Edited by dwil4, 27 July 2012 - 05:41 AM.
4
'99' XR 200R JETTING ?
Started by
dwil4
, Jul 26 2012 07:03 AM
27 replies to this topic
83 posts
Location: North Carolina
Posted 26 July 2012 - 07:03 AM
i did some minor mods to the airbox like taking out the 2 cross sections of the snorkel and taking out the screen from the filter cage, also the baffle was remoned from the muffler by previous owner....any suggestions to whether these should cause a need for re-jetting?? what were stock jetting's on the '99' model ?...(110/38 needle 3rd groove down from the top)?? i currently have a 115/40 set up...plug looks to b in the accepable range but damn if this thing doesnt seem too hot as far as engine/muffler heat...obviously isnt running very well either..runs best with the choke half on....thinking i need to try maybe a 112/38 set up???........thanks in advance for any input from u guys..
115 posts
Location: Washington
Posted 29 July 2012 - 07:30 PM
I did the same mods except I left the stock jets in there 110/38 and just reset my idle. Feeds it fine and doesn't go lean, you can feel the extra go, not much but enough to feel.
7076 posts
Location: Washington
Posted 29 July 2012 - 08:05 PM
These engines are jetted marginally rich from the factory, opposite of later dirt bikes that are jetted marginally lean. I've found that carb float levels can be off enough to indicate a richer pilot or needle clip position, so checking the float level is important before changing jets.
I have one 200 with a big bore 10.5:1 piston, K&N pod filter, Powroll pipe, and a FMF Q4 muffler; jetted stock except one size up on the main and the needle one clip rich. This engine doesn't show richness until 5000 feet on a hot day, which can be fixed by dropping the needle one clip and adjusting the mixture screw.
I have a stock 90 XR200R without muffler tip, no snorkle, and Unifilter; runs stock jetting.
Taking out the backfire screen does nothing except increase the risk of a filter fire. The stock snorkle, (# 11 called a Cap), fits into the center port of the duct, (#10 called a Duct). Pulling the snorkle (#11) increases air box inlet area but increases risk of water ingestion, Pulling the duct allows water that collects on top of the air box to run inside onto the filter, I ride in the wet PNW so I kept the duct to protect the filter from water.
110/38 needle 3rd groove is stock jetting for 87-02 XR200Rs, except CA models. Sounds like a complete tune up is in order including a thorough carb cleaning.
.gif)
I have one 200 with a big bore 10.5:1 piston, K&N pod filter, Powroll pipe, and a FMF Q4 muffler; jetted stock except one size up on the main and the needle one clip rich. This engine doesn't show richness until 5000 feet on a hot day, which can be fixed by dropping the needle one clip and adjusting the mixture screw.
I have a stock 90 XR200R without muffler tip, no snorkle, and Unifilter; runs stock jetting.
Taking out the backfire screen does nothing except increase the risk of a filter fire. The stock snorkle, (# 11 called a Cap), fits into the center port of the duct, (#10 called a Duct). Pulling the snorkle (#11) increases air box inlet area but increases risk of water ingestion, Pulling the duct allows water that collects on top of the air box to run inside onto the filter, I ride in the wet PNW so I kept the duct to protect the filter from water.
110/38 needle 3rd groove is stock jetting for 87-02 XR200Rs, except CA models. Sounds like a complete tune up is in order including a thorough carb cleaning.
1207 posts
Location: New Zealand
Posted 30 July 2012 - 01:41 AM
May also be worth checking your timing. But +1 above stock jetting should be okay. It could be advanced too much. Chuck would be able to offer better advice than me on this.
You could try a completely new carb kit.
You could try a completely new carb kit.
83 posts
Location: North Carolina
Posted 30 July 2012 - 10:11 AM
GEOF, on 29 July 2012 - 07:26 PM, said:
What is your elevation above sea level?
83 posts
Location: North Carolina
Posted 30 July 2012 - 10:42 AM
chuck4788, on 29 July 2012 - 08:05 PM, said:
These engines are jetted marginally rich from the factory, opposite of later dirt bikes that are jetted marginally lean. I've found that carb float levels can be off enough to indicate a richer pilot or needle clip position, so checking the float level is important before changing jets.
I have one 200 with a big bore 10.5:1 piston, K&N pod filter, Powroll pipe, and a FMF Q4 muffler; jetted stock except one size up on the main and the needle one clip rich. This engine doesn't show richness until 5000 feet on a hot day, which can be fixed by dropping the needle one clip and adjusting the mixture screw.
