Carb Synch Cold Hot Weather...

[Seaking]

Here's an interesting one for you... regarding carb synch.. This is a little unique for me as I travel north south and hit 40-50'F temp change within a couple of days..

 

Before going on this previous road trip, I had synch'd my carbs as precise as I could and on test runs it ran smooth and sweet in 38-41'F weather we had here mid month of May.. But once I get down to South Carolina, in the 90's temp and I can feel thumping as I put power onto the bike at highway speeds, so that could be head winds?

 

When I got back here today, I could barely feel that thumping.. I had thought perhaps it's my clutch plates acting up or something... like that.. hot oil, clutch oil heating up etc.. but when we got up here.. it smoothed out.. but it's still there under the surface..

 

So is what I'm feeling more to do with my clutch or with my carb synch, and does temp make that huge of a difference on it?

[Freebird]

I've never experienced anything like that on my '99. I've synched the cards and then ridden it in weather from the high 90's all the way down to freezing temps and did not feel that they were affected by the temperatures.

[CaptainJoe]

Difference in fuel perhaps?

[Condor]

Fouled a plug??

[Guest scarylarry]

Southern air is less polluted than northern air:rotf:

 

Maybe a change in altitude...

[Seaking]

various answers... good to see comedy isn't dead around here

 

I don't think it's a fouled plug as it felt more pronounced while in the south than up here in the cold.. I used fuel conditioner down in the south after a while and though it made throttle response much better, it did not affect the symptoms described.. I don't think altitude had much to do with it either due to areas we were riding in... the main contributing factor seemed to be the heat..

 

Hard to tell.. I'll redo a Synch later on and be extra vigilant on the needles.. perhaps I had one out of synch the whole time.

[N3FOL]

Yep, there is a possibility that synchro went out of spec. after the trip. It wouldn't hurt

to re-synchto ensure all 4 are balanced. As mentioned before, I also have never experienced

that kind of behavior from my Venture.

[CaptainJoe]

So your saying the carbs went back into sync when you returned? doubtful...

 

Different fuels/ mixtures dirty carbs and or bad plug wires can reak havoc. Try spraying water on them and see if it starts running crappy.

I also use BP exclusively... as it seems to be a pretty consistant blend. Carb syncs should last longer than that...

 

electrical i believe, would be more apt to be intermittant...

 

Guess I'm assuming you regularly checked your engine oil ?

[Seaking]

I think some of the readers are missing the point.. I don't think the Synch went out of synch.. the bike felt like it was while down in the heat and resumed acting normal when I got back up to the cold..

 

Either the Canadian fuel is different, not too likely.. or it's something entirely different causing that effect.. I'll be working on the bike tonight / tomorrow and see what's what..

 

The whole run from Maine to Halifax was the smoothest running the bike had been since first hitting the heat down in DC or thereby last week on the down south from here..

 

Just odd is all

[MiCarl]

Temperature shouldn't affect the sync.

 

If you're rich it'll show up more in warm temps than cooler. Ever mess with the mixture screws? Air filter clean?

[CaptainJoe]

With all other other things remaining constant, the only variables are fuel, amount of water in the air due to heat and the viscosity of the engine oil (would thin out in warmer temps). As Seaking didn't say anything about increased engine noise I'd have to 'ass u me' it is bad fuel (low octane) or a borderline carb mixture...

Just wondering though, what was the SAE of the oil and brand name. Some people have reported clutch slippage when changing or mixing brands. And it would definately be affected by temperature change.

[Seaking]

well the oil is the YamaLube.. I did an oil change down in Oxford Alabama and there wasn't any appreciable difference in the thump vibes.. I had done some clutch oil bleeding that helped with the clutch when stopped on the I95 and other highways.. (an hour of slow riding on an interstate in the heat.. too slow to completely stop, too fast to completely let the clutch out.. ugh.. )

 

I'm not thinking it's anything with fuel as I was feeling it no matter what fuel company, which state, which octane fuel or even when I added SeaFoam or Yamaha fuel stab and conditioner..

