View Full Version : Sparks and Smokes

03-09-2003, 09:37 AM
Hi all..

Today I have done a little of maintenance on my 250'...
changed Spark's and Oil.... and other minus stuff.... just 2 questions... :

1) After I have removed the 2 old sparks ( BR9ECM ) I found them like wet of oil and quite dark... , Next time I should change them with a hotter one ? BR8ECM ? just let's consider here temperature is usualy hot... 18/20C in winter and 35/40C in summer.. ( if it effects something... ):mad:

2) after changed gear Oil I have noticed that the lower exhaust was smoking white and cold smoke while, the top one was hot and transparent . May it was normal ,had only need to warm up a bit ???:smokin:

03-10-2003, 07:43 AM
standard plugs should be fine, i run my priller in same summer weather (today 41 c), yes, hot weather can need you to alter jetting but should be ok stock. dont let it sit choked up on idle !!, warm the motor properly to operating temp then give ride it sensibly "on the pipe", the exhaust should clean up. two strokes hate chugging about and if you dont let her stretch her legs now and again she'll oil up, always replace gear oil with same kind !! yes, lower cylinder can behave different to top, if a cylinder is not firing due to oiling up (probably lower) , or the smoke stays, then you have go the next step. how is the bike riding, you gapped the plugs??
I hope that helps,:D

03-10-2003, 09:28 AM
I drove it for about 10 Km, so to worm it up, well.. both exhaust's where equally hot... so seems all ok! maybe it only need a warm up... For the sparks I left the new 9 ECM's, did not have other's to try out... . The bike sounded better in acceleration, but surely because the temperature went cooler....

.. anyway.. how do you alter jetting ?? and how do you understand when you have a good jetting without Dynoing the bike:rollin: ?

03-10-2003, 07:43 PM
always let 2 strokes warm up before riding in the power band. (ask your dealer for warm up sequence.) Jetting is done in carburettors by changing actual jet or setting, best done by good 2 stroke proffesional. good jetting your plug will be a brown colour (of some shade, not too light), all 2 stroke will smoke when cold, rs250's are designed to be ridden at well over 5,000 rpm if you don't rev the bike to clean it(over 9,000 regularly) it will oil up, plugs will go wet if you leave choke on for too long or ride around at 2-5,000 rpm all the time. standard jetting/plug is ok for your weather temp range, bike went better in acceleration probably because all excess oil/fuel expelled and motor could breath.:D
hope tht helps.

03-11-2003, 02:50 AM
Yes, yes.. I kwno all about warming up.. but really nothing about jetting and other deep mechanical stuff :) ....

I just was wondering what the hell does my mechanic when I bring the bike for periodical services...

Well... at this point, as you explained me, it shold not be re-jetting the bike... as for rejetting it.. he should change the needles in the carbs , correct ?

.. he did never change bit's and pieces...

Maybe he tunes up the mixture Air/Petrol in the carburators?

how do we tune this up ? ;)

03-12-2003, 04:36 AM
by the sounds of it he's not doing much at all eh? he would probably just screw the air/fuel screws to standard position give or take a bit, the two wouldnt be identical. yes to change the jets is basically to take the carbs main jet or others out and go bigger/smaller to rich or lean out the ratio at different rev range. unless you change the pipe, porting or whatever i wouldnt go chasing the jetting or mess with the oil supply or reliability can go, my stock rs250 feels a bit rich in summer (35-42c) and over oiled most of the time but it aint worth the hassles. :D

03-12-2003, 06:13 AM
well, figure for a periodical maintenance I was paying something like 125 Euro's.. and I live in Italy, land of Aprilia :) seems a bit much too me.. , considering that you will never know if the mechanic does ALL the steps of the maintenance list....

What he does ?? well looking at the bike, I can see he greases many mechanical parts ( not in the engine ), regulates the chain, and surely tunes up the carburation, 'coz I feel it a bit different..

For the other stuff I am not too sure he changes *FOR REAL* oil or sparks and other similar stuff... I should verify it... but...

anyway for that price, I think that will be better to do all by my self.. or at least try to do it...

So how do you get the best Carburation tuning ? I guess the best should be have a dyno-bench ? or maybe a gas-analyzer....

anyway howo do it alone ? ...Is possible to to it just with your own ears and eyes ? ::cool: