TOPIC:

I still cant get my z650 b3 running right on pods.

I've got a 4 into 1 exhaust and some moxi pods. And yes I know it's better to have the airbox but thats not possible on this bike because it's a cafe racer and it has the electrics located underneath the seat and the rear triangle opened.

Heres the bike:

Nameless z650 cafe racer by Andy Turner , on Flickr

I'm not looking for ultimate power or even perfect fuelling at this point. Just having it run fairly good would be fine for a start

Last night I tried various combinations of larger and smaller pilots and mains starting with 15 pilots and 117.5 mains (needle on 4) but I still get the same symptoms. Basically it's great and pulls well up to about 5-6k on 3/4 throttle but it doesn't want to rev past that unless I close the throttle down to just below half. The odd thing is that no matter what I change I still get those same symptoms. for example 15 pilots and 122.5 mains results in the same thing, bogging when you snap open the throtle at idle or open it past around halfway on the road, same with 117.5 mains or even 105.

I've tried moving the needle up and down a notch and that didn't seem to make much difference either.

I ended up with 15 pilots and the 102.5 (or possibly 105, I couldn't quite make out the markings but they were the original) mains and that seems very slightly better (but barely). I re-set the timing with a strobe to the correct mark, I even tried advancing it a little but the same. I can see the advancer do it's thing but my strobe didnt want to work when I revved it so I couldnt see it if works all the way up. The only things I haven't yet done are to sync the carbs and check/adjust the valve gaps.But I dont have the equipment to do that. I think I may have to give up and take it to a grown up with proper tools and actual experience next

Bit stuck. Hoping it's not something more serious.

Check your valve lash to see if it needs to be adjusted.
It looks like those Moxi's are like our Emgo's here in the States.
Wire mesh with a step or reduction in the inside diameter.
That step is what is causing your problem.
The air bleeds in the inlet side of the carb are not getting the airflow they need.
Try a filter like K&N or Uni.


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From your flicker build pic's it looks like the only engine difference from before is the filters.
If it was running ok before then it's only the filters causing the glitch.
Have you tried the bike without the filters to see if it improves ( I would guess it does but fluffy/flat on the bottom end)
Those cheap filters can actually restrict air flow and cause a massively over rich mixture above half throttle.
In the past I have had exactly the same problem with these (including shutting off the throttle) and the solution was to open up the chrome end cap and fit some brass mesh over the hole.
Warming up the end cap with a hot air gun softens the glue enough to remove the cap.
Drill a large hole in the center and then replace the cap with the mesh sandwiched behind it.
Warming the cap up again to re-soften the glue will enable the cap to be refitted with the mesh trapped in between.
You may still have a stutter/flat spot from idle to 1/2 throttle which is caused by a weak primary fuel delivery and can be fixed using those Leon Moss developed air restrictor jets that were sold by LEDAR/Freeman automotive in the 80's and hard to find now.
They are a small M5 threaded brass grub screw with usually a 0.6 mm drilling which is fitted in to the air bleed for the emulsion tube and they richen up the mix at the bottom end.
If you are handy lathe with a etc it's easy enough to make your own.

Cheers guys. Yeah the only real difference is the filters and jetting. I'm gonna get the valves checked to make sure alls ok and then go from there. I have heard about that step reduction on the pods being a problem so I'll defo look into that too though I tried revving it with no pods and I still have the bogging though that could be due to wrong jets I suppose. I've got it booked into a local bike place that specializes in older bikes to get a few things done including chopping the exhaust and putting a new can on & doing the valve clearances so once thats done they're also gonna take a look into the fuelling so I'll report back with the results

If the timing light goes dark at full advance, that suggests it's electrical.
Steve

After the rest is checked out you could try 17.5 pilots, clip on the 5th and 110 mains......hopefully they can check the advance in the shop.

as far as when you snap the throttle at idle and it bogs down or hear like the engine is sucking a lot of air ...you need to turn in your air screw. With pods you should be between 1/4 to 1 full turn out.
Or both issues could be your timing advancer....I have never had to move the needle for a stock engine with headers and pots

Was the motor running ok before the build.
If so why start mucking about with the ATD, shims or electrics .
It's like the dentist recommending glasses to cure your deafness .
Just put all the jetting back as it was and needle in middle position.
Run it without the pods = open carbs and extra air which will create a lean condition.
Up the mains a couple of sizes to put the WOT in a safe zone and sort the lean bottom with the restrictor jets.
Once you are somewhere close like that fit the pods and see what happens.
The pods will be more restrictive than the open carbs so you will have to do as I described earlier to get the air volume back.
Those cheap pods are shit and don't do much filtering and you may be better off with velocity stacks ( bellmouths )
Where in Uk are you.

Ok so, I just went out and rode the bike without the pods on, ran like shit as expected until I opened the throttle at about 3k and it took off like a stabbed rat! So you're right, the cheap pods restrict the carbs badly. So the premise that I've been working from that the pods will let in too much air was wrong. Seems like these MOXI pods are pretty useless. At least now I know what the problem isn't! So my next question is what to replace the pods with? Ive heard that the k&n are more restrictive than the UNI pods is that true? In general are the foam filters less restrictive than the oiled cotton ones? It's hard to get hold of the UNI filters over here but you can get Ramair ones which are also foam and look pretty much the same. I don't want to spend more money on pods that don't work

Cheers for the info about the pods, it seems like it was bang on the money. Wether it's to do with the stepped reduction or restrictive element is another question.

Sounds like Moxi = Poxy
Save your money and modify the chrome cap with a meshed hole to let in more air or stick on some bellmouths ,
Up the mains then sort the shit bottom end which is due to a lean condition.
For a temporary solution to get it rideable for tootling about with the pods as they are you could try dropping the mains to stop the choking that's caused by the massive richness over half throttle but you will probably hit a wall or run out of steam in the upper rev limit, probably a good 20/30 mph short of top speed in any gear.
As the revs rise the pods air flow restrictiveness will take over again pushing up the A/F ratio same as before but not as severe and later in the rev range.