|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Jetting problems /cgi-bin/YaBB.pl?num=1397766150 Message started by Henrik on 04/17/14 at 13:22:30 |
|
Title: Jetting problems Post by Henrik on 04/17/14 at 13:22:30 I just cannot work this out. Bike info: Open K&N filter, and short muffler with less recistance, simliar to a Jardine muffler. (sealevel) 1. I installed 55/155 jets and 3 washers on the needle. Result was that the bike ran fine and felt good throu the hole range and alomst no backfire. BUT, I could start it cold without choke and also turning the mixture screw inwards didnt affect the idle at all. Outwards I had to turn something like 4 turns and it started to stall. Therefore I asumed that it was a bit rich. 2. Rejetted down to 50/150. Result, bike was ok in the low and midrange, but started to backfire and bogging when adding full throtel. It got a litle better when the bike warmed up. 3. Rejetted ones again to 50/155. Result, bike is still backfiring on hard acceleration but just occasioanly, and mostly on high revs and especialy on second gear. Third and fourth gear works better almost no backfire. Runs fine on low and midrange. Max idle is somewere 1,5-2,0 turns out. Could it be something else? Recently did valve adjustment after fixing the cam chain tensioner and plug leak, so the valves should be ok. Should I stay on this setting 50/155 or go back to 55/155? I havent had the time to check the color of the plug yet (by the way the plug is new) Exhuast leak? vacum leak? Could it be normal to get some backfiring on max revs and full throtle? :-? |
|
Title: Re: Jetting problems Post by verslagen1 on 04/17/14 at 13:42:48 I'm assuming the backfiring occurs during gear shift. Sounds like 50/155 is working best. You might never get rid of the backfiring due to the open exhaust. Is it a pop or a KERPOW? a little higher idle may help. |
|
Title: Re: Jetting problems Post by Dave on 04/17/14 at 14:21:16 If the backfire occurs when you let off the throttle or shift gears....ignore that for a bit while you concentrate on what makes it run best. For the main jet size..... keep going up in size until you notice the bike becomes slower and less responsive - then back down a size. There is a roll off test that can help to determine if the main jet is too rich - while under full throttle slowly roll the throttle closed a bit....and if the engine speeds up or runs smoother as you close the throttle a bit...it indicates you may be too rich. For the Pilot, Mikuni claims that the best pilot jet size is the one that allows you to get the best idle mix at 1.5 turns out. If it takes more than 2 turns to get the best idle mix....go up a size on the Pilot Jet. Then ride the bike and see what happens as you open the throttle slowly from idle and accelerate slowly. If the bike runs smooth and accelerates well you probably don't need to fuss with the needle. If the bike surges and doesn't accelerate smoothly - you need to raise the needle by removing another washer. If you raise the needle it could richen up the mix in the upper rpms and you may be able to drop the main jet size. Backfire/afterfires - As Versalgen indicated, less restrictive pipes make the backfire louder and more noticeable. The backfires occur on a bike that is jetted to run properly.....and making the engne run richer does help to reduce backfires at the expense of performance and mileage. The backfires occur because when you close the throttle you are dropping the tapered needle into the needle jet and closing off the fuel supplly. The carb then is only providing fuel through the idle circuit, and the engine goes so lean that the spark plug cannot ignite the mixture. As you continue to coast the unburned fuel builds up in the exhaust and is either ignited by the hot exhaust - or is ignited by the flame the next time the spark plug does ignite the mixture. You can minimize this by raising your idle speed a bit which allows more fuel flow, or by rolling off the throttle slowly when you shift so that the slide does not drop all the way back to idle between shifts. An engine that backfires on deceleration is more a product of a free flowing exhaust system than it is of one that is jetted wrong. Backfiring on acceleration is an indication that something is wrong. To lesson the backfires between shifts you can increase the pilot jet size to richen the mixture - but doing so will make the engine run a bit rich while riding normally and will hurt the fuel mileage. |
