2017 300 xc lost power, boggy. Need help.

[lrbest4x4xfar]

Recently my 2017 KTM 300 xc lost its power and gets boggy when climbing into the powerband. Feels like the choke is on when it's not. Thought it was my Lectron carb, rebuilt it. Rebuilt upper end with new Piston, no luck. Checked the centrifugal assembly, all looks good. Repacked exhaust, no effect. Plug looks great.

 

At a complete loss...it's just choking when RPMs starting to climb and won't hit.

 

Any ideas? Timing? Help!

[slytheslayer]

Dumb question but have you looked into the CDI? If you've checked everything else I guess electrical might be the next step. CDI might give you those troubles with bogging. Slavems has them for about $150.

[Clutch44]

Check the power valve.

[Ew83]

Recently my 2017 KTM 300 xc lost its power and gets boggy when climbing into the powerband. Feels like the choke is on when it's not. Thought it was my Lectron carb, rebuilt it. Rebuilt upper end with new Piston, no luck. Checked the centrifugal assembly, all looks good. Repacked exhaust, no effect. Plug looks great.
 
At a complete loss...it's just choking when RPMs starting to climb and won't hit.
 
Any ideas? Timing? Help!

Have you done a compression test?

[lrbest4x4xfar]

Not yet, I'll do that this morning. It has an S3 cover and inside cylinder and chamber looked like new.

[lrbest4x4xfar]

Dumb question but have you looked into the CDI? If you've checked everything else I guess electrical might be the next step. CDI might give you those troubles with bogging. Slavems has them for about $150.

Good point, I'll purchase one from Slaves tomorrow. Only have a stock CDI. Today I'll check timing and make sure something weird like sheared woodruff key isn't the problem.

[hezzdown]

6 hours ago, Clutch44 said:

Check the power valve.

2nd this response. I'd pull the right side power valve cover and check to see if you can open/close the power valve manually. No sticking or tight spots. 

[lrbest4x4xfar]

2nd this response. I'd pull the right side power valve cover and check to see if you can open/close the power valve manually. No sticking or tight spots. 

It moves freely (not loosely though). How loose should it be?

[Trailryder42]

23 minutes ago, lrbest4x4xfar said:

1 hour ago, hezzdown said:

2nd this response. I'd pull the right side power valve cover and check to see if you can open/close the power valve manually. No sticking or tight spots. 

It moves freely (not loosely though). How loose should it be?

Pull the keeper clip, pop the rod end off the ball and manually work the mechanism thru its whole arc of travel.

[hezzdown]

27 minutes ago, lrbest4x4xfar said:

1 hour ago, hezzdown said:

2nd this response. I'd pull the right side power valve cover and check to see if you can open/close the power valve manually. No sticking or tight spots. 

It moves freely (not loosely though). How loose should it be?

It should have some resistance, that is normal.

[bnr]

Reeds?

[Ew83]

15 hours ago, slytheslayer said:

Dumb question but have you looked into the CDI? If you've checked everything else I guess electrical might be the next step. CDI might give you those troubles with bogging. Slavems has them for about $150.

This is probably my lack of understanding, but how could the CDI cause this? Being that it's analog, it would seem either it works or it doesn't. It sounds like he has more of a fuel/air problem by the description. What would make you think the CDI was causing bogging?

[Armbarn sailor]

I will say reeds chipped or broke, or you need to get that carb sonic dipped. Did you go a long period of time with no riding?

[slytheslayer]

This is probably my lack of understanding, but how could the CDI cause this? Being that it's analog, it would seem either it works or it doesn't. It sounds like he has more of a fuel/air problem by the description. What would make you think the CDI was causing bogging?

I am just going off another bike that I had, where it was similar and come to find out some connections were broken or loose in the CDI and caused bogging and sometimes complete power loss. It was sometimes happening so fast that the bike would be turning off and on so quickly you couldn't tell where it was coming from but the bike was bogging down in higher throttle.. This was also an XR650L but just throwing it out just in case.

[allwashedup]

had symptoms similar to described problem. bike was passed all over from up and down. found previous repair shop glued pipe to cylinder with big gobs of silicone sealer. excess sealer broke off and passed through exhaust and got caught in spark arrester screen. stuff would fall in after motor was shut down and run fine until motor got revved and restrict screen and refuse to rev past mid throttle as if a rag was stuffed in carburetor. cleaned screen and it ran fine afterwards. worth checking

[lrbest4x4xfar]

Reeds?

Reeds were solid.

[lrbest4x4xfar]

Found the culprit... The spark arrestor screen was clogged with packing! Not sure why it had packed up so bad so quickly but that was the problem. Unfortunately when I put the clutch case cover back on (to check power valve mechanisms) the Kickstarter spring popped out of the home hole the end of it fits into. Wham! On start it broke off the Kickstarter gear on the inside case. $2k in damage, just like that. All over not checking the exhaust in the beginning.

[Busted Nuckles]

Thats a rough one. Just the way it goes sometimes. Hope you get it worked out

[Dirtstache 556]

Sucks man. Just a good lesson to remember to trouble shoot in order of how cheap/easy the fix might be vs. what you think the likely culprit is. I do this all the time, get in my head that it's a serious problem and spend a ton of time and money to fix only for it to be something simple.