 

I'm synch'ing the carbs this afternoon and will see if that was the culprit after all.. ya never know..

 

but I will let you know.

 

Thanks for the comments and suggestions.

[Seaking]

Ok so I spent a good amount of time doing my carb synch, using two different type of gauges (dial needles and Carb Tune) to confirm what I was seeing..

 

at 1,000 rpm idle, the carbs are perfectly synched.. but when I rev and hold the throttle at 3,000 rpm they were no longer in sync.. not by much but enough to want to try to synch them up at that higher rpm.. but back at idle rpm, one was slightly off.. Hmm.. Ok take it out for a test ride..

 

I think I will leave it there for now as the highway riding, where I spend most of my time riding was totally different indeed! I still have that thumping vibe which now leads me to believe it might be time to rough up the clutch plates next...

 

But synch'ing the carbs at 3,000 rpm really made a marked improvement at the smoothness of the bike when traveling at 55 to 70 MPH (calibrated speeds). Running the bike at 70 MPH in 4th was super smooth and impressive on this bike, I actually had to verify I was in 4th and turning at 4,000 rpm.. wow.. now THAT was fun.. MUCH!

 

Keep in mind that the difference is half a bar on the gauge, but man.. I'm sold. I'll be running it this way for a while to see if anything else appears different over time.

 

Now to de-glaze the clutch discs.. hopefully that will cure the thumping I feel (little up here in the north, a lot down in the south last week)

 

Cheers

[CaptainJoe]

Thats great, a lot of riders are synching at a higher RPMs.

 

Did you use 30 or 40 weight yamalube?

When I used the 10w30 weight (they were out of the 10w40) in my 650 vstar it made all kinds fo noises. Went back to the 10w 40 and all is quiet.

[pickinfred]

Now to de-glaze the clutch discs.. hopefully that will cure the thumping I feel (little up here in the north, a lot down in the south last week)

 

Cheers

Seaking, Could the thumping be the result of the Plug Cap? I experencied pretty much the same, see thread

http://www.venturerider.org/forum/showthread.php?p=591189#post591189

[Seaking]

Thats great, a lot of riders are synching at a higher RPMs.

 

Did you use 30 or 40 weight yamalube?

When I used the 10w30 weight (they were out of the 10w40) in my 650 vstar it made all kinds fo noises. Went back to the 10w 40 and all is quiet.

 

I'm using the YamaLube 10W40 up here.. same as what they put into it in Alabama..

 

Some say it's not the best oil you can use but its the Yamaha oil.. it can't be that bad.. However, due to the amount of miles I toss on the bike (just rolled over 85,000 miles on this trip) I go through a lot of oil and filters in the course of a summer

[Seaking]

Seaking, Could the thumping be the result of the Plug Cap? I experencied pretty much the same, see thread

http://www.venturerider.org/forum/showthread.php?p=591189#post591189

 

I saw that thread.. I'll look into it tomorrow and see if I spot anything "odd".. certainly can't hurt.. Good read for sure! With the age of the bike and miles I'd racked up, there might be something there worth investigating.

 

Cheers

[twigg]

I think some of the readers are missing the point.. I don't think the Synch went out of synch.. the bike felt like it was while down in the heat and resumed acting normal when I got back up to the cold..

 

Either the Canadian fuel is different, not too likely.. or it's something entirely different causing that effect.. I'll be working on the bike tonight / tomorrow and see what's what..

 

The whole run from Maine to Halifax was the smoothest running the bike had been since first hitting the heat down in DC or thereby last week on the down south from here..

 

Just odd is all

 

Temperature won't affect the sync, but it might affect the combustion enough for you to notice.

 

Have you ever noticed how, and a crisp winter morning, your car seems to drive particularly well?

 

You are not imagining it, it is running better

 

Engines adore cold, dense air. They get more oxygen and the whole combustion process is enhanced.

