1983 R65LS complete rebuild first start

[Charlespvdw]

Hi Guys

I have been restoring a 1983 R65LS to its original condition the last year.

I have completely rebuild the engine and gearbox, but did not touch the wiring harness as this was still in good working condition before I stripped the bike.

Yesterday I came to the point where I could actually turn over the motor.. which was a monumental moment...but.. no start.

There is definately a wiring issue as I have the following symptoms:

When I turn on the ignition all the way to the right, the head light is not burning until I pull in the clutch??
I can turn over the engine with the kill switch in the off position.
I only get spark when I pull in the clutch.

And from a mechanical point of view I only get ingition on the left piston as the exhaust is hot after turning over the motor a few times, the right his cold.
I completely rebuilt the carbs as well and all ports are clean. What base settings can I use for the carbs?

Sorry for the long post but I would appreciate your guys help.

[Rob Frankham]

First things first... You really do need to get a manual of some type (Haynes, Clymer or BMW) most of the questions here could be answered from any of those.

There are obviously at least two faults here and I would suggest you need to sort out the unilateral firing issue and why the bike won't run. The first thing is to establish whether there is a spark at both plugs. Simply pull both plugs, insert them into the plug caps and rest them against the metal of the cylinders. Crank the engine with the ignition on (and bearing in mind the other issue, with the clutch pulled in). It should be possible to see a good spark at both plugs. If one of the plugs isn't firing, you need to be looking at the relevant plug, plug lead or coil. As far as I can see your model has only one coil... if this is grey, then you would probably be better off replacing it with the later black coil. The grey ones are notorious for cracking.

I assume that the timing has been static set...

If You're getting a good spark at both plugs, then the problem is probably carburation. Here are the initial settings...

• Jet needle set to third position from the top.
• Pilot mixture screw, 1/2 turn from fully closed (3/4 turn for US spec machines)

It's also worth checking that the 'chokes' have been assembled correctly. Hopefully, you dismantled the carbs seperately so you can be sure that the right (rotary) choke slide is in the right carb. The left choke is different to the right. If you aren't sure, then you need to look in a manual to make sure it's right. Even if you are sure that the choke slides are on the right side, they can still be assembled wrong. In the end of the slide, you will see a punch mark offset to one side... for the choke to work correctly, this punch mark must align and be close to the end of the actuating arm where the cable attaches.

Another point to check is that the diaphragms are sound (no pinholes) and that theye are correctly seated in the carbs.

With any luck, this will get the engine running and you will be able to address the electircal issue(s)

Unfortunately, there isn't enough information to diagnose the electric issues (there appears to be more than one) It would be helpful if you could confirm whether the bike is a US or EUro spec machine... the wiring is different.

At first sight, there would appear to be interference between the kill switch circuit and the clutch circuit. With the kill switch to 'off' there should be no spark, no idiot lights and no cranking. With the clutch pulled, the idiot lights should be on but no cranking.

My best advice would be to check the connections one by one against a wiring diagram to check that the right wire is going to the right place. If you need miore assistance, please give more information about what is working electrically and what isn't... that way it should be easier to come up with an opinion as to where the fault(s) lie.

Rob

[Charlespvdw]

Hi Rob

Thank you for your response.

My feedback after going through everything is as follows:

I do have a Heynes manual.
I do have good spark at both plugs only when I pull in the clutch.
I have replaced both diaphrams on the carbs and the chokes are correctly assemblied (verified with a youtube video of boxer2valve)

I have resprayed the frame, could it be that where all the grounds come together mounted to the frame needs to be clear of paint and mounted bare netal?

I went through all the relays and connections and all seems fine.

Fuses are all in tacked.

I did not do any modification on the harness when I stripped the bike. I just unpluggged and plugged up again when I re- assembled the bike, taking into account that the bike did run before I disassbled it.

[Rob Frankham]

Hi,

If you have a good spark on both plugs, and the timing is about right, then the failure to start must be due to something else. If youre completely satisfied that the carbs are assembled correctly and the initial settings are correct, then it has to be something more 'fundamental'. Sadly, the only way to approach it is to go back to basics and check everything (including eveything you've checked before) Without knowing exactly what you've done to the engine, it's difficult to highlight anything in particular but you need to be sure of the following:

Compression within limits
Ignition timing set correctly
Valve clearances set correctly
Valve timing correct
Carburettor initial settings correct and throttle butterflies set slightly open.
Fuel is actually getting through to the carbs
No air leaks in the inlet tracts
Battery fully charged and in good condition.

