1981 Midnight Maxim 650 has pilot fuel jet size 45

My 1981 Midnight Maxim 650 has pilot fuel jet size 45 and main jet 107. I believe the bike to be all original and if I remember correctly worked fine until put away several years ago. I only question this as the website list size #40 and 110 as stock?

I have one pilot fuel jet plugged and was thinking of just replacing it with the same #45.

any comment if I should replace them all with the suggested 40 and 110 jets? or just replace the one needed replacing with the same jet(#45) (cheaper this way).

Thanks

Steve

 

Full Tilt, welcome to the site. You mentioned that it was running just fine a few yrs ago? Why change something that is working fine. If your bike is running well with the current setup and you liked it when it ran, why change?

 

Why not clean the one that's plugged? A soak in Berryman's, followed by a poke with a brass wire if needed.

 

unless you owned it from new out of the dealership you never know what was done along the way.
different countries got different jetting.

could be PO rebuilt carbs with what was on hand. your jets do not match any listing

http://xjbikes.wikidot.com/carb-specs

 

doesn't look like you could replace them if you wanted to
https://www.jetsrus.com/a_jet_kit_street/yamaha_650_XJ650LH_MIDNIGHT_MAXIM.htm

 

Thanks for your comments, actually got the jet cleaned. Just took some patience! I really didn't think I was going to get it cleaned.

anyway I am not sure why the jets are different then listed but the bike runs real good now after sitting for several years.

 

Just keep an eye on the spark plugs to make sure they are not too lean or too rich. All depends if you want to make the bike OEM complaint or just ride it and enjoy the rest of the season.

 

So it’s a Canadian bike but does it have original exhaust? You may have to check with a Yamaha dealer and have him look at oem microfiche for original jet size

 

all the jets work together, what size are the air and needle jets, float levels near specs ?

 

I have known and worked on this bike since it was 8 years old. My friend decided to give it to me can't see why any mods would have been made before then. Eventually replaced the exhaust with 4 in 1 but no work ever done on carbs. I called the local Yamaha dealership a couple days ago just to see if they had old parts. They came back with the #45 size (part number 4H7-14948-45) as OEM for this bike.

I didn't check the other jets but that would be interesting to know if they are different too!

I am driving it now but plan on taking the bike apart this winter to restore as much as possible. perhaps I will look at the other jets to see what the whole picture is with everything. plugs looks good and drives great now. so....don't plan on changing anything with 41,ooo km on it to date