Monday K100 Cafe Prototype Ride - Throttle Troubles
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- เผยแพร่เมื่อ 13 ก.ย. 2024
- Today I ran some errands before I go ahead and put the K100 back away to be finished. I washed parts of the bike off and got some slide shots for the next build episode. The bike was running great the previous few days but it seems to have developed an issue with accepting throttle. I imagine some worn out old rubber may have just worn even more under stress lol.
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![[Ep 06] 1986 BMW K100 Cafe Racer Project - Will It Run?](http://i.ytimg.com/vi/EXGk_YTTCi8/mqdefault.jpg)
![[Ep 06] 1986 BMW K100 Cafe Racer Project - Will It Run?](/img/tr.png)
![[Ep 14] 1986 BMW K100 Cafe Racer Project - Wrenching Endgame](http://i.ytimg.com/vi/jRToB3lNU0U/mqdefault.jpg)
00:10 God the damn backfire knocked the gooch juice off my chest hairs
I laughed way too hard at this 🤣🤣
at first i thought it was a clunk between 1st and 2nd and i was like oooh that doesn't sound good, then i realised its the damn backfire and i was like yeeeahhh this is awesome!
Brotha, i am thoroughly impressed with the progress of the brick. When you first bought this thing, i was skeptical on how the turnout would be but im loving it. Good to see someone thinking outside the box and taking some chances. Im loving what i am seeing.
Replace the Coolant Temperature Sensor if it has one, its BOSCH Jetronic which is very prone to sensor failures. Keep 3 or 4 handy as they fail often and suddenly and make it run like shit.
I highly recommend converting this to CARBS or aftermarket fuel injection. The bosch system used on these bikes (and VWs/bmw cars of similar vintage) is SHIT and is really flaky.
You may also have a bad Mass Air Vane (the big box attached to the intake tube, between the throttle body and the filter). These also suck and are prone to mechanical failure. Good news, is that 1988-1992 VW Golfs and Jettas use the SAME unit, as do many BMW cars of the same era. Not hard to find em.
The ECU is also sensitive to HEAT, so keep it away from the engine (i noticed you mounted it to the block in the last video, bad move). Make sure the ECU has a REALLY REALLY good ground strap, as a bad ground strap will cause running issues, or will COMPLETELY fry the ECU, causing your injectors to stick OPEN and flood your engine with gas, causing it to hydrolock. This has happened to me personally and is not a fun time.
Thank you Sir, thats what i wanted to write as well. Some older Mercedes (w123, w124, w201) share the same fault-prone technology..
Wow, good info bro
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them. The ECU is mounted under the seat so it's isolated from heat. As far as everything else goes, I'll keep it all in mind. Id rather keep the stock injection to make things simple
@@Theillestrator1050 , your on right track, my 91 K75S runs like a top with it's original fuel injection system. During build I took apart and cleaned all hose couplers on throttle bodies and have not had any problems for 3yrs.
See you at 2wheel Tuesday's.
@@Theillestrator1050 Good find, these systems REALLY don't like unmetered air.
I still recommend, at some point later down the road, switching to carburetors. These systems have left me stranded far too many times for me to want to trust them again. In the long run, carbs will be the simpler solution. For now though, if you can figure out all the problems, it should do.
So badass this thing runs and drives. Very nice work. Keep it up man
Thanks, that's the plan.
Had a 1993 K75 and it was having issues getting enough fuel. Pulled out the fuel pump and there was quite a bit of sludge in the bottom of the tank. Drained and cleaned the tank and replaced the screen on the fuel pump and problem solved. Stellar build!
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them. The inside of this tank is honestly pristine... like surprisingly pristine but it wont hurt to check when I put the bike away
Oh hell yeah, I just watched ep 1-5 yesterday. Can’t wait to watch this after work
Well don't forget about episode 6 😉
You can spray carby cleaner on suspect hoses while the bike is running and listen for a change in revs. This can help narrowing down leaks. Good luck!
