proformance issues between morning and afternoon ride

[mike_Parson]

i have an 84 interstate that when i ride to work it seems to just top out at 70MPH and 4K rpm and it seems to growl and shake when up that high. the outside temp in the mornings is around 65. this is a one hour commute and it does it all the way to work. In the afternons when its 80+ degrees outside i can get well over 80 MPH and over 4K rpm and it runs like a scaleded cat. why does my bike seem to run so differently when the temps are not that far apart? Is 65 degrees still cold to a GL1200 engine? This is my first bike like this so im just wondering is something is wrong or if its just normal for it to run this way.

I am running standard 10W 40 oil in it and the plugs are the standard plugs as i jsut changed both the oil and the plugs in it.

Thank you for any ideas on this. If its normal actions then i can live with it but if i need to find somethign to fix i want to get it fixed so i have the best bike i can.

[neoracer]

really sounds to me like a carbs need soem work

[mike_Parson]

i have thought about that. maybe trying to sync them and se if that will help it run better in the mornings. i dont know when they were last done. Thanks Neo again for all the great advice....

[neoracer]

i would doubt if syncing will cure that problem,its got to be something more serious than that

you might want to check for sparkplug wire leakage,overnite could could soaking up moisture,which dries out later in day from the morning heat,but that's just a guess

in the morning will the biek run out to 45-5000 in lower gears?

correct air gap on pg's?

[Oldsmores]

That's really strange, and I can't believe it's related to ambient temperature. I think neoracer might be on to something with moisture. Does the bike sit outside at night?

[mike_Parson]

yes it will run out to 5K on lower gears in teh morning but in top gear it seems to stall at the 4K mark. i keep the bike covered at night but that dont mean some moisture couldnt get in i guess. I check teh PG gaps when i had the engine out a month ago for a repair on the stator and i check it then and it was good acording to the manual.

[ghostrider52005]

Im going to go out on a limb here since my wifes bike does partly the same thing. Without going into the gory details Id say you have a pin hole in one of the diaphrams in one of your carbs.

[bs175dths]

I live in Southern California, some 3 or 4 miles from the beach, where the day-to-day temperatures can change like my daughter changes outfits.
It can get into the low 40’s at night, damp and foggy. My 1984 Interstate stays outside, covered and I don’t have the same issues you describe.
A thorough carburetor inspection may be in order. Make sure the diaphragms are seated properly and not folded, torn or have pin holes. Also that the return springs for the diaphragms are seated properly. Make sure the intake o-rings are in place and the bolts are not loose. Make sure the bands between the carbs and the intakes are tight and haven’t come loose. Check all your vacuum hoses including the one which goes from the intake to the box (forgot its name) in the shelter near the pull-out storage box (it has something to do with the engine vacuum and 5th gear – a little help here folks)
Carb. sync is not humidity or temperature related, you have a mechanical failure.

If the bike will rev. in neutral or in 1st, 2nd, and 3rd, gears and has a problem in 4th and/or 5th, check the integrity of the hose on number 4 intake manifold.

Keep us posted…..

-Ride On