Skip/miss after braking

[Guest motomaniac]

On the way home from work last night, I noticed that every time I came to a stop at a traffic light, my bike would miss and almost cut-off just after it settled to idle speed.

 

Any ideas?

[jrt]

Is it running hot/lean?

J

[Guest motomaniac]

I don't know. But it hasn't been doing it through the winter. It just started last night, and maybe this past weekend a few times. Could the air temperature have anything to do with it?

[Guest philbo]

On the way home from work last night, I noticed that every time I came to a stop at a traffic light, my bike would miss and almost cut-off just after it settled to idle speed.

 

Any ideas?

49123[/snapback]

 

Mine used to do that as well. I'd be going down the highway at around 80 MPH for a few miles, get off at the exit ramp and stop at the bottom. The engine would either splutter or cut right out while I was idling at the lights. I never solved the problem but it did go away when I installed a PC-III with a standard map. I assume it was a mixture problem with the stock setup.

[al_roethlisberger]

It is almost certainly valve-lash related. Loosen your valves to Euro or Raceco specs, and the problem will go away.

 

The issue is that North American EPA regulations made MG use very tight valve lash settings for noise compliance(we assume), and once the bike gets good and hot, the valve train ends up too tight to tick over well.

 

I had this problem for almost a year, and after several unsuccessful trips to the dealer, we eventually found the problem ourselves. In fact, the dealer had a 2002 LeMans demo bike that they couldn't get to run worth a damn because of this very problem, which I found ironic

 

See the following threads, or a search on "tight valves" or something like "hot stall" will return even more:

 

http://www.v11lemans.com/forums/index.php?...l=tight++valves

 

http://www.v11lemans.com/forums/index.php?...l=tight++valves

 

http://www.v11lemans.com/forums/index.php?...l=tight++valves

 

http://www.v11lemans.com/forums/index.php?...l=tight++valves

 

 

Valve Adjustment FAQ

 

 

It could also be vapor-lock related, but I doubt it from your description.

 

Vapor Lock and Tank Suck FAQ

 

al

[Guest motomaniac]

Al,

 

I've just read the thread by Lex on how to adjust the valves. What's the purpose of re-torquing the head bolts?

 

And when I'm adjusting the valves, how tight/loose do the valves need to be on the feeler guage?

[Guest Brian Robson]

I always set the valves so that the right size (0.20mm/0.15mm) moves through and the next size up won't go in.

[dlaing]

I use the "should be as snug as a sheet of paper(or a bookmark) pulled from the middle of a dictionary"(1500 page).

But then I use a method similar to Brian's to verify: If I am shooting for 0.15mm I find two gauges that match up to 0.14mm and 0.16mm and they should be discernably too loose and too tight, respectively.

I find it more important to get the right and left valves to be as close to each other more so than being right on 0.15mm intake and 0.20mm exhaust. So, if they end up being 0.16mm intake and 0.19 or 0.21mm exhaust that is fine, as long as it is consistent from right cylinder to left.

However if you made a custom PCIII map, I would always set the valves to what they were at the dyno-tuning.

Also, don't be like me and use old rusting feelers that are inconsistent and hard to read.

Instead pony up a few bucks for new gauges every few years.

[al_roethlisberger]

Al,

 

I've just read the thread by Lex on how to adjust the valves.  What's the purpose of re-torquing the head bolts?

 

49202[/snapback]

 

 

This only really needs to be done after the first xx?? miles on a new bike, or if you ever take the heads off.

 

The cylinder studs will stretch a bit as the bike breaks in, and you will need to retorque the heads probably about the same time as the first valve adjust. If you have your dealer do the first service, I think this is included in the process, although I'm not certain.

 

It should not be required again, although it might be a good idea to check the torque values during your once-a-year going over. It only takes a few extra minutes while you are in there(well, you do have to remove some more "stuff" first )

 

al