carb swap question...

[ross]

hey there folks....my buddy with the '78 xs11 standard e is looking to replace the factory carbs with carbs off a 81 midnight special....he is running pods and i'm not sure what main's hes got in the original carbs.....you might have seen it run on the "another bike lives...." thread.....he asked me if it would work...i told him i would have to run it past my people.....so.....people.....is this possible...r there any rejetting issues he must address.....pros, cons, in betweens....been theres.......please feel free 2 comment.....i don't know why he wants to replace the standard carbs with midnight special carbs other than looks....any and all comments r appreciated.....thanx in advance...talk 2 ya later...ross

[petejw]

Hey Ross,
The carbs themselves are a straight swap from engine 2 engine,
If hes running pods, he'll probably have to rejet depending on the exhaust system he uses.
When rejetting, the carb jets are totally different sizes, so jet according to the model carbs you are using and not the model of the engine the carbs are going onto.
The only advantage i see in using later model carbs are that there is more parts available for them, if theres nothing wrong with his carbs, changing to later model carbs
wont do anything more than the carbs hes using atm.

[DGXSER]

Were the MNS carbs painted black? Otherwise the MNS concept eludes me completely. And honestly, I think the tower design for the mix screw in the later model carbs is a PITA!! Just gathers crud to freeze the screw.

[tarzan]

DGXSER,
The MNS carbs were painted black,at least the ones I've seen are.
For the pilot screw towers.I cut those down on a buddy's.Just used a hack saw
then filed smooth.The material is real soft aluminum.Very easy to do.

[TopCatGr58]

Hey Ross,

Pete got it, the 81's have the bowl vent built into the carb inlet bell, so it doesn't have the upper "T's" to vent, the vacuum slide needle is mostly non-adjustable aside from putting in little washers to raise it if desired. But still may need to be rejetted dependent on Indy pods and exhaust. Stock were around 110 to 120 mains. Also yeah, the pilot screws are down inside that small tunnel instead of being visible and accessible on the outside with the earlier model.
T.C.

[ross]

thanx 4 advice folks....

hey there folks....thanx 4 the advice....i knew you guys would have the correct answers to the problem....i was wondering myself why he would want to do such a crazy thing, but this is my buddy adam and he luvs to make things go faster than they should no matter what the cost.....christ sakes, he just got pulled over on his "frankenstein" bike paced by a michigan state trooper at 105 mph....(honda 750 motor, kawasaki frame and brake system, clubman bars, custom seat, and sorta looks like an old cafe racer on steroids?)....(gonna have 2 get photos of it for u guys....he calls it phonebook as that was what he had a seat when he originally make it...ouch?)..will pass the info on and let him know it is not worth the swap.......thanx again 2 u all...talk 2 ya later....ross