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
It does appear you have developed a air leak somewhere. Even on Fridays video you can hear the popping which tells me it's running a little lean. You have done a great job so far so I have no doubt you will get it all corrected and running right. Hats off to you for taking on a project like this. It's no small feat and so far it's a job well done ! Keep us all posted on what you discover and just keep up the great work I'll .
Thanks for the praise man, I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
Reaching to the left bar with your right hand is the perfect recipe for a bad day, speaking from experience :D Good vid, love it :)
That seat tho 😅 looking forward to the upgrade on that eventually 😊
Also getting closer to 50k! 😲
The seat is a work of art man 🤣
@@Theillestrator1050 modern art. Brutalist, by the look of it.
All the joy of riding a bike turns into rage when it wasn't running well. I've been there LOL
Much like Frankenstein’s monster, IT’S ALIVE!!! Great work :)
Thanks, it's pretty fun to ride with those short gears
It was nice seeing the brick up close yesterday. Looking forward to seeing the footage of the show. It was a good time and i learned more about bikes than i thought i would just by being there.
Thanks for coming out fam, it was a good chill time!
Looks a lot better without fairings! This build was 💯💯
Beautiful Job! Don't need to mention the seat, Because I know you will fix it and it is going to look nice! Congrats Buddy!
Yeah eventually lol. Thanks
I love the way it looks and sounds (when it's running properly) lol. Great job. Be safe out there, your squidding it!
really surprised you have no speed cameras in NY. wait till they come, your days of tearing the tarmac will be limited!
lovely job!
Oh no we have many speed cameras. The thing is, I know where they are, and I live in the hood so there aren't as many as in nice areas.
This made more then my day 💚👍
This is ending up really good, regardless of problems. Are you going to use a Motogadget gauge?
F’king badass!! the illest.... this is very inspiring!
I love that blast when you turn off accelerator. Absolutely the same as my k75!
Check the tank for disintegrated rubber and metal. My K-75 had similar symptoms. Was a falling apart fuel sending unit. Clogged the filter and injectors.
dude it sounds amazing ! sounds like a rally car with the open exhaust
Sounds kinda automotive right? Lol
Even though it’s running weird, it sounds amazing.
Dude, you ever imagine yourself being an "actual" (whatever that means) bike builder ? I'm a product designer with a knack for bikes, for like the past year or so I've been really researching stuff and watching videos on builds and how they work and history and all of that, mig / tig welding and plan on doing the kind of stuff that you're doing after i get my license. I feel like its a good place to start and build. Do you feel like its a far away dream or do you think it's an actual possible plan to go further into the future with ( being a bike builder). Thanks dude, really enjoy your content ! Keep it up! :)
The backfires and throttle response loss all def seem like throttle body issues, read build the throttle body assembly
I plan to rebuild it, but if it comes to that, then im not doing it until way later.
@@Theillestrator1050 www.motobrick.com/index.php?topic=364.0 That guy mentions ways to tell.
prrrraaaaaamm plop plop plop.... my favorite song
That shit sounds mean my dude. The bike honestly has that industrial/drifter type look right now. Ride safe brah
Thanks, if I didnt have the FZ1 I wouldnt mind riding this as is for a little
sounds like an old mercedes, bangin!
Awesome man! Get that fueling figured out and it’ll be a ripper!
its the engine breather z tube or air leak above the throttle bodies.
the rubbers often look ok. but the age suggests they are overdue
Awesome build so far dude! On the k100 there is a little tube that goes between the plenum and the crankcase, if it’s cracked or missing it will run like garbage, also being that your bike has so much filth when you got it, I’d double check the temp sensor and it’s plug to make sure they are clean, mine were corroded and it made the bike run bad. Stick some dielectric grease on your connectors to stop them corroding further. Best of luck!
I've already replaced that breather tube but I'll look into the temp sensor.
Yeah! Usually, when something gets gradually worse on a motor vehicle, it's either rubber or copper. Something's wearing out fast!
