Sorry, should have noticed the ping post.

 

Ignition too far advanced will pink/det and be low on power.

Not enough advance will have poor vacuum and feel unresponsive. Will be high HC with 4gas emissions tester.

 

I found map sensor for Dignition was way still way off with the twin carbs as much lower vac. That might not be the case with motorbike slide carbs,

 

5 minutes ago, dvderlm said:

Sorry, should have noticed the ping post.

 

Ignition too far advanced will pink/det and be low on power.

Not enough advance will have poor vacuum and feel unresponsive. Will be high HC with 4gas emissions tester.

 

I found map sensor for Dignition was way still way off with the twin carbs as much lower vac. That might not be the case with motorbike slide carbs,

 

Uh oh, could this be just a case of ignition timing rather than lean jetting?

AFAIK the ecu will still give an advance map off the hall sender in the dizzy, obviously just less accurate. 

Pinging is only noticeable at high rpms so am i safe to say that rules out too much  advance?  The curve should go from less to more advance with engine speed right? So ignition if anything would be too far retarded at the higher rev ranges where it sounds like its pinking

yep, higher engine speed the more before TDC it has to spark because piston is moving faster, but flame propagation is the same. (centrifugal advance)

When throttle nearly closed needs upto 15 more as cylinder filling is poor.

 

At higher engine load (wider throttle opening, less vacuum) needs less advance because the cylinder fills faster with ignitable mixture.

 

You don't want extta vac advance at wide throttle, it ll pink.

 

Will the original TPS fit on the bike carbs?

 

Edited 27 November, 20205 yr by dvderlm

16 minutes ago, dvderlm said:

yep, higher engine speed the more before TDC it has to spark because piston is moving faster, but flame propagation is the same. (centrifugal advance)

When throttle nearly closed needs upto 15 more as cylinder filling is poor.

 

At higher engine load (wider throttle opening, less vacuum) needs less advance because the cylinder fills faster with ignitable mixture.

 

You don't want extta vac advance at wide throttle, it ll pink.

 

Will the original TPS fit on the bike carbs?

 

Thats what i meant! I wasnt planning on using the sensors in the first place its only an afterthought.

i was more asking whether my pinging/power loss could be caused by the ignition advance as opposed to the more obvious problem of the jets potentially being too small.

 

On a side note i tried to get the original tps out of the throttle a while ago and its pretty tight in there so gave up. I'm not sure its actually a removable part on my engine. The plug is in a completely different location to the throttle shaft so i think it'd be a case of hacking up my stock throttle body, which id rather not do.

Saying that, The ECU could actually be setting the timing to closed throttle/low revs and leaving it there? I'd be surprised if that was the case though.

I'll plug it into vcds and see if it'll let me read the ignition timing. 

Standard Lambdas not likely to be much use in tuning is it? Don't know how wide they range

Definitely. If ignition timing curve is wrong you won't get power. Flame front needs to be expanding rapidly to push the piston back down again. I think optimum is 20 degrees after TDC, but ignition point has to be BTDC.

narrowband lambda not much use with carbs.

I see 11.5 to 16.2 AFR (and it was 9 to 18 before I sorted it all).

 

Vacuum gauge is best for ignition timing.

2 minutes ago, dvderlm said:

Definitely. If ignition timing curve is wrong you won't get power. Flame front needs to be expanding rapidly to push the piston back down again. I think optimum is 20 degrees after TDC, but ignition point has to be BTDC.

Magic i'll give that a go tomorrow, by ignition point do you mean initial timing at idle?

Not really, idle ignition is start of the curve. The static timing advance (so where dizzy is turned), plus any vacuum related advance.

http://www.s262612653.websitehome.co.uk/DVAndrews/timing.htm

 

https://www.enginebuildermag.com/2017/09/understanding-ignition-timing-making-maximum-power-means-knowing-science/

 

Be careful turning dizzy too far clockwise.

Edited 27 November, 20205 yr by dvderlm

10 minutes ago, dvderlm said:

Not really, idle ignition is start of the curve. The static timing advance (so where dizzy is turned), plus any vacuum related advance.

http://www.s262612653.websitehome.co.uk/DVAndrews/timing.htm

 

https://www.enginebuildermag.com/2017/09/understanding-ignition-timing-making-maximum-power-means-knowing-science/

 

Be careful turning dizzy too far clockwise.

Thanks for your help, will report back

Okay so been on the road again today, 

I’ve refitted the carb rubbers for a better seal and Blocked the main air corrector jets with blu tack temporarily on the advice of Danst,

The car pulls much better now but still pops rapidly on the overrun (it’s almost like a hum due to how fast they’re occurring) 

On the way home it decided to start popping even more up to the point where giving it any throttle just produced exhaust sputter, similar to the time I had a cracked ignition coil and it did this in the wet.

The engine then died leaving me at the side of the road scratching my head. Checked the fuel pump as the inline filter seemed dry, ht leads etc.
On cranking again the fuel pump came to life and the engine eventually started, albeit very rough. Managed to get home and checked over everything, got one dodgy ht lead which is getting replaced.

But 10 mins after this the engine seems to start and run fine again? Could this be damp getting into ignition again? I’d be surprised as it was after a good thrash getting the engine hot, not before while cold and damp
 

Also pulled the no4 plug (only one I could get to) and it looks like this: 

lean still?

That plug is not shiny white of lean Tip of ceramic might even be tan.

But not sooty like I'd expect with closed air correctors.

 

One of

Higher float level, bigger mains, different emulsion tube or changed needle profile?

 

More fuel will cool the cylinder head.

 

These are CBR 600cc bike carbs on 1.4 right?

If I can find the choke size I can make a good guess at the main jet a Weber twin carb would need.

 

 

 

 

1 minute ago, dvderlm said:

That plug is not shiny white of lean Tip of ceramic might even be tan.

But not sooty like I'd expect with closed air correctors.

 

One of

Higher float level, bigger mains, different emulsion tube or changed needle profile?

 

More fuel will cool the cylinder head.

 

These are CBR 600cc bike carbs on 1.4 right?

If I can find the choke size I can make a good guess at the main jet a Weber twin carb would need.

 

 

 

 

Theyre cbr600 on a 1.4. Think the carbs are 38mm. 

Pretty sure the float levels aren't adjustable, bigger mains might be necessary but a lot of people running 1.3 mk2s seem to be on similar sizes to me? (140 ish.) 

I'm definitely with you on needing more fuel, but does that plug not look rich? Cheers for your help

 

Going to try and waterproof the pump wiring and ignition stuff a bit better, hoping todays random breakdown wasn't a carb issue as i don't fancy having that happen on the outside lane of the motorway. Can they ice up under the warm bonnet of a car? Plenty of cold damp air here in manchester.

I'm on a phone screen, but no not rich. Rich looks like soot or coal coating.

There's some darkness lower down, but that might be from choke.

 

1390cc / 1272cc = 1.093

is how much more air is pumped by your engine.

1.093 x 140 diameter (as circle cross-section using pi radius squared) = 146.

 

That feels right ball park for 38mm, which should rev really well.

 

What sort of air filter are you using? Oil impregnated cloth style needs more fuel than pleated paper.

3 minutes ago, dvderlm said:

I'm on a phone screen, but no not rich. Rich looks like soot or coal coating.

There's some darkness lower down, but that might be from choke.

 

1390cc / 1272cc = 1.093

is how much more air is pumped by your engine.

1.093 x 140 diameter (as circle cross-section using pi radius squared) = 146.

 

That feels right ball park for 38mm, which should rev really well.

 

What sort of air filter are you using? Oil impregnated cloth style needs more fuel than pleated paper.

Very nice, so by that thinking my jetting shouldn’t be grossly wrong?

 I’m not running any air filter at the moment (I know not great.) Been looking at some foam “sock” type ones designed for my carbs as there’s not much room for anything else under the bonnet. I’ve been holding off buying them as I want to make sure it’s working in principle before chucking more money at it.

 

On another note Have you ever heard of carbs icing on a car? Difficult to know why mine ever breaks down as the fault never seems to stick around long enough to diagnose it lol

46 minutes ago, rusty said:

Can they ice up under the warm bonnet of a car? Plenty of cold damp air here in manchester

Engine sucks it all in. Icing is gradual power loss.

