Hi there guys.just a quick question.i have installed a 15 pilot jet in my mikuni carb but it doesn't run great with that so I install the 17.5 and works great.but iv noticed upon on screwing it in it doesn't screw as far up as the 12.5 or 15 pilot jets.must be about 3mm difference in screwing it in? Is this normal pilots are same in length but the end of the pilot with the breather holes are a tad thicker in diameter than the lower pilots.thankyou :thumbsup:
Hello England,
Welcome to OldMiniBikes. Your in good company.
Something is wrong. Check and match up all the pilot jets with a magnifying glass. Count the threads. They all should be the same length. I doubt it is cross threaded, but check inside the carburetor for signs of cross threading. I have installed many jets. I have a tool box full of Mikuni jets. Some are from a 28mm Flatslide, different than the 22mm roundslide.
Some people will ask you to post pictures. Examine the carburetor. Something doesn't seem right?
TT :thumbsup:
Welcome to OldMiniBikes. Your in good company.
Something is wrong. Check and match up all the pilot jets with a magnifying glass. Count the threads. They all should be the same length. I doubt it is cross threaded, but check inside the carburetor for signs of cross threading. I have installed many jets. I have a tool box full of Mikuni jets. Some are from a 28mm Flatslide, different than the 22mm roundslide.
Some people will ask you to post pictures. Examine the carburetor. Something doesn't seem right?
TT :thumbsup:
OK,
Let's talk about your motor.
The 17.5 pilot is very big. I run a 15 pilot jet in a fully modified motor. 15HP and above. In my other bike that has a 28mm. I do run a 17.5 pilot jet. Pilot jets are for take off only 1/4 throttle and become useless after your up to full throttle as you know.
So, needing a 17.5 pilot in a stock motor is overkill. We do not know what motor you have? We do need to know that for sure. If the jet on the "bubble side" is fatter or longer it may or may not be defective.
Let's determine what your needs are first. Try the 15 pilot jet one more time. If it does not perform well then by all means go up from there. Also, what does the spark plug look like? Is it chocolate brown?
What main jet are you running?
I think standard is: 15 pilot and 130 main.
TT :laugh:
Let's talk about your motor.
The 17.5 pilot is very big. I run a 15 pilot jet in a fully modified motor. 15HP and above. In my other bike that has a 28mm. I do run a 17.5 pilot jet. Pilot jets are for take off only 1/4 throttle and become useless after your up to full throttle as you know.
So, needing a 17.5 pilot in a stock motor is overkill. We do not know what motor you have? We do need to know that for sure. If the jet on the "bubble side" is fatter or longer it may or may not be defective.
Let's determine what your needs are first. Try the 15 pilot jet one more time. If it does not perform well then by all means go up from there. Also, what does the spark plug look like? Is it chocolate brown?
What main jet are you running?
I think standard is: 15 pilot and 130 main.
TT :laugh:
My motor is just the basics Clone gx200 de governed ,straight pipe and mikuni 22mm,15 works ok but a little sluggish on takeoff,then I go up to a 17.5 and all is ok,plug does go sooty black abit but runs much better on the 17.5 what I have 2 and a quarter turns out,On 15 plug seems to be a little on the lean side,My main is currently 110 jet and works great,only problem I have is if I'm holding the throttle between idle 1/4 it bogs and hunts and wants to get away,soon as wot applied it shoots off.The bubble side is same length as the 15 but just fatter.if you look on YouTube under my videos wearcabs1 got a little video of my bike in action on the 17.5 pilot and 110 main thanks again:thumbsup:
All right,
You need to listen up. Save or purchase a billet connecting rod and a billet flywheel for your motor. It is very important since you removed the governor. There is a sticky you need to read also about OldMiniBikes Forum participants and removal of the governor. We here are safety conscience and don't want your motor to explode between your legs. So, please read the sticky about this. We can help you as much as possible. I am surprised nobody else has jumped in yet. Welcome to OldMiniBikes!
PM Hent for these parts...
TT :thumbsup:
You need to listen up. Save or purchase a billet connecting rod and a billet flywheel for your motor. It is very important since you removed the governor. There is a sticky you need to read also about OldMiniBikes Forum participants and removal of the governor. We here are safety conscience and don't want your motor to explode between your legs. So, please read the sticky about this. We can help you as much as possible. I am surprised nobody else has jumped in yet. Welcome to OldMiniBikes!
PM Hent for these parts...
TT :thumbsup:
As we speak now mate am tearing the engine out as i am getting a full rebuild with aftermarket parts , conrod flat top piston gx160 head flywheel and other bolt on's .am gettin it proply built as I'm not a engine builder really,I can set carbs up ect but not building engines,would u say I would need a higher pilot on my future mods mate,thankyou for all your advice and help its all appreciated :thumbsup:
Hi mate I presume it's a genuin 1 as it was advertised as a mikuni,saying that after inspection on the pilots the numbers are different,how they are engraved on,the look and style of them.not sure if this matters.yes the needle was in the middle for the 17.5 and was great but on the 15 didn't work well,as vo it was trying to go but was getting held back,so I lowered the needle and it made it worse.scratching head times lol:laugh: