Dr Big
Bikes playing up ! - Printable Version

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+--- Thread: Bikes playing up ! (/showthread.php?tid=3217)



Bikes playing up ! - bigrob - 25-07-2020

Morning all, 
hopefully someone may have an idea whats up !

I took the fuel tank of the mighty DR650RS last week, refitted it and the next time I rode the bike, it starts fine, ticks over nicely. But, when I ride the bike now, it has lost some performance, a bit like a twin with one cylinder not firing correctly and it vibrates badly at 3000rpm then smooths out after 5000. Performance is bad at all speeds. If I'd disturbed some crapp in the tank and blocked a jet, would that cause this problem.

I'm removing the tank today to take a look !

Cheers, Rob.


RE: Bikes playing up ! - BigBob - 25-07-2020

Kinked fuel line? Vacuum line not connected?


RE: Bikes playing up ! - spendango - 25-07-2020

Is it a twin plug ??? maybe a duff plug but probably fuel issues


RE: Bikes playing up ! - bigrob - 25-07-2020

Yes, twin plugs, but 2 new iridium plugs 70 miles ago. Doesn't mean one's not farked I guess. I got sidelined by messing about with my TTR today so will look tomorrow.
Thanks for getting back to me fellas. I'll keep you informed !


RE: Bikes playing up ! - spendango - 25-07-2020

(25-07-2020, 06:31 PM)bigrob Wrote: Yes, twin plugs, but 2 new iridium plugs 70 miles ago. Doesn't mean one's not farked I guess. I got sidelined by messing about with my TTR today so will look tomorrow. 
Thanks for getting back to me fellas. I'll keep you informed !
I remember Bob saying if the 800 goes off a plug it runs like shite


RE: Bikes playing up ! - bigrob - 27-07-2020

Plugs look OK, but, very weak looking spark. All the rest of the tubes look ok. I have notice that the cam chain is very noisy. Just ordered a couple of gaskets so I can take off the auto tenchiner and check out the spring etc. My mate reckons that if the chain is slapping about, the valve timing will be out. Is that possible ?


RE: Bikes playing up ! - BigBob - 28-07-2020

My mate reckons that if the chain is slapping about, the valve timing will be out. Is that possible ?

Yep, that is entirely possible, and the chain should definitely not be slapping about.
The tensioner is robust and I`ve never heard of one failing so it definitely needs investigating.


RE: Bikes playing up ! - bigrob - 28-07-2020

Haha, not so much flapping about, but it has got louder. I'll investigate and get back to you.


RE: Bikes playing up ! - bigrob - 27-08-2020

Bike went into the bike shop yesterday to sort out the vibration. I reckon the balance weight chain is not being tensioned correctly, and the weights are out of synch . Update soon.


RE: Bikes playing up ! - BigBob - 27-08-2020

My guess is that the balance chain has snapped as it is very hard for it to jump teeth.
I had a balance chain snap on a Big about 20 years ago, and on tickover it was jumping up and down with both wheels coming off the ground at once, and completely unrideable.
It`s not  a hard fix providing you have the correct puller to get the rotor off. Fiddly job aligning it all though.
Of course, it may be the cam chain that has jumped a couple of teeth.