R65 Siebenrock Kit

[tlangman4]

Hi everyone-

After my recent purchase of an ‘81 R65, I am in the middle of an overall evaluation process of work that needs to be completed. The odometer indicates 38k, but the bike looks a lot more tired than that. A top end rebuild appears necessary, and perhaps other engine work as well.

I have been considering the Siebenrock 860 kit as an alternative to the stock top end. After searching for comments regarding the topic on this forum, there have been indications from a few who have used the kit that have indicated it to be a solid upgrade. Yet, there appears to also be an issue with the squish area due to the piston shape, etc.

I am interested in hearing from anyone who can provide more long-term detail regarding this issue, and what the possible effects this may have on engine life, or other potential concerns that exist with the kit.

Thanks again for all the help and advice!!

Tom

 

[20774]

I only have 10K miles on the Siebenrock top end for my /7...so far so good. As for piston shape and head configuration, I find it hard to believe that Siebenrock wouldn't have researched that. You could call Ted Porter at the Beemer Shop and get his input.

 

[179212]

Hi everyone-

After my recent purchase of an ‘81 R65, I am in the middle of an overall evaluation process of work that needs to be completed. The odometer indicates 38k, but the bike looks a lot more tired than that. A top end rebuild appears necessary, and perhaps other engine work as well.

I have been considering the Siebenrock 860 kit as an alternative to the stock top end. After searching for comments regarding the topic on this forum, there have been indications from a few who have used the kit that have indicated it to be a solid upgrade. Yet, there appears to also be an issue with the squish area due to the piston shape, etc.

I am interested in hearing from anyone who can provide more long-term detail regarding this issue, and what the possible effects this may have on engine life, or other potential concerns that exist with the kit.

Thanks again for all the help and advice!!

Tom

I have a friend with r 65 purchased new his odometer says 20 or 30 thousand but is off by 200,000. ( odometer has rolled over twice)

 

[Lendog]

I picked up a r65ls that’s been sitting and have a 77 r100rs engine but I was concerned about the reduced lean angle from the wider engine, my first bmw was a r90/6 and the valve covers were dragging regularly,
I have a k1300gt and a 1000 Guzzi that are awesome but heavy, I am getting old and considering selling the heavy bikes, keeping my 74 Commando and installing a 860 kit on the r65, I am curious about the 860 performance, I know the Pridmore engine had a reduced stroke as well

 

[stevenrankin]

I have been on the fence for awhile in regards to buying the 800 to 1000 kit. Talking to Ted, a few years back, as long as I use the original heads on my 800, there is no issue with buying the upgrade kit.

Still, before I drop the hammer and order, I will make a phone call to Ted and double check. St.

 

[skibum69]

I have heard going to a double plug setup is good for the displacement upgrade.

 

[Lendog]

I pulled my r65 out of the marketplace today, I miss my r90/6 and need a airhead back in my life

 

[Lendog]

I have been on the fence for awhile in regards to buying the 800 to 1000 kit. Talking to Ted, a few years back, as long as I use the original heads on my 800, there is no issue with buying the upgrade kit.

Still, before I drop the hammer and order, I will make a phone call to Ted and double check. St.

the 800 and the 1000 have the same stroke, the r60 & r75 also have the same stroke, the r45 & r65 are short stroke

 

[stevenrankin]

So the reason I am on the fence is because I am looking at two different ways to approach my upgrade. The first is to by the 800 to 1000 conversion kit and it is still questionable in my mind if the increase in power is worth the cost as this approach sticks with the small valve heads and small carbs the 84 R80RT came with. Or swap out the small Bing carbs for DelOrteo carbs. EME has the carbs on hand, I am not sure about cables.
The second option is to go with the 1000cc replacement kit, substitute the small valve heads with big valve heads from an earlier year bike. Get rid of the small Bing carbs and install 40mm Bing carbs. In this case I am not quite sure what plumbing I would need to connect the carbs to the air filter. I do NOT want to resort to velocity stack air cleaners. Functionally, this upgrade would be the same set up as my 78 RS with two exceptions, one nikasial cylinders and 38mm exhaust pipes versus the 40mm pipes my RS had.
I have the parts on hand for either conversion.
I love the 800 until it comes time to pass a car, it is not as quick as my RS was. There is no substitute for HP and torque. St.

 

[PGlaves]

I love the 800 until it comes time to pass a car, it is not as quick as my RS was. There is no substitute for HP and torque. St.

The substitute for horse power and torque is good judgement.

 

[Lendog]

So the reason I am on the fence is because I am looking at two different ways to approach my upgrade. The first is to by the 800 to 1000 conversion kit and it is still questionable in my mind if the increase in power is worth the cost as this approach sticks with the small valve heads and small carbs the 84 R80RT came with. Or swap out the small Bing carbs for DelOrteo carbs. EME has the carbs on hand, I am not sure about cables.
The second option is to go with the 1000cc replacement kit, substitute the small valve heads with big valve heads from an earlier year bike. Get rid of the small Bing carbs and install 40mm Bing carbs. In this case I am not quite sure what plumbing I would need to connect the carbs to the air filter. I do NOT want to resort to velocity stack air cleaners. Functionally, this upgrade would be the same set up as my 78 RS with two exceptions, one nikasial cylinders and 38mm exhaust pipes versus the 40mm pipes my RS had.
I have the parts on hand for either conversion.
I love the 800 until it comes time to pass a car, it is not as quick as my RS was. There is no substitute for HP and torque. St.

I hear ya, with the big valve heads & pumpers it will want to be ridden differently, the Bings can cause chicken strips if you’re not paying attention

 

[Lendog]

I rode a r90/6 for 19 years and when I rode a r80rt I was surprised how peaceful it was, all r80’s need the 1000 upgrade

 

[stevenrankin]

LOL, Paul, I get it, haven't had a oh %$^ moment yet with the R80, I have to wind it up a bit aways back with plenty of room. The RS required less.
Caution has kept me out of trouble for the most part. St.

 

[melville]

I've got an R100/7 with 32s and an R100RS with 40s. I don't have much seat time on the RS, but the /7, essentially an RT with a Lufty fairing, has no problem getting around traffic, even two-up. If you want to go 1000cc, I would suggest keeping the R80 heads, especially if you can get a healthy bump in compression.

 

[Lendog]

the small valve heads produce a quick throttle response and a little off the top end that many people are not aware of

 

[Lendog]

the 800 and the 1000 have the same stroke, the r60 & r75 also have the same stroke, the r45 & r65 are short stroke

for clarity the r50, r60, r75, r80, r90,& r100 have the same 70.6mm stroke, the r65 has a short stroke, 61.2mm with the r75 bore

 

[stevenrankin]

LOL, thanks for the information regarding this change, the more I get the more I lean toward one way of going or the other. Finances are not an issue as I have most of the parts on hand except of course the jugs and pistons. Which ever way I go will determine which kit to buy.

I can say prices for jugs, and pistons has come down over the years. If things had been cheaper back a number of years and the 800 to 1000 kit had existed, I would have used it when my R80, needed its first rebuild. St.

 

[Lendog]

I am a mechanic and don’t have much money but the “Plug & Play” is sweet for me because I don’t make money working on my own machines, also BMW engines are tight and it takes very high quality machining equipment and dedicated operators

 

[Lendog]

for clarity the r50, r60, r75, r80, r90,& r100 have the same 70.6mm stroke, the r65 has a short stroke, 61.2mm with the r75 bore

the r65 stroke was supposed to say 61.5mm,
FFS again

 

[20774]

the r65 stroke was supposed to say 61.5mm,

You can go back and edit your post to correct it for the future!