Big problems with my NC23
Posted: Tue Oct 21, 2008 1:05 am
Right, a quick intro, my name is Adrian, studying for a degree in Mechanical Engineering at the University of Nottingham.
(By the way the problem with my bike is entirely a result of my own foolishness, but please don't judge me as a total idiot, its very unlike me to do something like this, I am the opposite and would rate myself as not a bad mechanic).
I bought my NC23 as a wreck back in February it was pretty much a frame with engine, and a box of bits. I blagged an MOT on it after throwing it together and rode it round for a bit. There's a hundred and one problems still. Basically the carb plate that mates with the airbox had a nasty hole/chunk missing where someone previously had overtightened a bolt, I naively ignored this not thinking it would be to much of a problem. Im sure you can all guess the result, Im assuming that cylinder drew in to much air and ran to hot. The bike then was laid up for about 3 or 4 months, before I arranged to have it couriored up here to Nottingham with me.
I was going to fix the engine myself and then a lower mileage one came up on ebay cheaply. Iv changed the engine over and patched up that carb flange with chemical metal. I am very confident in the engine change, and did nothing wrong at all in terms of a straight swap. The only corner I cut was not replacing the exhaust gaskets as I didnt have time to wait to order a replacement set. There was a very big reason I needed transport at the weekend, please dont ask what it was as it is personal. I think the flange sealant and old gaskets have done the job, but now its off the road again I will replace these properly.
Now here is the problem, it didnt feel right to ride instantly, I shouldn't have ridden it at all, but in desperation due to current circumstances I was foolish and did.
It felt like it was always struggling, and I did push it to hard, praying the problem would go.
Heres a run up of what happened:
1) It was struggling, not running smoothly, but felt more uniform then my old engine (also a much better gear box, it didnt jump out of gear like the old one used to).
2) I was pushing it a little hard, something was definetley wrong, but I kept my eye on the temperature gauge afraid of a seizure. The temperature didnt change at all. It kept going for 5 or 6 miles then....
3) It started to die, it was just struggling more and more and more, I was rolling to a halt with the throttle wide open and it was still trying to run.
I attempted to start it after it had cut out, and all the pistons etc sounded free but it just wasn't firing. Once it cooled down however it would start and tick over happily - I didn't ride it again though.
I did run it to hard after an engine change and without doing some important things. I just hope I haven't cause damage to the engine.
My main thoughts are that the carbs are completely out of balance and require an overhaul. Im going to carry out a compression test on each cylinder and hopefully get some positive feedback, I have also thought about using colourtune and carbtune to sync the carbs and ensure the mix is right.
Do any of you guys on here have any thoughts as to why the bike will start fine again, and what damage I may have caused to the engine by running it so hard (by hard it felt hard, but never went above 9000rpm)? Im hoping the reason it cut out was due to either flooding or the spark plugs fouling up and not due to overheating, valve problems or pistons/rings.
Thanks for reading
Heres a picture of the bike just to brighten up the thread a little:
(By the way the problem with my bike is entirely a result of my own foolishness, but please don't judge me as a total idiot, its very unlike me to do something like this, I am the opposite and would rate myself as not a bad mechanic).
I bought my NC23 as a wreck back in February it was pretty much a frame with engine, and a box of bits. I blagged an MOT on it after throwing it together and rode it round for a bit. There's a hundred and one problems still. Basically the carb plate that mates with the airbox had a nasty hole/chunk missing where someone previously had overtightened a bolt, I naively ignored this not thinking it would be to much of a problem. Im sure you can all guess the result, Im assuming that cylinder drew in to much air and ran to hot. The bike then was laid up for about 3 or 4 months, before I arranged to have it couriored up here to Nottingham with me.
I was going to fix the engine myself and then a lower mileage one came up on ebay cheaply. Iv changed the engine over and patched up that carb flange with chemical metal. I am very confident in the engine change, and did nothing wrong at all in terms of a straight swap. The only corner I cut was not replacing the exhaust gaskets as I didnt have time to wait to order a replacement set. There was a very big reason I needed transport at the weekend, please dont ask what it was as it is personal. I think the flange sealant and old gaskets have done the job, but now its off the road again I will replace these properly.
Now here is the problem, it didnt feel right to ride instantly, I shouldn't have ridden it at all, but in desperation due to current circumstances I was foolish and did.
It felt like it was always struggling, and I did push it to hard, praying the problem would go.
Heres a run up of what happened:
1) It was struggling, not running smoothly, but felt more uniform then my old engine (also a much better gear box, it didnt jump out of gear like the old one used to).
2) I was pushing it a little hard, something was definetley wrong, but I kept my eye on the temperature gauge afraid of a seizure. The temperature didnt change at all. It kept going for 5 or 6 miles then....
3) It started to die, it was just struggling more and more and more, I was rolling to a halt with the throttle wide open and it was still trying to run.
I attempted to start it after it had cut out, and all the pistons etc sounded free but it just wasn't firing. Once it cooled down however it would start and tick over happily - I didn't ride it again though.
I did run it to hard after an engine change and without doing some important things. I just hope I haven't cause damage to the engine.
My main thoughts are that the carbs are completely out of balance and require an overhaul. Im going to carry out a compression test on each cylinder and hopefully get some positive feedback, I have also thought about using colourtune and carbtune to sync the carbs and ensure the mix is right.
Do any of you guys on here have any thoughts as to why the bike will start fine again, and what damage I may have caused to the engine by running it so hard (by hard it felt hard, but never went above 9000rpm)? Im hoping the reason it cut out was due to either flooding or the spark plugs fouling up and not due to overheating, valve problems or pistons/rings.
Thanks for reading
Heres a picture of the bike just to brighten up the thread a little:
