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

adventurco · Oct 5, 2018

Well, no luck on that "fix"

Its running super lean at idle. Won't go beneath 2k RPM and still backfiring through the airbox so its gotta still be leaking vacuum somewhere either in the carbs or the intake manifold.

There were some cracks inside the intake boot where the lip of the carb seats, but nothing on the outside. No used intake manifolds available and new is $127.

canyoncarver · Oct 5, 2018

Liquid electrical tape.

adventurco · Oct 5, 2018

canyoncarver said:
Liquid electrical tape.

Hmm. Probably worth a shot. I wonder if that stuff can tolerate the heat? Stuff I looked up on Amazon had a heat tolerance up to 175*F.

trek97 · Oct 5, 2018

Maybe.
Plasti-dip is good for 200 degrees on their website

trek97 · Oct 5, 2018

Plasti-dip also makes Re-rack. A fix for dishwasher racks...but don’t give a heat tolerance.

Maritime · Oct 6, 2018

Get the self fuzing tape its silisone, hi heat and fuel safe. Wrap that around all thw rubber it will sealmit all and stay pliable.

bvander · Oct 6, 2018

This stuff.
http://www.vintageconnections.com/Products/Detail/133

adventurco · Oct 8, 2018

Ordered some of the self-fusing tape from Matt. Will wrap the intake boot up as well as I can and see how it fares. If it improves or fixes the issue I'll go ahead and order a new intake boot.

Will report back.

irk miller · Oct 8, 2018

Intake boots get too hot for self fusing tape. It'll last a few days, tops.
*unless it's Pyrosil

irk miller · Oct 8, 2018

Also, don't forget, these carbs are unfortunately prone to have issues if the air box isn't in perfect condition. You can be lean because of the air box side, not just leaky intakes.

irk miller · Oct 8, 2018

Just to be sure: Did you thread the crank lock in when you pulled the top end to rebuild it?

irk miller · Oct 8, 2018

Also, make sure you've been here: http://faq.f650.com/FAQs/BackfiringFAQ.htm#Airbox%20to%20Exhaust%20Header%20Line

adventurco · Oct 8, 2018

irk miller said:
Just to be sure: Did you thread the crank lock in when you pulled the top end to rebuild it?

Yessir. Checked and double checked cam alignment, turned motor over a few times and checked it again.

irk miller said:
Also, make sure you've been here: http://faq.f650.com/FAQs/BackfiringFAQ.htm#Airbox%20to%20Exhaust%20Header%20Line

Been through there a few times. I am convinced I need to deal with the intake boot before moving on, as spraying starter fluid around the intake boot caused surging. That and the high idle condition lead me to believe it is an issue on the intake side rather than exhaust gaskets etc, most of which I have checked.

adventurco · Oct 22, 2018

Nothing super exciting to report. I pulled the carbs completely apart for the 100th time and went through them with a super fine tooth comb. Threw the bodies in the ultrasonic cleaner, along with the brass. Replaced all 4 o-rings in each carb. I noticed that the PO had placed the plastic spacers on the needles above the circlip, rather than below (toward the slide body). So I reassembled those correctly. Set float heights to 14.6mm and set the mixture screws to the stock setting 3.5 turns out.

Hurco550 · Oct 22, 2018

I hope that's all it needed man. TIME TO RIDE!

adventurco · Oct 24, 2018

https://youtu.be/ZjLq0EIvXCs

She’s running great after the thorough go-round with the carbs. I’m sure it was a combination of the incorrectly assembled needle spacers and crusty old o-rings.

Next up is to address the chatter in the clutch. I pulled the left side cover off again and removed the clutch assembly for inspection. I checked all the fiber discs and pressure plates on a flat surface, and everything looked great. They were pretty sticky as there was hardly any oil between a lot of the plates. It’s been a few years since this bike has moved under its own power so that’s not surprising.

I wiped everything down, generously oiled up all the discs and reassembled. Clutch springs all measured right where they should be. I need to grab the correct moly grease for the clutch activator rack & pinion, then I’ll slap everything back together and test it again.

I drained the oil before pulling the side cover, there was a tiny bit of residual crap in the bottom of the OIF tank from the leaky head gasket, but no more nasty chocolate milk oil!

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