1982 R100RS Running better in cool weather

[jsf14469]

Weekend trip. Weather quite warm Friday and Saturday and bike felt seriously out of power, but otherwise no symptoms. Returning home Sunday, weather much cooler, 60 vs 85 and bike felt much better, however as day warmed up again felt underpowered. Valves recently set, carbs balanced, timing checked (very jumpy timing mark, perhaps in need of timing chain- closing in on 200,000mi).

Have also checked for good fuel supply.

Where to go next?

 

[20774]

What about heat sink paste on the ignition module? Could be that the extra heat is getting to the module and somehow affecting how it works.

 

[jsf14469]

Heat sink paste being dielectric grease?

 

[20774]

No, heat sink paste is designed to thermally connect two items and help with heat transfer. Dielectric grease is an electrically isolating compound. Heat sink paste can be found most anywhere, Radio Shack being a commonly suggested place....if you still have stores in your area. I googled and saw that Walmart had some. Auto parts stores should also carry it. Here's at least one thread on this:

https://forums.bmwmoa.org/showthrea...et-heat-sink-paste-for-mounting-ignition-unit

Here's another thread about a problem with the motor cutting out...not necessarily your problem, but general stuff to consider:

https://forums.bmwmoa.org/showthread.php?88770-Airhead-cuts-out

 

[jsf14469]

Heat sink paste tricky to locate. Radio Shack either gone or going. Places do show it on their website, but not at stores. Have resorted to online order. This will be interesting. Thanks for your thoughts.

 

[SCBuckeye]

I have found that on the last few bikes I have owned ('78 R100, 2011 Suzuki LS650) that they run MUCH better in cooler weather - especially in the mornings. Now living in SC, I assumed that moisture content in the air (much higher here than up in Ohio) had something to do with it.

Which leads me to believe that re-jetting could also be part of the "solution."

 

[lkchris]

Well yeah, this is why turbo vehicles have intercoolers and most have cold air intakes.

Have seen air filter housings with swiss cheese drilling to augment the plastic scoop.

"Good fuel supply" means float levels?

Don't let your tankbag interfere with gas cap breathing.

Use quality fuel.

 

[guenner]

very jumpy timing mark

Could be the ignition sensor or the ignition coil.

Did you check the timing after the warm ride home?

/Guenther

 

[FELAW]

hot weather

On a frosty March day a friend and I went out on our airheads. After an hour of spirited riding we stopped and he remarked "These old airheads sure do love the cold dense air, don't they?" I hadn't really thought about it, but it's true. You might want to try a hot weather plug chop to see if you're running too rich. Just a thought.

 

[Darryl Cainey]

Vent might be clogged in the gas cap.

When running crack open the cap & see if it runs better.

 

[jsf14469]

Have tried the easy stuff - heat sink paste, check gas cap vent. Weather cool today, so running good. Appreciate the thoughts.Will check valves and timing again