95 R100RT running poorly

Trying to get my 95 R100RT that I bought last Septemer on the road running correctly. 45K on the bike.
The problem now is low power and it almost quits accelerating between 3500 and 4500 RPM. Need to play with the throttle to get it to gain speed. Takes a while to get to 80MPH too. It feels like a fuel problem.
Very little vibration and bike sounds good.

I have checked all the obvious things like timming, gone through the carbs, compression is about 145 PSI.
Hooked a vacuum guage to it today and it reads about 4 inches of mercury while traveling the road at about 55 MPH. Go to accelerat ing it drops to 2".

Been doing 95% of my own work in the 30 years and 350k miles I'v ridden. Good thing the 91 R100RT is running very good.

Ray

Sounds like torn diaphragms in the carb but you said you went through the carbs. What about floats...could they be set so that they cutoff filling the float bowls too soon? I've heard about a possibility of creating a vacuum inside the tank due to the cap not venting properly to let air in as gas exits through the petcock. See if the problem gets better by cracking the gas cap at speed when the problem appears.

Better check;

The valves too, if not already been there. Tight ones will do your power band no favors. The carbs come second imo; My first checks would be the jets, needles set correctly, and possibly the diaphrams. I've been in so many and have found all these in various conditions from not even the same sized jets from each side! The needles are at the same level and if so the right level??? Next; the electrics! Ohm meter your plug wires, as age and improper storage can "kill" these easily. Coils are not a likely fail point so go there last. You can ohn the entire plug to plug wiring, which will include the coils. Somewhere very near 22/24 ohms resistance should be present. A very easy plug wire check can be done at night in a very dark garage, as the wires will bleed sparks all over at rpm's above3000 and mostly unnoticed when riding the bike. The first time I saw this years and years ago, I could hardly believe it, but seeing is believing. Happy Trails,Randy13233

i dont know so much about later bikes...

I agree with Kurt-- sounds like classic torn/holed carb diaphragms

other than that,

what about the ign advance? how is the atu in the bean can-- is it sticking? [does it have one??] have you checked the advance with a timing light or just static timing?

isnt there something about the later bikes that the ignition module needs thermal heat paste?

hope that helps

Polarbear said:

You can ohn the entire plug to plug wiring, which will include the coils. Somewhere very near 22/24 ohms resistance should be present.

Click to expand...

I'm sure you meant to include the "K" on the ohms...it's 22000 to 24000 ohms...

benway said:

i dont know so much about later bikes...

I agree with Kurt-- sounds like classic torn/holed carb diaphragms

other than that,

what about the ign advance? how is the atu in the bean can-- is it sticking? [does it have one??] have you checked the advance with a timing light or just static timing?

isnt there something about the later bikes that the ignition module needs thermal heat paste?

hope that helps

Click to expand...

What he said. It could also be sticking slides in the carbs.

1505 said:

Trying to get my 95 R100RT that I bought last Septemer on the road running correctly. 45K on the bike.
The problem now is low power and it almost quits accelerating between 3500 and 4500 RPM. Need to play with the throttle to get it to gain speed. Takes a while to get to 80MPH too. It feels like a fuel problem.
Very little vibration and bike sounds good.

I have checked all the obvious things like timming, gone through the carbs, compression is about 145 PSI.
Hooked a vacuum guage to it today and it reads about 4 inches of mercury while traveling the road at about 55 MPH. Go to accelerat ing it drops to 2".

Been doing 95% of my own work in the 30 years and 350k miles I'v ridden. Good thing the 91 R100RT is running very good.

Ray

Click to expand...

An area over looked by many is the top of the carb's leaking.
Bike runs fine an all, but under acceleration she won't perform.
Bing says they can reseal the tops for $$$.
Others have used silicone "inside" or glued small BMW roundels on the top.
Check here for the leak.