Author Topic: 87 K75C, Bone Stock and DONE. (Read 211330 times)

Spent the weekend Whitetail hunting w my buddies 8 yo son. We saw deer everywhere but in front of us. LOL
Even still it was a riot. We had a great time.

Got up early this morning so I got busy replacing that pesky weeping O-ring on the sending unit before leaving for work.

Dont drop the lock washers from the fuel pump connections into the tank. Ha

Nasty.

Fair amount of pitting. If it continues to weep I will have to re-visit w a light smear of metal mender.

cleaned bolts and a small dab of teflon sealant.

Fresh self adhesive heat shield I will cut and fit after paint.

trek97 · « **Reply #138 on:** December 11, 2016, 07:50:27 AM »

Checked valves, all in spec.

Fresh seals and bolt grommets ready to go in...Just waiting for Parts Plus to open for a dap of RTV.

Removed a bit of wear and tear from the cover.

Martin · « **Reply #139 on:** December 11, 2016, 10:58:49 AM »

Good job but now your going to have to polish the whole engine, otherwise it will look odd. :clap:
Regards Martin.

trek97 · « **Reply #140 on:** December 11, 2016, 02:27:34 PM »

Quote from: Martin on December 11, 2016, 10:58:49 AM

Good job but now your going to have to polish the whole engine, otherwise it will look odd. :clap:
Regards Martin.

Ha, I have a funny feeling its gonna look odd to some, no matter what I do.

trek97 · « **Reply #141 on:** December 14, 2016, 08:24:16 PM »

Hey guys, Ive never heard of this and Im not understanding the reason step 4. (Lean drop) Would someone please clarify the benefit? Thanks

Ive got plenty of carb experience but zero fuel injection experience.

kennybobby · « **Reply #142 on:** December 14, 2016, 09:29:37 PM »

i don't know where you got that, but don't adjust, or try to adjust, the butterfly screws. There is a brass by-pass screw on each throttle body that is used for synch adjustment. The butterfly valves were set at the factory and the screws locked.

If you've messed around with honda carbs then you probably know about adjusting the pilot screws for idle rpm drop. This may be some equivalent approach for fuel injection but it's not anything i would try.

Laitch · « **Reply #143 on:** December 14, 2016, 10:18:29 PM »

Quote from: trek97 on December 14, 2016, 08:24:16 PM

Hey guys, Ive never heard of this and Im not understanding the reason step 4. (Lean drop)

Step 4 is an adjustment used in the absence of a CO gas analyzer to insure that—all other adjustments being accurate—the engine is not running rich and emitting excess CO and causing other performance problems. That's the presumed benefit. A discussion of the throttle body balancing technique in this K100 Forum thread is also illuminating.

All this may seem eerily similar to synching dual or multiple carbs in olden times except with K-bikes, a manometer and tachometer are being used to attain balance instead of just a pair of ears listening to the engine performance during the carb adjustments while Led Zepplin is throbbing in the background. :giggles

Wrenchers who want to relive those golden moments should get a /5. :yes

trek97 · « **Reply #144 on:** December 14, 2016, 10:26:16 PM »

Quote from: kennybobby on December 14, 2016, 09:29:37 PM

i don't know where you got that, but don't adjust, or try to adjust, the butterfly screws. There is a brass by-pass screw on each throttle body that is used for synch adjustment. The butterfly valves were set at the factory and the screws locked.

If you've messed around with honda carbs then you probably know about adjusting the pilot screws for idle rpm drop. This may be some equivalent approach for fuel injection but it's not anything i would try.

Thank you sir and yes, I read all about not touching the butterfly adjusters. And adjusting the synch w by pass adj. (BMW doesnt seem to have much faith in customers abilities. LOL.) Dont get me wrong. Butterflies can certainly be very cantankerous and critical things. Amateur do not attempt sorta stuff. Way more to butterfly centering and setup than the much over advised "use a pair of straightened paper clips to set up synch" adjustment procedure. :yes

As with the grossly over simplified idle rpm drop procedure for carbs. Which, even still your using to find the fastest rpm. Not being directly advised to screw it up.

Thats why I question this procedure step 4. It seems like it may very well be a bad piece of info.

found the procedure pdf link here...
[size=78%]http://www.motobrick.com/index.php/topic,692.0.html[/size]

trek97 · « **Reply #145 on:** December 14, 2016, 10:31:46 PM »

Quote from: Laitch on December 14, 2016, 10:18:29 PM

Step 4 is an adjustment used in the absence of a CO gas analyzer to insure that—all other adjustments being accurate—the engine is not running rich and emitting excess CO and causing other performance problems. That's the presumed benefit. A discussion of the throttle body balancing technique in this K100 Forum thread is also illuminating.

