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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: TimTyler on January 09, 2015, 01:37:20 PM
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I will be replacing my bike's throttle body assembly in a few days.
My engine has never run as smooth as other K's and the TB's are about the only thing that haven't been overhauled or replaced. Against some recommendations I adjusted the butterfly screws last spring right after a valve job and that improved things a little, but the engine still idles a little rough.
I found a clean '93 TB on Ebay for $50 with the blue paint still on the butterfly and idle screws. I'll also be replacing the pressure regulator and intake manifolds. The airbox bushings and fuel lines are almost new, and the injectors were overhauled about a year ago @ MrInjector.
I was thinking of spraying out the new TB's with carb cleaner. Wish I could find fresh O-rings for the brass adjusting screws and injectors. I'll install a new fuel filter too.
Any advice before I get started?
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this link may help with o-ring search or maybe a caterpillar diesel shop, they use more o-rings than most any one else.
http://www.oringsusa.com/ (http://www.oringsusa.com/)
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I will be replacing my bike's throttle body assembly in a few days.
My engine has never run as smooth as other K's and the TB's are about the only thing that haven't been overhauled or replaced. Against some recommendations I adjusted the butterfly screws last spring right after a valve job and that improved things a little, but the engine still idles a little rough.
I found a clean '93 TB on Ebay for $50 with the blue paint still on the butterfly and idle screws. I'll also be replacing the pressure regulator and intake manifolds. The airbox bushings and fuel lines are almost new, and the injectors were overhauled about a year ago @ MrInjector.
I was thinking of spraying out the new TB's with carb cleaner. Wish I could find fresh O-rings for the brass adjusting screws and injectors. I'll install a new fuel filter too.
Any advice before I get started?
Definitely spray them with carb cleaner. Or dunk them in Pine-sol overnight. O-rings should be standard metric ones. McMaster-carr probably has every one you need, just make sure you use some that are oil and gas safe. Injector O-rings are standard. You can buy them at any Auto store. Just say they are for a 1984 BMW 318i.
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Thx, Koapono.
Looks like the BMW part# for injector O-rings is 13641730767 superseded by 13641286708 and the spec is 7.52 X 3.53. South Sound BMW had one of each and inspected them for me over the phone. The old part# is a dull rubber and the new is shiny rubber with a slightly smaller I.D.. Maybe the new one is fuel resistant Viton. It costs 4x as much too. Mr. Injector now sells bulk packs.
The O-ring on the air adjuster screws has never been available separately from BMW and the $8 screw w/ O-ring is not even available from BMW in the US.
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I got those little o rings from BMW last year. I just used carb cleaner to clean mine, checked the throttle shafts were not worn, and applied some lube on all the moving parts. I like LPS, but other types will work well.
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Injector O-rings are standard. You can buy them at any Auto store. Just say they are for a 1984 BMW 318i.
Cool. Thx.
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A "while your there" tidbit...the o-ring/gasket that's located between the actual block and the throttle body bushing/riser I think can go bad pretty easily, ie. high temps, metal to non-metal contact. May want to replace. One of mine had grains of sand/dirt? visibly on it when I carefully pulled the risers, compared to the others...you may have already replaced at one time, just mentioning. Good winter project!
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I know that O-ring exists for the K1100's, but do the K75's have them too?
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I know that O-ring exists for the K1100's, but do the K75's have them too?
The K75's don't have those.
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donts know abouts o rings... butts i knows a thing or too abouts hoe rings...
j o
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I know that O-ring exists for the K1100's, but do the K75's have them too?
The K75's don't have those.
When I did the throttle body refurb on my '85 K100, I put a small bead of Permatex in there. I decided to do that after I realized that new replacements (as I recall BMW calls that part the "manifold," and there is no separate O-ring) were $50 per each.
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Bill, Is their a place for an o-ring, or did you just add sealant between the two flat surfaces? Oh, I see - you added sealant since you did not restore the manifolds.
I found OEM manifolds a little cheaper at $41 from http://www.ecstuning.com/ES1900132/ (http://www.ecstuning.com/ES1900132/) I suspect the high cost is due to their ability to withstand the heat. Hopefully take delivery in a few days. ECS told me they order them from BMW and then ship.
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There's a place that looks like a place for an o-ring, but it's not. That's where I put the Permatex.
You're getting a good price on new manifolds. Plus, you get the K75 discount: you only have to buy 3 of 'em.
