Problems with my XR650R SM - cutting out

I got my PIG on the weekend, she was a pig to start, took me 2 days to start her. After 2 more sore foot days I pulled the carb and adjusted the valve clearance. Now I start her first kick when hot or cold. I do still need to drop from 185 to 175 on the main and from 68 to 65 because I am at 5000 ft - I will do that on the weekend

I rode her for 3 days with the hard starting and she ran fine, cleaning the carb and unblocking some holes on the emulsion tubes fixed the hard starting but since then she just suddenly cuts out with no warning from idle maybe 2 or 3 times every ride, she is idling at 1400rpm and stops dead. Although I can start her first kick hot or cold when she cuts out she takes me 2 or 3 kicks to get going - Any ideas? Spark plug is in good condition and I don't have a spare to test with yet, gap is spot on. She does not appear to misfire while above idle and does not cut out either. I did also wash her with the tank off 2 days ago when I set the valves and cleaned the carb but I don't think it is a water issue as I have done over 100km since.

Blocked pilot jet, or sticking float ?.....

Mauser wrote:Blocked pilot jet, or sticking float ?.....

Anything possible but I will check it out when I change the jets. She runs 100% when not at idle and idles smoothly, just cuts out from time to time for no apparent reason

I'd remove the tank, drain it, remove fuel tap & take it apart.
You likely will find dirt/problems here, worth checking.
Also install an in-line fuel filter.
Only then will cleaning the carb assure you that it will remain clean - oh, and use compressed air to clean eh?
Also, set the float level to 17mm - 1mm more than spec, prevents some problems.

BuRP wrote:I'd remove the tank, drain it, remove fuel tap & take it apart.
You likely will find dirt/problems here, worth checking.
Also install an in-line fuel filter.
Only then will cleaning the carb assure you that it will remain clean - oh, and use compressed air to clean eh?
Also, set the float level to 17mm - 1mm more than spec, prevents some problems.

Thanks, I will try all this but I don't believe it is a fuel supply problem as she runs fine even at speed on the highway

Hopefully I will get a chance to stop at my mates workshop today to change the jets as he has a compressor

Ok, so this morning I stopped at a light, I just held her a bit over idle 1800 - 2000, she still cut out. I notice she is not harder to start when this happens, it is more like I am in a hurry to get her going in the traffic and don't kick her 100% like I should to get her going. When I arrived at work I left her idling and about a minute later she cut off and farted through the carb (not really a backfire

Have you done basics ?....changed the plug... checked connections etc ?

Mauser wrote:Have you done basics ?....changed the plug... checked connections etc ?

I changed the jets yesterday for what I googled should work for 5000 feet. I rode home after that, about 25km and she did not cut out so I will test further this weekend

I suspect dropping from 68 to 65 may be a bit lean but I am not sure. Now when I am decelerating (throttle closed) there are some small backfires from the exhaust. Is this an indication of a lean pilot or a healthy PIG?

I need to check the routing of the throttle cable. Since I changed the jets the idle increases at full steering lock both ways

Chris_w_65 wrote:I need to check the routing of the throttle cable. Since I changed the jets the idle increases at full steering lock both ways

Ok, that one is solved, The tank mounting hooked on the throttle cable and pushed it down so it was looped under the mount.

On lhs of carb find a little cover.
Take it off, behind there lives a small membrane.
In the cover is a tiny bore > plug it with epoxy or silicon, a tiny droplet is all you need.
Remount the lot.
On overrunning the carb won't lean off the mix anymore, hence less burbling/backfiring - which is in any case normal on a big single.
If backfiring bothers you then seal off the slipjoints in the exhaust system, as sucking air here causes it.

I love my backfire.....specially down the lanes.....

BuRP wrote:On lhs of carb find a little cover.
Take it off, behind there lives a small membrane.
In the cover is a tiny bore > plug it with epoxy or silicon, a tiny droplet is all you need.
Remount the lot.
On overrunning the carb won't lean off the mix anymore, hence less burbling/backfiring - which is in any case normal on a big single.
If backfiring bothers you then seal off the slipjoints in the exhaust system, as sucking air here causes it.

Thanks, my exhaust does have quite a bad leak where one of the headers goes into the Y. Is there a sealer I can use when I assemble the exhaust? Otherwise I will either have to get the flare on the Y crimped or get the header pipe expanded slightly to make a tighter fit

I don't mind the backfiring, was just concerned that my pig might

She is much more responsive off idle now with the new jetting and she did not cut out on this morning's ride

What is the best way of fixing the leak and can you identify these headers and tail pipe?

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Plain ol' transparent silicone will put paid to that leak.
No idea what headers those are, never seen them, neither the silencer.

BuRP wrote:Plain ol' transparent silicone will put paid to that leak.
No idea what headers those are, never seen them, neither the silencer.

Will silicone handle that kind of heat?

Could be custom made headers and I believe the silencer could be the OEM unit off another off road bike. Seems to work ok, not very loud at low revs/idle but plenty loud higher up

That looks like a custom job man , never seen system like that before , not bad actualy .