SSR XF250 high speed hesitation/sputtering

[SirKng]

Since I'm a noob can anybody tell me what this might be? Valve adjustment? Carb jetted too lean? CDI already giving out? Bike seems fine a lower speeds and RPM. It does it at high speed cruising at about 60 MPH.

[CaesarVis]

From all the information I have got from here I'm going to suggest:

Check valve lashing
Main jet may need to be increased to 110 (what is it currently?)
Needle may need to be shimmed
Idle mixture screw should be 1.5 turns from bottom

[culcune]

Member dh should have some insight into what to check, but I agree to start with valves as CaesarVis suggests.

[SirKng]

I have no idea what main jet it has. I haven't taken apart the carb yet. But I did talk to someone one on Reddit. The guy was suggesting taking at look at the needle too so that's where I think I'll start. I'm gonna take another look at the idle mix screw too. I have to run it about 2 and a half to 2 and 3/4 turns to get my bike to idle best.

[2LZ]

I'd be surprised if the valves were out of adjustment. Qingqi usually sends them out spot-on. In 10 years, I've only had to check Q's. They simply don't move. Weird.
I also doubt it's the CDI. These usually don't come with the normal Hondoid CDI that's sometimes subject to failure.

My guess would be lean jetting. Hopefully dh will show up shortly. The 250 has a different carb than my 200.

[SirKng]

My spark plug is grey too if that helps anyone. I checked it yesterday but haven't had time to post that info until today.

[dh]

Originally Posted by SirKng

Since I'm a noob can anybody tell me what this might be? Valve adjustment? Carb jetted too lean? CDI already giving out? Bike seems fine a lower speeds and RPM. It does it at high speed cruising at about 60 MPH.

Sounds lean, but the stock jetting and idle mixture should work fine. Messing with jetting or the needle could treat the symptoms but not the problem. Qingqi CDIs are solid. Not much to do with the needle on this CV carb. Gotta be something else. I'm with 2lz on the valves, but never hurts to check if you want.

Did you mod the air filter or exhaust?
Did you add a fuel filter?
Has the bike been parked in a 160 degree garage like my poor bike? I ask because this could be a Vacuum issue.

Check intake/ airbox seals for leaks, maybe use a spray mist of starting fluid or (unlit) propane maybe with the bike idling. Someone might have a better/safer suggestion than this, but unplug the side-stand safety switch if you haven't already.

Check vacuum lines between carb and charcoal canister under the seat to see nothing's had come unplugged
Check Pair/EGR valve on the header for leaks. If the vacuum line between the egr and airbox looks crispy or burnt it is time to delete the EGR. Keep us updated!

[SirKng]

I have an update but I haven't pulled it apart to check anything yet. The bike will hesitate from closed to wide open too. It picks back up almost immediately after hesitating. I have the day off tomorrow so I'll likely take my bike apart then.

I forgot to add but I have no mods and the bike sits in a fairly cool garage compared to the outside ambient temp.

[SirKng]

Update. Did not find and crispy or disconnected vacuum lines. Did however find a leak at where the air box seals to the carb. Gonna try to figure out a temporary fix until I can delete the airbox and run a cone filter.

[SirKng]

Ok. So I tried to fix it. I couldn't. I don't know if it is the clamp or boot that sucks but what ever it is it is poorly designed. I tried to seal it but that didn't work. Anybody have any ideas on how to seal it up? I'd rather not delete the air box unless I absolutely have to.

[dh]

The air box works works well with the 200 but doesn't mate perfectly to the 250 which was fit in the bike later on. If you can make it work it would be ideal however. Mine had problems separating where the boot fits into the air box with a metal spring/band. The airbox and boot just didn't seem to be close enough to want to cozy up well.

I might removing the stock airbox and boring out the mounting holes and remounting with the ability to get it a hair closer to the motor. If you can get it snug to the boot, it should seal ok. Use a hair dryer to warm the boot up for reassembly.

[SirKng]

Originally Posted by dh

The air box works works well with the 200 but doesn't mate perfectly to the 250 which was fit in the bike later on. If you can make it work it would be ideal however. Mine had problems separating where the boot fits into the air box with a metal spring/band. The airbox and boot just didn't seem to be close enough to want to cozy up well.

I might removing the stock airbox and boring out the mounting holes and remounting with the ability to get it a hair closer to the motor. If you can get it snug to the boot, it should seal ok. Use a hair dryer to warm the boot up for reassembly.

It feels like it is close enough already, I just need to seal the boot to the carb better. I'll give that a try.