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Wish I could find fresh O-rings for the brass adjusting screws
I bought three for $1.87 each for my K75RT from Bob's not a week ago, PN# 13111257819 "Gasket Ring" aka "O-ring Choke Valve." Same part is used in a bunch of airheads:
http://www.maxbmwmotorcycles.com/fiche/PartsSearch.aspx?&searchtype=partnumber&parts=13111257819%0A (http://www.maxbmwmotorcycles.com/fiche/PartsSearch.aspx?&searchtype=partnumber&parts=13111257819%0A)
I guess if you tell them it is for an airhead they will make an exception ;)
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I bought three for $1.87 each for my K75RT from Bob's not a week ago, PN# 13111257819
Thanks! Ordered.
Manifolds and Suzuki clamps arrived today. Might get to work on this tomorrow if it warms up a touch.
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Old
New
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Tim.
I Like those clamps, wish I had known last year when I did this job. Can you supply details please.
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Tim.
I Like those clamps, wish I had known last year when I did this job. Can you supply details please.
3 x 09402-48208 CLAMP (Suzuki) $3.04
3 x 09402-50208 CLAMP (Suzuki) $3.12
I bought them from Partzilla.com (http://www.partzilla.com/parts/detail/suzuki/SP-09402-48208.html)
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What are the sizes on those clamps?
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Uppers are 50, lowers are 48.
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Thanks Tim
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Uppers are 50, lowers are 48.
Great, thanks. I need to get some clamps on mine. Will order some from McMaster-carr.
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A standard clamp is usually to wide to fit in the groove.
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But there are ones narrow enough from McMaster-Carr which is what I used, but those Suzuki clamps look better.
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The Suzuki clamps are the correct width for the bushings. I use them on my K75. Careful with positioning them properly though; the clamp screws can easily interfere with the operation of the throttle cam because they are so tall and the clamp screws so long. Try to orient the lower clamps like this:
(https://lh4.googleusercontent.com/-5EWwuch3K3A/VLLrajhXstI/AAAAAAAAEPE/KOek_8NMH5w/s640/101_Throttle%2520body%2520boot%2520clamp%2520locations.jpg)
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All back together again (well, almost...)
Runs great with the default 1.5 turns on the brass screws. No fuel leaks. I'm eager to balance the TB's
Didn't take too many pictures. Too cold, dark and messy. I don't have a garage.
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The Suzuki clamps do fit perfectly on both the upper bushings and the intake manifolds. My manifold clamp screws are aligned just like RBM's.
Some things I learned...
I noticed when I removed the old manifolds that the screws were just tight enough to be tight. Low torque. Seems the toque value is just 80 INCH-pounds or about 6.5 foot-pounds. I don't have a torque wrench that goes that low so I just used a small hex wrench and got them past-snug. The new manifolds have a circular raised lip on the bottom side with a groove beside that. The lip must be designed to fold into the groove once tightened. The old manifolds had the groove but were otherwise flat. If I were re-installing old manifolds I'd use some sealant like Bill.
Consequently, my old manifolds were still supple and showed no signs of cracks or wear. They must have been installed not long before I bought the bike at 80k miles even though I don't think they're mentioned in the service history. My existing manifold clamps were 46mm screw types (not Oetiker or Suzuki) so I it would seem somebody had done some work on them.
The easiest way to remove and install the throttle bodies is with the airbox (accumulator) attached. Disconnect at the manifolds and the whole thing tilts in/out easily.
It's possible for the injectors to sit too far into the head's injector ports. They can't be connected properly to the fuel rail like this though. So connect the injectors to the fuel rail and then insert everything into the engine ports. Lube the injector O-rings at both ends with fresh engine oil.
The "axle" (where the TPS connects) on the old throttle body is not centered in it's hole on the TB mounting frame. The replacement is centered perfectly.
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Is there supposed to be adjuster hardware (#3,4,5) on my throttle bracket? There's not. The white plastic end of the throttle cable fits perfectly into the bracket.
Edit: Never mind. I'm an idiot. The adjuster is on the other end of the cable. :hehehe
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Is there supposed to be adjuster hardware (#3,4,5) on my throttle bracket? There's not. The white plastic end of the throttle cable fits perfectly into the bracket.
These three parts for adjusting the cable is mounted at the upper end.
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Thx, Inge.