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
As soon as I heard that pop at 0:12 I knew this BMW was sick. Still, it’s an awesome ride!!
Holy crap!! She really does sound angry. 😳😳 That's awesome dude!
Sorta like a car almost right? Lol
Mad props son
I'd say your about right in your diagnosis of the throttle body could be leaking. The popping is a sign of a lean condition. It could just be lean and need to be jetted since your running pod filters too.
Check out the fuel pump. Boot around the throttle body. Fuel pressure regulator. Injector O-rings. check all the vacuum hoses. Mine was the fule pump not giving enough fuel.
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
Sounds like my bike when the ignition wasnt firing correctly. Nice build man 👍
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
I helped my buddy remove the muffler of his k100, it ran like total shit afterwards.
It might sound cool but that engine desperately needs backpressure.
Loving your videos and insta updates man. Massive inspiration for my own k100 build. Gotta get me one of those flying brick stickers thogh! Cool as f*ck! Keep it up man, true shed build! 👍
I love the whistle the engine makes, it sounds like a turbo spooling down. lol
These engines are very whistley lol
Sounds like it's running lean check for vacuum leaks .
I was going to say its crackling because its running lean
Sounds like it's not firing properly on all cylinders tbh
Yeah man. Too bad she's not running great now but, she sounds great when running properly. I just wanted to mention, I noticed ya using the choke to keep the engine running and it reminded me of a similar issue on my dad's bike. His Yamaha has a bad carb-boot that doesn't seal nicely against the head. The result is air sneaks through the little gap, causing one cylinder to run lean. He diagnosed the issue by spraying starter fluid near the boot with the engine running, listening for the revs to temporarily increase. Until he fixes the boot, he has to use the choke while he rides. However, his bike also runs better once thoroughly warmed up. Maybe none of this applies to the K100 seeing as it's fuel injected, but maybe it could help ya diagnose what's wrong. Good luck, my dude.
I'll definitely test for leaks using that starter fluid test. Good idea.
That backfire though
I had a similar thing happen to my 2003 CBR600rr and it was the Throttle position censor.
You'll get there. Love the videos.
Oh heellllll yeah been waiting for this
Plug wires might be arcing out somewhere... good to see it moving under it's own power. Bound to have bugs to work out on a custom build.. nice job 👍
"It's a good sound, though, I will admit it" Lol damn right
She looks awesome bro! Is it dumping fuel? I'm constantly looking for older bikes, and then I got stranded on my pops' cb900, which is nearly flawless. It kind of put me off a little.
Left you stranded how?
Miko Polo yeah how’d it leave you stranded
Nah it's not leaking any fuel, it's likely gonna be something with air
Dam dude almost 50k ! i swear u had like 5k last time i saw u
Sounds kinda like an old Datsun 510. That bike is looking awesome! Sometimes if you spray staring fluid around the throttle bodies while it's running and you can hear a different rpm the throttle bodies are definitely leaking. I think you can use smoke too to see if it's getting sucked through.
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
Nice! You'll get her dialed in. Probably a pain finding new parts for that thing. Good luck brutha. Thanks for the awesome content!
Sounds like a rally vw beetle. NOICE!
Gotta fix those fork seals if they're leaking. It'll get on your brakes and they'll fail. It's a bit of a job, but if you pull them off and take just the legs and new seals to a shop it shouldn't be too expensive to have them do it. Be good to get fresh oil in anyway.
And yeah, if it runs rough at low RPM and struggles to take throttle but does okay higher up it's probably got a vacuum leak somewhere. Spray some carb cleaner at the intake boots while its running and if the revs go up then you've found your leak.
I'd check the fuel filter also. Could just be clogged from all the junk that was sitting in the fuel system.
nice ride bro....
spray some starter fluid around your throttle bodies/intake/ and listen for a spike on RPM fastest way to find vacum leaks
Pretty cool exhaust sound. Is that aftermarket exhaust pipe on your bike? I remember hearing that exhaust sound a few times in the Bronx. I think some Ricers have that same exact exhaust sound from your bike.
