Hello,

I have been refurbishing a 1985 K100 RT. I knew the original owner (who passed), so the miles are as real as a K100 odometer can be. 

I've done extensive clean up, new rubber all around, full spline lube maintenance, new tires, new (aftermarket) fuel pump. I got it running and have put just under 3k on it since.

This winter (now) I'm breaking it down again to check the Water Pump, Valve Lash and Timing chain. There's more noise from the engine than I'd like or expect. And the bike puts out an amazing amount of HEAT!

Also - I MAY pull all the trim/fairing and paint them anew. The bike sat under a car port for ~15 years dormant. I dealt with the Aluminum "rust" with bead blasting, fixed the mouse eaten wires (after removing the mouse nest on top of the block), but can't do anything except repaint the mildew damaged paint.

"BaldShins" is because the heat from the engine has fried the hair off my Shins during the summer of riding.

Welcome to the forum......

Seems you have found the Ks a long time back.

Heat.....there are some rubber blocks and deflectors under the gas tank, worth making sure they weren't used to make the mouse nest. There are also horizontal deflectors where the lower panels meet the main fairing, possible for them to get lost. Even with that there is quite a bit of heat.

Water pump doesn't 'check', if you take it out as far as I know you have to replace the seals as taking it out destroys them. But taking off the front cover will tell what kind of impeller is in it. If its never been done then bite the bullet, new shaft, impeller, seals etc. DONT try to reuse the old one. The impeller 'disappears', the nut breaks, the shaft get spitted. If it sat 15 years it will be toast.

Nice to see you and look forward to some photos.

Olaf

Hi Ya Baldy welcome to the Knuthaus

You'll love it Baldshins and the LT fairing will suit the climate there nicely. Enjoy the forum.

88

Welcome!  Everything you need to know is somewhere around here, all you need do is ask.

About the heat, it's an unfortunate byproduct of the RT fairing.  There has been a lot done to reduce the amount that goes for roasting the rider and there is a lot written on the subject both here and in other places on the interweb.  Seems to be two schools of thought, deflect it away from the rider, and let it flow wherever it wants but get it out of there.

Various fixes include insulation blankets (AKA Johnny Blankets), fuel coolers, lower fairing removal in summer, and additional air baffles around the engine.  A search on K100 heat will yield a plethora of information.  First thing I would recommend would be to check the presence and condition of the factory baffling around the engine against some of the parts list illustrations at Max BMW's website.  I think many here would agree that it is not unusual for some of it to have gotten misplaced  over the years.  The baffling won't eliminate the heat problem, but every little bit helps.

Also, make sure the radiator isn't too clogged up with dirt.  Most of the air that flows through the fairing and over the engine gets in there via the radiator.  Reduced airflow will not only cook your shins, but it's tough on the engine as well, especially in hot weather.  Remember that more air flowing through the radiator will remove the same amount of heat at a lower leaving temperature than less air.

RicK G wrote:Hi Ya Baldy welcome to the Knuthaus

I feel out of place in this thread......

Thanks you all for the warm welcome! 

I'll take all the advice to heart as I start the Winter work! I be sure to pre-order all the seals for the Pump...and maybe some of the internals as well.

On the upside of the RT HEAT issue - The Winter test rides will be close to bearable!

You are correct about the winter rides.  Took my RT out yesterday and was cursing the fuel cooler I installed last winter.  I was really missing that warm tank in the 40 degree weather.

Welcome!

Welcome baldshins! 
Your introduction gave me a chuckle as well as a memory.  Way back when these bikes were introduced I rode home from a rally accompanied by another rider mounted on a K100RT. It was summer and were riding through a hot, dry area.  At a rest stop he exposed his legs and I was shocked to see they were actually blistered!  
That helped to put me off of K-bikes for decades as I was very happy with my series of airheads during that epoch.  Now, much later, I've been lucky enough to find a nice K100RS that neither throws off too much heat nor puts my hands to sleep with vibration.  I can't really explain why that is so, I'm just grateful!

So far I've been partially lucky. I added some air wings to direct air onto my legs. So no blisters. As for vibration, I'm not bothered by it on my particular bike. But I am going to balance the carbs as suggested above just for the experience. Love the bike!

brickrider wrote:Welcome baldshins! 
Your introduction gave me a chuckle as well as a memory.  Way back when these bikes were introduced I rode home from a rally accompanied by another rider mounted on a K100RT. It was summer and were riding through a hot, dry area.  At a rest stop he exposed his legs and I was shocked to see they were actually blistered!  
That helped to put me off of K-bikes for decades as I was very happy with my series of airheads during that epoch.  Now, much later, I've been lucky enough to find a nice K100RS that neither throws off too much heat nor puts my hands to sleep with vibration.  I can't really explain why that is so, I'm just grateful!

I have ended up with a bad burn like sunburn on my shins and inner thighs because of the hot tank and the air flow. I went through all the openings in the fairing and under tank trying to seal it and make the air go out the vents but only had limited success. I put a fuel cooler which solved the hot tank but as .75 said the winters are not as warm.

Some of us in another part of the world go bottomless...that is remove the lower parts of the fairing. Where I live the temperature in summer is any where from 30 C to 47C...and dry. I have also moved the upper fairing 35mm forward so I can put my legs behind the fairing and not have them resting on the fairing.

+35 mm fwd appeals!

The mention of vibration got me thinking. My 92LT had the K vibration at 4,000rpm.....the 84RT runs smoother, feels sharper and has no vibration. Wondering what the differences might be, apart from things like balance and injectors.

On heat I did notice one thing with having the fairing off so many times over the years. The air duct from the little intake grille at the front of the radiator on the RT/LT fairing to the air box wasn't properly seated on either bike when they came to me, taking in warmed air from behind the radiator. Intercoolers are used to COOL the incoming air but from behind the radiator its superheated, complete opposite of what you want. Do make sure that little duct is properly seated. Remove the two 7mm bolts at the side of the frame to be able to seat it properly.

In the course of many years of airhead ownership I learned that valve lash and carburettor balance  have a huge influence on the vibration of the boxer engines. When they are properly adjusted the engine runs notably more smoothly.
My experience last summer with an intermittent electrical short showed me that ignition issues impact the perceived level of vibration on the K-bikes.  I rode the machine many hundreds of miles with intermittent interruptions in the ignition and - most likely -  insufficient voltage for the coils to function properly.  The vibration level during that ride was significant, reaching a point where my fingers began to tingle. 
After sorting out the electrical problem(s) the engine has returned to its former, smooth self   There is a world of difference in the machine now as compared to how it ran during that summer tour!
Bottom line for me is that engine balance could make one K-bike feel smoother than another but one should not ignore the possibility of other, more easily corrected factors, playing havoc with the engine.

+1 that.... Lower voltages can also increase the response time of the injectors, reducing fuel flow and leaning out the mix resulting in higher engine temperatures. Injectors can also be affected differently by this depending on their condition resulting in uneven fuel delivery and increased vibration. Coil resistance, solenoid and valve wear, crud build up and corrosion on the connector will impact the operation of the injector.... not to mention the all important earth connection.

Welcome Baldy

Where we live we kinda like the 'toaster' effect on our K75RT - it only gets real hot here for a couple of weeks each year   

Only use our A/C for 2 weeks a year. And even on 'hot' days we usually have sweaters on while sitting around the campfire - not for nothing that they call this area 'the frozen north'

You will love this forum, everyone is kind & helpful.

Cheers from Canada

Lorne & Joanie