Ashley James Posted June 25, 2012 Report Share Posted June 25, 2012 Surely if tickover is rising, it's not mixture because that will be constant unless the needle valves in the float chambers aren't sealing, in which case fuel will dribble in and may cause the problem. The other possibility is that the dashpots are sticking, so make sure they drop with a nice, solid clunk. Ash Quote Link to post Share on other sites
sandandlime Posted June 26, 2012 Author Report Share Posted June 26, 2012 Morning all, Thanks for everyone's replies and apologies for the dealy at coming back to you. I had to take my wife for a hospital appointment, 2 1/2 hour drive each way, plus the appointment as well as taking my son 40 km for his last exam of the year. So by the time that was all done with I was only ready for a nice cold beer! Hopefully, I should be able to get my head beneath the bonnet later this afternoon. Thanks again and I'll be in touch soon. Tony Quote Link to post Share on other sites
Peter Cobbold Posted June 26, 2012 Report Share Posted June 26, 2012 Check they are not a PO's bitsas in respect of this: check the dome is drilled ( ca 1 to 2mm bore) at the top of the damper tube to connect its bore to the space above the piston. That ensures the damper does not hang up upon closing the throttle. If the drilling is not present the hex cap on the top of the damper rod must be drilled through to vent the damper bore to atmosphere. Quote Link to post Share on other sites
Guest ntc Posted June 27, 2012 Report Share Posted June 27, 2012 Check they are not a PO's bitsas in respect of this: check the dome is drilled ( ca 1 to 2mm bore) at the top of the damper tube to connect its bore to the space above the piston. That ensures the damper does not hang up upon closing the throttle. If the drilling is not present the hex cap on the top of the damper rod must be drilled through to vent the damper bore to atmosphere. Peter Totally bog std carbs under 4000 miles from new on my 3 and there are no holes? Quote Link to post Share on other sites
stuart Posted June 27, 2012 Report Share Posted June 27, 2012 Peter Totally bog std carbs under 4000 miles from new on my 3 and there are no holes? But the dashpots have a sloped piece on one side at the top with Brass damper tops = no need for holes in the top. Stuart. Quote Link to post Share on other sites
Guest ntc Posted June 27, 2012 Report Share Posted June 27, 2012 But the dashpots have a sloped piece on one side at the top with Brass damper tops = no need for holes in the top. Stuart. Sorry chap but no sloped piece either car runs spot on Quote Link to post Share on other sites
sandandlime Posted June 29, 2012 Author Report Share Posted June 29, 2012 (edited) Tony, How did the air leak test progress ? Mick Richards Thanks for everyones continued input to this thread and apologies for taking sp long to provide feedback. It took me a few days to get back to Ludo with sufficient time and in the right frame of mind but today I managed to get under the bonnet and out on the road a few times. With respect to air leak testing, I didn't have spray brake cleaner to hand but instead sprayed various volatile substance around the inlet manifold and carburettor shafts. Nothing had any effect on engine revs so I presume that I don't have any vacuum leaks hereabouts. I did notice that the rubber boot linking the vacuum advance to the carburettor didn't seem to be a good fit but neither did it seem a cause of leakage. I will see if I can get hold of a new or better fitting boot to see if that helps though. For the most part, there have been two things that I have been looking at; trapped air in the cylinder head and mixture. With respect to the former I've had the front up on the air since last Sunday and have been massaging the hoses each time I went passed to try and burp the air out. I've also run her for a while without the radiator cap whilst burping to see what effect that has, other than spraying coolant all over the place. I think that he process has been reasonably successful and reckon that I might have managed squeeze in another half litre or so (it's hard to be sure as most probably went straight on the floor or has provided a nice speckled finish to the engine bay). Today I dropped the jets to 55 thou and took her out for a run of about 15 miles. Checking the plugs when I got back, combined with the engine cutting out on long downhill deceleration, suggested, much to my surprise, that she was still lean. I dropped another 10 though and found she was more settled and there was better colour on the insulators. Finally, I dropped them to 70 thou at which point she ticked over very smoothly, the best I've had