Hey guys/gals...I never seem to ask too many questions...but I would be interested to see what others may have to say about this problem.

I just did the top end on my banshee....new pistons...and I verified that I have ~140 lbs of compression in each cylinder, spark is good, fresh fuel..etc.

Now to the carbs.....

3rd clip on the stock needle...25 pilots and 280 mains. As far as I know..All other jets were left stock. The airbox is open lid running fmf fatty pipes and silencers.

...the bike just will not start for anything..unless I prime the cylinders with fuel...then it runs great.

Does anyone have any ideas as what I might check into about the not starting problem? I have never had this before.......I've always done all my own work on the banshee...and never had , what I assume are carb problems, to this point.

I'm a little stumped on this one....it's almost like the carbs are not pumping fuel into the cylinder...possible vacuum leak? Which is not noticable to me anywhere...the carb boots are tight...and not a drop of leaking anywhere I can see.

I am at or around 500ft elevation. 40 - 50 degrees outside temperature.


Things I question:
The choke does not stay out on it's own...I have to hold it there.

Anyone have any ideas.....I have a yamaha mechanic for a friend...he will come to help me I'm sure...but I like to try to figure things out on my own.

Again...I am not new to the banshee...I have tuned numerous banshees for friends and myself...they always just seem to run. I'm wondering if it's time for a full leakdown test.

thanks

 

First of all make sure the equalizer tube betwwen the carbs is in place.Second I would run atleast a 27.5 pilot if the timing hasn't been touched.If it has go to a 30 pilot.I always ran clamp-ons but my main jet was always about a 300.Hope this helps.

 

I'm starting to lean towards the pilots myself.... The bike used to have a dyno jet kit in it...with the special needles they supply. It was also running their pilots. But when I went to check/clean the carbs after this last overhaul...I changed all jets back to stock with the exception of the 280 main.

This does not explain the hard starting to me though....the bike should still start..though it may not run through the revs properly....It's almost impossible to jet a carb that i cannot get up to temperature....and under no circumstances should I have to prime the cylinders before it will start.

confused for sure...but i'll get it.

 

Sounds like it's not getting enough fuel on the idle circuit. My brothers Fattys came with a 30 pilot(s) and needles that taper much more on the end of the needle....allowing more fuel for the idle circuit. I would change back too the other needles. The bet the choke is just a worn issue.

 

Like Fbombers said check the equalizer tube, and clean out does carbs very good and with fattys you will always have a tuff time starting with a 25 pilot, these pipes like a fat pilot I say to go to a 30 or 32.5

 

Thanks a bunch....what you say makes sense. I guess I should go pick up some 30 pilots and give that a try.

Someone mentioned the crossover/equalization tube...thats all in check...and the carbs are clean as can be...I have a parts washer in my shop.

I will also try to go back to the longer tapered needles that were in it before...I put it back to stock to get a baseline to start with.

The bike has always ran great...which baffles me. But I'll get it....It's still too muddy in upstate NY to hit the trails...so I spend the spring messing with settings.

 

Just wanted to give an update on what the problem was. The jetting was fine as I had it.

I have never seen this before....I actually had a pin hole in the bottom of the left carb float. One of them was filling with fuel and apparently weighing it down. When I would drain the carbs, the fuel would also drain from the floats. So when I checked the float level with the carb apart, it all appeared fine.

Long story short...new floats solved the problem with the hard starting.

A couple of you also mentioned getting rid of the stock 25 pilots and going larger. I went up in size one at a time and ended up stopping at 30...good call...thanks.

I've put about 10 hrs on the new pistons and it's running stronger than ever.


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