CARBS

[randka]

 Daft question, I am in the process of rebuilding and giving my carbs  a good clean on my CB 400F, could any one tell me if on the pilot jets there is a hole which goes straight through, end to end. I have owned this bike for over 25 years and has been off the road for a couple of years so is in need of cleaning, any tips would be appreciated

[Yoshi823]

The pilot jets have a very small orifice & great care should be taken in trying to clean them out using just carb cleaner & compressed air initially.

[mickwinf]

i had a problem with my 550, the pilot jets were completely blocked and refused to be cleaned.in the end i got some new ones, but had to order from Canada ! They dont like being left unused,if yours has been running they should clean ok.

[randka]

thanks for the replies, I have rebuilt the carbs and have put two back together, I had a feeling there might be a hole through them, they are blocked then I will have to have another look , like you say I may have to buy some new ones

[470four]

My CB400F carbs were all gummed to hell, had the same problem with a 1990 CBR600 I've just restored which had been standing for 6 years?







Soaked the jets in new petrol, tried 3 different sorts of carb cleaner to no avail... in the end the only thing which worked was holding the jet and blowtorching them.  

The gummy gak burns up and turns to ash, easily teased out...

** If your pilots are in a bad way then your pilot circuit will be too!

[randka]

thanks for putting the photos on, my brass ware isn't as bad as yours but need cleaning, my pilot jets are blocked I didn't realise, the hole is so small they are difficult to unblock, a calm hour is required or buy some new ones although I don't like to give up.
super cycle cleaner S100 is very good for cleaning the surface of your carbs inside and out also WD40, worked for me anyway, if any one can guide me to a good item to clean that hole in the pilot jet I would appreciate it

[Yoshi823]

What I am about to suggest may be frowned upon, but it works. I have a wire brush with just the right size wire that goes into the main orifice on the pilot jets on Teresa's old CB550F2, which I had to use when I was about to sell the bike. It wouldn't run on all four cylinders, so used the wire method & it worked quickly & easily.
One of the problems with this method may be that the pilot jet size for the 400F are smaller than the 550F.

Machine Mart now sell an ultrasonic parts cleaner. This might be a good & worthwhile purchase.

Good luck.

[470four]

What I am about to suggest may be frowned upon, but it works. I have a wire brush with just the right size wire that goes into the main orifice on the pilot jets on Teresa's old CB550F2, which I had to use when I was about to sell the bike. It wouldn't run on all four cylinders, so used the wire method & it worked quickly & easily.
One of the problems with this method may be that the pilot jet size for the 400F are smaller than the 550F.

Machine Mart now sell an ultrasonic parts cleaner. This might be a good & worthwhile purchase.

Good luck.

Seconded... I used a long-bristle wire brush wire to clear the jets on the CBR600. 

Lidl sold an ultrasonic "jewellery" cleaner for like

[randka]

Carbs are back on and the old bike fired up straight away, noticed the off side outer exhaust was luke warm so had to take the carbs back off and found the pilot jet was still blocked although I thought I had cleaned it, any way carbs back on and it sounds good, obviously it will want tuning up properly and I won't know how its running until I take it down the road.