New issues or messed something up tuning?

[scott]

Hard starting- i.e. "choke" seems to do nothing- indicates clogged passages, probably in this circuit as well as the pilot jets. Yeah, back to thorough carb cleaning. Strip, dip and blow out all the passages. In case others are coming on late, remind folks that you did valve adjustment.

I hate to say it but this thread is really sounding to me like you need to pull the carbs and do them again. I just read this from start to finish and it sure sounds like dirty carb passages to me , bad idle , no choke , hard starting . Prime examples of dirty carbs

Okay - I just wanted to make sure it made sense before I started all that again. I was hoping I could be lazy and just do Carbs #1 and #2 or not do the full dip but I know that's a bad idea. I assume a full 24 hr dip isn't necessary though. It's been a few weeks since I've had the carbs off so I've ALMOST forgotten how much of a pain it is to get them back on.

Hopefully Tom's theory is right and it was the cam timing mis-alignment that caused something to gunk up the carbs so after this cleaning I won't have to do it again for a while. Then again, it was right after the cam timing adjustment that my choke seemed to work correctly for the first time since I had the bike (causing RPMs over 2000) so who knows. As luck would have it, I have some parts on order that would require the carbs to be off (float bowl drain screws, cam chain tensioner spring, etc.) but they probably won't arrive until after I've got them re-assembled and back on the bike. They're not crucial parts at least.

I had been thinking: since my cam timing was pretty far off, maybe instead of a PO messing it up, something was wrong with the bike caused it to go out of alignment and it happened again (like a faulty cam chain tensioner allowed it to "bounced" out of alignment again). Not sure how likely that is and it doesn't sound like that coincides with my symptoms anyway.

 

[jasper]

For what it's worth - your symptoms are very similar to mine, also a GS550E.

My bike starts without any problem at all, but won't run with the choke. It pulls strongs and idles fine at stoplights for the first 30 minutes of a ride. After that, it gets quite hot and will not idle and then gets very rough in the mid range. Eventually it won't run at all and won't start again until it cools down (30 minutes later)

I stripped and dipped the carbs, blew them out with compressed air and replaces all teh o-rings including the manifold. I sealed my intake boots, I set my valves...although I should check these again. Turning in the mix screws makes little to no difference, very occasionally I get a racy idle.

I also replaced my ignition with a Dyna-S and verified the impedance at the coils. I have a strong spark, I'm certain this is a fuel issue.

I'm going to attempt a proper synch this weekend, I've been working with a bench synch, my ears and header temperatures so far. Once synched, I'll do a proper fastest idle mix adjustment. I have a suspicion the basic issue with poor hot idling will not be resolved however.

I thinking this problem is due to it to rich running which fouls the plugs. If my carb tune doesn't work - I may consider smaller idle jets. My exhaust is clapped out so it's like I'm running a sport exhaust. I am also going to try hotter B7E plugs.

You're not alone.

 

[tom203]

scott said ..."Hopefully Tom's theory is right and it was the cam timing mis-alignment that caused something to gunk up the carbs so after this cleaning I won't have to do it again for a while"

Actually, I was surprised that your bike ran at all with intake cam running behind that much! To me, everything points to re-cleaning the carbs- a few members have reported having to this twice. Certainly no fun, but part of the joy of these old bikes. Who knows why cam timing got messed up- I doubt it was made that way- most likely something loosened or someone fiddle at some point. When you have carbs off, take off tensioner and play with it till you grasp how it works- it's a simple device but I've found lots of folks get confused with simple things.

 

[scott]

For what it's worth - your symptoms are very similar to mine, also a GS550E.

My bike starts without any problem at all, but won't run with the choke. It pulls strongs and idles fine at stoplights for the first 30 minutes of a ride. After that, it gets quite hot and will not idle and then gets very rough in the mid range. Eventually it won't run at all and won't start again until it cools down (30 minutes later)

I stripped and dipped the carbs, blew them out with compressed air and replaces all teh o-rings including the manifold. I sealed my intake boots, I set my valves...although I should check these again. Turning in the mix screws makes little to no difference, very occasionally I get a racy idle.

I also replaced my ignition with a Dyna-S and verified the impedance at the coils. I have a strong spark, I'm certain this is a fuel issue.

I'm going to attempt a proper synch this weekend, I've been working with a bench synch, my ears and header temperatures so far. Once synched, I'll do a proper fastest idle mix adjustment. I have a suspicion the basic issue with poor hot idling will not be resolved however.

I thinking this problem is due to it to rich running which fouls the plugs. If my carb tune doesn't work - I may consider smaller idle jets. My exhaust is clapped out so it's like I'm running a sport exhaust. I am also going to try hotter B7E plugs.

You're not alone.

I've read several threads (including yours I think) that have similar problems but couldn't find the magic answer. I don't have a clear understanding of what it means when something changes when the bike is hot or how a properly tuned bike behaves when hot. I'm hoping the carb cleaning will address the hard starting at a minimum. During my last Carbtune attempt I could see that when I synched at 1800 and then dropped the idle to a normal level, my Carb 1 & 2 vacuum dropped quite a bit so I was thinking that may be related to my idle stalling. Hopefully it's just some gunk in those carbs causing the problem. Maybe in general the bike will struggle some when hot but on my bike it's only operating on 2 cylinders at idle when hot so it REALLY struggles? I suspect my bike is running rich too but I'll revisit that after the carb cleaning.

scott said ..."Hopefully Tom's theory is right and it was the cam timing mis-alignment that caused something to gunk up the carbs so after this cleaning I won't have to do it again for a while"

Actually, I was surprised that your bike ran at all with intake cam running behind that much! To me, everything points to re-cleaning the carbs- a few members have reported having to this twice. Certainly no fun, but part of the joy of these old bikes. Who knows why cam timing got messed up- I doubt it was made that way- most likely something loosened or someone fiddle at some point.

Right - I'm pretty sure it wasn't dripping when I first got the bike but I never checked the timing until after I noticed the dripping so who knows...

When you have carbs off, take off tensioner and play with it till you grasp how it works- it's a simple device but I've found lots of folks get confused with simple things.

I seem to be in that group of folks

 

[cowboyup3371]

Carbs don't fully take away the hard starting issues; you'll have to adjust your valves too.

 

[scott]

Carbs don't fully take away the hard starting issues; you'll have to adjust your valves too.

I adjusted the valve clearances a few months ago and then re-checked / tweaked them when I adjusted my cam timing last month. Interestingly, I had to decrease my IN1 and IN2 clearances which seemed odd but I chalked that up to measuring error the first time I did the adjustment. Unless I messed up the measuring again, as of last month, the clearances all seemed to be at 0.08 - 0.09 mm except for EX3 which was at 0.06mm. Since it seems like I'm having issues with #1 and #2, maybe there is something to that. If it's not my incompetence at measuring and the clearances are changing that much / often, something else must be wrong.

 

[scott]

I adjusted the valve clearances a few months ago and then re-checked / tweaked them when I adjusted my cam timing last month. Interestingly, I had to decrease my IN1 and IN2 clearances which seemed odd but I chalked that up to measuring error the first time I did the adjustment. Unless I messed up the measuring again, as of last month, the clearances all seemed to be at 0.08 - 0.09 mm except for EX3 which was at 0.06mm. Since it seems like I'm having issues with #1 and #2, maybe there is something to that. If it's not my incompetence at measuring and the clearances are changing that much / often, something else must be wrong.

I just checked for the heck of it. The cam timing seems unchanged since I adjusted it last month: exhaust cam is "slightly" above the cylinder head surface but would below if I shifted a tooth, intake cam is 20 pins from exhaust cam. I checked the clearances quickly to make sure they were in spec: confirmed that a 0.10 mm feeler didn't fit and a 0.05mm feeler did fit.

 

[tom203]

I just checked for the heck of it. The cam timing seems unchanged since I adjusted it last month: exhaust cam is "slightly" above the cylinder head surface but would below if I shifted a tooth, intake cam is 20 pins from exhaust cam. I checked the clearances quickly to make sure they were in spec: confirmed that a 0.10 mm feeler didn't fit and a 0.05mm feeler did fit.

