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Old 01-09-2006, 03:09 PM
mikeki mikeki is offline
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Join Date: Aug 2006
Location: wrexham
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Default Rough running engine

Just finished building xj900 trike pre diversion. Engine sounds and runs rough dont know if it wants tuning or I have some major engine problems. Does any body know of a company or person in the wrexham area that could tune or at least tell me if the engine is Knackered.
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Old 04-09-2006, 03:45 AM
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John Hopkins John Hopkins is offline
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Join Date: May 2006
Location: Tredegar, South Wales
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Default running rough

Get or borrow a Gunson Hi gauge compression gauge from ebay for 5 or halfords for little more. run the engine for about 10 minutes to warm it up and do one of the following...1. take all the plugs out and connect the gauge to one plug hole, Turn engine over a few times on the starter motor, take maximum reading. disconnect gauge and reconnect to next plug hole take next reading, repeat for all cylinders.
2. Run for ten minutes, remove one plug, fit gauge,start engine, take reading,replace plug, remove next plug, start engine, take reading, repeat for all cylinders. all cylinders should read the same, if you have a difference on one cylinder of over/under 20% then you have a problem in one cylinder, If they are the same, Look elsewhere
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Old 05-09-2006, 10:48 PM
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IPC_Jules IPC_Jules is offline
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how is it running rough?

i completely rebuilt my xj900 engine, i was lucky though when i cleaned the carbs and put them on it fired straight up, bit ropey idle but revs smoothly. Just need to get the balancing kit out and set them up

1. if you can look into the mouths of the carbs when its running (dont worry about having no airfilter for a few mins) watch the plungers going up and down... when you rev it they should all go up around the same time when you open her up. if one stays down compared to the others the carbs may need balancing or a diaphragm may have gone. a quick test do see if they are leaking is to push them up and put your finger over the port for it and see if it drops back down. it shouldnt

2. if the carbs seem ok then run it up and let it get nice and warm. rev it a bit and hold the throttle open for 5 seconds or so and then hit the kill switch. pull the plugs and see what colour the ceramics are. golden brown is good, white is too lean and black is too rich... if they are all wet and skanky its either far too much petrol or oil. which could indicate the carb letting too much petrol through or oil getting into the combustion chamber (more serious)

hope that helps a bit


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