|
Title: Re: Jetting problems Post by Henrik on 04/17/14 at 14:40:12 The bike is not backfiring on gearshifts, but on the end of hard acceleration. What can indicate acceleration backfire? |
|
Title: Re: Jetting problems Post by verslagen1 on 04/17/14 at 15:02:45 0F2229352E2C15470 wrote:
From wiki answers... Quote:
There are some clues in this answer, so questions to clarify... Is it true backfire (out the intake)? or afterfire (out the back end)? About what rpm does it backfire? you say after a hard accel, but is it medium, high, or really high rpm? and you're trying to go faster in the same gear? and it could be... dum dum dummmmm... bad petcock! |
|
Title: Re: Jetting problems Post by S-P on 04/17/14 at 15:13:56 567B706C77754C1E0 wrote:
You could try 52.5 and 152.5. It sounds like you are close with the 50/155. |
|
Title: Re: Jetting problems Post by Henrik on 04/17/14 at 17:37:16 I have changed to a raptor petcock so it shouldnt be an issue. I think the backfire comes thru the exhaust. It is during acceleration, but happens in the end on high revs. |
|
Title: Re: Jetting problems Post by Dave on 04/17/14 at 18:36:01 Did you install an inline fuel filter? If so....you might be running the float bowl dry under hard acceleration. |
|
Title: Re: Jetting problems Post by Henrik on 04/17/14 at 23:49:54 Nope, no fuelfilter |
|
Title: Re: Jetting problems Post by Henrik on 04/18/14 at 00:07:28 Since I had no backfire on accelration with the 55/155 setting I guess it has to have something to do with the jetting. Or could the rich mixture camoflauge a timing issue? |
|
Title: Re: Jetting problems Post by Dave on 04/18/14 at 03:10:12 I have never heard of these bikes having a timing issue. The ignition system works.....or fails.....not much in between. |
|
Title: Re: Jetting problems Post by Henrik on 04/18/14 at 07:00:11 0C373A2D3C302B2D363E332C5F0 wrote:
Ok, thats good to know! |
|
Title: Re: Jetting problems Post by Henrik on 04/18/14 at 07:07:55 Tested the bike today. Had some backfire but it got better as the bike got varmed up. Going to order 52,5/152,5 jets to se if it gets better. Another question, I noticed that I have a small exhaust leak were the muffler mets the header. Could feel pulsations with my hand. Possibly this can contribute to the issue, but from what i have read this should give deccelration backfire? |
|
Title: Re: Jetting problems Post by WD on 04/18/14 at 07:32:55 That can cause them at any time. Savages make a lot of exhaust noise, that can't ever be fully dialed out with the stock CV carburetor. Relying on air pressure to do a cable's job... |
|
Title: Re: Jetting problems Post by Dave on 04/18/14 at 07:46:47 5043070 wrote:
I have converted my bike to a VM36 Mikuni Round Slide. It is not inexpensive, and most likely not for eveyone, and it does not make the rumbling popping afterfire noise go way completey - but it does make it easier to control and the bike is faster to react to throttle changes. If you want to ride nice and quiet you just roll off the throttle a tad while you shift - and when slowing down you don't let the throttle close completely. It takes just a little extra brake as the engine is not doing as much (or any) compression braking when the throttle is not completely closed. If you want to make a lot of noise then you go ahead and let the throtte slam shut when you shift (Pow), and when slowing down you close the throttle completely (Bang, putt putt putt, Bang, putt putt). It all deponds on your right wrist how much noise you want to make. The same is true with the CV carb when jetted correctly and you can reduce the amount of noise you make....but the VM carb is a little more responsive about what you choose to do with the throttle. |
|
Title: Re: Jetting problems Post by WD on 04/18/14 at 08:34:55 What we really need is an o-ring equipped solid manifold, like HD uses. The factory rubber boots have too much leak potential. Engine heat can make them brittle and/or distorted. The intake stub on the 98 has a crack you can put a quarter in, and it will stay in place without any glue... |