The exhaust is just the stock headers but with no muffler. This engine is pretty automotive in nature so that's no surprise
might be something simple like over heating, just have to keep moving.
Your swing arm seems to be angled down more than the retrorides bike making the back of the bike sit higher. It's also noticeable in the horizontal lines of the engine because they are angled forward also. Is this from using a different shock than the retrorides guys? Do they offer the exact shock that they used?
Ah, the good old Bosch L-Jet. I'd call it impossibly cranky if it weren't so reliable. That it runs better after key-off and restart points to some variety of heat issue.
Fuel pump may be overheating. When the bearings start to go they'll run ok for a bit the fall off as they warm up. Ignition coils start to suffer heat soak as they age too. They'll test ok cold on the bench, but as they warm up resistance spikes and they go flat till they cool off. ECU will do that too if you relocated it someplace hot. Heat = resistance = voltage drop across circuits. That computer's likely older than you are and won't take kindly to such things. Don't know if you have an idle air control module, but if you do it wouldn't hurt to clean that out as well. And as always, check both sides of all your electrical connections for corrosion, and keep that old wiring well away from heat.
I'll take note of this info, but I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
I'm not an expert but it does sound kinda off. cant help you as to why but i really cant wait to see this bike at its 100%
its finally here
beautiful
For now, but then it will go back to being built
So, after removing the "lunchbox" (stock speedo/tach), how did you address all of the problems that entails? These bikes won't even charge the battery without that assembly connected.
Sounds so fucking good
🤟🏾😎 when it's running right atleast lmao
Seawolf is popping (*POW*!) on the overrun because I've got exhaust leaks at the joints to my mufflers. You might also consider grit in the tank. (Add an in-line fuel filter?) That's a thing that can develop and degrade things too lean after initial nice behavior.
Nice, muscular visual composition to that K, and some beautiful gestural sweeps. It feels satisfying, delicious to look at. Nice work.
And, SHIT, I coulda gone to that bike show! Duh, duh, duh.. smh.
Thanks man, as far as the problem goes, I've found tears on the throttle body hoses that react to starting fluid being sprayed directly onto them
Sounds like you have either a faulty coil or sparkplug.
Strangely it looks pretty good in the "unfinished" state. Maybe paint the tank matte black and get a proper seat made, other than that it's good to go.
It's a nice rough and tough look... if it were my only bike I wouldnt mind running it as is for a few more weeks but I can't really do that
Check your air fuel ratio, it's the usual issue for popping
You might want to look into replacing the ignition coils. This repair may fix a whole lot more than your throttle issue!
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them. I'll look into the coils when I'm tearing it down again though
@@Theillestrator1050 Coils are kind of a bastard, because they can be intermittent. I was fighting what I thought was a carb tune issue for a couple years that turned out to be a coil going in and out. It checked out good in the driveway, and read the right resistances. But take it into a shop with fancier tools, and it's bad. Those are often a thing to get new rather than new old stock, because the NOS ones can be getting bad on a shelf and tend to be way over priced.
@@GunFunZS I had an old Triumph Trophy that used to emit a whole plethora of symptoms upon weak coils. It would range from backfire, to stalling, to losing my tachometer. I actually had the same type of symptoms with a kinked vaccum line as well though. Old bikes are fun. They keep us on our toes!
Yeah that sounds like a very erratic throttle lean running condition, happens with vacuum leaks. Very vague, unresponsive, high idle, mind of it's own. Probably 16:1 or greater air/fuel with leaks. Gets worse when the engine and intake heats up.
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
@@Theillestrator1050 Sounds logical. I know mechanics often use propane gas from an un-lit torch to do the same thing.
horay the KDF bike is back
i love it
timing maybe with all the popping and backfiring?
it sounds like a turbo 4 banger with straight pipe exhaust some times
like an srt4 neon lol
I missed any video where you messed with the carbs and synced them. I guess the intake is the same box, but I would just guess lean, main jets have to go up in size. I turned nice chrome blue once, it sounds like mine did.
