2800rpm miss, grrrrrrrrr

[ScottS]

Scott, FYI - there are many posts on surface cracking of intake rubbers.

 

FWIW, I had the same concern as yourself 6 years ago and bought a set of new ones, with the idea that I wanted a set on hand for what appeared to be impending failure. I still have them in ozone-protective plastic bags in "spares stock", still with no problem with the orignials -- and this is after the stress of working them off and back on for gearbox warantee work 6 years ago.

 

A definitive test for leaking intake rubbers is to open an (unlit! ) propane torch at idle, and direct the flow around the area. If there's a leak, RPMs will rise very noticeably.

 

Hope this helps.

 

 

Thank you for this info, its terrific. I really appreciate it .

 

My bike seems to have had a lot of UV exposure , but I just assumed the cracking was unique to me . I will research it , but just on general principles I will replace the rubbers

 

But I understand that it may not be my problem

 

 

Thanks agian

[motoguzznix]

Mine(2000 V11) does exactly this- odd random misfires at 2800. Since I bought it used , and it always does this , I have no idea what caused it- but I can see my throttle body rubbers are definitely cracking , I have new ones.

 

Once our riding season is over ( November sometime) I will replace the rubbers, do a valve adjustment and set the TPS's so I know what i am dealing with

 

Although I kinda like cruising through town at 2800 rpm and listening to her burble through the CF cans !

 

3500-7000 RPM she runs awesome

Some years ago I did some A/F measurements of my KR V11:

 

A/F graph stock KR

 

The stock engine runs very lean at approx. 2900 rpm which explains the "miss" sufficiently. Richening the mixture via a power commander or some other device at that engine speed will make this issue disappear. Mine also pinged at that rpm accelerating at full throttle.

A very careful tune up of the injection system can also make the symptoms much better.

[JoeV11]

Some years ago I did some A/F measurements of my KR V11:

 

A/F graph stock KR

 

The stock engine runs very lean at approx. 2900 rpm which explains the "miss" sufficiently. Richening the mixture via a power commander or some other device at that engine speed will make this issue disappear. Mine also pinged at that rpm accelerating at full throttle.

A very careful tune up of the injection system can also make the symptoms much better.

 

 

All the years I've been on this forum, that's the general consensus - I'm surprised it took a page and a half before someone mentioned it. Mine has become worse this year so it's probably time for another tuneup. Joe

[dangerous]

Some years ago I did some A/F measurements of my KR V11:

 

The stock engine runs very lean at approx. 2900 rpm which explains the "miss" sufficiently. Richening the mixture via a power commander or some other device at that engine speed will make this issue disappear. Mine also pinged at that rpm accelerating at full throttle.

A very careful tune up of the injection system can also make the symptoms much better.

Thats the sorta info Im after, so those here with PC I expect you dont have this issue?

and yeah I did notice some pinging last w/e.

 

All the years I've been on this forum, that's the general consensus - I'm surprised it took a page and a half before someone mentioned it. Mine has become worse this year so it's probably time for another tuneup. Joe

ahhh ha, ok let us know how the tune goes and what ya find, Im to sort the same out so will reply when I get the chance.

[luhbo]

... I'm surprised it took a page and a half before someone mentioned it. ....

 

The reason is, that this info is just plain nonsense. Ernst is posting an ARF curve recorded on a dyno at WOT. The other guy is complaining about misses under cruising conditions, throttle nearly closed. Do you really believe these two things have to do with each other?

 

Going WOT below 3000 and then complain about pinging

 

Hubert

[GuzziMoto]

At ANY throttle position V11s (and newer Guzzi's) are on average lean at lower rpms and rich at higher rpms. This is done to meet emissions standards. PC's allow you to correct this and improve the way your bike runs but the results are only as good as the guy creating the map. You do not need a PC to have a great running Guzzi but it helps.

[dangerous]

The reason is, that this info is just plain nonsense. Ernst is posting an ARF curve recorded on a dyno at WOT. The other guy is complaining about misses under cruising conditions, throttle nearly closed. Do you really believe these two things have to do with each other?

 

Going WOT below 3000 and then complain about pinging

 

Hubert

"other guy" you mean me?

come on now no engine should be back firing through the carb and missing firing at TDC at any rev... shit around town if you crack the taps open like you sugest a bike should be riden then you would end up in the back window of a cage... come on man in town a gear change at 3000rpm is perfictly normale and at the rev you would not expect the engine to detinate causing a stall.

[luhbo]

"other guy" you mean me?...

 

Yes, you. I was just too lazy to scroll up and look who had started this thread.

 

But I'm afraid you've got me slightly wrong. Sorry for not having formulated clearer my above posting. I was just saying that your problem as described in your first post and this ARF curve posted by Ernst probably have not very much to do with each other. He's taken this curve at WOT, your problem normaly becomes evident at small opening angles. And if this curve is correct (what I doubt) then it is from an early V11, your bike surely has uploaded something completely different.

Besides that: I'm running a My15M in my KR to my great and daily delight , but even this fine tool can do nothing against a crapy running engine if the peripherals are out of tune - cracked rubbers, worn TPS, misbalanced T/Bodies, incorrect valve settings, things like that.

 

@GuzziMoto:

You're right when you say a PC is not necessary but it helps. In my eyes it's nevertheless a rather crude tool and as such not an elegant solution. More of the type "If something breaks then make it thicker, it's obviously not heavy enough".

 

Hubert

 

PS:

Some weeks ago someone posted a nearly perfect ARF curve also taken from a stock V11. Anyone remembering in which thread this was?

[raz]

Some weeks ago someone posted a nearly perfect ARF curve also taken from a stock V11. Anyone remembering in which thread this was?

I don't think you mean Ryland's but it's awesome: http://www.v11lemans.com/forums/index.php?...st&p=135731

 

Stock mapping, standard filter, airbox cover removed, Staintune mufflers. Definitely no need to touch that ECU.

[luhbo]

Yes, it was not this one But it looked similar. He did no changes at all, stock bike, stock map, straight ARF line.

 

Hubert

[tricatcent]

My bike sometimes has the slight backfire at 2800 RPM. One time it got really bad. It happens only when the throttle is just barely open. Usually the bike will be slowing down. I have had an airfuel ratio gauge on the bike and it shows that this backfiring occurs when the mixture goes quite lean. I think if I remember correctly that is when the ratio goes to about 15 to 1.

 

I have found that this leaness is due to incorrect balancing of the throttle bodies. I learned how to make the bike do this backfire. Once I could make it do it, I fiddled with the plastic nut that syncs the throttle bodies until the problem when away.

 

You can fiddle with the nut at stop lights. Make a mark on the nut to keep track of the starting position. The first time I did this I found the nut had to be turned one full turn to correct the problem.

 

The trouble with a fuel injected bike is that if the throttle bodies are not synced then the mixture on one cylinder will be wrong also. This is because the throttle position sensor is on one throttle body only. Of coarse if the throttle position sensor is set wrong to then you have even less chance of the machine running well.