2003 RX-1ER no top end mid range stumble

[JohnnyG383]

I just bought a 2003 RX-1 only has 1,070 miles on it and the first time I rode it and noticed it has a mid to upper stumble and not really any top end only got to 60mph on the street. What rpm is this sled go up too and I can’t tell if it’s an engine issue or a clutch issue? Low end is great in the trails and the engine is running great not missing or have any lights on

 

[smallheadz]

10200-10400 rpms, start with cleaning carbs. With only 1k miles and 17 years old it could be lots of things depending on where the sled was stored. Carbs, bearings froze, clutch, coils, plugs, etc...If in doubt clean the carbs twice. 03 coils were notorious for arching

 

[JohnnyG383]

10200-10400 rpms, start with cleaning carbs. With only 1k miles and 17 years old it could be lots of things depending on where the sled was stored. Carbs, bearings froze, clutch, coils, plugs, etc...If in doubt clean the carbs twice. 03 coils were notorious for arching

Hi thank you for the reply. The sled was stored indoors and looks mint super clean I did all the maintenance before I rode it. Just a little background I’m new here from two stroke forum. The engine is not miss firing. I do all my own work I’m an automotive technician. When I slow down you can hear the clutch make a noise when it disengages. I’m no expert with the clutches.

 

[smallheadz]

the back shift on the clutch is normal and some of them will whine too. There are some youtube videos you can see and hear it.
Pull the rubber from the top of the coils and start it in the dark to see if spark is jumping in the cylinder. Some people have wrapped them in electrical tape or use dielectric grease. Tons of post on here about it. You most likely wont feel the miss even if it's jumping spark.
If you have not cleaned the carbs please do it. Most on here do it every year. I just pulled mine and rebuilt with an ebay kit, it's about $100.
The pilot jets plug easy.
What kind of RPM are you getting?

 

[JohnnyG383]

the back shift on the clutch is normal and some of them will whine too. There are some youtube videos you can see and hear it.
Pull the rubber from the top of the coils and start it in the dark to see if spark is jumping in the cylinder. Some people have wrapped them in electrical tape or use dielectric grease. Tons of post on here about it. You most likely wont feel the miss even if it's jumping spark.
If you have not cleaned the carbs please do it. Most on here do it every year. I just pulled mine and rebuilt with an ebay kit, it's about $100.
The pilot jets plug easy.
What kind of RPM are you getting?

First off thank you again for your help! I will check the spark as I do the same thing with cars wile checking a missfire. I’m seeing around 6,000 rpm that is just ripping up the street.

 

[smallheadz]

Yea 6000 is way low. Have you had the carbs off? There are screens under the needle/seat that can plug too. My guess carb related, make sure you sync them after you clean them.

 

[JohnnyG383]

Ok checked the coils all are sparking even got me on a few of them. Pulled the plugs checked the gap that was good. Plugs were on the black side.

 

[03RX1-ER-LE]

 

[maim]

might need to pull apart the clutches and clean them. there might be some corrosion on where the bushings run and that could be your problem. take the primary clutch bolt out and the cover off to pull the spring. then re assemble with the spring out and make sure it slides smoothly and all the rollers and weights move smoothly as well.

 

[03RX1-ER-LE]

I sure do not miss dealing with the annual carb cleaning from my RX1 days. Nothing like EFI

 

[JohnnyG383]

Guys you’re right the carbs had the fuel gelatin balls in the carbs and one carb had the float needle stuck closed. My question is the mixture screw on the bottom of the carbs does anyone know the spec on how many turns out? I can see one is out more then other 3 carbs.

 

[smallheadz]

Factory is 2 turns out, a lot of people run them at 2.5 . I myself run at 2.25 turns out.
Make sure you sync carbs when done. Also make sure your pilot jets are clean, they are tiny 17.5 and plug easy. I keep a spare set clean at all times and change out any time I have the carbs off.
Cleaned and syncd carbs are key to this sled running right.

 

[JohnnyG383]

Factory is 2 turns out, a lot of people run them at 2.5 . I myself run at 2.25 turns out.
Make sure you sync carbs when done. Also make sure your pilot jets are clean, they are tiny 17.5 and plug easy. I keep a spare set clean at all times and change out any time I have the carbs off.
Cleaned and syncd carbs are key to this sled running right.

thank you for the info. I can not sync the carbs now as I do not have the gauges and to be honest never done it before and have no clue what your looking for when doing it and what you adjust

 

[Pairodice]

How does it idle? Does it run better with the choke on? My money is on the carbs. I would also drain and flush the fuel tank with fresh non corn fuel. Fuel with ethanol goes bad much faster. Is the intake and exhaust stock?

 

[smallheadz]

basically all you are doing is making sure they all have the same vacuum. If you are going to keep the sled or work on any carb stuff then I would purchase a set. They hook to the nipples on the intake boots. The carbs adjust by phillips screws on the linkage inbetween 1-2, 23,3-4. So there are 3 screws total that you adjust until all the carbs read the same. Moving one screw changes 2 carbs. Once you do it you will be amazed at how easy it is. Make sure you Y into the vac lines for the fuel pumps so that it will stay running as you do it. You can also build your own , there are plenty of posts on here about it. If you need to buy a set they run $40-$100 online like ebay.
Someone local to you may be able to help too.