SuzukiSavage.com /cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Trying to tune it up /cgi-bin/YaBB.pl?num=1236369251 Message started by Justinmkantor on 03/06/09 at 11:54:11

Title: Trying to tune it up Post by Justinmkantor on 03/06/09 at 11:54:11 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.

Title: Re: Trying to tune it up Post by Moofed on 03/06/09 at 16:55:39 I don't know the differences between a stock carb and the vm carb, but on the stock the main jet has little to do with gas mileage.  You should be looking at your pilot jet, or whatever takes its place in a vm carb.

Title: Re: Trying to tune it up Post by Justinmkantor on 03/08/09 at 10:59:27 I guess I will try to drop my pilot from 20 to 17.5 and see what happens.

Title: Re: Trying to tune it up Post by SV og LS on 03/08/09 at 11:59:33 On everyday riding needle height is more important than main jet size. Lower the needle a notch or two and adjust the idle mixture. Considering the fuel mileage it must've been set up horribly rich.

Title: Re: Trying to tune it up Post by Justinmkantor on 03/08/09 at 12:20:40 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?

Title: Re: Trying to tune it up Post by seviersavage on 03/08/09 at 13:37:41 Justin, I have the vm Carb. I am at 17.5 on pilot and needle set at highest position. I was having a stumble at about 1/4 throttle, just a hesitation and I moved needle down to lean a notch and It got worse. Finally ended with it all the way up, at  the richest setting before stumble went away. Methinks 20 on the pilot is too rich and 190 may have been too rich. For me 170 was too lean on the main. I'm in the mountains at about 2500 ft though. At least the vm carb is easy to tinker with. I would play with different needle settings. I can't see how the petcock could change your carb though, the vm doesn't have a vacume port like the stock carb right? All that could change would be the speed of the fuel flowing to the bowl right? It took me a few days tinkering to get it right but it's worth the time. My mileage basically stayed the same although I tend to twist the throttle now more than I did with the stock carb. :P Seviersavage

Title: Re: Trying to tune it up Post by Justinmkantor on 03/08/09 at 14:30:32 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?

Title: Re: Trying to tune it up Post by verslagen1 on 03/08/09 at 14:47:01 The CA model has a carbon canister between the carb and tank.  Vapor recovery usually feeds on the other side of the filter in the air box to prevent backfires from finding there way into the tank.

Title: Re: Trying to tune it up Post by Justinmkantor on 03/08/09 at 15:16:04 Good point on backfires, are there any vented caps for savages?

Title: Re: Trying to tune it up Post by verslagen1 on 03/08/09 at 18:53:48 they all have them, but I don't know which one. Bike bandit denotes CA and get this, it's more expensive. So the one that has an inlet and an outlet is cheaper.  go figure.

Title: Re: Trying to tune it up Post by Justinmkantor on 03/10/09 at 17:30:04 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?

Title: Re: Trying to tune it up Post by verslagen1 on 03/10/09 at 17:38:53 With CA non vented cap I'd leave it open.  Just run a line down to the bottom of the frame or to a catch bottle.

Title: Re: Trying to tune it up Post by odvelasc on 03/10/09 at 18:11:40 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.

Title: The magic of seafoam Post by Justinmkantor on 03/11/09 at 10:11:09 The old seafoam trick helped. Poured it directly into the spark plug hole (2oz) and let sit overnight. Backfiring is way reduced, runs smoother. Some people say there is no mechanic in a can but I imagine the tiny scrubbing bubbles commercial from days of yore for this remedy. Running a 17.5 pilot 175 main needle setting at the middle and runs pretty well.

Title: Re: Trying to tune it up Post by justin_o_guy2 on 03/12/09 at 09:46:44 If yuo poured somethng in on the piston & left it, you should change oil.Stuff can get down between the rings & into oil.

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