sort of like a Brand H bike would. I hadn't felt that on this motorbike before yet. A side question, is it a good thing to have the left front exhaust and right rear exhaust routed together through a common muffler and vice versa or not? It is not the way that Mamma Yamahama did it originally and so I have to wonder. It seems like it would be easy to add a crossover pipe between the two rears if it would make things fabulous.