SOHC.co.uk Forums > CB750
Rewiring K2 with later high beam switch
the-chauffeur:
Ah - OK. Don't want to fry the generator, so I'll work out what to do with the wiring later.
I'm pleased to say the neutral switch turned out to be a simple fix - I'd put the little locating plate in upside down. Turned it over, did up the bolt and it pushed the switch further into the mount - which meant that when the drum turned, the ball bearing was depressed far enough to switch the neutral light off.
I'm less pleased to say that whilst trying to get the engine set up yesterday - carb balancing and so on to try and cut the clutch rattle down - it got very hot and started squeaking. Couldn't locate the source of the squeak, and pulled the plugs to make sure it hadn't overheated and/or reduce the danger of it seizing. The engine's undergone a rebore, new gaskets and seals and heavy duty studs, new bearings throughout (plain and ball), new chains, camshaft, valves and all sorts. I also had some 2 stroke oil in the petrol to give the pistons an easy-ish time. And I know from using the kickstart it's got great compression.
So anyways, I had too much oil in the engine - following Hondaman's guidance, I'd filled the oil pump before fitting it and that (in part) threw off my filling calculations. I'm hoping the squeak - and the quick heating up - was caused by oil overfill increasing the crankcase pressures and maybe oil squeaking up past one of the pistons. One of the spark plugs looked more oil-fouled than the others, and since the valve guides and seals were all replaced, that could explain what was going on there. I don't s'pose it helps that I was working on the bike in a sheltered (read warm-ish) garage with little airflow, which wouldn't aid cooling at all. But at least I know oil was getting up into the head - taking two valve caps off it was spitting out.
After draining some oil off, I've run the bike briefly this morning, and it seems to be OK. It's not MOT'd yet, so I can't take it out and ride it around, but I'm hoping to get that rectified later this week. I'm just praying the squeak isn't something more serious - I've just had to overhaul the top end of my 450 because a shop I'd asked to set it up moved 2 of the rocker adjusters too far and the shafts have been running eccentrically in their journal holders. The really worrying thing for me is that the giveaway was that it was squeaking, too . . .
Hoping for some good news.
the-chauffeur:
Well, the squeaking noise turned out to be bad news. From cold it seemed quiet . . .
. . . so I got the bike as far as the MOT garage and home again (about 3 miles all round), but about halfway back the bike started protesting - more squeaking and hard running. Just about made it home and it died. Pulled the plugs again and things weren't looking great on #4 so I took the rocker cover off (thank God for the removable frame section over the top of the engine). Long story short, no oil has been getting to top RHS.
Yup, the lack of anything coming out of the oil jet in the head on the RHS has caused the brand new camshaft and cam tower/caps to lunch themselves, burned the rocker faces and caused some wear on the rocker arms. Pardon my language, but #@%$ me, I'm not having any luck with this bike. This is my third attempt to get the engine rebuilt and I went all out to do it properly (pistons/valves/rebore/headwork/allsorts) and spent ages making sure I'd got everything right - only to have it all screwed up by (I'm guessing) a 1mm hole.
The head's still on, so I can't tell whether it's the jet that's failed or something lower down, but I'll get there soon enough. What's more disconcerting is what I'm going to find in the barrels - I'm praying the bores/pistons aren't damaged. Where the RH end has been running dry, it's ground itself up and there's a quantity of fine paste trapped inside the tower footprint; there's also some very small quantities of fine dust outside of the tower, but since there's been no oil circulating down that end, I'm desperately hoping none of it has gone south.
Another (K4 I think) head is on its way with most of the top end bits I need, but I really don't need this now. At least next time (!?!?!) I'll know to build the top end onto the engine while it's in the frame and test the jets before putting the towers on.
UK Pete:
Hi Niel , that is real bad news, i feel the hurt for you, i am not sure if you remember my post but when i put my F2 together i heard strange noises and so i cut the frame open removed the rocker cover only to find my cam sprocket nuts working themselves loose, anyway when i rectified the problem i also took the opportunity to turn the engine over and check that oil was making its way up to the cam towers , it is something i will always do from now on with my sohc bikes as i have heard so many stories of blocked oil jets,
As you say your luck in rebuilding this engine has been really bad, if you want a second pair of eyes and a bit of assistance remember i am 5 minutes away from you and i can pop round for any support or help you may need,
Dont let it get you down, at the end of the day it will all be worth it and you will look back and laugh at it all or cry at the money side of things
Pete
Bryanj:
Sorry to hear that mate, i don't got any more towers like the ones you had before but i can find you a "runner" if you need it.
kaceyk2:
Got a nice pair of towers should you need. ( of a late K8 and in great shape)
sad to hear this happened to a new built motor, theres a lesson for all here, at the very least blow an airline through the towers with some oil before fitting and check the oil is coming out where it should be?
Guys something else here, I have seen folks on two stroke forums say this as well and it is pure rubbish,
Do not add two stroke oil to fuel to "give things an easy time " It has the opposite effect.
If you water your fuel down with two stroke oil, your still sucking the same amount of air in, but now with LESS fuel, you have just given your newly built motor a weak mixture, which makes it run HOT, this is EXACTLY what you didn't want to be doing. Especially so to a motor that is still tight.
The same applies to newly built two stroke motors, it will make them run Weak and therefore HOtter, and with a newly built motor, bad news.
Suzuki, for instance NEVER had the autolube pump set higher for run in periods, this is just plain wrong, right from straight out of the crate, it was set where it always should be, take a screw out of the left hand carb, when the throttle is opened till the dot shows, it should line up with a marker on the pump.
This is how they came brand new out of the crate.
Two strokes /four strokes the same rule applies: add two stroke oil to the fuel, it will run weak and therefore hotter.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version