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Stolen speedy now struggles to crank

5K views 58 replies 7 participants last post by  fredsprint 
#1 ·
My bike was stolen and recovered. The right handlebar is bent so they might have dropped it.
They also took the turn signals. Other than that I don't think they did anything. But it has a really hard time cranking. THey didn't open the fuel tank so maybe they tried to curcumvent the fuel line. I don't see anything obvious.
The bike starts but after a lot of cranking and usually dies after the first start. After The second start it stays running.

Any ideas?
 
#8 ·
I would do a compression test.


You don't know what kind of abuse your bike endured.

On the first attempt (when it dies the first time) the bike is running only on two cylinders.


While cranking, I can hear a noise, like something striking. Roughly once per turn. Don't think it's normal.


Fred
 
#10 ·
OK so I had replaced the sprag already but replaced it again this week, this time with the hayabusa hack from https://www.triumphrat.net/speed-tr...a-sprint-sprag-clutch-replacement-option.html

When I first got the bike back it had trouble starting and turns out the starter had a magnet dislodged.

I now get a cracking sound: https://drive.google.com/file/d/1-9RKkiKtJ7gB-h3zXPgMUm1P5IONqEOF/view?usp=drivesdk

It doesn't sound the way it did when my sprag failed on me the first time.

The big unknown is what the thieves might have done to the bike.
 
#13 ·
The crunching sound was with the jump start. I'm kind of afraid of trying too much. I might try hill starting it but if it fails it means pushing it up the hill.
Any ideas where the crunching sound could come from? Not obvious if it's starter gear area or engine.
 
#22 ·
It was jump started during the recording, so I guess the battery is not the cause.


Being a little more optimistic we can imagine multiple factors leading to that state: sprag constantly slipping causing a slow crank rotation, one of the coil or plug faulty (or a bad coil to plug contact) causing one of the cylinder not to fire up.


A simple test would be to remove the plugs and being in gear, rotate the rear wheel and see if it rotates freely.



Fred
 
#25 ·
Well it hill started without nasty sounds, so it must be the sprag. That would mean that my two year old replacement sprag failed AND the hack from https://www.triumphrat.net/speed-tr...a-sprint-sprag-clutch-replacement-option.html didn't work for me.
The sprags do make different bad sounds at startup so it's the sprag.

Separate issue: when hill starting it has a very hard time going and will die at idle unless I give it gas. What could that be? (or should I start a new thread for that?)
 
#31 ·
Yes, in this case the battery was completely full, and then I hill started. So it should not be an electrical issue.
Also when I recovered the bike they used an industrial grade jump starter and that behavior was present. It needed a lot to get started (could be sprag), but then would die without throttle.
After the bike was warm it didn't threaten to die without throttle though.

[And as for the charging system I found the major culprit (connection from RR to fuse box which was very hot), so I've been getting over 13 volts and usually over 14 from the RR.]
 
#32 ·
The absolute test would be charging the battery and disconnect the RR. Then start (even better: hill start). If the behavior is the same then the charging system is not the culprit.


What DEcosse meant is that a faulty/failing charging system may generate a perturbed voltage that could cause problems to the ECU (spikes, under-voltage or irregular voltage and so one).


I think the ECU is internally powered w/ 10.5 V regulated. But spikes may be dreadful to a CPU.


Fred
 
#33 ·
I think the ECU is internally powered w/ 10.5 V regulated. But spikes may be dreadful to a CPU.
The R/R is good and I've never seen spikes in voltage on my monitor.
And it was getting over 10.5V. I was getting over 13 volts measured at the battery. It's also never behaved this way before and I had electrical issues for along time.
I could pursue this avenue, but could anything else cause something like this?
 
#36 · (Edited)
Unfortunately it's very hard to run a compression test when I can only hill start it.
Once I get my sprag working I'll try it.

Although maybe someone can recognize these symptoms:
- very hard to hill start (or regular start). I have to open the throttle.
- once started it will die if I don't have the throttle open. This lasts for about 5 minutes. After that it idles ok on its own.
- one of the three pipes coming out of the engine is at 145 degrees, while the other two are over 300 degrees.

So there's clearly something wrong with one of the cylinders. I had checked its compression earlier this year and it was ok.
 
#37 ·
The problem with one pipe cooler was because I didn't tighten the valve cover enough.

I ran the compression test and all three cylinders are between 145 and 155.

What else could be the cause of the hard start and wanting to die for the first 5 minutes?
 
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