G'day Just bought a GB 250 project bike - currently stripping her down to figure out how she died... then to rebuild her. Any tips or info on this bike would be much appreciated as turns out its pretty hard to find! Cheers
Seeing as how Honda used the XL/XR engine in these I don't think it would be too hard to get bits for them. Are you doing a restoration or going to chop it up to make something trendy?
That's good news! I've grabbed the Jap manual off the site so I'll see if it gets me anywhere. Just want to rebuild engine, reassemble as is and get riding - play around with cafe looks later... At this stage just stripping engine down bottom end to find out extent of damage after a seized piston I bought it as is. THe mechanic who diagnosed it as dead to the last guy reckoned probably had been run out of oil - opened up top end to find wear to valve train assembly, no compression. Though I've dropped nearly 1.5L of oil out of it, so maybe it's an issue of oil being blocked somewhere? No huge discolouration to piston so maybe coolant was getting in? Will oversize and rebore, but need to find the cause first.
How could coolant be getting into an air cooled engine? Was the oil black or did it look clean? What did the filter look like? That piston has been detonated, badly. Not by lack of oil, but by lean mixture or advanced timing and lots of revs. I would just give the bottom end a flush out with kerosene/petrol and check that the big end bearing is ok, take the right sidecover off and check the suction pick up filter (and adjust the balance chain while your there) is clean and put it back together with rebore and new piston/gaskets.
Good point - not coolant then, absolute noob here first time I've broken into an engine Oil was dead black, filter looked full of black grit, and pretty grimey. Right cover off and working my way towards big end bearing at the moment or do you mean just visual inspection and wiggle shaft to see how much play in the bearing? Overrevving would probably fit the bill