Have faith- the cam timing won't change- no sense sneaking up on it! Your valves are close enough, so get those carbs off. Don't forget the "choke" vent passage in fuel bowl rim. Basscliff has nice pic of it, but winter would probably set in before I found it.

 

[scott]

My final carb (#3) is in the dip. I've been doing a shorter dip (4-8 hrs each) since they really don't seem dirty and I just did the 24hr dip a few months ago.

I did notice something interesting. I finally got a magnifying glass and have been checking my jets.

• Carb #1 - seems like stock sizes
• Carb #2 - is stock I think but I can't read the pilot jet numbers (seems worn off)
• Carb #3 - haven't checked, still in dip
• Carb #4 - stock EXCEPT the Pilot Jet is a 45 instead of a 40

When cleaning, I haven't been able to poke a wire through the end hole of my Pilot Jets except for on #4 (that should have been a red light). Is it a big deal that I haven't been able to poke the other jets as long as I can see light through the hole?

So I guess this would explain why my #4 spark plug looks darker/richer - the larger Pilot Jet lets more fuel in at idle correct? Is this a big deal or can I compensate for this by just turning in the mixture screw more? Any ideas how much more this one should be turned? Say 3 turns out for the 40 Pilot Jets and 1 turn out for the 45 Pilot Jet? Would I be better off putting the 45 in a different Carb or is 4 as good/bad as any?

 

[tom203]

My final carb (#3) is in the dip. I've been doing a shorter dip (4-8 hrs each) since they really don't seem dirty and I just did the 24hr dip a few months ago.


I did notice something interesting. I finally got a magnifying glass and have been checking my jets.

• Carb #1 - seems like stock sizes
• Carb #2 - is stock I think but I can't read the pilot jet numbers (seems worn off)
• Carb #3 - haven't checked, still in dip
• Carb #4 - stock EXCEPT the Pilot Jet is a 45 instead of a 40

When cleaning, I haven't been able to poke a wire through the end hole of my Pilot Jets except for on #4 (that should have been a red light). Is it a big deal that I haven't been able to poke the other jets as long as I can see light through the hole?

So I guess this would explain why my #4 spark plug looks darker/richer - the larger Pilot Jet lets more fuel in at idle correct? Is this a big deal or can I compensate for this by just turning in the mixture screw more? Any ideas how much more this one should be turned? Say 3 turns out for the 40 Pilot Jets and 1 turn out for the 45 Pilot Jet? Would I be better off putting the 45 in a different Carb or is 4 as good/bad as any?

Seeing the light is good, but poking is still a good idea in case something is stuck. You've done a lot of work, so I think all the jets should be identical, but I'm unsure if this is a big deal. Blow out/ poke the choke pickups and passages in fuel bowls.

 

[scott]

I confirmed that all of my jets seem to be stock except for the pilot jet on Carb #4 being a 45 instead of 40. I set the float heights, did a bench synch and set the mixture screws to 3 turns out for Carbs #1, #2 and #3 and 1 turn out for #4. After I got the tank on, I realized I forgot to attach the hose between the breather cover and the airbox but decided to give it a try anyway (I'll take care of that soon).

Things definitely seem better. It started with a little difficulty but I may not have primed the carbs long enough. In any event, it started much easier than before I took the carbs apart. Also, the choke seems to have an effect again (it raised the RPMs) so that's definitely good. I took it for a very brief ride so I probably shouldn't make any judgments yet. I seemed to have the issue where the RPMs take longer to drop than normal when engaging the clutch. I've had that issue before but I'm not sure what I did to correct that. I haven't done a vacuum synch or anything yet. I also didn't get the bike warm enough to really test the stalling at idle when hot condition. It feels like some progress at least! Thanks again for all the help!

I guess my next step is to attempt a vacuum synch.

 

[tom203]

Hooray, I hope! Hanging rpms' usually mean intake air leaks, so check boots/clamps, etc. for tightness, but it might improve with a synch.