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Post by richard on Aug 16, 2021 14:23:10 GMT
hello
just bought the superdream 250n this afternoon [ pictures are on the "hello" section of the forum ]
after driving 66 miles back home, i noticed the following issues
1 - it starts on the button but only one the left hand cylinder, but once warmed up it runs on two [ and when warm, starts on the button and runs on both cylinders ]
2 - the right-hand header pipe is blowing quite a bit, from a split on the bottom bend 3 - the right-hand cylinder spark plug is sooted up, the left spark plug is fine 4 - poor power on inclines, hills etc - even dropping down a couple of cogs has no effect, i can feel her choking up until i back off slightly 5 - she dosnt tick over at the traffic lights, junctions etc, just quite happily stalls 6 - couldn't see much of a spark on the right-hand spark plug 7 - petrol dripping out of the overflow pipe under the bike with the odd puff of what looks like steam ? coming from the same pipe [ although could be water, not petrol i guess ]
so she is running rich on the right cylinder, but i am not going to rush in and take everything apart, i will tackle one thing at once, starting with the header downpipe and then clean the carbs, then i would need a spot of help pointing me in the right direction for everything else..
for now i intend to get some exhaust paste and bandage, until i can find a suitable header pipe, theres one on fleabay from a seller in cornwall, but they dont look that healthy, i also found a new pair for about £100, but i suspect they will be single skinned [ not that it matters to much ]
i am out of work just now, so cant afford to simply go buy bits off the shelf
thanks richard
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Post by johnjones on Aug 16, 2021 15:08:36 GMT
Hi Richard, hope you did your research about these bikes, they picked up a nick name at the time and it stuck.
A wet dream.Tge modern nick name is super slug.
I ride one, it don't like hills or headwinds but go amazingly well in a tailwind and are real fun on back roads
At least you got it home.
I presume it was used regularly before you bought it ?
How many miles and any hint of an oil leak or sealer at the front of the engine between the cylinders.
If you look at the front of the engine, below the cylinders you will see the "seam" between upper crank case and lower crank case. Clean that seam area and look for any sealant used there as well.
Post a picture of that area when clean.
The crank case split horizontally and sealer is used to make the joint oil tight.
Reason for asking is to establish if the engine has been apart.
Any sealer seen anywhere else like at the back of the engine ( a bit difficult to see but seam by rear brake light switch is visible ) and under the flywheel cover.
How black is the engine oil ?
You know of balance chain adjustment and issues as well as the 4 centre head bolts hopefully not being problematic, linked to front centre engine oil leak and sealer.
As to engine running, the carbs are the last port of call, other stuff to be done before going to them.
Does/did the bike rev over 5k revs or seem to "surge" and any evidence of exhaust front pipes blueing or even glowing?
Your labour is free and you have time on your hands, I know the feeling being "financially challenged".
You know of CMSNL for the exploded views...free resource and very informative, study and or print off if you can.
You have a manual and basic hand tools ?
2 special tools you will need at some point for the engine.
A peg spanner for the clutch nut and extractor bolt for the flywheel.
HT leads are not removable from the HT coil unless it's buggered. Even wobbly HT leads at the coil is potentially bad.
Note, the cam cover is insulated , so no sparks on there....
If your first job is the exhaust leak, do not (DO NOT !! ) Shear the studs !
I assume you have a small grinder, blow lamp, selection of hammers ( small ones are so so so much better ), 8mm thin walled hex socket 1/4 and 3/8 drive and a low range torque wrench.
Dmm, strobe timing light etc..
So...
1. Does engine rev over 5k ?
2. Any oil leaks or sealer at the front of the engine ?
3. Any blueing of exhaust front pipes ?
4. Any thumping from engine low down ?
5. Any rattles or knocking noises in engine ?
6. Any ticking noises from the top of the engine ?
7. Any chain type noises from the engine ?
If answers are 1=yes and the rest no, then you may have got a goodish one, in need of a full service, tune up and complete fuel system clean out, hopefully...and that's just the engine.
CMSNL print offs and study, time well spent.