|
Title: Re: Jetting problems Post by JayDuta on 04/18/14 at 11:56:47 Interesting observations, I'm having some issues as well. I'm running the jet set provided by Ryca on a 96 which suggested using the 55/152.5. set up with replaced washers. I'm out here in Northern California. I was able to start and ride the bike around my neighborhood at 2 turns out and a nice idle after trying to start it quite few times. I was sure it was tuned properly. The next day the bike wouldn't start up. I checked the spark plug and there are black deposits on it. I assume it's running too rich? Should I try the other jets? 147.5 main jet or 150 main jet with 55 pilot jet? I'm also using fuel that I have stored. Not sure if gas is the issue. The bike wont start now, my battery is fully charged even with jumpers and the starter seems ok. Any suggested on what to try next? |
|
Title: Re: Jetting problems Post by S-P on 04/18/14 at 14:30:49 49716667767762030 wrote:
Try fresh gas and cleaning the plug before you start re-jetting. Bad gas is... well, bad. |
|
Title: Re: Jetting problems Post by Henrik on 04/18/14 at 14:43:07 How about you other guys how has a air filter like a K&N cone filter, and a muffler similar to the Jardine, what is your jetting setup? Just so I can compare what should be a "normal" setting. |
|
Title: Re: Jetting problems Post by JayDuta on 04/18/14 at 15:00:22 I rejetted my carb using the stock jet and 150 main jet. 2 turns out on the carb scew and it runs like it should now. I've got a k&N short filter and reverse cone pipe. On my Ryca Bobber. Gonna drain old fuel and put fresh one in. Hope this helps some of you. |
|
Title: Re: Jetting problems Post by Henrik on 04/18/14 at 15:18:14 053D2A2B3A3B2E4F0 wrote:
what is the stock jet size? |
|
Title: Re: Jetting problems Post by pgambr on 04/18/14 at 15:20:39 I have an 06 with the standard carb. I’m guessing the pilot jet is 47.5 and the main jet is 145. I’m at an elevation level of 300 ft and it is very humid. I have a dyna muff and kn drop-in. Runs great! The only thing that I see that concerns me is a small drip of gas when it idles for a long time. Also, I’m getting somewhere between 45-50 mpg depending on how I’m riding. Not sure if this helps, just thought I’d add my .02. |
|
Title: Re: Jetting problems Post by JayDuta on 04/18/14 at 15:27:09 It's 47.5. Here check out this vid http://youtu.be/rFFuF9QZ4IM |
|
Title: Re: Jetting problems Post by pgambr on 04/18/14 at 15:59:24 Nice vid, thanks. |
|
Title: Re: Jetting problems Post by Yoshi on 04/18/14 at 20:02:04 Im trying 52.5 pilot and 155 main with a pretty opened MAC exhaust and stock air filter, I'll check plug color after some run time and mod from there It seems to be working really well with 2 turns out on the air/fuel needle Was too rich, I went with a 152.5.. |
|
Title: Re: Jetting problems Post by S-P on 04/18/14 at 22:09:28 I have a Dyna muffler and cone filter. 152.5 and 52.5 and two washers (Lancer's kit). 2 1/4 turns out. I still get a small POOT backfire on shut down occasionally and a little backfire at shifting gears if I'm gunning it, but the bike runs great. |
|
Title: Re: Jetting problems Post by Henrik on 04/19/14 at 10:05:07 Just thinking, which has the highest impact on jetting air filter or muffler |
|
Title: Re: Jetting problems Post by Henrik on 04/20/14 at 15:08:03 Just want to share my experience. Had a breaktrough today. My father also owns a Savage, and he had "borrowed" my old Jardine pipe since i bought this new universal short turnout muffler. It sounds great, but i discoverd that it has a rather small hole compared to the Jardine muffler. So I was thinking what if it got alot less recistance compared to the other? So I did a switch, and bammm!! Suddenly things just worked out, much!! more power and no bogging and backfire on acceleration. Runs realy sweet. Right now i got a 50/155 "1,8" turnout on the mix screw, 3 spacers on the needle. Maybe it is a bit rich on the main, but what a hugh change in performance and response. For knowledge, I got a rather BIG pancake K&N open air filter, so my analyse is this: there was a BIG bottleneck in the exhaust part of my system wich made the engine stumble and backfire on full throttle. Also its telling me that it was on to rich setting until I swichted the exhaust. And some exhaust sound bad, but in fact they arent so evil as they loook :) Next step is to ride on this for a while and to do a sparkplug check in different ranges to finetune the jetting. thanks to all of you for you imput! Now it is time for a big whiskey! |
