Two Stroke rich or lean?

[maxmax]

i have a motorhispania furia, which uses the minarelli am6 engine, same as the aprilia rx50 before derbi bought it.

it has always been derestricted sine i bought it, but i recently had to fit a new exhaust, a tecnigas enox, derestricted.

my problem is now i have lost low end power, but top end power is fine, so i can still reach the same speed, but there is something coming out of the silencer, maybe unburnt oil or petrol or something called spooge? are these signs of running lean or rich? and is this bad news for my engine?
____________________

[DJH]

Do a plug check to see if your running rich or lean. Did you fit new rollers?

[maxmax]

the thing is i just put new plug in, but i found out the old one wasnt the correct one for my bike, and the electrodes were way too far apart, so that could be why it was black? and i dont want to ride it with the correct plug incase it seizies the engine, and nope, just fitted the new exhaust
____________________

[Damon]

Just chuck the new plug in and do a plug chop to check how its running. It won't sieze the engine by running the plug for a small amount of time.

You might even find with the correct plug it sorts itself out anyway.

Damon

[maxmax]

okay, well il tell you if the new plug fouls. but the wrong spark plug didnt affect the power through the revs before, its only happened since the new exhaust. im wondering if i can just adjust the carburettor, to increase air or fuel, or if i need to get a bigger main jet?
i wish i knew more about engines
____________________

[garyd]

Never fails to amaze me how folk think that bike manufacturers just waste money on r&d,put it back to standard
____________________
CRF230 all you need

[DJH]

You will be running lean if you haven't up-jetted and it was bog standard before. I'd do a plug check asap as it will be doing harm to your engine running lean. Pretty sure you need lighter rollers aswell.

[Vincent]

[maxmax]

the problem i have is i bought it second hand, de restricted, so im guessing it was already up jetted, but will it be running lean if i went from a de restricted standard exhaust to a de restricted performance exhaust? sorry to sound stupid, i just don't know very much about engines because this is my first
____________________

[maxmax]

sorry, also forgot to say, when its running, and i use the choke, it doesn't sort out the problem, does that suggest its too rich not too lean?
____________________

[DJH]

[maxmax]

thank you! so now the question is, is a new main jet in order? if it is, smaller or bigger, and this will also resolve the problem of the loss of low end power?
____________________

[Vincent]

[maxmax]

okay, well im going have to do my research to find that out, the manual if around 10 pages long as it absolutely useless. https://www.adrenalin-pedstop.co.uk/p/TECNIGAS-ENOX-EXHAUST-SYSTEM-F-3198.aspx that is the exhaust i bought, its restricted for UK roads, because apparently anything over 30 is unsafe for anybody on a 50cc ;(
getting the jets isn't a problem, the website i got the exhaust from sells them all, its just which jet i need the garage i have taken it to aren't sure themselves
____________________

[Vincent]

Have you tried contacting the web site that sells them? Pretend you want to buy one and ask them if you'd have to change the jets from the original ones. You still need to find out standard jetting though. There's a good chance the exhaust was designed to run on the original jets and air filter, this makes them easier to sell.

[DJH]

[maxmax]

okay, this is what i have found, on the minarelli website,
https://www.minarelli.com/pdfeng/am50.pdf
https://www.minarelli.com/prodottieng.html

it has a specification for the carburettor, but i can't make sense of this, help!
____________________

[maxmax]

NEW THEORY!

https://www.dansmc.com/EXHAUST_2.htm the paragraph just before the 2 pictures of the exhaust cycle, has the different shape of the expansion chamber caused my loss of low end power, and the cause of the black liquid from the silencer, because at low revs the pressure isnt pushing all the air/fuel back intot the cylinder?
____________________

[stevo as b4]

[Vincent]

[evoboy]

Is the oil pump setup correctly?

If the bike was unrestricted and now its restricted, it MAY of had the jets changed. Only way your gonna tell is to strip the carb and check the jet number to see if its the same as standard.

I get this 'spooge' you talk of on my x7 exhausts. Ive still not sorted the jetting 100% but cos of my intake mods and exhaust changes ive had to go from an 87.5 main jet to a 100 main, even then it seems a tad lean on the top end.

Exhausts on 2strokes do make a difference to the power delivery. For example, when i used the stock pipes on my x7, the power delivery was quite flat and smooth. When i stuck the expansion pipes on, the bottom end became i bit more lax, but it has a severe kick at 6krpm, enough to lift the front up just from pinning it through the revs in 1st.
____________________
Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[maxmax]

yeah, i guess the only real solution is buy jets and change until i find one that works.
i suppose my real question is if, by small chance, my loss of low end power and spooge is simply from a new shaped expansion chamber, can i get away without spending money? or will skimping now cost me a lot in repairs later on...

and its always been derestriced, and i fitted the new exhaust myself, so i know no jets have been changed. im sick of 50cc's. It will be so nice to be able to move up in a few months
____________________