Every now and then I get a haunted one. Newer street motor recently installed into an older frame. Rejetted the carbs (Factory Pro), new M4 full system, cleaned up some stuff. Compression is really good. Bike starts and runs great. Bit of a vibration but hey it's an older bike. Throttle response is crisp with no load.. BUT When pulling off with a load it spits a bit till the RPMs coem up and as it heats up (within 5 minutes) it starts to act like it's lean on the pilot. It'll hesitate a bit more on a roll on from idle but is strong after that. After a couple of more minutes it'll start to really stutter off idle, load or no load. Within 10 minutes it'll not rev through it and eventually spit / sputter and die. Like it's out of gas. I can't tell if it's dropping a specific cylinder it just seems to bluck, bluck, bah bluck, blaaaahhhhhhh................ Here's what I've checked: Thought it was jetting. I've been from 1.75 turns out to 2.75 turns in 1/2 turn increments. I can "feel" the adjustments but no matter where it is it'll still eventually die. I've tuned this setup before and this one hasn't been any diffrent. Plugs - orginally sooty but dry. Cleaned and replaced. Replaced the plug boots. Checked spark (bright blue / white). No oil in water and no water in oil. Gas is good and new. Petcock works. Fuel pump works....... Hmmmmm I'm gonna check that one again. My next step is just to pull it all apart and look at everything again. The part that it does it when it's hot or after it's run awhile really throws me a curve. That usually means a jetting issue or "doesn't" mean things like a vacuum leak...
I'm working on a 89 GSXR750 Trying to sync the carbs, I could not get vaccum on #1. Found the the O-ring was swollen, and not seating. It would idle, and then once I reved it, the RPMs would raise by 1500.So I don't think it vaccum related. Did you build the carbs? Take them totally apart,check the screen below the float needle.Sounds like it's starving. But then again those friggin SV gremlins are fun
Yeah I did the carbs. I think you're right I just need to hit them again. I need to break out of the "I think it's spark" loop. But both carbs at once? Guy did tell me I could burn it if it got to be too much of an annoyance! That'd actually be pretty cool! Specially if it had a gas tank full of bottle rockets! I think an SV burning in the cul-de-sac would be the last straw for my neighbors though.
check the white plastic clip that holds the needle in place in the carbs. sometimes one of the fingers breaks and the needle just bounces up and down whenever it wants .
I got the answer...come see me I have a new 4 gas ega makes your life much easier. It takes the guess work out of it. Plus I owe you one I will give you a freebie...
Way ahead of you on that one! One was broke and I replaced it when I rebuilt the carbs. $30 some odd bucks from Chip before I remembered I had a box of carb parts (like 2 sets) over at Martin's house! Dammit! Hahahaha Tank venting sounds like a good thing to check! Wish I had another key to do the old "pop it when it starts to die" trick. Whatchu got Charlie? Can you email me please? I'm pretty busy this week and need to get it running.
Just a thought. Plug wire or coil breaking down under load. Had that happen on a fizzer. I finally had to ohm out the wires and coils to find it. And, is the SV battery dependent? I had trouble with the same bike under high RPM loads. Bike ran ok for a few laps then began to sputter at high RPMs. It became worse the longer it ran and sputtered badly even at low RPMs. Battery replacement cured it.
LMC and Kendall get the Cupie dolls! Swapped coild last night now bike go vroom vroom and make 67.7 on the dyno (DJ 200) after a bit of tuning. Thanks everyone for your help.