All this may seem eerily similar to synching dual or multiple carbs in olden times except with K-bikes, a manometer and tachometer are being used to attain balance instead of just a pair of ears listening to the engine performance during the carb adjustments while Led Zepplin is throbbing in the background. :giggles

Those who want to relive those golden moments should get a /5. :yes

Thanks Laitch. I will certainly read through the procedure in the morning.
Setting carbs on an air cooled unit to the lean side at idle will certainly produce hesitation on take off as well as overheating while sitting in traffic. I just dont yet know enough about this whole "fuel injected, liquid cooled black magic". HA

K1300S · « **Reply #146 on:** December 15, 2016, 01:20:42 AM »

Quote from: kennybobby on December 14, 2016, 09:29:37 PM

i don't know where you got that, but don't adjust, or try to adjust, the butterfly screws. There is a brass by-pass screw on each throttle body that is used for synch adjustment. The butterfly valves were set at the factory and the screws locked.

If you've messed around with honda carbs then you probably know about adjusting the pilot screws for idle rpm drop. This may be some equivalent approach for fuel injection but it's not anything i would try.

actually, those instructions are perfect and the standard way to tune the FI. the instructions say butterfly BYPASS SCREWS. not the other verboten adjusters. the last step is as Liatch describes. leans out the mixture just a touch. 50 rpm ain't much, but enough to get the AFR close without use of WBO2 sensor.

follow those instructions to the letter. they work.

ps - i did a lot of work with dual sidedraft carbs on old BMW cars. was never a real fan of the listen/idle drop tuning. always used carb synch tools, lots of jets and an installed WBO2 meter to get them right. FI is so much easier!

Martin · « **Reply #147 on:** December 15, 2016, 02:18:06 AM »

Easy to check the mixture, with the engine warm and idling at 1000 rpm press the green starter button. If the mixture is correct the idle will stay the same or rise slightly. If it drops or rises significantly it will require adjusting, either lean drop method or exhaust gas analyzer. After having three different places try to get mine right and failing, I bought my own Gunson Analyzer for about $300.00 about 19 years ago, it has paid for itself multiple times. Screwing the 5mm allen head adjustment screw CW leans the mixture CCW richens it. If you do adjust it use very small increments. http://cgi.ebay.com/ebaymotors/Gunson-Gastester-exhaust-gas-analyzer-/281777542267?hash=item419b40147b:g:H7UAAOSwu4BV1LsH
Regards Martin.

trek97 · « **Reply #148 on:** December 15, 2016, 06:40:31 AM »

Quote from: Martin on December 15, 2016, 02:18:06 AM

Screwing the 5mm allen head adjustment screw CW leans the mixture CCW richens it.
Regards Martin.

Thank you Martin! Exactly the info I was looking for. Thus "Lean drop" is actually setting it up to run a bit richer at idle. To avoid popping on decel along w eliminating take off hesitaiton. Im sure, being watercooled, these bikes are less prone to overheating if they go a bit leaner on acceleration. Still none the less dont want to burn a valve. The CO tester would make a fine addition to the tool box. :2thumbup:

I have installed dual digital O2 sensors on my 76 Honda 360.
It has proven to be a great success. (As compared to seemingly endless plug chops to "read" plugs.)
It shows A/F mix in real time. For tuning idle as well as jetting throughout the entire rpm range while riding. Those CV carbs can be a real pain.
Also, been looking at purchasing a second header for modification to do the same w this K. A modified (slightly longer) header w a single bung welded for an O2 sensor would be easy enough to swap in and out for quick springtime check, set and forget. Because the injectors arent tuned as individuals. The sensor would require mounting twixed the header and muffler.

kennybobby · « **Reply #149 on:** December 15, 2016, 07:13:29 AM »

the air flow meter provides the provision for idle mixture adjustment. There is a screw in the housing of the air flow meter that is used as a valve for an air bypass channel. The air flowing through this channel is not measured by the air flow meter and so affects the fuel/air mixture. Turning the screw clockwise blocks off the channel and so richens the mixture. Turning the screw counterclockwise opens the passage and so leans the mixture, as the extra air is not measured by the air flow meter and so the computer does not compensate for it.

Whether it's carburators or throttle bodies, whenever a thread like this pops up there is always someone who has an "uh-oh" moment that has removed the plenum plate or dismantled the carb rack or twiddled with the butterfly screws...

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Author Topic: 87 K75C, Bone Stock and DONE. (Read 211330 times)