1997 BMW F650 ST Bluebird - Repair, maintain, ride.

The Jimbonaut

Active Member
Me (KLR) and mate (DR) went for a midnite ride around the city last night - dual sports on quiet city night streets is f-u-n. You're gonna have an absolute riot on this thing mate, hope you're in the saddle soon!
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Was able to get the cooling system filled up, oil system bled and primed and filled up with oil. Hooked up the bottle and she fired up after 2-3 cranks. Seems to be running well. A little backfiring at low RPM but I may have the idle speed set too low. It’s also puking petrol through the T inlet to the carbs so I’ll have to pull the carbs again and adjust that to fix that issue, may be contributing to the backfiring as well if it’s running too rich. I also had a couple of vacuum lines (emissions stuff I think) disconnected so I’ll straighten that all out later.

https://youtu.be/GzjlCsvvcVE

Going out of town for the weekend so I’ll get back on it next week. Fix carbs, reinstall the fuel tank and seat and we should be on the road.

Getting closer!



Sent from my iPhone using DO THE TON
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
I tried to take it for a test ride yesterday, but its running like garbage and backfiring like crazy. Found some vacuum leaks around the carb boots so I guess I have to pull them off again and check the intake boot. Will also check the exhaust headers for leaks, the nuts on the studs for the exhaust only call for 10 nm torque which is barely even tight so I may snug those up some more now that its been heat cycled a few times.

ALSO. I pulled the clutch in and something popped in there and I completely lost the lever. I hope nothing broke :mad:
Going to have to pull the LH cover off and investigate. Probably going to have to drain the coolant again to get in there. ::)
 

Maritime

Active Member
SO this is a big single with 2 carbs and 2-1 intake? Can you swap it out to a single carb intake? That would have to be easier to tune etc? Or maybe not. but one thing I know about German shit, it's usually over complicated when it doesn't need to be.
 

The Jimbonaut

Active Member
Maritime said:
but one thing I know about German shit, it's usually over complicated when it doesn't need to be.
Aint that the truth. I took apart a BMW mid 80's K100 throttle assembly at work the other day, and there was some kind of chain and gear assembly in there connected to the throttle cable. Great when it works, bit of a nightmare when it went south.
 

Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
its funny you say that, and I wonder where the "turn" came in design, because my 76 r90/6 BMW is really one of the most well thought out machines to work on that I've ever owned. Now my buddy drives a late model (2010 I think) bmw something or other car, and talk about an overcomplicated piece of kit.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Yeah Mike, its a big single with 2-into-1 cylinder intake and 2 Mikuni BST33's. I know others have fit different carbs (irk's TMs) but not sure whats out there on single carbs.

Regarding the simplicity - the motor is made by Rotax in Austria and the entire bike is built/assembled by Aprilia in Italy. That should say a lot ;D
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Maritime said:
SO this is a big single with 2 carbs and 2-1 intake? Can you swap it out to a single carb intake? That would have to be easier to tune etc? Or maybe not. but one thing I know about German shit, it's usually over complicated when it doesn't need to be.
I have a 2-into-1 intake for these. Just need a carb to fit the wishbone in the frame. The intake is off of a DS650 Bombardier. This Rotax motor is incredibly reliable, very well engineered, and not complex at all.

If you popped the clutch when you pulled the lever, make sure you have the adjustment right. That's what it does when the lever is in the wrong starting position.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
irk miller said:
I have a 2-into-1 intake for these. Just need a carb to fit the wishbone in the frame. The intake is off of a DS650 Bombardier. This Rotax motor is incredibly reliable, very well engineered, and not complex at all.

If you popped the clutch when you pulled the lever, make sure you have the adjustment right. That's what it does when the lever is in the wrong starting position.
You mean the lever/arm on the LH side cover (where the cable end attaches to?). It may need to be turned another notch.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
As you know, since you had to replace it, the clutch actuator is a worm gear. The actuator shaft (the part that the cable turns) needs to be in the engaged position when the arm and cable is put on so that when you pull the lever it actuates. Before you put the arm and cable on, you can spin the worm gear completely in both directions all the way to the end of the gear, so it's easy to get confused where it needs to be to hook up the cable.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
irk miller said:
As you know, since you had to replace it, the clutch actuator is a worm gear. The actuator shaft (the part that the cable turns) needs to be in the engaged position when the arm and cable is put on so that when you pull the lever it actuates. Before you put the arm and cable on, you can spin the worm gear completely in both directions all the way to the end of the gear, so it's easy to get confused where it needs to be to hook up the cable.
Yes, I realized that the first two times I put that back together. The clutch seemed to engage/disengage as normal before I attempted it while the bike was running. Now there seems to be some slop between the actuator and the actuator shaft (which doesn't seem right at all). I'll post a video later. I really don't want to drain the coolant and pull the entire cover off again.

Is there a specific position that the shaft needs to be at when the cover is installed? Or is it all just relative to the arm and cable once its all back together?
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Don't give up on this thing. They're super reliable once all sorted. You just bought into an abused bike.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
So the last time I ran it, there was some major vacuum leak issues going on. I hate pulling the carbs on this thing so I've been putting it off.

Last night I pulled the carb rack and removed the intake manifold to check it for cracks. Some minor cracking inside the boots but nothing that went all the way through and the rubber is still soft and pliable. I smeared a thin coat of Yamabond between the manifold and the head and reinstalled it. Normally I would just do 1 thing at a time but if I never pull these carbs again I'll be happy. So I blew out the jets and passages again, and double checked the diaphragms for cracks. Everything there checked out, so I put a thin coat of Yamabond on the mouths of the intake boots where the carbs seat. Re installed carbs, I'll let the Yamabond set up and test fire after work today to see if its still leaking.

If it is I guess I'll source a new intake manifold.
 

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