bobsled53
New member
My son purchased a 91 exciter II . He wanted me to clean the carbs . He didnt think it was running as good as it should . I ended up braking the arm that holds the pin andfloat lever. I figured it was unfixable. I went to a couple of local snowmobile salvage shops'' neither of which had a 91' carb to match the one I had. The guy had a 89' carb, but I noticed it did not have a molded passage way on the outside cast right in the body of the carb from the float bowl to the veturi like the 91' carb. .next he came out with a pair of 88 carbs that he said had a power surge on them i felt i would give these a try since they were matched. After cleaning and putting them on i did have some problems wit the HORS but then bypassed them . the machine runs strong up to 6000 RPM but thats it . Iv ben told it should rev to 8000 when i pull the plugs one is very dark brown to oily , the other is black and oily. The main jet in the 88 carbs are three twenty i found some specks in this forum that states all of the main jets priar to 91 were 320 . In 91 the standard main jet is 310. I dont understand this!!! I fugured i might be running rich and maybe should put 310 main jets in the 88 carbs or maybe go with an after market air cleaners with the 320's for more air. I checked the old 91 carb and it had a 320 main jet in it. This contrary to specks . I am assuming i am dealing with a carboration problem because it wont rev and the [plugs arnt burning clean. Are the 88 carbs compatable with the 91 570 engine . id appreciate any help from the knowledgeable guys out there !!!! I really like this sled and would like to see it running as well as iv herd it can.
first off, if you still have the piece that broke off you can jb weld it back on. i just did my carb. lot of carbs out there that are fixed this way.float level is important.make sure it is set to spec, if it is too high you will run too rich
bobsled53
New member
I wish I would have thought of that . I did find the broken piece. but i gave my good 91 carb to the guy as adeal for the two 88s. if all else fails i could probably get it back. i've been reading some things about engines blowing up in the earlier exciters because of the metering needles. i had to pull the needles from the 91 carbs and put them in the 88s because they came without them. i guess i figured everything in these carbs would be pretty much universal and compatible. now i see they must have made a change in the taper of the needle and also there are different size needle jets. i was unaware the float hight could make it run rich. but would the fact that its running rich keep it from hitting higher rpm? thanks for the advice ramblnman when i get a chance i'd like to check that float level. i'm wondering if i have too much mixed match parts or if this carb exchange is feasable.ramblnman said:
89 is when yamaha came out with updated needle and needle jet setup and even after that some exciters still blew up. these engine had a harmonics problem in the midrange that would shake the carbs and cause air bubbles that would lean out the mixture and cause a seizure.i had a 87 exciter years back and bought special carb weights that were held on by a set screw to the fuel bowl drain bolts along with the updated jet setup and never had another problem. just recently bought another 87 and i put exciter sx carbs on it and it runs awesome. no problems as of yet
bobsled53
New member
Thanks for the info. thats interesting .i do have acess to the needle jets from the 91 carbs. right now just the needles from the 91 are in the 88 carbs. before i had just assumed that all the needle and needle jets were the same. the 88 carbs didnt come with needles.i just picked up some jb weld and i am going to try and repair the 91 carb that i have.if i can fix the carb and get my hands back on the good 91 carb for 50$ i am wondering wether to go that route or pull the 88s off and put the 91 needle jets in. what ever carbs im dealing with i will definitely check the float level. iam wondering what improvements they made in that carb body from 88 to 91? if any. also i may have neglected to get the righthand carb on the right side . i see in a 89 shop manual the 2 carbs have different power jet sizes. any thoughts on this? thanks!