[Video] Help Diagnose Bog / Low power 600 xtc

Sgtlange

Sgtlange

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Joined
Nov 27, 2014
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45
Location
Fenton, Michigan
Hey Guys -

I've got a trip coming up and i'm struggling to figure out how to resolve this power issue. The engine under load has very little power, more power as it climbs in speed & RPM but nowhere near where it should be.

I pulled it out this season, cleaned the carbs, added a new secondary, vForce reeds, cleaned up the clutches and it rode fine for the few rides i took it out on the lake. The last ride just in the yard / lake it started to run worse but as i would hit top end the performance loss was gone. If you came back to idle and took off it would bog badly until higher rpms and speed and seem fine. I noticed i left the choke at half on accident during a short run and figured i fowled out the plugs so parked it in the garage. Changed the plugs but nothing changed.

Today I took the carbs off, removed the float bowl and cleaned as much as i could. Didn't find any plugged jets, but still gave it a good cleaning. Put it back together and still runs like crap.

Check out the videos below and let me know your opinion on what's next. It feels like fuel issue, but i have noticed the exhaust sounds a bit different since the issue started happening.

1.) https://youtu.be/TaiZYmKbLsY

Engine running on the stand, it idles fine but bogs on throttle. After a bit of playing it will pick up rpms. The choke made a difference in the video but i turned it off shortly after and it did the same thing.

2.)https://youtu.be/GwHqh2sktlo

Quick ride up the yard - you can hear the engine under load

3.) https://youtu.be/XF0o8X_PRu4
Another run in the yard

Thanks for your input!
 

Looking at the plugs they have me puzzled too. It's like there is no spark on the clutch side (clean plug) but it is wet. I took the plugs out and pulled it a few times and saw spark on both plugs. Maybe a dead cylinder under load?

I also tried bypassing the tors system but not difference.

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Both good tests. I don't have a compression tester but will find one and run the test. I tried to swap the coil wires around but the one isn't long enough to get on top of the plug
 
You can take your coil loose so you can swap plug wires. However, it appeared to run on both cylinders only when you opened the starter circuit which suggests that the carb on that side is plugged. Be sure to check the air jets, pilot jet, main jet and nozzle. I would also double check my reeds.
 
Confused said:
Tors?
Click to expand...

At first it acted like TORS, but the starter circuit should not have made any difference. If you do bypass the TORS be sure the sled side plugs are plugged into each other. The carb side doesn't matter and they can just hang free.
 
Sorry, I deleted my post after I seen he checked it. Sure seems like the TORS kicking in. Need to do a compression test. I bet one is low.
 
Ya, start with a compression test and then swap plug wires. Once those 2 things are eliminated you are pretty much dealing with an air flow or fuel supply issue.
 
Although, I did have a similar problem with my SRX. Fought it for almost 2 seasons. Ended up being the high speed coil was out on the stator. Tested fine. Used stator solved the problem.
 
Ding said:
You can take your coil loose so you can swap plug wires. However, it appeared to run on both cylinders only when you opened the starter circuit which suggests that the carb on that side is plugged. Be sure to check the air jets, pilot jet, main jet and nozzle. I would also double check my reeds.
Click to expand...

What does swapping the coil wires do? just confirm I have a miss? Also what do you mean by when i opened the starter circuit? Anyone have a detailed guide to clean the carbs on this sled? I've only cleaned them by removing the bowl and two jets so if they're plugged i'm not sure where to look next after taking them off again.


For the TORS Check - I only attempted to bypass it by disconnecting the two small wires on top of the carb then plugging them into each other. Is there more to it then that?

Thanks for the help
 
Good help on the tech pages which can be reached from the TY home page. Good write-ups with pictures.

Swapping coil wires can help determine if the wire or plug cap is causing any trouble. If the miss moves to the other cylinder when you switch wires you know it is something with that wire.

The starter circuit is often mistakenly called the choke. In reality it lifts a plunger that opens up a very rich fuel circuit for cold starting (fuel does not atomize well when engine is cold).

Yes, you need to do more in your carbs. This is the most likely source of your issue.

For the TORS you need to connect the two wires that go back to the sled, not the ones that go to the carbs. The ones that go to the carbs don't matter as they just go to a "normally closed" switch.
 
Thanks Ding. I'm going to try the other tests today and if the problem doesn't follow the wire i'll pull the carbs off again and do a more thorough cleaning.
 
If you had it out and it ran fine then suddenly started running bad on low end , I hardly doubt your carbs are dirty, They don't usually get dirty by running the sled ,as they would, by letting it sit for months. you said you put v-force reeds in er, It sounds to me like those reeds went bad ,with the symptoms you described. I would look into that!
 
Very interested in the solution of this problem, as I have exactly the same problem. Sled seems to flood both cylinders and foul plugs, both are black after a good run. Carbs were cleaned, I have them off again to double check that I didn't miss anything. Reeds are good. Checked fuel pump, it's good. I need to double check compression with a better gauge. Might try a different coil to just for fun. If I figure it out I'll post my findings.

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Did you check compression? I just double checked mine. Only has 100psi on each cylinder. That would cause a lack of power for sure. Looks like new pistons for this guy 😠

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