No carbs on K-bikes.
@@KalebWR Sorry, totally missed that part, now it's looking better because I hate carbs.
@@KalebWR Went back to look, Episode 2, he mentioned the fuel injection. I'm getting old.
Sounds like it could be a couple things
Vacuum leak, throttle body boots, Ccv
Hall sensor oil leak in the timing chain cover or even bad hall
Boiling fuel (unlikely but you said it’s hot and some of these bikes have no vent)
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
Definitely sounds like its got some sort of air leak. For sure start at the throttle body vacuum lines. Thing looks dope though!
Thanks, poor throttle response would be a result of lean running right?
- The illestrator - With a big enough air leak, yes. Usually I would just say to synchronize the throttle bodies for throttle response off idle, but with all the popping and stalling it makes me think air leak for sure.
Who needs instrumentation or mirrors?
valve sitting might be your problem ???
before they pull you over they probably already ran your plates and should know it's registered. DUDE how are you getting V-tec pops with a carburetor =P
All k-bikes era fuel injection.
That's the best case scenario lol. But if they DON'T run them and just pull me over immediately, they'd ticket me for OTHER shit while I'm stopped
How's that rear suspension feel though?
Ok, so I have been wanted to build my own k100 and i've always been wondering if the bike seems as heavy as everyone is saying. Is it true?
Just do it.
It's not a light bike by any means and although I've shed quite a bit of weight here, when it was stock it definitely had some heft to it that feels compounded by the huge overall size and the weird skinny bars. It's an over built bike.
How did it pass inspection?
lmao, I'd forgotten about that seat. Boy that seat lookin' like a single layer of cake covered in "carbon fiber" fondant. Get yourself right asap! Good lord.
Hope ya get it sorted though.
Ironically the seat may be the last thing I do lol.
Bruh - you movin fast with this build fr 👌 I'd say rebuild the throttle body like someone else has said. I'm only but so knowledgeable though. Check the forums (as I'm sure you have) - good luck 🤓 you're most of the way there
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them. There's a guy who rebuilds these throttle bodies for customers so I spoke to him and it'll be worked out for the finished product
It rides!!!!
Yes it does!
After I put an aftermarket exhaust on my k bike I had to adjust the carb so it could get more fuel it was making a ton of backfires it sounds good but the bike runs a lot smoother and feels faster with the carb adjustments
Do you mean the fuel injection?
It seems like there aren't many ways to adjust this old system
@@Theillestrator1050 yes knowing you have a after market exhuast and a different intake the bike is most likely running lean so i would check the injectors and make sure they are all clean and you can adjust the injectors and i would check the valves and valve clearences
oh, rev the thing to redline, thats what they are designed for not labouring like you rode it
Ayeeeeeeee! My n-word that shit is hella tight! Also this bike sounds like a straight pipe KA24DE
These bikes sound oddly automotive
Yessir!!!!!👍😎
Nice
Thanks
Runs lean with these pops. Its carburetor, right? I have an interesting tool, its a spark plug with a glass in it, so when you adjust the mixture you can see the flame color.
Be careful you may overheat your engine if it runs lean
It's fuel injected, I'll inspect around the intake area
I don't know what device the engine uses to meter it's air. But that's what I'd check
I've actually since found tears in the rubber hoses between the plenum and the bodies. They react to starter fluid so I've found the issue...or atleast one of them.
@@Theillestrator1050 keep on keeping on brother. I've only just found your channel and I'm really enjoying it so far. I'm about to buy a project bike. I'm torn between a Honda CB or a k series. So super interested seeing how you're doing.
Sounds like it’s running lean
or dirty injectors too
Check tips. Mix all over the place.
Ooh hello, that sounds fruity..... 😁
Cafe racer?