Tried to balance the TB's today. Couldn't get the idle down lower than 1300rpm. Throttle and choke cable both have a little freeplay. Idle set screw on TB is touching it's mark. TPS is disconnected from TB. I even screwed the brass screws in almost all the way. It's weird. If I turn all three screws out one turn the Carbtune balance is stair-stepped at 1300 rpm and gets better as rpm's go up. Carbtune looks grreat at 4000rpm and the engine sounds smoooooth.
I took a propane torch with a short hose all over the TB's and couldn't get the rpm's to change. Air must be getting in somewhere though.
Took it out for a spin and a fill-up. Feels great except for the high idle.
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For future reference y'all, Bosch injector o-rings are widely available and cheap. Online or your LCAPS should have them for under $1 each.
NAPA has 'em for $7.19 at my local http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Fuel-Injector-Seal-Kit/_/R-MPF312087_0374829705 (http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Fuel-Injector-Seal-Kit/_/R-MPF312087_0374829705)
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Thanks, Tony. I'll try that tomorrow.
This new-to-me TB has blue factory paint on the main throttle adjustment screw too. Is that unusual?
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Installed fresh injector o-rings from Napa this afternoon. That definitely helped.
Attached Carbtune and could see that there was still a hint of less-than-smooth coming from cylinder #2.
Removed the spark plugs and they all looked about the same. They have about 25k miles on them. But the spark plug gaps were crazy-big! :mbird Like almost 1.00mm. They're supposed to be about 0.65mm. Installed fresh plugs, properly gapped. Note to self: Change the plugs once a year, which for me is about every 10k miles.
Runnin' smooth. TB's balance at 1200rpm and keep balance up at least as far as 4000rpm.
I'm calling this job done.
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:easy: Peesy!! :yippee:
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I don't want to hijack this thread but here is some interesting data regarding plug electrode wear. According to NGK, electrode erosion in four stroke engines is 0.01~0.02 mm/1,000 km (0.00063~0.00126 inches/1,000 miles. In wasted spark systems the wear is twice as fast. 10,000 mile intervals is a good choice for at least checking the gap.
I don't know if it is the Bosch plugs or something else that causes these bikes to eat plugs, but my K75 opened the gap from .025" to .039" on the Bosch plugs in only 8500 miles. Always had good results with NGK in previous bikes so am trying a set of D7EA's for 2015 to see how they wear. Just put them in and did a TB balance, so far the engine runs very smooth with good balance with them. Will have to wait for some warmer weather to really see how they run.
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I don't want to hijack this thread but here is some interesting data regarding plug electrode wear. According to NGK, electrode erosion in four stroke engines is 0.01~0.02 mm/1,000 km (0.00063~0.00126 inches/1,000 miles. In wasted spark systems the wear is twice as fast. 10,000 mile intervals is a good choice for at least checking the gap.
I don't know if it is the Bosch plugs or something else that causes these bikes to eat plugs, but my K75 opened the gap from .025" to .039" on the Bosch plugs in only 8500 miles. Always had good results with NGK in previous bikes so am trying a set of D7EA's for 2015 to see how they wear. Just put them in and did a TB balance, so far the engine runs very smooth with good balance with them. Will have to wait for some warmer weather to really see how they run.
Those are probably car figures. Our bikes fire more than twice as often as a car for a given distance. And they are wasted spark. So between 12 and 24 thousandths. That being said, I should probably check the plugs on my bike when I clean the GPIS tomorrow.
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With three coils on the K75, are these ignition systems running on wasted spark?
I can understand the difference between a car and our bikes. My K75RT is like driving around in nothing but 1st and 2nd gear in my car.
Would be nice if we could get a platinum or iridium plug equivalent in life to what are being used in cars. Since the EPA regulations of the late 80's all of my cars have run at least 100k miles on a set of plugs with no loss of performance or change in emissions. Some of these plugs have lasted nearly 200k miles.
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With three coils on the K75, are these ignition systems running on wasted spark?
The hall sensors is on the end of the crankshaft, ie...you have a spark at every revolution.
Would be nice if we could get a platinum or iridium plug equivalent in life to what are being used in cars.
If I remember correct :hehehe I've read on other forums that Denso have a iridium type that fits old K's.
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I took the newly tuned TB's on a cold, 60 mile round-trip slab ride this afternoon to pickup the little idle-screw o-rings from the dealership.
I am happy to report that the engine has never run as smooth as today. My handlebars have always had a little bit of vibration but that's totally gone now. The mirrors were free from any vibration at all speeds. Looking forward to installing some hand warmers and hitting the road in the spring! :riding: