ChrisW
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| posted on 24/5/15 at 12:30 PM |
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Yamaha YBR125 won't run
Hi everyone
I know we have some bike enthusiasts on here.
I have a Yamaha YBR125. Picked it up dirt cheap as a non-runner to see if I like this whole two-wheel thing. It's a 2007, first year of fuel
injection.
It starts up and idles but as soon as you try to raise the revs it dies, won't even go back to idle.
I've heard that the fuel pumps are notorious on these but all the reports I have read are that they die completely, not even idle. Also I can
hear the pump priming when I turn the key so it's certainly running. Of course it may be that it's not producing enough pressure.
Unfortunately I don't have any way of pressure testing.
Anyone got any experience of these engines and offer any words of advice?
Is there anyone local with the necessary kit to test fuel pressure to prove the pump one way or the other?
Vid of problem: http://youtu.be/siE7MOj707E
Cheers, Chris
[Edited on 24/5/2015 by ChrisW]
My gaff my rules
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MikeRJ
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| posted on 24/5/15 at 03:45 PM |
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A failed MAP or TPS sensor could cause this. See if you can read any fault codes using
this method.
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ChrisW
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| posted on 24/5/15 at 04:31 PM |
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I was thinking TPS or MAP. TPS is obviously, but I'm actually I'm not sure where the MAP is. Any ideas?
EDIT to add...
No fault codes are being read.
I'm thinking maybe the TPS, IAT and MAP are all part of a single module on top of the throttle body as when you unplug that I then get fault
codes for all three.
Someone has mashed a brass screw on the side of what I think is the idle valve. Not sure if it matters, but as there are complete throttle bodies on
eBay with the sensors attached for around £25 I think I'll take the plunge and buy one.
Actually, just found out (from that same site) that my theory is correct and that module does all three functions so fingers crossed!
Chris
[Edited on 24/5/2015 by ChrisW]
My gaff my rules
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mark chandler
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| posted on 24/5/15 at 07:31 PM |
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Get it running then get rid
Then pay for a direct access course, three enjoyable days and take your test then get a 600cc bike or better.
A 125cc will not have the power or brakes to get you out of trouble.
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whitestu
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| posted on 25/5/15 at 08:55 AM |
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Personally I prefer little bikes, and if you ride properly a 125 shouldn't be dangerous at all.
I did thousands of miles on my cb100 when I was a lad and thoroughly enjoyed it.
I really fancy a CBR250r now as it looks like a great combination of size, handling and power.
Stu
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ChrisW
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| posted on 26/5/15 at 09:06 AM |
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I know 125's are not the most desirable bikes, but having never ridden one (on the road) before this seemed like the cheapest and easiest way to
see whether I like it or not and get a bit of experience in anticipation of doing a DAS. I plan to be very much a fair weather biker, in fact I doubt
I'll ride it much more than down to the local cafe on a Sunday with a couple of mates who did the CBT at the same time as me.
For what I paid for the bike if I can get it going cheaply I should be able to ride it over the summer, turn a profit on it come the autumn and
I'll know whether the 'two wheels' thing is for me. Can't really get much cheaper motoring hobbies than that!
Chris
My gaff my rules
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ChrisW
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| posted on 29/5/15 at 01:55 PM |
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Ok, replacement throttle body (complete with sensors) arrived today. Just popped out and put it on but it's still doing the same.
Of course the sensors on the replacement one could be knackered too.
Any other ideas people?
(Could really do with finding someone with the same bike to test out the parts for me!)
Cheers, Chris
My gaff my rules
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ChrisW
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| posted on 2/6/15 at 08:56 PM |
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Ok, following some advice that 'it's always the fuel pumps on those', and despite being able to hear the fuel pump running and
seeing fuel come out when the injector was disconnected, I took the plunge and changed the fuel pump.
To my absolute surprise it worked - I have a running bike! 
Have to say, I bought a £30 kit from eBay and was very impressed with it. How long it will last is another question of course...
So next step is insurance and an MOT then I can decide whether I like being on two wheels. Either way I've probably doubled my money on the
bike now it's running so it's a result.
Thanks for the advice everyone!
Cheers, Chris
My gaff my rules
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