Hard start. Won't idle without stalling. Backfire.

[Slug]

Back again... I'm getting really redacted sick of this bike right now. I've had more issues in the last 2 months than I've had over the last almost 3 years of ownership....


Rundown of what's going on...



Bike was hard to start today, temperature wasn't the issue because I've started right up in much colder than todays 55F.. Had to kickstart, figured battery was low on juice. But seemed to idle fine at this point.


Head out and less than quarter mile into the journey I noticed a little bit of stuttering. But I didn't think too much into it at the time.



When went to jump on the bike to get home I again couldn't electric start, but kicked it a couple times and it turned over.



This is where the issues really started... As I was going to leave the parking lot the bike stalled and I struggled to get it started again over the next 10 - 15 minutes, battery had also started beeping, so it's low..


The bike wasn't staying at idle without giving throttle, but no backfire yet. Took backroads so I didn't have to stop and risk stalling it again.


At home I pull the plug, didn't see any problems with it but changed out anyway. Again could barely get it started and was still stalling and now I've got backfire as well.


Pulled the pod filter off and put the airbox back on to see if maybe that's causing some weird problem, but nope, same thing.


A side note; over the last couple of days I felt power loss around 4th gear where it wasn't climbing like it used to. But those were colder days.


TL;DR: Bike hard to start (electric & kick). Stalling at idle. When giving throttle at idle to keep running it backfires. Sputtering. Recent power loss in 4th and 5th gear.


2020 TBR7

[JerryHawk250]

When was the last time you checked the valve lash?

[Thumper]

Personally, I am no TBR7 fan (we had major issues with frame build quality, and components, but NOT the engine which actually ran great).

But Jerry is right. You need to methodically go through the standard maintenance procedures. And tell us what you did.....

-Valve adjustment is easy on this engine. Take your time and make sure that is good. Many posts on this for the 167FMM CG clone.
-You also didn't tell us what you've done to the carb.
-Any other mods?

These two might be the top of the list for you to either address. Third is mods you might have. Really. Valves are important, and the carb is right behind. Otherwise, these little engines are pretty bulletproof.

[Slug]

It's been quite awhile since I checked valves. I was going to do that back in August-Sept when I had a different issue. But that problem resolved itself overnight.


The more I'm thinking about it now, this does have a lot of valve adjustment symptoms. Didn't think it would cause a completely no start though.



I spent another 15 minutes just now trying to kick it only cranking over once for a couple seconds.

[Slug]

Originally Posted by Thumper

-Valve adjustment is easy on this engine. Take your time and make sure that is good. Many posts on this for the 167FMM CG clone.
-You also didn't tell us what you've done to the carb.
-Any other mods?

Mods list:
Nibbi PE28 40 pilot, 120 main jet.

Pod filter or Airbox. have used both on this carb.
CDI Box.

Battery upgrade.
Irrelevant stuff like handlebars, grips, mirrors, headlight bulb, turn signals.

[JerryHawk250]

If you installed one of those so called performance CDI boxes I would go back to the stock CDI and test that too. But definitely do the valves before anything else.

[Thumper]

Originally Posted by Slug

It's been quite awhile since I checked valves. I was going to do that back in August-Sept when I had a different issue. But that problem resolved itself overnight.

I can't interpret this. Nothing resolves itself!

Bottom line, take the time and make certain that your valves are adjusted. There are TWO of them. Easy Peasy!!!

The carb settings sound reasonable, but I never bothered to replace my perfectly good original carbs on any Chinese bike, and I can't offer any opinion on that.

[Slug]

Originally Posted by Thumper

I can't interpret this. Nothing resolves itself!

The previous problem was an issue after riding in heavy rain. Bike stalled as I got home and wouldn't start back up. Let it sit overnight and it started and ran like normal the next day.

[clash 168cc]

Use a spark checker to see if you are visually getting a consistent spark. I have seen small engines that sheared the flywheel key and the flywheel is out of place and sparking at the wrong time backfiring and hard to turn over. Rare but possible.

[Slug]

Originally Posted by JerryHawk250

If you installed one of those so called performance CDI boxes I would go back to the stock CDI and test that too. But definitely do the valves before anything else.

I'm so glad I kept the old CDI instead of tossing it.

Put the stock one back in and guess what...? The bike started right up no problems and idled fine.


On the next warmer day we get here I'll dig into the bike to adjust my valves just to make sure that's not an issue anytime soon.


I want to thank you so redacted much for saving me such a headache. I've been losing my mind over how many issues I've had lately.

[JerryHawk250]

Originally Posted by Slug

I'm so glad I kept the old CDI instead of tossing it.

Put the stock one back in and guess what...? The bike started right up no problems and idled fine.


On the next warmer day we get here I'll dig into the bike to adjust my valves just to make sure that's not an issue anytime soon.


I want to thank you so redacted much for saving me such a headache. I've been losing my mind over how many issues I've had lately.

I was happy i could help. I never had much luck with the so called performance CDI's.