 

Damp and dodgy electrics is never good. 

 

Check all the plugs and leads. Those multi-electrode can carbon oil foul across one point.

 

2 minutes ago, dvderlm said:

Engine sucks it all in. Icing is gradual power loss.

 

Damp and dodgy electrics is never good. 

 

Check all the plugs and leads. Those multi-electrode can carbon oil foul across one point.

 

Yeah I get that, seems like every problem I’ve had with this motor over 3 years has been damp related somehow haha.

New plugs are on the cards anyway, don’t like the multi electrode ones much but they seem the easiest to find 

Oh yes. Had my Polo ice up with a Weber DMTL and  K&N filter on a dual carriageway up out of valley, and on moorland A road. Wait 5 minutes or so and it restarts.

 

Fitted a warm air hose from exhaust manifold to near it to solve that.

Partially covered front of radiator too.

 

Not had it with the DellOrtos which have a cold/warm air feed to near carbs.

I once had to sit out a storm at side of road in Manchester/Salford (in a Hillman Imp). It rained so hard the single speed wipers were struggling on the upstroke. I could only see half the time.

 

Nope don’t fancy that haha, once had a Range Rover blast through a flood ahead of me on the Manchester ring road, the resulting wave not only blinded me for 20 odd seconds at 50mph, but managed to put so much water on my openair roof that it started pissing out of the dome light onto me. Wasn’t a good start to the day lol 

Stuck 1390cc and 38mm in my Weber program.

 

147 main jet with 190 air. It'd be good for 9500rpm, says the program, yeah right🙄. Not with that stroke.

 

In real life that'd be boggy with a fixed venturi Weber without matching cam.

But probably fine with slide carbs.

More progress today,

Investigated why the fuel pump died yesterday, turns out the original injection pump was putting up quite a fight and restricting the flow massively. Removed that from the sender unit and added some hose going to the strainer at the bottom.
That Coupled with a quarter turn out on all the pilot screws, idle is now much better with much less popping, suspect the carbs need further balancing though. pump sounds like it’s under even less strain which is good.

Blocked off the main air jets permanently with epoxy under the rolling road’s advice.

 

I did attempt to fit the pump in the space between the tank and the hatch under the rear seats, ran very well like this but couldn’t get the pump to fit properly under the hatch,  Didn't fancy grinding the opening larger around the semi open, half empty fuel tank though 🔥  

Moved it back to the engine bay slightly lower down and seems to run well still fingers crossed.

 

If I’m still running a bit lean, is there any way to tell if damage is occurring?
I’d guess the temp gauge would be reading hot before any piston melting occurs but is this actually right? Luckily I’m Not experienced in that area lol but I’ve got a 120 mile drive coming up the week after next

 

 

Take spare plugs, perhaps one grade colder than normal.

If it is too lean the plugs will probably melt/weld at electrode.

Or it will burn edge of an exhaust valve.

 

Another cheap balance and check for lean method. Get an IR thermometer and check all exhaust branches are equally hot. If one is much hotter give it more fuel.

 

It's a poor man's EGT probe. I see about 260C on a stainless manifold. Dunno how accurate the thermometer is. My engine is high compression and cruises leaner and hotter than most. It's standard radiator is shared with VW Santana. 

 

Thanks man, I like the IR thermometer idea, think aldi have them in at the moment for daft prices. Will investigate, there’s definitely a lean cylinder or 2, not badly enough for the pulling ht leads trick to tell me anything though 🙃

12 minutes ago, dvderlm said:

Take spare plugs, perhaps one grade colder than normal.

If it is too lean the plugs will probably melt/weld at electrode.

Or it will burn edge of an exhaust valve.

 

Another cheap balance and check for lean method. Get an IR thermometer and check all exhaust branches are equally hot. If one is much hotter give it more fuel.

 

It's a poor man's EGT probe. I see about 260C on a stainless manifold. Dunno how accurate the thermometer is. My engine is high compression and cruises leaner and hotter than most. It's standard radiator is shared with VW Santana. 

 

Will a non IR thermometer do the trick? Flatmates a pizza chef and might be able to grab a probe one from work, the ovens are like 3/400c so could be a cheap option haha