XBR 500 turns off when it warms up.

[Cristóbal]

Hello everyone. I am fixing an 87 xbr that has been sitting for several years, it is my first time working on a motorcycle and I am very excited about it.

As I mentioned in the title, when the motorcycle heats up, it suddenly turns off. If I leave it at idle it runs great at 1100 - 1200 rpm but if I accelerate it to high revs it stops suddenly an after that it won't idle anymore. All this while the motorcycle is resting on the central leg without moving because I am deoxidizing the fuel tank. 

At the moment I have adjusted:
- valves (and stroke cable).
- changed the motor oil and the filter.
- Air filter.
- New spark plug.
- Front caliper rebuild and rear brake pads.
- Front fork suspension rebuild (fork seals and oil).
- I did a manual cleaning of the carburetor, the jets looked good.
- And a lot of deoxidizing...

Any help will be greatly appreciated because I'm a little lost and after so much work I'm starting to get very frustrated.

Thank you very much.

C.

[themoudie]

Aye Cristobal, welcome to the forum.

I have never had, or worked on an XBR, but there are many on here who have, so hopefully they will be able to help.

From your decsription the fault sounds very similar to one that I have been having with a Moto Morini 125H. The engine readily starts and will tick over between 1,100 - 1,200 rpm for a long time. BUT, if you try to increase the engine speed (revs) above 2,000 - 2,500 rpm when the ignition would start to advance, there is a lot of stuttering and then the engine cuts out. With my Morini this is being caused by the ignition not being advanced by the CDI, from the trigger coil signal. Spares are unobtainable for the Morini, but this is not the case for the XBR, so far as I am aware.

So, I would suggest that if possible, you test the CDI, timing trigger coil, and ignition coil to see if they are all functioning correctly. I do not know what the test procedures and values are for the XBR components and others should be able to help advise with this.

Do you have a Honda Owners manual?

And may I ask if you are resident in the UK or elsewhere, it helps with replies, if you are asking for spares information in your country.

I hope that you can sort the problem out and get to enjoy riding the XBR, as that is what we all enjoy.

Good health, Bill

[Cristóbal]

Hi Bill. Thanks for your quick response.

After reading a lot last night, I came to the same conclusion you suggest. I'm going to test the ignition coil and cdi to see if that's the problem. I will post the results here.

I am located in the north of Spain, Cantabria to be more precise.

Thank you so much.
c.

[themoudie]

Hola Cristobal,

My pleasure.

Just to be clear, the problem with my Moto Morini 125H lies in the trigger coil insulation breaking down internally and not sending a signal to the CDI. The CDI and the ignition coil are both in good working order. None of the available potential replacement trigger coils (Ducati Electronicca, Chinese, Indian) are compatible, as they have sufficient windings for a 2 stroke engine that doesn't require the same advance as the 4 stroke 125H. So, no advance at the 2,000 - 2,500 rpm stage!

However, I would like to think that you wouldn't have the same trouble obtaining either a trigger coil, CDI or ignition coil, for the XBR.

Here's wishing you success.

Bill

[iansoady]

It's not really possible to test the CDI unit as such. However, you can buy a generic CDI and coil from ebay for less than £15 - in the UK, but I'm sure they're available to you in Spain Cristóbal. They do need slight rewiring: pin 5 needs to be connected to earth rather than to the switched side of the starter relay. Other than that work straight out of the box, and at that price well worth trying. The coil is an added bonus.

I also spent (wasted?) over £100 on a CDI unit from a Dutch company called Carmo. The box itself was fine but it came incorrectly wired and with no instructions whatever. I was not impressed!

I understand that the solder joints in the original CDI unit deteriorate over time causing all sorts of malfuntions. On mine I was convinced the problem was carburation as the bike would start but ran very badly once the throttle was opened. I'd be very happy to share my experiences further if it would help.

https://www.ebay.co.uk/itm/394249416594

[Itsme]

Hi Cristobal

Sorry I can't add anything not already said by the more knowledgeable people, but welcome to the forum and I hope you sort the XBR soon as they are lovely bikes.

Ian

[Cristóbal]

Hi Ian, Bill and Ian, thanks so much for all the advice. They are very helpful and I really appreciate them.
   
I did a quick search following the link Ian posted and found a ton of options regarding cdi and coil so I assume there are still options available for my xbr (relief), it's just a matter of finding the good one. As Ian suggests, for the price it is worth buying the replacement parts and seeing if that solves the problem. When I have them installed I'll tell you how it well.
And yes, it certainly is a wonderful motorcycle, Ian.

Thanks a lot!.
c.

[iansoady]

Good luck and please keep us informed. By sharing experiences we all benefit.

[richardeblack]

Hello Christóbal
Welcome to the Thumper and XBR community. I love my XBR. Done huge mileage and smileage on them over the last 30 years.
I know  Ian and Bill are much more knowledgeable than me and I haven't experienced your problem myself so can't add anything to what they have said but there is a wealth of used spares in the UK. I certainly have all of the components they suggest, from admittedly old machines, but the cost of selling stuff from here to the EU is difficult now due to our chaotic departure.
What I am happy to do is send these spares to you, if you decide that is the issue, at postal cost (hopefully no duty if no charge) . If they work we can discuss payment or return of the components you need.
If you are interested just let me know.
Good luck
Richard.