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Aug 11, 2009 20:26:36 GMT
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So......
Apart from trying to get the viva through an mot for RRG (double caliper rebuid and a few other little demons), I'm trying to sort my bike out..
It's the '76 Z in readers other modifications that had a few few problems and was smoking like a badden. Story goes it was smoking - a lot for a four stroke. It burned an entire engine's worth of oil in two journeys to and from work and blew itself up. I had to get another lump from the bay, build a good one out of the two and stick it in, which I have just been working my as5 off putting back together again.
It's looks great but on riding it today for a while, it still smokes like hell. In fact, it burned most of it's oil today. I'm sure that Zd's are supposed to be reliable and a good motor, so what's up? Air leak between the inlet manifold trumpets and the head? Trumpets and carb? mixture?
Getting a bit bored with it! Thanks for reading.
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purplevanman
Posted a lot
Way too orangey for crows
Posts: 3,829
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Aug 11, 2009 20:51:34 GMT
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it still smokes like hell. In fact, it burned most of it's oil today. I'm sure that Zd's are supposed to be reliable and a good motor, so what's up? Air leak between the inlet manifold trumpets and the head? Trumpets and carb? mixture? Getting a bit bored with it! Thanks for reading. never my favourite bikes but it shouldn't be this bad  An air leak would make it run lean and possibly rough and lead to overheating, doubtfull it would be anything to do with oil consumption. If it is smoking under power it is generally worn piston rings/bores, if it smokes on over run then it is usually valve guides/stem seals. To use this much oil is a big problem somwhere ! What bits did you use from which engine to build this up? What were the bores like, did you try the rings in the bores? Did you try to move the valves side to side to see if the guides were worn? New head gasket, O rings in right places? |
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Aug 11, 2009 21:31:23 GMT
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not gonna be anything to do with mixture if using oil
does it idle ok? and nice and low and smooth.. if so the fuel/air is probably ok as slightly out will cause issues in that department
did you use the same head from the engine you blew up? has it warped? possibly cracked oil galley? or if your using the same pistons... make sure they have all the rings intact..
maybe do a compression check over all cyls and make sure they are ok... at the same time check the plugs... see if you can find the culprite cylinder/cylinderS by the colour or oil on the plugs..
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Aug 12, 2009 11:12:11 GMT
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Nice one. Thanks guys. It's a 400 twin. The engine I bought was off ebay and the dude said he had re-built the top end (new valves - used parts) for a bobber project that he never got around to putting together. It has good compression on the kick but that doesn't tell all stories about any scores in the barrel or what ever. The only work I did to the lump was replace the dynamo, starter motor and re-tapped the cylinder and put in new studs for the exhaust clamps, so I didn't have to take it apart. It does idle, and starts well too, and it only smokes when it's hot. Also, when it is hot and smoking, it is more liable to stall when ideling for a few seconds. Also, the tickover is a bit too high - I've just replaced the o-rings on the main jets which improved it greatly, but It's still too high when running at temperature and I have run out of adjustment on the tickover screw. Could this be a contributing or resulting factor? the plugs look like it's burning oil-heavy for sure and by the clouds that come out the back the oil consumption, I'm going to get pulled over by the road-going equivalent of the rainbow warrior any day now. this is the machine in question..  The more I think about it, the more I'm thinking maybe total stripdown.... |
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Aug 12, 2009 11:16:29 GMT
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you checked breathers?
crankcase and head breathers?
when these block up can can cause the oil to be forced where its not ment to be e.g pass the rings and or valve stem seals?
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Aug 12, 2009 11:16:51 GMT
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yeah your gonna need to strip that lump mate at least building it yourself youll have piece of mind... i bought a beetle lump once .. supposedly built by a pro engine builder... fitted it and started it... oooh look no crank bearings... on replacing them noticed the centre line of the case hadnt been machined and wouldnt seal.. and there was no flywheel oil seal ... gotta be carefull, and work you can do yourself is better off done by YOU!  |
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Aug 12, 2009 17:55:00 GMT
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True. Oh well I really don't have the money at the moment to do it, and having just been made redundant it's going to have to be an on-going project. I spent quite a bit of money on the bike as well so that sucks! Yeah, breather hose, air filter and top cover all removed and checked for general breatherness. Thanks for the input guys. Oh yeah, mot on the viva is tomorrow at 6 so fingers crossed on that one.... |
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