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Post by richard on Aug 16, 2021 15:57:09 GMT
hello
no not much research, i had a 250n about 32 years ago, but i thrashed up and down the country attending various rallys for a couple of yrs etc....after that i had 750 kawasaki [ hardtailed, single seat etc ] then a gpz600r, then a break of about 12yrs and back to the superdream
no, to being used regularly, the bike was owned by an elderly guy, who bought it over 12 months ago, and just started it once a week, he had never ridden it [ but he is 80yrs of age ] and the guy he bought it off hardly used it either
19,500 miles on the clock and from a cursory glance no oil on the outside of the engine [ but will give it a good going over in the next day or so ]
no unusual engine noises, seems quite quiet [ aside from the header pipe blowing ]
engine oil is fine [ has just been replaced along with a new oil filter ]
yes the bike will rev over 5k [ on the flat ] but nowhere near the red line [ and as the seller hadnt used it, i was being overly cautious to ensure i got home ] but now shes home, i have various roads that i can open her up on, and that if anything doses go wrong it wont be far to push her back !
no blueing or glowing on the pipes
i have plenty of tools, having owned and worked on landrovers over the past few years, although my torque wrench for the landys was to " tighten till my teeth hurt "
but yes, no torque wrench,or strobe light, but do have a multi-meter, grinder, dremel, blowtorch, big and small hammers etc
i had already sourced a pdf workshop manual, but the seller furnished me with a haynes printed manual, with no tell tale signs of oily fingerprints on any particular chapters
wasn't aware of CMSNL or any other sources really, i don't have any options to print stuff out unless i download images and go to the library to have them printed for me
but i will go though your check list, and post the relevant pictures, and make any observations along the way and post my findings
thanks richard
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Post by johnjones on Aug 16, 2021 17:07:31 GMT
Same here with print outs but the libraries are still not quite up to speed, I have a load of stuff to print out...
So engine revs over 5 k which is a good sign, but won't rev to say 9 k , even in 3rd gear ?
A good service, valve clearances, ign advance check, cam chain and balance chain and then onto carbs.
Start to clean them at the filler cap...
At that mileage it should be in reasonably good condition but suspect the balance chain adjustment will need adjusting, an ideal time for a good engine flush....check CMSNL to see if it has a cush drive balance system. The rubber segments go rock hard, break up and end up in the oil and blocking the course pick up pipe filter...since you have had one of these before you will know all this...
Enjoy
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Post by richard on Aug 16, 2021 17:41:18 GMT
Same here with print outs but the libraries are still not quite up to speed, I have a load of stuff to print out... So engine revs over 5 k which is a good sign, but won't rev to say 9 k , even in 3rd gear ? A good service, valve clearances, ign advance check, cam chain and balance chain and then onto carbs. Start to clean them at the filler cap... At that mileage it should be in reasonably good condition but suspect the balance chain adjustment will need adjusting, an ideal time for a good engine flush....check CMSNL to see if it has a crush drive balance system. The rubber segments go rock hard, break up and end up in the oil and blocking the course pick up pipe filter...since you have had one of these before you will know all this... Enjoy |
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Post by richard on Aug 16, 2021 18:05:23 GMT
hello
front of engine...rocker cover has been cleaned up, but no oil leaks on the main engine block rear of engine....is the same both sides, although it appears that it has had new carb rubbers fitted, with a obviously shiny bolt !
thanks richard
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Post by richard on Aug 24, 2021 18:18:55 GMT
hello
ok, i received the new header pipes today from " classicbikeshop.co.uk " i was originally going to use exhaust bandage etc, but on closer inspection of both header pipes, it was obvious that they would both need replacing, i had already knocked the seller down as by £150, so i had that amount to spend anyway..so new header pipes,exhaust sealing rings and collector box gaskets renewed..
i cleaned the carbs as best i could and the right hand float bowl wasn't set correctly [ hence the petrol overflow issue ] so both are set to the recommend 15.5mm or there abouts
she now starts and runs on both cylinders from cold [ with the choke ]
after taking her for a quick blast down my local B road, she is reving alot better [ picks her heels up quite smartly in the lower gears ] but still holding back very slightly on full throttle [in the higher gears ] i couldn't really get more than an " indicated " 60 ish mph on the flat, although it felt faster than that, i am aware of all the comments about the superdreams power [ or lack of it ] but i will take my handheld gps out next time to check the speedo
my riding style has never been to have the valves bouncing, but i like to think i know from experience if something is almost there, but just not quite..if that makes sense ?
so the next thing to check is the valve clearances... but i don't currently have a strobe light to check the timing
one thing i did notice on tick over after a run out, was that rocker cover breather pipe was chuffing away quite happily ? [ any insight into that would be helpful ]
i will take the plugs out tomorrow and see if the right hand cylinder is still sooty [ hopefully it will be a stranglers song colour..i,e golden brown... " ]
having altered the tick over speed she no longer falters setting off or ticking over at the traffic lights [ although a slight hiccup now and again ] the air screws were also out of sync, but are both now set to two full turns out
so in anwser to johnjones questions/advice there are no signs of the engine being apart, no oil leaks, no unusual rattles, bangs or thumps from the engine, she revs over 5k in the lower gears [ but have not red-lined her in every gear ]
one thing i did notice is that the right hand lead from the coil to the right-hand cylinder is a little chewed up, telling me that somebody had tried to tighten or undo the lead from the coil, maybe not knowing that they are not replaceable, but its not loose, so i dont think there is much of an issue there
thanks richard
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Post by johnjones on Aug 24, 2021 19:08:37 GMT
Chuffing away from the cam cover breather, piston/rings blow by, do a compression check after valve clearance check.
You got the cam cover off now ?
Post a picture...of all valves and head bolts, and of cam timing marks when flywheel set to T.
That HT lead, does it "wobble" in the tower ?
You said something about the clutch, the clutch arm in your picture is approaching/past the optimum a bit so loosing mechanical advantage....did you take the clutch cover off ( clean clean clean oil pressure switch area else crap that collects in there drops over the drive gears when you take the cover off ) to attend to clutch/ balance chain adjusting adjustment, and a good sump floor/k starter oil trough/
clutch basket finger inner surfaces ( centrifugal crap trap ) flush out of the combustion/clutch debris crap ?
Also think about a magnetic sump plug...
New gasket and enjoy...
Further to the chuffing, how bad is it, like a steam train, 2t exhaust, and at idle does the oil light come on, even flicker ?
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Post by richard on Aug 24, 2021 19:39:06 GMT
hello
no, as i write this reply the cam cover isnt off [ i dont have a garage, so weather permitting i will remove it tomorrow ] and then check the valve clearances, after that i will have a look on fleabay for a cheap strobe light to check the timing
the ht lead is firm where it connects to the coil, although somebody has definitely tried to see if it was removable
the clutch cable is adjusted to its limit at the handlebar end, but i have new clutch springs and plates to go in if necessary, but currently no issues with the clutch slipping either at take off, or at higher revs, nor is there any clutch creep
as far as the chuffing goes, its a little like the steam from a kettle [ but not as thick ] but no oil lights come on at any point, so its not pouring out, but does chuff a wee bit..
thanks
richard
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Post by buster on Aug 26, 2021 15:52:02 GMT
just a thought, if one cylinders running very rich (black sooty plug) I'm wondering if theres a stuck piston ring or two?
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Post by richard on Aug 26, 2021 19:23:11 GMT
just a thought, if one cylinders running very rich (black sooty plug) I'm wondering if theres a stuck piston ring or two? hello
today was a dry day, so prior to taking a run out i checked and set the valve clearances, they were all spot on, apart from 1 inlet valve on the rh cylinder, i also checked/cleaned and set the spark plug gap
so a quick recap:
valve clearances correct two new header pipes and associated gaskets carbs cleaned, float height set, and air screws set as per the manual carb manifold rubbers and inlet rubbers are perfect, no splits etc
she starts and runs ok at the lower rev range, haven't completely red lined it in the lower gears, but gets up to 7 thou quite quickly before i back off got 4 miles out of town to check the rh plug, and the engine/ spark plug was way to hot to touch [ should have taken some eggs and had a fry up ] got the plugs out, the left was a nice golden brown, the right covered in soot [ not wet ]
at around 45/50mph on a slight downhill stretch [ no headwind ] fully opening the throttle has no effect, she just fades, and if anything it feels like she is getting starved of fuel, if i very gently apply the throttle [ by very very small increments ] she will slowly pick up speed ] i adjusted the rh air screw mid run, but this had no effect
i have ordered a timing light, to check the timing, but dont know how to check the coil ? i intend to remove and make sure the petrol tap is clean and free of debris
and i will take the carbs back off and give them another clean
thanks richard
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Post by buster on Aug 26, 2021 20:14:04 GMT
I'd have done just the same as you have so far, it could be time for a compression test
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Post by richard on Aug 26, 2021 21:23:47 GMT
I'd have done just the same as you have so far, it could be time for a compression test hello
well i will check the timing first, and the fuel supply, then see where i am at after that.. it will be next week before the cheepo timing light will arrive, but weather permitting i can check the fuel supply tomorrow
thanks richard
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Post by johnjones on Aug 27, 2021 7:55:50 GMT
Hang fire until ign advance is checked.
Valve clearances now done but please post some pictures of cam area and bolts, valve springs should all have a yellow top meaning springs fitted the right way up.
I have come across one that had one incorrectly fitted spring from the factory and several ones fitted upsidedown by owners.
Only one copper washer on each centre bolts holding the cylinder head down ?
How was cam timing marks when crank set to T and how is cam chain lift ?
Compression test, even "thumb" test, rough and ready.
When checking ign advance, check one HT lead up to say 8k revs, then check the other the same.
Red neon plug caps that flash as they pass HT are good real world bits of testing kit, but you will need to make a "connector".
They can be used when riding the bike, and used for HT comparison.
You could make a HT coil tester but you have the bike for an "acid test".
How's the air filter, and, a long shot on an SD, blockage/reduction of air into the air box, such as a rag under the seat or restriction caused by the seat when all your weight is sitting on it.
Balance chain adjustment adjustment can wait until the clutch is done...
Carbs are your last port of call but you have removed those and thouroly clean them ?
Maybe air problem to main jet emulsion tube for the "rich" carb ?
As said do/check all the other stuff, carbs last.
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Post by richard on Aug 27, 2021 15:40:06 GMT
Hang fire until ign advance is checked. Valve clearances now done but please post some pictures of cam area and bolts, valve springs should all have a yellow top meaning springs fitted the right way up. I have come across one that had one incorrectly fitted spring from the factory and several ones fitted upsidedown by owners. Only one copper washer on each centre bolts holding the cylinder head down ? How was cam timing marks when crank set to T and how is cam chain lift ? Compression test, even "thumb" test, rough and ready. When checking ign advance, check one HT lead up to say 8k revs, then check the other the same. Red neon plug caps that flash as they pass HT are good real world bits of testing kit, but you will need to make a "connector". They can be used when riding the bike, and used for HT comparison. You could make a HT coil tester but you have the bike for an "acid test". How's the air filter, and, a long shot on an SD, blockage/reduction of air into the air box, such as a rag under the seat or restriction caused by the seat when all your weight is sitting on it. Balance chain adjustment adjustment can wait until the clutch is done... Carbs are your last port of call but you have removed those and thouroly clean them ? Maybe air problem to main jet emulsion tube for the "rich" carb ? As said do/check all the other stuff, carbs last. hello
great check list to go through !
i forgot to take pictures of the top end when i set the valve clearances, but dont remember seeing anything yellow..but its only a 5 min job to remove the rocker cover, so i will post pictures in the next few days
forgot to add in my previous post that i have a new air filter, soaked in gear oil and the excess squeezed out, but nothing under the seat, nor does the seat compress much [ i dont weigh alot ]
i cleaned the carbs as best i could, however i dont have a sonic bath etc
went out for another ride about today, but nothing has got better with use, upto about 50mph everything is fine, anything above that is hopeless, i keep telling myself its nothing major, the bike had not been used on the road for 18 months, only being started weekly on the sellers driveway, and having low mileage for a 42 yr old bike [ 19k ] i dont think its been messed about with to much...but then you never know..
thanks richard
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