Info Video on Pilot Air/Fuel Screw Adjustment explanation.

Found these videos on YouTube and thought they might come in handy for everyone here on how to achieve the best settings and if you need to change the pilot jet.

Single Carb.


Multiple Carbs


The multiple carb video is really worth watching all the way through as he talks about how changing the size of the pilot jet can change how the bike runs and fuel economy.
Thought his explanations were really good.

Also explains what needs to be changed if the bike drops below idle when revved or if it hangs at higher revs before returning to idle when revved.

The video and explanations have confirmed what I need to adjust on the ZZR250 as it constantly bogs down below idle and nearly or does stall, when blipping the throttle. Running too rich. Which probably explains why the bike never needs choke on to start and when it does have choke on - it won't start or if the engine has just started and I turn a bit of choke on to idle it up a bit, the engine instantly dies.

 

I realise I need a hot engine. I don't understand what your point is?

If you are referring to my issue with the ZZR. The problem with revs dropping below idle and nearly (and sometimes) stalling before coming back up to idle again.

Yes - this is when the bike is fully warmed up and even after a good 1/2 hour ride it still does this. When cold - even after a week of sitting, it never needs choke to start up. Using choke causes the bike not to start. Even after starting, putting the choke even a little bit on to try and get the engine to idle up a little bit causes the engine to instantly die. Checking the plugs - they are black - even after a good run and yes, I've changed them. Motor is running too rich which also explains why I think it doesn't run as good as it should. I'd like to be able to take another 250 for a quick 15min run just to compare to.. I have the 250 Bandit up and running, but its not road legal or registered - and will be a long time before its finished.

Maybe I'm expecting a bit much from this bike. Just thought it should go better than what it currently does. Rather than need to rev the nuts off this thing to get anywhere and even then I feel like I can run faster than this thing accelerates. Get to a hill even in lower gears and it just wants to die. Unless I am in 2nd or 3rd an revving it like there's no tomorrow.

I think that if I had to ride with a pillion on this bike, it simply wouldn't move. Whereas my old Honda CB250RS I had on my L's (single cylinder) would take a passenger without any problems at all. I keep thinking about an older couple I was chatting to at Gingers Ck a few months back. They were touring on a Yamaha 250 Virago, fully loaded up with gear and rider + pillion. They took off without any extra revving at all when they left Gingers Ck picnic area, and once they got going - the rider wasn't needing to rev the nuts off the bike to get up a hill. Right now, if I try and take off from idle or a little over idle say about 1500-2000rpm, on the ZZR, it just stalls. No, I'm not a heavy weight - I'm only 82kg.

If anyone who has a ZZR250 or similar thinks I'm expecting too much, let me know.. Just thought it would be better, especially considering that Murdo had the engine re-built and is now slightly bigger at 265cc.. Ok not much difference.. maybe its just the engine design that it needs to be revved out to go anywhere - all revs and almost nothing in torque.

But if I'm expecting a little too much, maybe its best to sell the bike and buy something learner legal and bigger like a GS500E or F model for my son once he gets his L's (doing the pre-learner course this coming weekend) and spends a few months on the bike. Or maybe just after he gets his P's, then go get a bigger LAMs legal bike.

 

Thanks for the tips/suggestions everyone..

Here's an update...


Well, as i don't like borrowing tools (nor lending my tools for that matter as too many have gone missing over the years with various excuses from the borrower) I went to the expense of buying a carby adjustment tool set today. The only one in town it seems - after phoning every tools shop and auto shop in town, but at least I got a great deal (nearly 1/2 price - as the tool set had been sitting in the shop for a long time, though still expensive, but very much worth it as it was a professional level tool set for motorcycle carbies according to the packaging)

Following the information from the video above and checking the pilot screws standard setting for the ZZR (1.25 turns out) I found that the screws were actually 3.5 to 3.75 turns out. (engine cold). So I reset them to 1.25 turns out as per the manual. Knowing that they would need adjustment (being the ZZR is a 265cc). At least it is a solid baseline starting point.

Woohoo.... the bike now needed the choke to start up and start up it did with the choke on and idled up the more I put the choke on. ... Good... seems I was heading in the right direction..

Once I got the bike warmed up and choke off, I adjusted the idle as best I could - the engine wasn't sounding happy at all, but I was expecting that. Was running lean - indicated by the revs hanging really high when I blipped the throttle, before returning to idle.

Adjusting each pilot screw at about 1/2 a turn at a time - the engine reacted the same as the one in the video with idle going up and the motor also sounding a lot happier. I also then re-adjusted the idle using the idle adjustment turn knob as by the time the motor was sounding happy - (with the revs increasing with each 1/2 turn of the pilot screw) it was revving up a lot higher than base idle speed.

I blipped the throttle several times after each adjustment as well and let the engine settle.

Following the video with trying more and less turns of the pilot screw - eventually doing 1/4 or smaller turns at times, up and down I eventually found that 2.5 turns out was where the bike was sounding very happy and idling very smoothly. Constantly blipping the throttle - the revs came down to idle speed and never dropped lower than the idle rpm set position.

I could easily spend more time on it to get it even more exact (and probably will). But thought a test ride would be good to test the settings and then a little more fine tuning after that, so stopped there for the moment. It was way better than before where revs would drop down to around 600rpm and pretty much stall the motor at times or cough and splutter its way back up to idle speed.

The motor sounded a lot happier, as well as being more responsive when blipping the throttle.

I then let the bike cool right down again.

Late this evening I restarted it and yep - the choke is now working properly and helps to start the engine and idle the engine up during warm-up. Rather than before where using the choke would just cause the engine to stop or not start at all.

Didn't have time to go for a test ride - hopefully tomorrow sometime. Might put a new set of plugs in as well. But will see how the test ride goes and keep everyone posted.

 

Went for a ride around town this afternoon, picking up a few bits and pieces and then went out along Daruka road through the 80kph area.

Start-up needed the choke - a good sign and the choke also helped maintain a higher idle for warm-up. So all good there.

Motor never dropped below idle at all when riding around town and stopping at the traffic lights. Still need a few revs to get going - but not as bad as before.

Performed much better.

Went out of town for a 15min spin through Daruka road and noticed that getting up some of the hills was much better - the motor held speed and didn't die on me. Acceleration was actually quite OK for a 250 that obviously does not have much torque and is all about revs.

Noticed that there is a bit of a kick at 5000rpm and then another one at around 8000-9000 rpm. That was never there before.

Bike is performing much better now, whilst not a fire breather, it is better than what it was. The vibration in the footpegs was also slightly less as well.

I think a bit more fine tuning is in order, but the bike is much better than what it was before.

Now I just need to sort out why the temp gauge doesn't move much - barely gets up to 1/4 off the bottom of the gauge. Engine is definitely getting hot and when it sits for a while, the radiator fan comes on - so all is OK there - but the temp gauge never moves past 1/4. New Temp sensor, so thinking it must be the gauge. Not a big deal, but would be nice to have it properly working.

I'll do some fine tuning of the pilot screw tomorrow after I take the bike for a run out of town and back and see how much better I can get it.

 

Yes. It is the one Murdo rebuilt. I'm wondering if a jet kit might also help. Being that it is now a 265cc. Granted, not that much difference.. but also tossing up if it is worth the expense, when thinking about how long my son will keep the bike.

 

Yep - Totally agree. My son first bought a very cheap ($200) GSF250V with a stuffed motor to fix up and learn about bikes. Which has turned into a long term project. Hence why he bought Murdo's ZZR250 as he wanted something he could ride now once he gets his L's. He is doing the pre-learner course this weekend. Took forever to get him booked into a course here in Tamworth.

Still a lot of work to go with getting the GSF on the road - but at least the replacement engine is working nicely, still needs rear shock, chain/sprockets, tyres etc etc plus the parts from @kiffsta - that he has set aside for me. Once it is on the road, I think he will be selling the ZZR and using the GSF instead.

 

@Linkin
Yep - I checked the carbies all over and could not find anything wrong.. whilst I am no expert. There was nothing glaringly wrong and no air leaks. Everything is clean and no damage that I could see and no parts that need replacement. @Murdo has done a very nice job here, just needed some fine tuning.

I've yet to fine tune the bike. Which I think it needs as I found that after a run, there was the odd time blipping the throttle that there was a very slight drop in revs below idle - not enough to stall, and it did come back up to idle after a second or 2. So possibly a 1/4 to half turn back in (leaner) on the pilot. I'll find out tomorrow as I was too busy doing other things today, working on the GSF250 Bandit. Will hopefully take it for a 20min loop and back home again when I run some errands tomorrow around town. I'll then check the plugs as well. I'll admit I could be wrong with the 2.5 turns as I didn't do a final check on how many turns it was when I finished - I was working on my starting point and then from memory on how many turns out and then turns back in I did.

The only way I would consider putting the bike on a dyno is if the cost was very minimal (which I know it isn't), and also only if I could get a test ride on another ZZR250 or similar bike to compare to, as this would tell me if there is something wrong with our ZZR. But if the bikes perform similar - then why waste the money. Right now - and considering what the bike cost, I'm not about to throw lots of dollars at it. All the aim was/is to just fix a few niggling things with it and leave it alone. Maintain and care for it whilst my son learns on it and then sell it on for something bigger. Its not a long term keeper and will most likely be sold when my sons part-time work becomes full-time.

I will also admit, that more than likely I am expecting too much from the bike as well - its just my mindset in what I am used to riding (much bigger/more powerful bikes).

@Murdo and others on the forum who have ridden the ZZR have all said it goes well. So - again, more likely my subconscious being too used to my bigger bikes and what happens when you rev them out to the same rpm levels. Problem is that I take my bikes out for a run first and then the ZZR250, so revving it out to say 8000rpm or so, I start thinking that I can walk faster, as the mindset is still tuned into the bigger bikes.