One thing I have found that sometimes kicks life into a reluctant engine is to remove both plugs, dribble a little fuel into each cylinder, replace plugs and try to start. If the problem is just minor adjustments, this can be effective. Also, if it is reluctant with choke, try without. Sometimes, if the mixture is a bit rich, the engine won't start with the choke applied... in fact it can flood the engine.

As far as the electrics go, there is obviously something wrong so something isn't the same as it was when the loom was unplugged. Yes, it is a good idea to ensure that the main earth is good by clearing back to bare metal... You also need to ensure that there is continuity in the ground between the engine casings and the frame. The battery earth is connected direct the the engine mass and a painted frame can prevent connection between the two. I am a great advocate of additional earthing to the frame and, if interested, you can see my thoughts here https://robfrankham.com/about-earthing.

As for the rest of the circuitry, the only thing you can do is work through the wiring diagram to make sure each wire is doing what it should. As I said, if you can supply information about what is and what isn't working (e.g., which lamps light up, when they light up and when they don't, are ancilliaries like the horn, brake lamps, indicators & etc., working as they should) then it might be possible to see a pattern and give some clues as to where to look but, with the information we have at the moment, it is impossible to make any sensible suggestions. Sorry it that doesn't seem to be much help but that's the way it is with electrics...

Rob

[Seth]

If you get spark only with the clutch pulled, maybe you swapped the wires between the ignition and the clutch interlock. Does the starter engage in gear and without the clutch lever pulled?

[Zombie Master]

I have found that most electrical problems are about poor grounding. Get that bare metal!

[Charlespvdw]

Hi Guys

During the lock down I have some time to actually work on the bike more than once in two weeks.. but I still can't get the bike to run right.

I was able to sort out the electrical problem, and Zombie Master you are spot on, the main grounds did not make contact to bare metal because the frame was resprayed. So at least that is sorted now.

Just to get everyone up to speed with what was done to the bike to perhaps help with the fault finding:

Engine was completely disassembled and replaced the following:
New crank bearings
New white metal big end and small end bearings
New Piston rings
New oil seals
New valve stem seals
New clutch and pressure plate
Both carbs have been rebuilt with new O-rings on all the jets and shafts, new diaphragm and floats
New air filter
New petrol lines
Tank has been cleaned out and sprayed a protective coating
New spark plugs (does have good spark on both)

All the electronics worked before the bike was stripped and was replaced as is.

The base settings on both the carbs are as follows:
Butterfly slightly open on closed throttle
A/F ratio screw 2 turns out

The bike starts quite easily but then only run on one piston, when I open up the throttle the second piston wakes up but when the throttle is closed its fades away again. With quick start the 2nd piston also runs until the quick start is finished.

While the bike is idling I tried setting the A/F on the 2nd carb but nothing changes?

How do I check the ignition timing on this bike as this is the only thing I have not tried to adjust, because the bike does misfire and does not run smooth when I open up the throttle.

[barryh]

The base settings on both the carbs are as follows:
Butterfly slightly open on closed throttle
A/F ratio screw 2 turns out

I might have missed something but I don't see anything which says these are anything other than standard carbs, in which case 2 turns out on the mixture screws is grossly too rich. The correct base settings are:

Throttle stop screw 1 turn out from butterfly fully closed

Mixture screw 1/2 turn out from gently seated

[Rob Frankham]

As Barry says, the basic idlse air setting for a R65LS is 1/2 turn on Euro spec machines and 3/4 turn on US spec machines.

I don't really see how you can hope to tune an engine succesfully if you don'y know whether the timing is right.. I suggest, before you go any further, you at least static set it.

If it still idles on one, once you've set up the idle screws and the timing, I would suspect either the slow running circuit or the 'choke' circuit.

Does the ione sided idle occur wuth the choke on, with the choke off or both on and off?

Are you sure that the choke slide went in the right way round when the carb was reassembled?. The centre punch mark in the end of the shaft needs to be aligned with the end of the actuating lever where the cable attaches.

Rob

[melville]

If one cylinder isn't firing at idle but come on with revs, the pilot jet on that side may be blocked. It doesn't take much as the pilots are tiny jets. Maybe more so on an R65.