Carby tuning - H100s with grey sparklug!

[motorbyclist]

Right, so since her "incident" on the northwestern motorway, Brown Fury has aquired a new air filter, racing reeds, and a .025mm bore out (takes her from 99 to 100cc :D) and is still running her RACE PIPE and standard plug

Now I'm unfamiliar with the carby - so if anyone has any pointers that'd be appreciated.

All i can see is two screws. one near the inlet and one on the slide. I assume the slide one is the idle adjustment and the on on the inlet is the pilot screw.

Running her in has been interesting; I had to raise the idle a touch to keep her running, and turned the pilot out ever so slightly to get some colour on the plug as the plug won't go brown. It goes grey. Haven't used more than 3/4 throttle yet.

She has been on two 10 minute pie runs and two 40 minute rides through auckland streets (to/from uni pub) without crapping out.

Correct me If I'm wrong:
turning this pilot out will enrich the idle mix.

raising the needle in the slide richens everything but not so much the top end

grey plug isn't good.

EDIT:I opened the carby and turns out the pilot jet was blocked with grit. Mystery solved.

Now she runs too rich!

http://www.kiwibiker.co.nz/forums/showthread.php?p=1129506845&posted=1#post1129506845

[mossy1200]

Grey is a little lean but not far off.Its white that is engine risky lean and black which is way too rich.
Tan is the colour of success.

[motorbyclist]

cheers.

ok reading the rx125 thread has been a great help.

so if anyone can comfirm that screw one the airbox end of the carby is infact the pilot i'll be set :)

[Yow Ling]

turning the air screw out leans the mixture, as it lets more air in. I wouldnt read too muchinto the plug colour if you are just tootling around, you need to run it at a constant load and chop it to get any real value from the plug colour, yu may be looking at the colour from idling etc when you pull the plug out after you get home.

[bucketracer]

Now I'm unfamiliar with the carby - so if anyone has any pointers that'd be appreciated.

Page 80 and page 90 of the ESE thread have large collections of tuning links, you may well find something useful there.

.

[motorbyclist]

turning the air screw out leans the mixture, as it lets more air in. need to run it at a constant load and chop it to get any real value from the plug colour, yu may be looking at the colour from idling etc when you pull the plug out after you get home.

really? ah. i thought the extra air would bring extra fuel at idle.... good thing i didn't tweak it much then


yeah to get the plug i've literally been pulling over (or arriving at destination) and checking without idling

ideally the bike will be "safe" to run on the open road again; she got me and a mate back to auckland from nelson via the east cape and coro loop without incident, but detonated a hole in the piston on the motorway to uni one morning. I'd rather not miss another important lecture/lab and would like to pootle up to cape reinga after exams....

[motorbyclist]

Page 80 and page 90 of the ESE thread have large collections of tuning links, you may well find something useful there.


the what thread?

which posts? (my posts-per-page is likely different to yours)

[speedpro]

If it was all good and then suddenly you had a hole in the piston I'd suspect a bad batch of fuel.

My last two cars have been sensitive to fuel variations and even going to the same petrol station for consecutive fills caused in one case noticeable changes in performance as timing was adjusted automatically to aleviate detonation on a turbo engine and in the other case the car would refuse to start when hot like after a trip and I just filled up. Low octane fuel caused that problem and using 95/96/98 it was all good, until I refilled just now and again and the problem would come back.

I'd be real careful if you are getting a grey plug. I've owned a MB100 which isn't too dissimilar and I always got a tan plug.

[motorbyclist]

If it was all good and then suddenly you had a hole in the piston I'd suspect a bad batch of fuel.


quite possible - i've had all sorts of fun experimenting with fuel in my yz400f; long story short, I no longer buy shell.



I'd be real careful if you are getting a grey plug. I've owned a MB100 which isn't too dissimilar and I always got a tan plug.

yep - bike always gave a tan plug pre-rebuild and was even running a bit rich in the low end, but would lean out to a lighter tan when topped out.

if it wasn't fuel, odds are the 5minutes of wide open throttle at 110kph were what caused the conditions for detonation:doh:. With two of us we rarely exceeded 90 and were mindful of the lean mix at full throttle...

[koba]

quite possible - i've had all sorts of fun experimenting with fuel in my yz400f; long story short, I no longer buy shell.



yep - bike always gave a tan plug pre-rebuild and was even running a bit rich in the low end, but would lean out to a lighter tan when topped out.

if it wasn't fuel, odds are the 5minutes of wide open throttle at 110kph were what caused the conditions for detonation:doh:. With two of us we rarely exceeded 90 and were mindful of the lean mix at full throttle...

Make sure the main jet is big enough. Its best to be quite a bit too rich if you are going to be on full throttle for long periods.

[koba]

If it was all good and then suddenly you had a hole in the piston I'd suspect a bad batch of fuel.


An air leak could be another possibility.

[motorbyclist]

I opened the carby and turns out the pilot jet was blocked with grit. Mystery solved.

Now she runs too rich!

http://www.kiwibiker.co.nz/forums/showthread.php?p=1129506786#post1129506786