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Post by Deleted on Jan 29, 2015 20:24:46 GMT
Hi, this is a long story, but please bear with me! I am going to build a superdream café racer and acquired two basket case's, one 250 and one 400. Both engines had not been run for several years and on both engines had the carbs removed and were left open to the elements. I wanted to run the engines to check on the bottom ends and for any noises. After a couple of days of fettling the 250 sparked into life and sounded very good, the 400 however took a bit more persuading! I removed the new sparks from the running 250, re gapped them and fitted them into the 400. After a few attempts of starting I removed the plugs to see if they were getting wet and found that the right cylinder plug gap had closed right up?? I then fitted another new set of plugs and tried again, on this occasion the same thing happened, but on the left hand plug?? I then fitted the old plugs (all the plugs fitted were NGK dr8es, even the old ones) and the engine started and now runs fine! I looked through the plug holes at the tops of the pistons and there are visible signs that the pistons have hit the plug. Has any body else come across the problem? am I missing something obvious? Any help is much appreciated my-fingers-are-crossed-smiley-emoticonAlan. |
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Post by marktrower on Jan 29, 2015 20:36:34 GMT
some plugs the electrodes stick out more and there short and long reach plugs are the plugs new you fitted. just some info there are a lot of fake spark plugs about
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Post by Deleted on Jan 29, 2015 20:45:06 GMT
some plugs the electrodes stick out more and there short and long reach plugs are the plugs new you fitted. just some info there are a lot of fake spark plugs about Hey Mark - can you enlarge the text just a tad?
I fear a lot of members will struggle with this.
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Post by Cheggy on Jan 29, 2015 21:00:46 GMT
I agree with Mr Trower, have you held the old and new plugs together to compare?
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Post by Deleted on Jan 29, 2015 21:12:55 GMT
Hi, I have measured all plugs and they are all within 0.5 mm of each other. I know the stroke is longer on the 400, but surly the tolerances are not that tight, are they? |
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Post by marktrower on Jan 29, 2015 21:37:16 GMT
ok now new laptop do not like this windows 8 this is when rich comes in and saves the day .did you put oil in the plug hole to lubricate the engine possible hydraulic lock can close the gap and have both sets of plugs got the sealing washer on just posabilities
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Post by Deleted on Jan 30, 2015 8:24:31 GMT
Hi no oil was needed, the engine turned over fine, I took of the clutch cover, cleaned out the old oil residue, refitted cover, added new oil, turned over without plugs to check oil pressure (which was good), checked compressions (both around 130psi) and then tried to start. Now I know the bottom end is good i will now be removing the top end to cure the oil leak (which thanks to this forum has pointed me in the direction of the head bolts!) so will see if anything shows up, I am just concerned, am I wasting my time with this engine?
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Post by marktrower on Jan 30, 2015 11:32:09 GMT
Hello salan you stayterd the engine run fine that rools out big end failure. you say the top as got to come of to sort the oil leak.I think after strip down it will tell you more about the condition. good 400 engines are hard to get so well worth the effort. The bottom end on these engines are very strong .the top pack's in first through abous and negligence. I think the 400 will make a very good cafe racer mark
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Post by Deleted on Jan 30, 2015 12:27:22 GMT
Thanks mark, will be stripping it down within the next week or so, so will keep you updated  |
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