Sudden bogging/stalling after 120 miles - Motomax 250

[CC-John]

The exhaust glowing red would indicate a very lean mixture, or a restricted exhaust. If this bike has a catalytic converter in the exhaust, it could be partially blocked. Try disconnecting the exhaust from the engine and fire it up momentarily to see if it will take throttle. Don't run it for a long period with the pipe disconnected as it's possible to warp the exhaust valve.

[jeffrey]

Check around the intake manifold at the head and at the carburetor for vacuum leaks. Also check the vacuum hose port on the manifold better yet if you havent done it plug the port off with a rubber vacuum cap. That hose goes to that emmisions control valve. The red glowing exaust pipe is a sighn of extreme lean condition.

[Thumper]

My Templar is doing the same thing. I suspect pilot circuit lean issue. I need to pull the carb and take a look. HOT exhaust, and won't idle after warmed up.

I am sure it is a carb problem. I have a spare to swap in, so I will probably do that.

[ADKRider]

Originally Posted by CC-John

The exhaust glowing red would indicate a very lean mixture, or a restricted exhaust. If this bike has a catalytic converter in the exhaust, it could be partially blocked. Try disconnecting the exhaust from the engine and fire it up momentarily to see if it will take throttle. Don't run it for a long period with the pipe disconnected as it's possible to warp the exhaust valve.

Same behavior. Dies immediately.

Originally Posted by jeffrey

Check around the intake manifold at the head and at the carburetor for vacuum leaks. Also check the vacuum hose port on the manifold better yet if you havent done it plug the port off with a rubber vacuum cap. That hose goes to that emmisions control valve. The red glowing exaust pipe is a sighn of extreme lean condition.

There shouldn't be any vacuum leaks as all bolts are tight, all hoses connected, but if you show me which hose you mean (i assume the one connected to EGR?) I'll try it.

Originally Posted by Thumper

My Templar is doing the same thing. I suspect pilot circuit lean issue. I need to pull the carb and take a look. HOT exhaust, and won't idle after warmed up.

I am sure it is a carb problem. I have a spare to swap in, so I will probably do that.

Let me know how it goes. txpowersports is sending a carb and CDI but they haven't given me a tracking number yet

[CC-John]

If that engine has an EGR system on it, a dirty EGR valve that won't close all the way can cause the symptoms you're having. That type of problem was pretty common on older carbureted cars and trucks.. Pulled and cleaned many an EGR valve back in the day to correct lean idle or stalling right off idle. The EGR valve is supposed to only open when the engine is at a high enough RPM to handle it without stalling or bogging.

Honestly, the best thing you could do is to just delete all that emission control crap to prevent ongoing problems as those parts age.

[ADKRider]

Originally Posted by CC-John

If that engine has an EGR system on it, a dirty EGR valve that won't close all the way can cause the symptoms you're having. That type of problem was pretty common on older carbureted cars and trucks.. Pulled and cleaned many an EGR valve back in the day to correct lean idle or stalling right off idle. The EGR valve is supposed to only open when the engine is at a high enough RPM to handle it without stalling or bogging.

Honestly, the best thing you could do is to just delete all that emission control crap to prevent ongoing problems as those parts age.

I had deleted it at one point during this saga, but was concerned about causing buildup in the cats In my exhaust. Can safely say that is not causing it because It was off of my bike for about 3 and 1/2 days of this.

That said, a future project of mine will be deleting the cats, deleting the EGR, and installing a nibbi carburetor.

[ADKRider]

Replace the carb and CDI as per txpowersports instructions. Same issue. Time to wait another 3weeks for them to ship more parts. I'm so effin fed up with this shit. It's goddamn brand new.

[Thumper]

Originally Posted by ADKRider

Replace the carb and CDI as per txpowersports instructions. Same issue. Time to wait another 3weeks for them to ship more parts. I'm so effin fed up with this shit. It's goddamn brand new.

I've been real busy with prepping the house for painting (carpentry) and garage door rehab. Finally got time to work on the carb. I installed a back up carb after rejetting it and it is doing exactly the same thing. Won't idle but midrange is great.

So I will check the valves now. Should have done it yesterday before putting the gas tank back on !

[ADKRider]

Originally Posted by Thumper

I've been real busy with prepping the house for painting (carpentry) and garage door rehab. Finally got time to work on the carb. I installed a back up carb after resetting it and it is doing exactly the same thing. Won't idle and runs like crap.

So I will check the valves now. Should have done it yesterday before putting the gas tank back on !

In my case the valves were the first thing I checked. While waiting on txpowersports, a couple coworkers who regularly work on small motors said to I should try checking compression. I'm completely at a loss. Lol

[Thumper]

Just checked exhaust valve. I need to verify I am on the intake TDC and check the intake valve.

I am starting to think I need to adjust the airscrew. It is on the airbox side, so should need to close that screw a little bit for more fuel.

It misses at idle, won't keep idling if I lower the tower to get a normal idle rpm (1200 to 1400rpm). But the responsiveness off idle is excellent and midrange seems fine. This is a new PE28 I got as a back up. Stock exhaust and intact airbox, so this carb should match well. I rejetted (main 120 to 125 and pilot 40 to 42). I am at 1 1/2 turns out, will try 1-1/4 and see if it gets better.

[Thumper]

Those valve are really stable in the 172-FMM (Templar X). They were right where I left them 6 months ago.

But closing the airscrew a half turn smoothed it out. Nice idle, instant and strong response to throttle twist. I should have known it was a minor carb adjustment needed.