Hello,
New member here.
A little background story:
I have acquired a '93 K75 RT as a project in 2018, which was a non runner at the time of my purchase.
The previous owner was adamant the bike did run with no issues, then he started the cafe project and never got to finishing it. When I purchased the bike, it looked complete (all fairing came separately as he's removed them ) and without the wiring loom attached, but again it came separately. I did the usual checks, changed the oil, the fuel and attempted to start it, but was not successful. When I checked the compression, there was none on cylinder one which led me to taking the engine apart and discovering nearly half exhaust valve on cylinder 1 was burned off and was missing.
Long story short... I've rebuild that engine. Had the cylinder head tested, cleaned. All valve guides replaced and new valves restated. I've put it all back together following the Haynes manual and other online sources. Not done the valve clearance yet just used the previous shims in the same order as pre rebuild. All gaskets, bolts, washers are new, etc. I have experience building several BMW car engines (I own a e30 car - old 3 series from the late 80s) and yes I have never build a K75 engine before but I understand the principle and would like to believe that I am competent enough to do it.
Here's the current issue:
First of all, I've put it all together and there was no fuel coming from the injectors (this wasn't the case pre engine rebuild).
Following the advises I've found on this forum, I did some troubleshooting with the multi-meter and came to conclusion that my injectors are stuck. I've borrowed another set of injectors from my mate and these do fire fuel. I've sent my injectors of in the mean time to have them cleaned.
The bike does not want to start though. It cranks, but does not start. If I crank it for a long time, there's eventually a big bang (usually supported by a fire) of the unburned fuel being eventually burned. It may also some have a little bit of fuel coming out by the exhaust manifold at this stage, so it appears like the engine is being flooded. I've tried starting with the throttle fully open, but no luck.
Upon removal, the Spark plugs are wet (they are not dark, but they are new spark plugs). Each spark plug produces a nice, white, spark when tested against the cylinder head. That suggests to me that the Coils and HT leads are fine.
The condition of the temp sensor, that's on the same part of the loom as injectors, is unknown. I've tried starting the bike with it unplugged but it made no difference. I don't know if it would have an impact on the bike's ability to start. I guess it could if the bike thinks the ambient temp is too low? When I measure across the pins on the plug, I get 2,5V going to 4V when I crank the engine.
Fuel pump works and there's fuel pressure in the lines as the fuel does squirt through the injectors. I've not measured the value of the fuel pressure though. The bike did not come with the vacuum hose between the FPR and the Throttle Body (the one inside the spring). I've ordered the spring but not the hose, so currently running a transparent plastic hose as a replacement in there.
I've not checked the engine compression after the rebuild. I can't find the adapter to fit K75 for my compression tester, so had to order a new one.
I've not installed any cooling system back on the bike, so it currently has no radiator, not fan plugged in, no pipes and obviously no fluid. I can't imagine this is needed, but perhaps bikes are different ?
I have no dashboard. I've jumped pin 5 and 6 on the dash plug to crank the engine. Again, I don't know if this would have an impact of my ability to start it. I have no fairings, no lights, no horn, no indicators plugged in. Again, I can't see this having an impact, but it's worth mentioning.
I've tried another ECU and Timing Module which I borrowed from my mate from a working K75 RT. No change.
Throttle Position Sensor was removed and reinstalled in the same position.
I've not tested the AFM, but the flap is shut and moves freely when I use my finger on it, so I assume air gets in the engine. My plan was going to focus on this element next.
Throttle bodies are original just cleaned, with new intake boots top and bottom ones.
Vacuum hose is new (the one linking the throttle body and cylinder head)
Side stand is attached, neutral gear engine and choke connected. The engine does crank without me pressing the clutch lever.
Battery is a small car battery (45Ah). The bike came with a small bike battery, which seems to run out of juice after few cranking attempts.
I have no exhaust, only the exhaust manifold.
Oil level sender is plugged in, but the temp sensor gauge is not (I can't find where do I plug it into?)
Hall Sensor was removed and reinstalled. I've made marks to reinstall in the same position, which were pretty much the default setting. I have not tested the sensor, but I understand it's not straight forward to do so.
Am I missing something obvious here please? Like not meeting a certain criteria for starting the bike?
Any advise would be appreciated as I got a bit stuck.
Thank you,