|
Title: Re: Jetting problems Post by Henrik on 04/27/14 at 02:00:42 So i have noticed this, when turning the mixture screw out for about 3-3.5 turns it starts to slow down and die. Turning it in somewere at 1.0 - 1.5 turn the idle is at max. But the weird thing is that turning it in more and all the way to bottom dosent make any differance. In teory this should mean that i have to step down one size, but that dosent make sence to me because than i would be at 47,5 jet that is stock for my bike, and that just feels way to lean. To check the sparkplug should i just run the engine on idle? Also could the main jet have any affect on this (155)? It runs fine on low and midrange. Is there any other way to analyse the pilotjet? |
|
Title: Re: Jetting problems Post by Dave on 04/28/14 at 03:21:05 5D707B677C7E47150 wrote:
If your best idle mixture is at 1.5 turns....then according to Mikuni your Pilot Jet is the correct size (Notice the Bypass hole and Pilot outlet in the attached drawing). It turns out the Idle Fuel screw is one of two holes that allows fuel to flow at idle....so even though you may be turning the screw all the way it....there is still a hole to allow fuel to flow. If your idle is set too high while you are adjusting the idle mixture....you may also be getting fuel flow from the slide needle....which will change the way the fuel screw reacts. I am also of the opinion that jetting your bike for good performance and fuel mileage.....will make the CV carb prone to pops and bangs when shifing gears or decelerating with a fully closed throttle. If you put a larger pilot jet in to reduce the pops during shifts - your mileage will decrease slightly. What happens is that when you fully close the throttle, the vacuum goes up really high and it pulls a lot of air past the throttle butterfly. The only fuel that can flow is being pulled out the Pilot Circuit, and it does not provide enough fuel to make a combustible mixture and the spark plug cannot ignite the mixture....so the air and unburned fuel gets pushed out into the hot exhaust pipe. When enough fuel builds up in the exhaust and is ignited by the hot exhaust pipe - or the spark plug happens to ignite mixture and the flame travels out the exhaust valve....the mixture in the exhaust system is ignited and makes the pop or bang. When you increase the Pilot Jet size you are allowing more fuel to flow into the idle circuit....and this can help to reduce the lean condition and help the spark plug to ignite the mixture when you are decelerating......The down side is that the idle circuit is richer under normal riding conditions and is using more fuel. Beyond 1/8th throttle the Pilot Jet doesn't do much of anything - so the mixture is controlled by the slide needle and main jet at larger throttle settings. |
|
Title: Re: Jetting problems Post by Henrik on 04/29/14 at 13:02:40 Thank you Dave! I havent yet had the time to test it out. I should defenitly try to lower it and see what happens. Make sence, i also have noticed that to low idle increases backfire. At the moment the bike runs fine. I do suspect it is a bit rich. One thing that i have been thinking of is this, do the jets activates in order so that at full throttle they are all engaged meaning that the pilot, needle hight, airscrew are all affecting the main jet? |
|
Title: Re: Jetting problems Post by verslagen1 on 04/29/14 at 13:47:09 58757E62797B42100 wrote:
The pilot jet and pilot mixture screw are only active when the throttle is near closed. This is due to the pilot circuit opens near the butterfly valve. Once the BV is open enough to be on the other side of the BV, not much air/fuel is going to flow thru it. The needle jet regulates the main from closed to full open throttle. change the needle height and you open the main sooner. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |