high rpm

I was given a maxim 550 a few years back. When I picked it up, the previous owner and I got the thing running. It then sat for two or three years without running. Last year I started working on the bike...it wouldn't start. So, I tore apart the carbs and started cleaning. I ended up messing up one of the pilot jets pretty bad, but I found a used set of carbs for a 550, and decided to swap them out. When I put the new carbs in, the bike would start, but it would immediately redline.

So, I pulled them again. I ordered new 35 pilot jets (stock, because I couldn't get the other original ones out) To make a long story short, I put the new jets in the "new" set of carbs. (As it turns out, the originals were 37.5.) I then started checking the other jets. I swapped out everything that I could find that was different. I swapped the emulsion tubes, jet needle and slide assembly, and the air jet directly below the diaphram. I replaced the o-rings on the float needle seats, adjucted the float levels. I got it running again this afternoon, but still, it just redlines :cry: . As far as I can tell, the only thing that's different is the pilot jets. I've read that the stock is set for sea level, which I'm at. The previous owner did live at a higher elevation, though not for the entire time he owned the bike.

I posted this question a little earlier, so sorry for the redundancy, but is there anything that I have missed...is it possible that Mikuni bodies (i.e., the internal ports, etc.) could be different? As far as I can tell (and I've made a few measurements) everything is the same. The only difference is that on the old carbs, on the output side, it has "3f" and on the new carbs it says "f2".

Could it have anything to do with the motor itself? A leak perhaps somewhere?

Any help appreciated.

Thanks,

Sal

p.s., here's a pic

 

Un-hook the throttle cable.
Look to see that the throttle cable connection isn't jammed-up under the cylinder head.
If it is ... you made a rookie mistake ... loosen the rack dont try to force it.
Leave it un-hooked until the carbs are tuned.
Back-off the Manual Idle Adjustment Rod between #2 + #3 out and see if the revs come down.

To be Redlining ... the linkages need to be Open.
See that they aren't binding.

 

Thanks rick. So I didn't check this afternoon if I the throttle plates are open (i.e., from inspecting the throttle rod), but I have in the past. I've got everything backed right off. When I've got the carbs off, the throttle plates are shut. When I install the carbs, and start the bike up, I don't see the throttle mechanisms moving at all. That's what's so weird! (I should have mentioned this.) But in order for it to be reving so high, those throttle plates have got to be open, right? I can't see any other way it could suck so hard. I can bring down the revs by covering up the intake with cardboard, but it's still up around 4- 5000rpm.....

Perhaps those throttle plates are moving on the throttle rod...though when the carbs are off, I've never noticed any play.

Anyway, I'm heading out of town to work tomorrow, so I won't be able to look at it untill june. But I'm taking my old carbs with me, and when I get so free time I'm going to work on pulling out the pilot jets, and mixture screws.

 

Yea ...

It's a good bet that if you're two-thirds up into the power band a little air has got to be sneaking in there somehow.

Some fuel; too ... huh?

Something ain't right unless the atmosphere of British Columbia is predominately Hydrogen.

 

Hmmm, hydrogen....perhaps that's why us west coasters have our heads in the clouds..... :wink: