carb needle shim, backfire, sluggish

[MR_NST]

carb work is getting old,


it just means youll get good at it... practice makes perfect. when i first tore into my carbs i was sure i was gonna screw something up. now ive got friends bringing carbs to me, and the results are excellent.

with good instructions, they are easy. my opinion is people are petrified with them. so they get overlooked and forgotten. it sure feels good to see things run great again.

and thats why this forum is great, because the help a person gets is just top shelf.

good luck,
evan...

 

[warp1]

Evan....agreed about the forum. Absolutely amazing. I've got a friend here in town that is patient enough to walk me through everything the first time and then I'm usually comfortable enough to do on my own. If there was 1 thing to be good at...I suppose carb work would be it, unfortunately I'm not "good" yet...just adequate

 

[06VMAXIMUS]

Thanks for all the help. Took 1 of the 2 shims and put her back together. I did feel one slide sticking/rougher compared to the other 3 so cleaned will a dallop of WD40. Runs like a raped ape now. Wish I knew if it was the excess shim or if the slide was sticky.

Side note...getting the tit/detent seated is the easiest part of the whole thing to me. Only one place for it to go and always try spinning the needle once the nylon screw it tight.

I'll find out at the dyno Tuesday if 1 shim at .019 was enough...carb work is getting old . Just saw that many on here had .038 shim in their signature line, especially with Mark's 4:2 exhaust...so thought 2 would be perfect....oh well.

When I put .038 under mine, I had to shim the plastic keeper screw up as well to relieve a bind in the needle. If you have the .038 under it, and the needle is tight, you will need to shim the cap up. See what happens at the dyno, and if you need more shim.

 

[SpecOps13]

Sounds like you've got things well under control... I use a wire feeler gauge that's bent and has about 1/4 inch past the bend. I insert it into the tit hole during and after assembly to insure the tit is poked into the hole...

 

[warp1]

Dammit...A/F is OK...but lost HP and torque. Time to talk to Mr Morely I'll post both dyno sheets when I get them scanned at work.

 

[warp1]

attached dyno sheet, the one March 2012 was after jetting 1 size down on the main jet, syching carbs, and shimming needles out .019.

The other is the initial run...stock VMax, marks 4 into 2, K&N airbox

 

[dannymax]

Thanks for all the help. Took 1 of the 2 shims and put her back together. I did feel one slide sticking/rougher compared to the other 3 so cleaned will a dallop of WD40. Runs like a raped ape now. Wish I knew if it was the excess shim or if the slide was sticky.

Side note...getting the tit/detent seated is the easiest part of the whole thing to me. Only one place for it to go and always try spinning the needle once the nylon screw it tight.

I'll find out at the dyno Tuesday if 1 shim at .019 was enough...carb work is getting old . Just saw that many on here had .038 shim in their signature line, especially with Mark's 4:2 exhaust...so thought 2 would be perfect....oh well.

Not always a good indicator warp....quite often the needle will spin in the spacer whether the de-tit is in the hole on not. Once the spacer 'snaps' past the stamped code on the needle many will spin freely.

 

[Maxine]

Bill,
That first run had the 155 mikuni's with no shims. Not the stock 152.5's. The bike made good power(120hp/81tq), maybe just A/Fed a little rich. I think we need to go back to the 155's and shim the "Y" on the airbox to lean it out a tad.

Hopefully you get a few other opinions from fellow maxers here as well...
Rob


Guy's...
Bill's not actually spinning the needle after the tit drops into the hole. He is gently wiggling it back and forth to feel and confirm the pin/hole are mated together.

 

[warp1]

Maybe wrote it wrong....After I get the nylon screw started threaded, I deliberately pop the spacer out of the detent and roll the needle around until it falls back in. I fully tighten the nylon and then try to rotate to make sure it's still there.

I understand your point and see how that could happen....thanks

 

[warp1]

Thanks Rob (Maxine) I always get the jet sizes screwed up. Need to take better notes instead of relying on you all the time...lol. I forgot we put 155's in with the pipes/K&N...assuming we'd need them and then jetted down (back to stock) after getting dyno results. I just knew I jetted down.....sheeesh.

I was thinking of doing that tonight after work.....haven't found a link yet on how much to shim the "Y". I'll keep looking.

 

[ouchez]

I believe Damon has a CD out on how to work, rebuild the carbs.

Probably A good thing for all of us to have.

Damon, how about a group price?
:clapping:
O