trying to get my engine tuned correctly. Have 1987, 13,000 miles, with Dyna exhaust and VM Lancer Carb and K&N cone filter. Jet is now set at 170. Petcock mod was just done so have on/off/res with machined plate instead of vac port plate on back. Bogs down after plate was installed thinking there was air leak before through the petcock cause now it bogs when cold. when hot runs much better. In monterey CA so almost ideal conditions at sea level with average temp now in 50's and 60's during the day. Got a new freind mechanic with dyno machine so this will help. Started with a 190 installed jet and that was too rich slowly dropped jets and we will see this weekend what happens. Has anybody used smaller jets than these in my conditions? Very low mpg at mid to low 30's, was getting better dropping jets before I machined the petcock plate. At one point it was 28 when I started thinking it was lean and went to 195 jet. Hints are appreciated, but I know internet diagnosis is difficult.

I guess I will try to drop my pilot from 20 to 17.5 and see what happens.

When Irecieved it I had a 190 and 20 with a needle notch setting of 2. I just put a plate on the back of the petcock which may have sealed very well. Enough to create more drw from that line. I did have a slight leak from there before I put the plate. I think what might have happened is when I sealed the petcock it increase the fuel draw which threw all else off because there was not any air leakage. It did change something though. Anybody have an idea if it is a bad idea to attach the "vapor port" from the tank next to speedo to the vacuum draw. Would think this would help decrease fuel milage if tuned better due to it is virtually completely atomized already. Also there is a port on the header side near the bottom of the bowl. Is this an overflow vent?

Well, in theory the vapors escaping from the tank would be put into the vacuum. I am at about 20ft sea level. It has been a while and it has never really run all that well. I am a shade tree mechanic so my experience is limited. When you say your needle is on the highest setting do you mean the notch closest to the tank, because isn't that more lean?

Good point on backfires, are there any vented caps for savages?

I have a CA model with the keys for ignition and cap being the same does that mean I can just cap the vent that comes out under the tank?

I have a 17.5 pilot and 165 main jet in my VM. I cant even get the darned thing to start. I have the dial a jet and UFO installed.

If yuo poured somethng in on the piston & left it, you should change oil.Stuff can get down between the rings & into oil.