Starting problems

[Seft]

Hi, been having issues cleanly starting the bike today, is it "normal" to need to give it some throttle even on full choke to start? Even when I have it's taken a 3 or 4 times. Bike had been sat for only three days connected up to an optimate and the battery's only a month or so old so presuming, maybe wrongly, that that's not a suspect here. Any thoughts? Should I just be able to start it on the choke just pushing the start button and not touching the throttle?

[92xjunker]

Opening the throttle adds air. So, I would not go full choke.

[Seft]

Opening the throttle adds air. So, I would not go full choke.

I'll give it a test with less choke tomorrow then but should it just start with the choke on it's own and no throttle, what's normal for these bikes? Genuinely can't recall what it used to behave like for starting before I left if for years.

[ZookRick]

I use full choke, no throttle, then adjust choke down as it idles. Depending on your idle mixture you might not want to use full choke.

[Seft]

I use full choke, no throttle, then adjust choke down as it idles. Depending on your idle mixture you might not want to use full choke.

Air/fuel mix is set to stock setting for mine which is 2.25 turns out. Idle speed is 100RPM faster than yours as per spec. I'll experiment with different amounts of choke, was expecting as it's all set up as stock that it should just start with no throttle. I say stock, only diff is the end can is a replacement one but sold as stock replacement, Motad Viper I think it's called.

[Kreylyn]

Choke is a fuel enrichment system on these bikes, not a real "choke".

Throttle opens the butterflies and adds air.

If you need to use throttle at any time for the bike to start, it's getting too much fuel.

The choke is not an on/off setup. You can adjust the amount of choke used to get a lesser fuel add. If your bike is set up to run a little richer, then full choke may not be necessary, and opening the throttle would help to lean / dry the cylinders back out after the quick flood of fuel from the choke.

I'd try to start the bike with no choke at all. If it starts on a cold engine, I'd say your setup up fairly richer to start with. If it won't start with no choke, then I'd suggest you slowly pull the choke open as your turning the starter over. Note were, maybe even mark where the choke lever is at for future ref... (grease marker works great for this as a temp mark that will wipe off). Next time you start it, move the choke to that point and see if it starts.

All of that was no throttle. I would expect the bike to start no throttle all ways. If your having to use throttle to start the bike at any time, there is an issue... may be minor, but there is an issue.

Krey

[Seft]

Thanks Krey, I tested based on earlier posts trying to start it with a little throttle and less (about half) choke and it fired up just fine. Having always been told I'd need to use the choke to start the bike from cold I'd never actually questioned it and tried without.

If I do find that there isn't a point where it starts without giving it some throttle am I likely to need to adjust the fuel/air mix for the pilot circuit or would it suggest that the choke plungers aren't sealing properly, or something else!?!??

[Kreylyn]

Thanks Krey, I tested based on earlier posts trying to start it with a little throttle and less (about half) choke and it fired up just fine. Having always been told I'd need to use the choke to start the bike from cold I'd never actually questioned it and tried without.

If I do find that there isn't a point where it starts without giving it some throttle am I likely to need to adjust the fuel/air mix for the pilot circuit or would it suggest that the choke plungers aren't sealing properly, or something else!?!??

If your questioning the a/f screw settings for the bike, I'd suggest doing the drop down method with a right angle screw driver to set them at the best setting.

Running a little rich isn't necessarily an issue unless you run into problems. Fouled plugs, poor performance... richer mix will make the bike a little cooler.

Krey

[Seft]

If your questioning the a/f screw settings for the bike, I'd suggest doing the drop down method with a right angle screw driver to set them at the best setting. Krey

Question around a/f adjustment was more hypothetical. Turns out that setting it at just over half choke means it starts up just fine, I don't think it every did previously before the carb cleaning etc, either way all is good now.

You mentioned tuning, seem to get a lot of irrelevent results from search engines for it but this came up http://bikeadvice.in/tuning-carburet...el-efficiency/ is this what you were talking about doing? If so only question I have is when they talk about adjusting the a/f screw do you do that on all the carbs one after the other or should I approach it one carb at a time?

[92xjunker]

Adjust one carb at a time all the way across. Use a good high flow fan in front of the oil cooler, as in could take some time just to get the driver on the screw.

[Kreylyn]

http://xlforum.net/vbportal/forums/s...ad.php?t=31262 is one example.

On a warmed up bike, set the rpms to around 800... adjust one of the a/f screws... turn it in till the engine stumbles, turn it out till it stumbles, set the final setting right between those two points. So keep close track of how far you turn it each way.

Example... you default set the a/f screws starting at two 1/2 turns out... you turn it in 2 turns (so it's .5 turn out) and the engine starts to stumble. Now turn it out until it stumbles again. Lets say 3.5 turns when that happens.

That puts the middle of the setting at 2 turns out.

You would reset the rpms now (as it could have changed with the single adjustment on one carb) to the lowest it will go again... normally about 800 rpms... and pick the next carb.

As mentioned, use a fan on the front of the bike to keep it cool (and help from roasting you). You will need to take the main fairings off, and you will need a right angle screw driver to do this adequately.

Repeat the steps, reset the rpms, repeat the steps... till all 4 carbs are done. Note each one's settings. Normally they should be pretty close to the same, but it is possible to have variances.

Krey

[Seft]

Thanks for the advice, went to get things set up to do this only to find the fan I had broke, it was a big desk fan which was fine for when I was balancing the carbs but not convinced it'd be good enough for the length of time this might take. When you guys are talking about a fan do you mean something this kind of size https://www.amazon.co.uk/d/ajl/Marko...ic/B01I9WP85C/ that's a 140W one, definitely more powerful than the desk fan I was using?

[Kreylyn]

Thanks for the advice, went to get things set up to do this only to find the fan I had broke, it was a big desk fan which was fine for when I was balancing the carbs but not convinced it'd be good enough for the length of time this might take. When you guys are talking about a fan do you mean something this kind of size https://www.amazon.co.uk/d/ajl/Marko...ic/B01I9WP85C/ that's a 140W one, definitely more powerful than the desk fan I was using?

That's a nice one, and if your shopping for a good shop fan, I'd say go for it.

But, need wise... a basic 20" household box fan will work just as well.

Krey