I have a stock 90 XR200R without muffler tip, no snorkle, and Unifilter; runs stock jetting.
Taking out the backfire screen does nothing except increase the risk of a filter fire. The stock snorkle, (# 11 called a Cap), fits into the center port of the duct, (#10 called a Duct). Pulling the snorkle (#11) increases air box inlet area but increases risk of water ingestion, Pulling the duct allows water that collects on top of the air box to run inside onto the filter, I ride in the wet PNW so I kept the duct to protect the filter from water.
110/38 needle 3rd groove is stock jetting for 87-02 XR200Rs, except CA models. Sounds like a complete tune up is in order including a thorough carb cleaning.
I have one 200 with a big bore 10.5:1 piston, K&N pod filter, Powroll pipe, and a FMF Q4 muffler; jetted stock except one size up on the main and the needle one clip rich. This engine doesn't show richness until 5000 feet on a hot day, which can be fixed by dropping the needle one clip and adjusting the mixture screw.
I have a stock 90 XR200R without muffler tip, no snorkle, and Unifilter; runs stock jetting.
Taking out the backfire screen does nothing except increase the risk of a filter fire. The stock snorkle, (# 11 called a Cap), fits into the center port of the duct, (#10 called a Duct). Pulling the snorkle (#11) increases air box inlet area but increases risk of water ingestion, Pulling the duct allows water that collects on top of the air box to run inside onto the filter, I ride in the wet PNW so I kept the duct to protect the filter from water.
110/38 needle 3rd groove is stock jetting for 87-02 XR200Rs, except CA models. Sounds like a complete tune up is in order including a thorough carb cleaning.
7076 posts
Location: Washington
Posted 04 August 2012 - 10:39 AM
My first suggestion is to check the timing to get that out of the way (check out "Powroll 218 Build" for a description) and then:
Adjust the mixture screw for best hot idle and then if engine runs good when hot, takes throttle Ok, etc, and doesn't surge when you go from WOT to 3/4 throttle then mixture is close. A plug check will verify the main jet. The bike should need full choke for initial cold start, then a few seconds of half choke, then no choke for warm up, but it will idle very slow or stall until warm; also while riding it may occasionally flame out until hot. If the needle and/or pilot and main are too rich the transition from coasting with a closed throttle to opening the throttle (common while trail riding) will be ragged or jerky rather than smooth. Normal throttle operation should be smooth but opening the throttle from idle quickly to 1/4 should be OK if the pilot jet, mixture screw, and needle clip position are OK. Opening it quickly from idle to above 1/4 throttle is not normal operation and the engine should stumble, and opening it full should create a very bad stumble or even a stall. on edit: Last item: if there is popping on decel, burbling is OK, then the mixture screw is too lean. If best idle is with less than one turn out the pilot is too big, more than 2 turns (maybe 2 1/2 turns) out the pilot is too small. Each carb seems to be unique but I've found changing the float level 0.25mm will change mixture screw setting and 0.5mm may require a different pilot.
Caveat; If the carb is clean, the float level correct and you have clean or new jets, needle, and center clip position the bike will run marginally rich, not lean. That is because these carbs do not have accelerator pumps and must be rich to compensate.
You can buy an infrared temp probe at Radio Shack or Home Depot to check pipe and head temperatures. I have Vapors on two XRs and these engines are not warm until 200F under the spark plug, fin temps will be lower. My temps will go above 300F if I pick up the pace, and I've observed over 400F on mountain switchbacks on a hot summer day. Oil temp is usually just over 200F for trail riding, never above 250F.
When tuned correctly the bike will feel like only a half kick is needed to start a hot engine.
Adjust the mixture screw for best hot idle and then if engine runs good when hot, takes throttle Ok, etc, and doesn't surge when you go from WOT to 3/4 throttle then mixture is close. A plug check will verify the main jet. The bike should need full choke for initial cold start, then a few seconds of half choke, then no choke for warm up, but it will idle very slow or stall until warm; also while riding it may occasionally flame out until hot. If the needle and/or pilot and main are too rich the transition from coasting with a closed throttle to opening the throttle (common while trail riding) will be ragged or jerky rather than smooth. Normal throttle operation should be smooth but opening the throttle from idle quickly to 1/4 should be OK if the pilot jet, mixture screw, and needle clip position are OK. Opening it quickly from idle to above 1/4 throttle is not normal operation and the engine should stumble, and opening it full should create a very bad stumble or even a stall. on edit: Last item: if there is popping on decel, burbling is OK, then the mixture screw is too lean. If best idle is with less than one turn out the pilot is too big, more than 2 turns (maybe 2 1/2 turns) out the pilot is too small. Each carb seems to be unique but I've found changing the float level 0.25mm will change mixture screw setting and 0.5mm may require a different pilot.
Caveat; If the carb is clean, the float level correct and you have clean or new jets, needle, and center clip position the bike will run marginally rich, not lean. That is because these carbs do not have accelerator pumps and must be rich to compensate.
You can buy an infrared temp probe at Radio Shack or Home Depot to check pipe and head temperatures. I have Vapors on two XRs and these engines are not warm until 200F under the spark plug, fin temps will be lower. My temps will go above 300F if I pick up the pace, and I've observed over 400F on mountain switchbacks on a hot summer day. Oil temp is usually just over 200F for trail riding, never above 250F.
When tuned correctly the bike will feel like only a half kick is needed to start a hot engine.
Edited by chuck4788, 04 August 2012 - 12:28 PM.
83 posts
Location: North Carolina
Posted 08 March 2013 - 03:24 PM
OK BEEN AWHILE BUT HERE IS WHAT I GOT NOW..BIKE IS RUNNING ALOT BETTER BUT NOT JUST RIGHT...112/38 JETS , NEEDLE CLIP IN THE VERY BOTTOM SLOT FROM THE TOP GOING DOWNWARD AND AIR SCREW ABOUT 2 1/2 TURNS FROM SEATED...THIS IS PLUG COLOR.. THOUGHTS??
Attached Thumbnails
7076 posts
Location: Washington
Posted 08 March 2013 - 08:10 PM
Plug color on the porcelain looks a bit lean but the pics don't show enough. Check out http://www.4secondsf...ug_reading.html
Too rich, the bike only needs a 110 main, 38 pilot, middle clip position for the needle, and 1 1/2 turns out. I suspect a plugged low speed passage in the carb or a low float level. There are two very small low speed discharge port in the floor of the venturi that easily can be obstructed, and they can be difficult to clean.
see http://www.thumperta...s/#entry7745927
Too rich, the bike only needs a 110 main, 38 pilot, middle clip position for the needle, and 1 1/2 turns out. I suspect a plugged low speed passage in the carb or a low float level. There are two very small low speed discharge port in the floor of the venturi that easily can be obstructed, and they can be difficult to clean.
see http://www.thumperta...s/#entry7745927
83 posts
Location: North Carolina
Posted 09 March 2013 - 04:54 AM
the plug looks lean but its jetted too rich? am i reading that right? could u clarify? thanks chuck
Attached Thumbnails
Edited by dwil4, 09 March 2013 - 05:00 AM.
83 posts
Location: North Carolina
Posted 09 March 2013 - 08:38 AM
so even tho the jetting is a little high (112) the air screw turned out too far can still make it lean? carb seems to be very clean as carb cleaner flows thru every passage..
85 posts
Location: Texas
Posted 09 March 2013 - 09:55 AM
Correct me if I am wrong, but opening the air/fuel mixture screw, 2 1/2 turns compared to 1 1/2 turns would allow more air into the carb, and not more fuel.
Your plug does look a tad on the rich side.
Kirk
Your plug does look a tad on the rich side.
Kirk
Edited by kirkallen143, 09 March 2013 - 09:58 AM.
83 posts
Location: North Carolina
Posted 09 March 2013 - 09:55 AM
went back to stock jetting 112/38 and air screw everywhere from 1/2 out to 2 1/2 out and still not running good???
7076 posts
Location: Washington
Posted 09 March 2013 - 10:05 AM
It is not an air screw, it is a low speed mixture screw; out is richer, in is leaner. the mixture is most effective at high manifold vacuum, e.g. idle or closed throttle during decel.
Best starting point for a stock engine is stock jetting, for your engine; 110 main, 38 pilot, F2351E needle clip in middle groove (3rd f/ top), Pilot screw initial setting out 1 1/8 turns, 12.5mm float level. When everything is correct these engines start easy and run well with stock jetting.
The level of fuel in the float bowl determines how easy or hard it is to draw fuel up through the jets and into the venturi. A bit low float level will need a slightly richer mixture screw setting.
And jetting can be rich at one throttle opening and lean at another opening.
An air leak in the inlet tract will lean out more at closed and near closed throttle positions (high vacuum) than full throttle. One source of an air leak is the washer and O ring on the mixture screw.
Popping in the exhaust during decel (a little burbling is OK) indicates a lean low speed circuit, turn out the mixture screw a bit.
