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08-29-2012, 01:26 PM, (This post was last modified: 08-29-2012, 01:31 PM by LondonFlyer.)
#1
pms adjustment v star
There was a request in another thread from someone on how to adjust the PMS on a Vstar Motorcycle. I thought I'd write up a quick summary so people would know how to do this.

I do not take responsibility for messing up your bike. Messing with this can be simple but it can certainly damage your engine, too. So just be careful and make sure you take it slowly. Also, I recommend writing down your settings as you go and taking photos with your phone (if you have one) so you can be sure to keep track of where you began. (double safety nets are the plan)

First, there is a Pilot circuit which is what the PMS screw control. It runs the primary fuel delivery at idle and throttle positions below about 1/4 turn.

Now, you have to understand some electronics here (well, you don't, but I'm going to explain them) and that is all the circuits in the stock carb settings work at all RPMs (except for the accelerator) and you will want these to be balanced for the optimum results. Now, like any internal combustion engine the responsibility for fuel delivery will change with what RPM your engine is running at. In this bike the PMS circuit never turns off. Anyway, I don't want to get too technical here but it can be a frustrating process to dial the settings in and some people just make adjustments now and then, and some people want to get everything done all at once. Personal preference and time and all of that factor in.

So, to begin with when setting up your carburetor I would recommend setting your PMS to a safe and rich setting based on the recommendations that have come with your specific jet. It is better to be a little rich than lean since fuel is much cheaper than a new piston or engine.

I recommend making adjustments in small increments, going for a ride to see if the adjustments worked, and then decide if you need to make another adjustment. When you do a test make sure you get up to full engine operating temperature, otherwise you won't know for sure what is going on.

Now, let's look at each scenario a bit:

If you get backfiring on hard deceleration runs (not just gentle coasting and not just braking, but letting off from the throttle completely) then you can begin by turning the PMs out by 1/2 a turn until it stops.

The next step is to turn the PMS in 1/4 to 1/3 increments until you go back to getting backfire on deceleration. This is a good happy medium here in adjusting your PMS and we now can find the best balance for operating temp.

If you have a slight hesitation at initial application of the throttle then turn the PMs out one more by and 1/8th of a turn. If you cannot get rid of the backfire on deceleration you may need a larger size pilot jet. You also may have to look at the other circuits of your carb...like the main jet size and needle clip position.

From here you can make the adjustments necessary. Lots of blackish smoke is generally too rich.

Anytime you change something on your bike that requires a re-jet you need to dial in the PMS again. Changing an air filter, removing baffles, or porting the manifold normally will require a re-jet since you're getting more air into the engine but not increase the fuel -- which can cause you to run lean, run hot, and damage the internal engine components. this isn't guaranteed to happen, but it makes much more sense to spend a little bit of money to prevent this from happening.

The main thing to remember is to make small adjustments, and if you need clarification post back here for answers. Remember to make small adjustments, get your bike warmed up, and we can tweak it as we go. If you get lost (I recommend writing down which turns you make) go back to the beginning to where you started, or go back to where your bike was running the best. If you run super lean get out of the throttle immediately (normally bad popping noises, but this CAN come from being overly rich too, but generally a lot of black smoke will come out if you're running rich).

Some other notes: If you ride in a really hot place, I'd run the bike a tad bit rich since the fuel can cool the pistons a bit and keep things a bit on the safe side as far as engine temperatures go. All in all, it is generally better to run rich than lean, at least a little rich instead of lean, but running way too rich can cause its own problems, too.

I just re-read this and it might be confusing so just ask questions away so it is good resource for everyone.
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09-01-2012, 02:15 AM,
#2
Re: pms adjustment v star
Great post LondonFlyer

Sent from my Nexus S using Tapatalk 2
Jmck
Two wheels moves me body and soul Cool
Reply
09-01-2012, 02:34 PM,
#3
RE: pms adjustment v star
Thanks buddy. Hope it can help some people out.
Reply
09-02-2012, 06:56 PM,
#4
RE: pms adjustment v star
LondonFlyer. Do will this help me in balancing the carbs? My bike is having problems. http://www.vstarforum.com/V-star-1300-sh...ems-Thread I think I need to balance my carbs but wasn't sure if this would help me. I'm new to this stuff so thanks for your patience.
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09-09-2012, 06:47 PM,
#5
RE: pms adjustment v star
I will speak for LondonFlyer. It depends on how severe yor problem is I think. I'll let him chime in to be sure, as he hasn't been here for a few days it looks like since I'm sure he'd respond. Put differently, I think a PMS adjustment is for minor issues, not major ones if that makes sense.
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01-21-2014, 12:54 PM,
#6
RE: pms adjustment v star
I have a 2003 V-Star Classic 650. It sat up for about 3-4 months and I got it out and couldn't get it to start. Put some more fresh gas in it and it would start and then shut off almost instantly. I bought a fuel additive and added it. It now runs with the choke out, but sounds like it's only in idle. Checked exhaust and top exhaust is warm and bottom exhaust is cold. Could this be clogged jets from the fuel sitting and clogging up? Also, the adjustment wheel on the fuel line, I adjusted back and fourth while trying to get it running. In order to get it back where it should be, what should I do? Is there a recommended start point? What should I do?
(08-29-2012, 01:26 PM)LondonFlyer Wrote: There was a request in another thread from someone on how to adjust the PMS on a Vstar Motorcycle. I thought I'd write up a quick summary so people would know how to do this.

I do not take responsibility for messing up your bike. Messing with this can be simple but it can certainly damage your engine, too. So just be careful and make sure you take it slowly. Also, I recommend writing down your settings as you go and taking photos with your phone (if you have one) so you can be sure to keep track of where you began. (double safety nets are the plan)

First, there is a Pilot circuit which is what the PMS screw control. It runs the primary fuel delivery at idle and throttle positions below about 1/4 turn.

Now, you have to understand some electronics here (well, you don't, but I'm going to explain them) and that is all the circuits in the stock carb settings work at all RPMs (except for the accelerator) and you will want these to be balanced for the optimum results. Now, like any internal combustion engine the responsibility for fuel delivery will change with what RPM your engine is running at. In this bike the PMS circuit never turns off. Anyway, I don't want to get too technical here but it can be a frustrating process to dial the settings in and some people just make adjustments now and then, and some people want to get everything done all at once. Personal preference and time and all of that factor in.

So, to begin with when setting up your carburetor I would recommend setting your PMS to a safe and rich setting based on the recommendations that have come with your specific jet. It is better to be a little rich than lean since fuel is much cheaper than a new piston or engine.

I recommend making adjustments in small increments, going for a ride to see if the adjustments worked, and then decide if you need to make another adjustment. When you do a test make sure you get up to full engine operating temperature, otherwise you won't know for sure what is going on.

Now, let's look at each scenario a bit:

If you get backfiring on hard deceleration runs (not just gentle coasting and not just braking, but letting off from the throttle completely) then you can begin by turning the PMs out by 1/2 a turn until it stops.

The next step is to turn the PMS in 1/4 to 1/3 increments until you go back to getting backfire on deceleration. This is a good happy medium here in adjusting your PMS and we now can find the best balance for operating temp.

If you have a slight hesitation at initial application of the throttle then turn the PMs out one more by and 1/8th of a turn. If you cannot get rid of the backfire on deceleration you may need a larger size pilot jet. You also may have to look at the other circuits of your carb...like the main jet size and needle clip position.

From here you can make the adjustments necessary. Lots of blackish smoke is generally too rich.

Anytime you change something on your bike that requires a re-jet you need to dial in the PMS again. Changing an air filter, removing baffles, or porting the manifold normally will require a re-jet since you're getting more air into the engine but not increase the fuel -- which can cause you to run lean, run hot, and damage the internal engine components. this isn't guaranteed to happen, but it makes much more sense to spend a little bit of money to prevent this from happening.

The main thing to remember is to make small adjustments, and if you need clarification post back here for answers. Remember to make small adjustments, get your bike warmed up, and we can tweak it as we go. If you get lost (I recommend writing down which turns you make) go back to the beginning to where you started, or go back to where your bike was running the best. If you run super lean get out of the throttle immediately (normally bad popping noises, but this CAN come from being overly rich too, but generally a lot of black smoke will come out if you're running rich).

Some other notes: If you ride in a really hot place, I'd run the bike a tad bit rich since the fuel can cool the pistons a bit and keep things a bit on the safe side as far as engine temperatures go. All in all, it is generally better to run rich than lean, at least a little rich instead of lean, but running way too rich can cause its own problems, too.

I just re-read this and it might be confusing so just ask questions away so it is good resource for everyone.
Reply
11-20-2015, 11:21 PM,
#7
RE: pms adjustment v star
I removed the exhaust baffles on my 1100 V-star and can't seem to get the bike running well since. It was backfiring on decel (not bad, and in hind-sight should have just accepted it as is), but no.... had to start playing with the jets trying to re-tune the carbs. Long story short, I've ended up with 17.5 pilot jets, and 115.0 main in front cylinder and 112.5 main in the rear. Both PMSs are set to 2.5 turns out from a light reset. And here is my question: When starting and idling, the bike runs better with the choke on slightly. Without the choke, turning the throttle will bog the engine down and it either takes a few seconds to respond or will just die - with what sounds like a loud click (backfire in the carbs?) When I have a little choke on, turning the throttle results in a fast and strong response. So, here's what i am thinking, but don't know if it makes sense, I am thinking that since the throttle response is so much better with the choke on (more idling fuel), then the PMS screws are to lean and I should begin backing them out a little at a time. Should I be looking for something else ?
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11-21-2015, 08:02 AM,
#8
RE: pms adjustment v star
https://sites.google.com/site/vstar1100k...rb-jetting increasing the mains one size is good for a pipe change. the mains come into play at 3/4 to full throttle so they are fine. 17.5 pilot is a stock, so there fine to.i think your pms should be set at 2 turns out, for only a pipe modification.in the link scroll down to the table box it tells what settings for each modification. exhaust or any air leak can cause popping check tubing and caps for cracking.
2007 1100 custom,cobra longs and pods,doubled clutch spring.
Reply
12-19-2015, 08:50 PM,
#9
RE: pms adjustment v star
Just a quick update for anyone else struggling with PMS adjustments on their V-Star 1100, after trying 2-turns out to 4-turns and back again, all in 1/4 turn increments, I finally went to Autozone and picked up a can of ether to check for vacuum leaks. Wouldn't you know it, after struggling with PMS adjustments for about a month, I found leaks on both intake joints from the carb to the cylinders. Pretty obvious with the ether - very obvious! So learn from my mistake - check for leaks between the carb and engine before spending any time adjusting the PMS screws. I'll need to pull the carbs again and replace the intake hoses and clamps to see if I can get it sealed up.

Does anyone know if the rubber high-temp hoses between the carbs and engine intakes are replaceable? I can't find them in the part catalog and the dealer says they come as part of the flange joint (SEL-13586-00-00 & SEL 13596-00-00).
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