 

That is also why turbo-charged engines have intercoolers. The compressed exhaust gas is very hot, and so it is cooled before it reaches the engine to aid combustion.

 

If there is anything at all that is "marginal" on your bike, it is quite likely that you would notice a difference when you move it to a hot climate.

 

Hope this helps.

[CaptainJoe]

One of your low speed jets "may" be partially/clogged dirty if you are experiencing differences at 1000 RPMs and 3000 RPM5 when doing carb syncs. If you tear the tank and upper air box off you can reach just about everything you need to.

Start up and look at the carb slides to see they are moving at same rate. Then turn off and depress each one and check rate. Then loosen (4) allen head screws at bottom of carb bowls so they can drain. If you take the carb slides out you can clean all the openings at the top and slide side with carb cleaner and about 30-40 psi air. Warning:(theres a tiny o-ring under diaphram cover)

DO NOT WORK ON THIS BIKE WITHOUT PLACING A TOWEL BELOW YOUR WORK AREA OR SPARE PARTS WILL FIND THEIR WAY INTO THE MIRAD OF TINY NOOKS AND CRANNIES ON THIS BIKE...(don't ask me how i know)

 

"If" your gonna check the clutches, while you have her apart you ought to pay the extra coin and get the Heavy duty springs that have been mentioned on here several times.

 

Thats is definately on my list of things to do when I get more miles on the bike.

 

As far as messing with fuel mixture screws... Believe I would defer to someone with the proper equiptment, as, if you get it to lean bad things will occur...

Edited May 28, 2011 by CaptainJoe

[Seaking]

One of your low speed jets "may" be partially/clogged dirty if you are experiencing differences at 1000 RPMs and 3000 RPM5 when doing carb syncs. If you tear the tank and upper air box off you can reach just about everything you need to.

Start up and look at the carb slides to see they are moving at same rate. Then turn off and depress each one and check rate. Then loosen (4) allen head screws at bottom of carb bowls so they can drain. If you take the carb slides out you can clean all the openings at the top and slide side with carb cleaner and about 30-40 psi air. Warning:(theres a tiny o-ring under diaphram cover)

DO NOT WORK ON THIS BIKE WITHOUT PLACING A TOWEL BELOW YOUR WORK AREA OR SPARE PARTS WILL FIND THEIR WAY INTO THE MIRAD OF TINY NOOKS AND CRANNIES ON THIS BIKE...(don't ask me how i know)

 

"If" your gonna check the clutches, while you have her apart you ought to pay the extra coin and get the Heavy duty springs that have been mentioned on here several times.

 

Thats is definately on my list of things to do when I get more miles on the bike.

 

As far as messing with fuel mixture screws... Believe I would defer to someone with the proper equiptment, as, if you get it to lean bad things will occur...

 

I have the Barnetts HD springs in there now, and I've had the misfortune of burning out my clutch a couple of times by over heating them on Advanced Rider courses last summer.. I'm either too harsh on my clutch friction zone (too high revs) or there is something inherently wrong with the setup from the previous owner as the OEM clutch started to slip not long after I owned it.. But I wouldn't know where to start looking at a possible culprit.. I've flushed my fluids a few times (yesterday) and what came out was grey and dingy looking.. But I have the synthetic DOT4 stuff in there now and hopefully that will last a little longer. I'll be pulling the plates off soon as I get a gasket and looking for a sandblaster shop that can clean them off with glass or plastic beads to get the junk out of the little holes on the steel plates, as someone had earlier suggested.

 

The bike has been running nice and smooth since the synch yesterday but still feeling that thump.. I rode my buddy's bike to compare and it's not there on his.. Hopefully its a minor thing but will give the stuff a cleaning as you suggested. I don't think I'm brave enough to start pulling things apart though.. I watched a friend do it once and wow, too much for me to remember what he did..

 

Its not a large issue to live with, I can well enjoy the bike with the slight thumping but curious to know what's causing it and how to eliminate it. If I ever get rid of it I'll let you know..

 

Cheers M8