1988 ratteling sound
 

I am almost three weeks into my trip to benos aires from boston on my 1988 r100gs and have had some minor challenges so far but thus one worries me some more.
So far i have notived so transmissiin oil leaking thru the final drive shaft as it dripped down the from seal on the exhaust. So far i was not worried and refilled the transmissiin oil every other day. This problem might be totally non related to the new one and i am fine with refilling the oil as replacing the seal or plugging that vent hole seems difficult.

Today we rode for a good hour at high speed 75-80 mph from matehuala to san luis potosi in mexico. Once it started raining we slowed down and i noticed a rattling sound mostly at decceleration and sometimes at acceleration. When clutch it seemed to be even worse. As it was dark and rainy i wanted to get to the destinatiin and decided at the gas station once in town to add some more engine and transmission oil. Hot the engine oil seemed very low opposite of what i measered that morning at cold. The problem did not occur since that on the 5 mile drive hostel but that was at low rpm.
I have been searching but was hoping could pojnt me in the right directiin locating the possible causes or tips for a shop in san luis potosi or surroundings would be nice. My plan now is to see tommorow if it happens again and if yes adjust the valves if i can as i have not been doing that since boston.

Thanks Bram

The noise could be as simple as valves, or not. Air head valve clearances get tighter over time, so with your distance travelled so far, It's about time to check them and adjust as necessary. Another cause of this type of noise is the end play on the valve rocker shaft. Whilst you're checking the valve clearances, try and move the rocker arm up and down on the shaft, there should be very little clearance at either end, just enough to squeeze a little bit of oil out of each end. If there is a lot of movement or no movement, the rocker shaft turret needs adjusting at one end only. If you have access to you tube, look at the videos by Chris Harris, he explains how to do it. Take care.

Other noises like this could also be the camshaft chain tensioner, or even the cam chain and sprocket needing changing.

If adjusting the valves and valve rocker don't rectify the situation, you need to check out the cam chain assembly.

Thank you for the answer i have manged to check the valves and adjust them. And i have been able to locate the problem the front u-joints broke on th drive shaft. I am thinking ordering this part from hendersen tommorow. Hendersen Precision - Indian Moto Cycle
Any remarks on that?
I will try to replace by myself.

Thank you
Bram

Read this it may help you decide which way to go.

R100GS Drive Shaft Roundup