TBR7 Won't start

[Douglass]

This sounds to me like either the cam timing is off, or your valve lash was set at the wrong TDC. There are two TDC points, one at compression and one at exhaust. If you set the valve lash on the exhaust stroke, where both valves are actually being activated by the cam a little bit, then your valve lash will be enormously out of spec. The easiest way to know is to roll the motor over, and watch the rocker for the intake valve. Once it actuates, the next T mark on the flywheel will be TDC for the compression stroke. It wouldn't hurt to double check and make sure you have this right.

Dan suggested to check this, Have you verified this is correct?

I would be interested to see what you are able to find with the cam timing.

I agree, if you can swap the carb, and it runs great in the hawk I think it's time to move on.

Also, if you are running super rich it can cause the cat to glow.

[Megadan]

Originally Posted by Douglass

Dan suggested to check this, Have you verified this is correct?

I would be interested to see what you are able to find with the cam timing.

I agree, if you can swap the carb, and it runs great in the hawk I think it's time to move on.

Also, if you are running super rich it can cause the cat to glow.

He did check it. He found the exhaust valve was way out of spec, but it changed nothing.

One thing I forgot to ask previously was, did the cat glow so much when you tried the Hawk carb on it? Or is that something that has only happened with the original carb?

I ask this because small details like that are important. With so many suggestions and trouble shooting steps being throw around it is easy to miss stuff. Sometimes it helps to just go back to square one, examine all of the evidence, and check off all the boxes. Swapping so much around and not noting changes, or having enough time to notice any changes can lead to confusion.

I think we can rule out ignition as far as the plug and coil are concerned.

We can rule out valve lash.

We can rule out the intakes - they were both swapped around as well.

I know this can be completely frustrating, so lets just put everything back to square one, clear our heads, and work with what we do know.

[Johnny_Sardine]

I'm turning the crankshaft counter clockwise when you are looking for the compression stroke right?

I double checked it again this morning and they're spot on.

The cat was glowing with both the stock hawk and the Mikuni. Both of those run on the hawk perfectly, and as of now the exhaust isn't even attached and the engine behaves the same.

I was hoping it would be easy to just take a couple covers of the engine and see if it's not on time but I can't even see where I'd be able to get at the cam sprocket.

[Douglass]

He did check it. He found the exhaust valve was way out of spec, but it changed nothing.

Hey Dan, I read where he adjusted the valves a couple times, but I did not see if he had verified the cam timing was good.

How does the compression check or feel? When you kick start the hawk vs the TBr7, do they feel about the same?

Dan and Jerry, if the spark timing is off could it cause the engine to behave this way? On these engines, can the spark timing be adjusted?

If the cam timing is off, I would think this would need to be handled with a warranty.

Johnny, try calling TaoTao direct to see if they would be willing to offer a warranty. I'm thinking it should not be this hard to get the bike to run. You have verified to have all the ingredients to make it run. With what you have done already, I would be looking at the actual cam timing, spark timing, and compression as the next move if I were in your shoes.

Tao Motors #
909-614-1661

[Megadan]

Originally Posted by Douglass

Hey Dan, I read where he adjusted the valves a couple times, but I did not see if he had verified the cam timing was good.


Dan and Jerry, if the spark timing is off could it cause the engine to behave this way? On these engines, can the spark timing be adjusted?

He double checked the valve lash, but not the cam timing.

The ignition timing is fixed as far as the pickup at the flywheel is concerned. The flywheel is keyed, so unless they key is missing, it can't shift. The pickup bolts to the side case and tabs into place. In theory it could be slid on the bracket, but they are generally bonded. There is a chance it could be a bad or shorted pickup signal going to the CDI causing it to misfire. A timing light can be used to verify the actual ignition timing. When rotating the engine, just before the T mark is two lines and an F, this is the ignition timing marks, and the slot in the case used to line up the T is also the point of reference for ignition timing.

In order to check the cam timing you would need to remove the flywheel and starter gear on the crank. On the crank is the pinion gear that drives the camshaft, and above it will be the camshaft (bigger gear). At TDC on compression there is a dot on each gear that should line up to one another at the point of contact between each gear. If the cam gear is not set properly and needs to be removed, the cylinder head and cylinder would need to come off, then you can remove the center pin for the camshaft and re-install it.


Given all of the things that have been swapped and all of the same issues as a result, I would definitely say either the ignition or cam timing is off. Given that the CDI itself was swapped with no change, if it was an ignition timing issue it would have to come from the source.

It would definitely explain the motor trying to fire and just coming to a stop as well. If the ignition is too advanced at start up it can explain the hard start and the random sudden stop of the engine cranking when you can clearly hear it try to fire.

Hopefully TaoTao can work with you directly and get this figured out.

[Johnny_Sardine]

Thanks, Douglass.

If the Q9 guys don't get back to me with something satisfactory tomorrow then I will call Toa tomorrow or Monday.

I should have a compression tool but I don't. Although when I kick it over, it feels plenty tough.

I'll keep y'all updated ! Thanks for the support.

[Hancadam]

Fwiw, that does sound awfully similar to when I assembled a Honda 200cc ohc engine incorrectly, timing chain sprocket was not bolted to cam right. Which I could see that allowing unburnt fuel causing the cat to glow.

[Johnny_Sardine]

Just an FYI. Toa motor will not deal with me directly.

I talked to the tech at Q9. The guy gave me a pretty vague answer which in short states: "I'm not really sure what the warranty entails, or how they will determine the engine is internally dysfunctional, or how they will want to handle the situation if and when they do determine that... I'll get back to you at some point"

This has left me a little disheartened. Of course I will give them some time but I'm worried that there's no incentive on their part to come through. I payed with PayPal so I'm not sure if I have any recourse through them... At this point I'd rather just box the thing back up in the case and return it.

[Megadan]

Originally Posted by Johnny_Sardine

Just an FYI. Toa motor will not deal with me directly.

I talked to the tech at Q9. The guy gave me a pretty vague answer which in short states: "I'm not really sure what the warranty entails, or how they will determine the engine is internally dysfunctional, or how they will want to handle the situation if and when they do determine that... I'll get back to you at some point"

This has left me a little disheartened. Of course I will give them some time but I'm worried that there's no incentive on their part to come through. I payed with PayPal so I'm not sure if I have any recourse through them... At this point I'd rather just box the thing back up in the case and return it.

Contact Paypal and discuss filing a claim with them. You have made attempts to correct the issue more than once and you have phone records to prove it. See what they say and go from there. You would be amazed at how quickly things tend to get sorted when all of a sudden their money and bank rating are in danger.

[Johnny_Sardine]

So I opened up a claim with PayPal. Technician wants me to get a compression tester and test the compression... not sure what difference it would make if I'm not going to open the engine.

A normal tester from the auto parts store should work fine right? It's a normal plug fitting, I imagine.

[Megadan]

Yep, any basic tester should work fine. Rent one from the parts store if you dont want to buy one.

[Johnny_Sardine]

Alright compression is at a whopping 90... I'm guessing that's low? Obviously had to test it cold...

[Johnny_Sardine]

I can't find out what it's actually supposed to be?

[Megadan]

Definitely not 90. It should be well past 100psi even on a cold test. Was the throttle open or closed?

[Johnny_Sardine]

Throttle was closed. I took the carb off and did it again, still cold, still with thte throttle closed. 152. Properly done?

I threw the stock carb on again and reconnected the airbox, got some fireworks... might explain the glowing cat. Gotta be timing, no?