Still Running like a dog!!!

[paulbaker1954]

Paul, wish you found root cause and issue is fixed!

Sadly road test not good, now down to air leaks at inlet rubbers I think. The new clips I bought from DSS just don’t clamp up properly. Ordered some thin jubilee clips from INOX fasteners to hopefully fix.

Did mention issues with the clamps a few weeks back!

Sent from my POT-LX1 using Tapatalk

Indeed you did but Graham commented this was only an issue with the 750 ones.

What really threw me is that I checked for air leaks with carb cleaner and couldn't find anything with engine running at idle in garage.

I then spotted that if I rock the whole carb bank up and down a bit then air then gets in and idle goes all over the place and misfire happens signifying air leakage.

I don't know but I guess also that when on the road and trying to pull away there is a a greater vacuum under load just making it all worse.

I checked one of the clips on a rubber and found that I can still rotate the clip just by hand when it is fully pulled up.

I think the these clips are DSS part number 9501844250 and they claim they are OEM that supersede the original part number. That said I am not 100% sure they are stamped with a number 44 on them. I think I will email DSS and get them to check their stock to see if they also have this 44 stamped on them.

I will report success or not when my new jubilee clips arrive this week.

I really hope this is the end of the road for what has been a very trying issue to get to the bottom of

[matthewmosse]

Fingers crossed its finally got to the root of it. Thankfully for the rest of us theres a ton of good checks on this thread which will be a good revisig point when one of us is having similar issues. Hope changing those clips finally sorts it.

[paulbaker1954]

Well new inlet rubber clamps fitted and still no luck

I have finally given in and going to take bike to a good local guy who does classic bike race prep etc and knows fours and is highly recommended

He and I think this is an idle circuit problem on carbs 1 and 2 but I am now valuing a 2nd opinion and am running out of time and patience

I made a video of the afterfire noise and would appreciate any opinions

Vid is here and the afterfire is on 1 and 2 equally

https://youtu.be/TlWc7hyagG0

[Nurse Julie]

Oh er, what a strange noise. Sounds like something is firing wrong or fuel is igniting somewhere it shouldn't be. Was it your pipes that were exchanged under warranty and has that noise started after fitting the replacement pipes? It's more of a futting noise than a proper back fire.

[paulbaker1954]

Oh er, what a strange noise. Sounds like something is firing wrong or fuel is igniting somewhere it shouldn't be. Was it your pipes that were exchanged under warranty and has that noise started after fitting the replacement pipes? It's more of a futting noise than a proper back fire.

I think the vid sound quality is poor it is really banging believe me

[K2-K6]

For each of the 1 and 2 carbs separately,  with it warmed and idling,  incrementally turn the idle airscrew from virtually closed to about 4 turns out in quarter turn movement to see if and what changes you get.

Does it make a difference? Good or bad? Which gives the best running, at what position ?

[Rob62]

Doesn't sound like a "normal running problem".... has the cam chain been off at some time? are you sure the valves are timed correctly??

[jon stead]

That sounds more like a valve sticking open and clacking shut

[Bryanj]

Could it be that the cam cover was not fitted carefully at some time and a valve is slightly bent?

[paulbaker1954]

Could it be that the cam cover was not fitted carefully at some time and a valve is slightly bent?

I don’t think so but you never know, as I have said before in this post this started after a head gasket change but I am sure I fitted all back ok and I have done head off a few times now

Doesn't sound like a "normal running problem".... has the cam chain been off at some time? are you sure the valves are timed correctly??

Yes but double checked valve timing

Plus what are the odds of this happening only on 1 &2 only and equally the same

As I said it’s getting shipped off to a good mechanic near me. If I spend any more time on it it will be the divorce courts 🙊🙊🙊

[philward]

Hope you get it sorted Paul - been following the thread and it must be so frustrating

[the-chauffeur]

Apologies for blundering in here but I've got a couple of suggestions that I don't think have been mentioned yet.  They're both a bit left field, but given how frustrating this can be, I thought I'd chuck them in for good measure . . .

 . . . first, I'll apologise for not being familiar with the Boyer kit, but when you say it comes with a rotor, is that a replacement for the spark advancer cam mechanism or is it the whole mechanism that's replaced?  I ask because if it's the former, you might want to check the springs on the spark advancer bob weights.  If one has lost some of its tension it'll flick out at inappropriate times - especially at idle - and you'll experience symptoms not dissimilar to those you're seeing.

The second is more dramatic and hopefully a very, very rare thing, but check then end the rotor is mounted to for deflection/out of round.  Get your guy to put a dial gauge on the crankshaft end, turn the engine over very slowly and check for round or play.  Again, if it's out you'll get some funny running and like I say, it's a bit out there . . . but it won't take five minutes to check when set up.

I can't take credit for any of this stuff.  I learned the first one the hard way over the course of about 8 years working on and off on a project - it drove me the same kind of nuts you're experiencing and no mechanic near to me could figure it out either.  Ultimately, Mark Paris (HondaMan on the US site) came to my rescue, and the crank suggestion came from reading his book.

Good luck.

[jon stead]

 . . . first, I'll apologise for not being familiar with the Boyer kit, but when you say it comes with a rotor, is that a replacement for the spark advancer cam mechanism or is it the whole mechanism that's replaced?  I ask because if it's the former, you might want to check the springs on the spark advancer bob weights.  If one has lost some of its tension it'll flick out at inappropriate times - especially at idle - and you'll experience symptoms not dissimilar to those you're seeing.
Good luck.

Boyer replaces the spring advance retard mechanism completely and electronically advances the ignition above 4,500 rpm. Dayna S system, does utilise the mechanical advance retard system.

[paulbaker1954]

Dropped bike off at local good reputation mechanic today, he thinks it’s blocked idle circuits/pilot jets so he is going to strip and clean carbs again and see how it goes

If that fails he is talking about doing a leakdown test etc

Let you all know how it goes

[paulbaker1954]

Ok so local mechanic who has a good reputation has had bike for a day and is convinced this is a valve problem. Says he has heard similar sounds/symptoms on other bikes down to slightly bent valves that stick when warmed up.

Am now thinking that maybe I have accidentally slightly bent the 1 and 2 exhaust valves when I reassembled after the head gasket change.

This all seems logical as this problem only started after the head gasket change and am sure nothing else was changed, valve timing is correct.

Also thinking back I seem to remember I had a bit of a struggle getting the rocker cover to go on back easily even though I thought I had wound back the adjusters as far as I could.

Started another thread now as this is getting off track