Ragged or rough throttle response from closed throttle to 1/4 throttle while riding (usually trail riding) indicates a rich needle setting and/or worn needle and needle jet. Try raising the needle clip position (lower needle)
Low speed fuel is provided by two tiny discharge ports both fed by the pilot jet; one is under the engine side of the slide, the other closer to the engine and metered by the mixture screw. Gotta see bright light thru both to insure they are clean, I use bright sunlight or a LED flashlight. Dirt in one of these ports can make cold starting difficult. The port under the slide is most sensitive to air flow so affects transition to the needle and engine starting.
A dirty, or partially plugged, air cleaner will cause a WOT rich condition , I had that problem with a K&N and had to replace it.
Plug reading is difficult via pictures because there are a lot of variables and different areas of the plug indicate different things which is why I posted the link.
Best starting point for a stock engine is stock jetting, for your engine; 110 main, 38 pilot, F2351E needle clip in middle groove (3rd f/ top), Pilot screw initial setting out 1 1/8 turns, 12.5mm float level. When everything is correct these engines start easy and run well with stock jetting.
The level of fuel in the float bowl determines how easy or hard it is to draw fuel up through the jets and into the venturi. A bit low float level will need a slightly richer mixture screw setting.
And jetting can be rich at one throttle opening and lean at another opening.
An air leak in the inlet tract will lean out more at closed and near closed throttle positions (high vacuum) than full throttle. One source of an air leak is the washer and O ring on the mixture screw.
Popping in the exhaust during decel (a little burbling is OK) indicates a lean low speed circuit, turn out the mixture screw a bit.
Ragged or rough throttle response from closed throttle to 1/4 throttle while riding (usually trail riding) indicates a rich needle setting and/or worn needle and needle jet. Try raising the needle clip position (lower needle)
Low speed fuel is provided by two tiny discharge ports both fed by the pilot jet; one is under the engine side of the slide, the other closer to the engine and metered by the mixture screw. Gotta see bright light thru both to insure they are clean, I use bright sunlight or a LED flashlight. Dirt in one of these ports can make cold starting difficult. The port under the slide is most sensitive to air flow so affects transition to the needle and engine starting.
A dirty, or partially plugged, air cleaner will cause a WOT rich condition , I had that problem with a K&N and had to replace it.
Plug reading is difficult via pictures because there are a lot of variables and different areas of the plug indicate different things which is why I posted the link.
83 posts
Location: North Carolina
Posted 09 March 2013 - 10:30 AM
yea my bad ,air screw is a 2 stroke right? def not popping on decel..if you twist it or try to wheelie or anything like that it just stumbles and wont really clean out when you open it up..runs much better with choke halfway.anyway i ordered a uni filter so i may wait till it comes in and see if that helps as the old filter looks a little iffy. will prob get a new mixture set-up to make sure there is no leak there also.i swear to all thats holy that this bike ran very smooth at all throttle positions and during quick throttle twisting until i took the pipe off and ground out the weld. i know that shouldnt really call for re-jet and i have tried different jets but cannot get it back. confusing as well as frustrating. and makes me come on here and ask tons of questions some of which may be dumb..lol. anyway thanks for your input chuck
Edited by dwil4, 09 March 2013 - 10:32 AM.
7076 posts
Location: Washington
Posted 09 March 2013 - 06:16 PM
I'm still puzzled by the carb problems but I'm sure you'll find the cause and let us know.
The occurrence may have coincided with the pipe mod but carb issues can occur any time.
You indicated that you have bogging on throttle roll-on, half choke helps, you need 2 1/2 turns out on the mixture screw, and the needle is in the full rich position; seems to me to be lean carb. Two questions I forgot to ask.
Does the bike have a fuel filter?
How often is the fuel bowl drained?
The filter keeps tank junk from entering the carb and draining the float bowl reduces crud build up.
Diligence with both is still not a guarantee that debris won't cause mischief, but the lack of either dramatically increases the odds of problems.
The occurrence may have coincided with the pipe mod but carb issues can occur any time.
You indicated that you have bogging on throttle roll-on, half choke helps, you need 2 1/2 turns out on the mixture screw, and the needle is in the full rich position; seems to me to be lean carb. Two questions I forgot to ask.
Does the bike have a fuel filter?
How often is the fuel bowl drained?
The filter keeps tank junk from entering the carb and draining the float bowl reduces crud build up.
Diligence with both is still not a guarantee that debris won't cause mischief, but the lack of either dramatically increases the odds of problems.
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users
Follow us: