HELP! Sparkplug problems (NSR250R)

[Ash250R]

Hay guys I'm one unlucky bugger, first of all yay! I finally have my learners after having to get an eye exam to find out that I have scaring on my left eye.

Now that I can be lawfull when riding I cant bloody well ride!! the nsr has graced me with another problem to solve, it now has a new custom ignition system that works very well but its deciding to foul the new factory plugs instantly.

Up on inspection the plugs look to be drowning, I kno its not a spark issue so that leaves fuel/jetting too look at, I did how ever decide to try a differnt type of plug before I looked at the carbs, the plugs I used are a differnt heat range and have an iridum tip that is not recessed in the plug.

I did measure how much clearance there was between the test plug and the piston at tdc befor I tryed them :yes:

And what happens the bloody bike runs fine on both cylinders cold with no choke, so i decide to let it run for a bit and see if these plugs will foul, after getting sick of waiting for something to happen I decided to stop the bike and inspect the plugs, they are both clean and dry:blink:

So my question is do I bugger around with the fuel/jetting or do I find some replacement plugs that have the same heat range but a differnt electrode design?

[hmmmnz]

hmmm, well it looks like you have just masked a problem,
are you running the original exhaust system and airbox and jetting??
if you have ditched the airbox then i would suggest that you go back to the standard system and jetting, clean and balance your carbs,

smokeys will blacken the plugs at low revs and idle, they arn't designed to be running at those rev ranges, if you know what i mean.
potentially you have made it too hot at higher up the rev range. and may melt a hole through the piston, may be not :D who can say,l
if you are willing to replace pistons if thing go wrong, then sweet as, i'd personally go back to standard, and make sure everything is set to factory settings

good luck

[Ash250R]

Also I better add that the plugs are brand new ngk's that are specified to use in the nsr, when I was useing these plugs the bottom cylinder was backfiring quite bad as if it was only ignighting on every 2nd or 3rd power stroke.

[Ash250R]

hmmm, well it looks like you have just masked a problem,
are you running the original exhaust system and airbox and jetting??
if you have ditched the airbox then i would suggest that you go back to the standard system and jetting, clean and balance your carbs,

smokeys will blacken the plugs at low revs and idle, they arn't designed to be running at those rev ranges, if you know what i mean.
potentially you have made it too hot at higher up the rev range. and may melt a hole through the piston, may be not :D who can say,l
if you are willing to replace pistons if thing go wrong, then sweet as, i'd personally go back to standard, and make sure everything is set to factory settings

good luck

Yep im well aware of the damage I can do with incorect plugs, I made sure they were in there for only a short run that consisted of idle and bliping the throttle to a max of 5k, the airbox is long gone I bought it with some stainless steel mesh type pods on it, im hopen that the jetting was done to suit as it was ment to of had a rebuild <4k ago, it now has notoll unipods to replace the ones it was bought with.

[hmmmnz]

arhhh well, i'd say that possibly the problem,, you know what te say,
assumptions are the mother of all fuck ups,

pull your carbs and check all the jetting, its a tricky thing on a smokey to run with out the stock setup,
you not only have to change the jetting in the carb, because you have more air you need more petrol, and because you have more gas you also need more oil....; you see where im going, even if the bike has been rejetted, has the oil pump been adjusted accordingly?
do they adjust the pump too much and now its too rich oil/petrol wise .... if so then its actually tooo lean fuel/air wise..
its a catch 22

my advice is get an air box and go back to the stock setup, its probably not what you want to hear, but it will save gas, probably add hp
and potentially save on future engine rebuild costs,

failing that take the bike to a 2 stroke mechanic and get him to set it up properly, setting up a smokey is a mystical dark art,
cock it up at your peril :D

[CookMySock]

I agree with hmmmnz. Put it back to standard before you incur expenses you will ill-placed to afford.

Also suggest that two-tangers are probably not good introductions to "riding", especially "project" ones.

Steve

[kwaka_crasher]

Clarify the conditions under which the plugs foul. Engine speed/temperature/throttle opening/choke use etc.

If it's on cold startup I'd say you're looking at leaking float valves.

[Ash250R]

Bloody thing doesnt even have the oil pump its setup for pre-mix, will look at getting the iriduim/platnium version of the factory plug, just realised they made one for the nsr when I was looking through the ngk catalog.

As for conditions for fouling its vertualy stright away on factory plugs with out choke from cold, havnt had to use the choke to start it, I shouldnt make a correction also its not actually fouling its drowning the plugs they are clean but very wet.

[Ash250R]

May have to do the carbs based on comments, it will be too big of a hasstle finding an air box so I will clean the carbs and check the jetting..... fun fun :(

[hmmmnz]

no oil pump either... ba jesus, that opens another kettle of fish, not only do you have to go larger because you are running pod filters, you also have to go larger to compensate for the oil that is now mixed with the fuel, instead of it being directed straight to the bottom end where its needed, you have a major job on your hands trying to get that running even half as good as standard,

as ive said, i would be trying to get every thing to get it to run as close to stock as possible, or find a reputable 2 stroke tuner, they are a dieing breed these days, but well worth it if you can find a master in the dark art

[Ash250R]

Find a reputable 2 stroke tuner, they are a dieing breed these days, but well worth it if you can find a master in the dark art

Yep being someone who has allways done there own engine work including full rebuilds I havnt ventured too far into the world of 2strokes, bought the bike as a learners bike and put alot of work into it so far but my motivation to keep going is getting less and less, planing to have it running mint with wof and rego soon then its time to get a 4stroke something that I will gladly do any repairs to.

[hmmmnz]

2 strokes are great, they are just a pain in the arse, when someone has butchered the intake system on the slim chance they thought they could get some more power,
id be contacting the breakers/wreckers to see if anyone has an oil pump and airbox, even try ebay.au or uk (for some reason postage out of the us is far too high for bulky bike bits, and they didn't get many road going smokeys anyway)
i'd pay more for a bike that had those bits, rather than the pod system, but who knows may be a learner/ newbie wouldnt care
it depends on who you want to sell the bike to.
but i bet once you get the bike running how it should you'll be tempted to keep it :D they are great when they go well :D

[eelracing]

As for conditions for fouling its vertualy stright away on factory plugs with out choke from cold, havnt had to use the choke to start it, I shouldnt make a correction also its not actually fouling its drowning the plugs they are clean but very wet.


Mate thats a pretty massive clue to where you should be looking.

Carb Float height/pilot jet would be the first things to try...but is useless unless you know the standard specifications.Get yourself a manual at the very least as they is gold.
Failing that get the specs from ya local Honda dealer for your model.

[Crasherfromwayback]

no oil pump either... ba jesus, that opens another kettle of fish, not only do you have to go larger because you are running pod filters, you also have to go larger to compensate for the oil that is now mixed with the fuel, instead of it being directed straight to the bottom end where its needed, you have a major job on your hands trying to get that running even half as good as standard,

as ive said, i would be trying to get every thing to get it to run as close to stock as possible, or find a reputable 2 stroke tuner, they are a dieing breed these days, but well worth it if you can find a master in the dark art

Pre mix delivers more than enough oil for the crank etc...more reliably too I might add

[hmmmnz]

Pre mix delivers more than enough oil for the crank etc...more reliably too I might add

im not doubting that at all, its just that you have to adjust your jetting accordingly, you can't just go from pump to premix without changing your jetting

[Ash250R]

I should have found all the required specs for the carbs, will have a go shortly, thanks guys I agree with all the comments Ive been wishing that the carbs were done during the rebuild but it looks less and less likely.

Will stick with the current setup as far as intake and premix go but making sure its tuned as good as I can get for that setup.

Wouldnt mind an air box but may be a too greater hasstle.

Cheers

[hmmmnz]

i gather your bike is the mc18?? it looks like it from the pic
heres an air box (http://cgi.ebay.co.uk/S-H-HONDA-NSR250-NSR-250-MC18-AIR-BOX-COMPLETE_W0QQitemZ280464461448QQcmdZViewItemQQptZU K_Motorcycle_Parts?hash=item414cfc0e88)
or there is a guy in christchurch wrecking one on trademe (http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Complete-engines/auction-276739476.htm) id talk to him about both bits

[Ash250R]

Can anyone reccomend a place in hamilton to get advice on correct jet sizes and if it comes to it repair?

Someone has butchered the carbs the majority of the screws are rounded off and even the jets have had the heads miss-shapen from incorect tool use.

looks as tho when the engine was rebuilt the only work to the carb was a clean, its very clean inside but the jets are still origional.

[hmmmnz]

http://mdlracing.co.nz/pages/wshop.html

ive only heard good things

[Ash250R]

Ha I should of found that auction allready but I search nsr not nsr250 I wouldnt mind asking if he will sell the whole bike no tm account tho, cheers for the heads up.

[quickbuck]

Ha I should of found that auction allready but I search nsr not nsr250 I wouldnt mind asking if he will sell the whole bike no tm account tho, cheers for the heads up.

Hint for searches....
Search NSR*
That way it doesn't matter if there is a space or a number after the R.

[Ash250R]

Nice to kno man will help with searching for a vh41.

[Ash250R]

Ok Im a bit behind at the moment but thanks to the bloke on tm selling mc18 parts I have now sourced a chain guard, muffler bracket and radiator reserve (my radiator reserve was accidently binned due to leaving it at the paint shop) I will be leaving the bike as it is running on premix and free flowing intake.

The new plan is to take the carbs to mdlracing and have a base jetting done to set the bike up for premix, free flow intake and to tune it for commuitung, lets hope I can sort this before the parts come up from chch.

Many of you will disagree with this but I plan to go back to a cage untill I have corrective sergary on one eye and have got my full class 6, so I will be selling the nsr once it is going and wont replace it untill I have my full.
Any interest in the bike gimmie a pm.

[hmmmnz]

i don't disagree with you leaving as is, i was just stating it had to be setup to run how it was,
there probably won't be much in the price difference between getting it set up correctly and buying the airbox and pump,

fair do's though,
keep us posted

[hmmmnz]

i don't disagree with you leaving as is, i was just stating it had to be setup to run how it was,
there probably won't be much in the price difference between getting it set up correctly and buying the airbox and pump,

fair do's though,
keep us posted