her, albeit at 900 rpm. I ran out of time to get her on the road again today but even at that setting a small lift of the carb pistons caused the revs to drop suggesting that she's still lean. Clearly, I need to see what the plugs look like after a decent run but I do feel that I'm on the right track now, even though I'm very surprised just how far down I've had to set the jets. Does anyone have a view on changing the needles from SM to TW? I presume that it would provide better low rev mixture control but would I lose out too much at the higher end given that she has a reasonably lively cam? As always, any advise gratefully received. Tony PS: the carbs are HS6. The Knurled plastic caps do have the appropriate hole and both pistons are well damped, well matched and take about 8 seconds to fall from the top, so I don't think that there's much issue there. I will order service kits from Burlens, including new floats but and unsure about needle options at this stage. Edited June 29, 2012 by sandandlime Quote Link to post Share on other sites
peejay4A Posted June 29, 2012 Report Share Posted June 29, 2012 If the piston slides take 8 seconds to fall then surely something is wrong. They are damped on the upward movement only. Quote Link to post Share on other sites
sandandlime Posted June 29, 2012 Author Report Share Posted June 29, 2012 If the piston slides take 8 seconds to fall then surely something is wrong. They are damped on the upward movement only. Hi peejay, Yeah. Sorry, didn't make myself clear. The pistons take about eight seconds to fall if the pistons and dashpots are removed, the piston lifted inside the dashpot and a thumb positioned over the hole in the dashpot to check the piston fit. I checked this to ensure that the pistons hadn't been installed in the wrong dashpot at sometime. With the exception of the front jet which is a bit sticky the overall condition of the carbs seems fine. It would be good to be able to adjust the jet height though. All the best, Tony Quote Link to post Share on other sites
peejay4A Posted June 29, 2012 Report Share Posted June 29, 2012 Ah. Understood. Quote Link to post Share on other sites
Icarus60 Posted June 30, 2012 Report Share Posted June 30, 2012 Tony Well done Tony, sounds like you are getting there. I havent heard an explanation of why this is necessary but I set mine around 0.065 some time ago and get good performance and fuel consumption on H6s on a standard engine with SM needles fitted. Suggest you consider buying the SU book in the Veloce publishing Speedpro series to set up for your modified engine. It is good read IMOP Regards Rog Quote Link to post Share on other sites
sandandlime Posted July 1, 2012 Author Report Share Posted July 1, 2012 Tony Well done Tony, sounds like you are getting there. I havent heard an explanation of why this is necessary but I set mine around 0.065 some time ago and get good performance and fuel consumption on H6s on a standard engine with SM needles fitted. Suggest you consider buying the SU book in the Veloce publishing Speedpro series to set up for your modified engine. It is good read IMOP Regards Rog Hi Rog, It's encouraging to hear that 70 thou may not be too far adrift with SM needles. Thanks for the book suggestion - I'll have a look for it online this evening. Ludo has an increased compression ratio and a fairly warm camshaft so perhaps needs to be a touch rich low down the rev range to enable everything to work better at the mid to higher end. I'm going to try and get out for a spin later on today but need to get some bathroom floor tiles cut beforehand to avoid getting too far behind. As usual, nothing is square so nothing is simple! All the best, Tony PS: I note that you list vintage British bikes as an interest; here's a photo of mine... At the moment he's short of tank and radiator as both are away for leakage repair. An irritating fuel leak that slowly runs into the crankcase - I know of one Scott that blew-up whilst at high-speed for a similar reason - and numerous damp radiator seams that just got too much to be held together with Fernox. Looking forward to getting the parts back and Alfred back on the road, soon I hope. Quote Link to post Share on other sites
Richard V Posted July 3, 2012 Report Share Posted July 3, 2012 The photos are opposite sides of the same plug. One side looks fine the other way too lean; something is definitely not working as it should! Hi, Does anyone know what causes this effect on the plugs. I have something similar on a recently re-built engine which runs fine, I am just interested to know what causes it. Cheers, Richard. Quote Link to post Share on other sites
sandandlime Posted July 20, 2012 Author Report Share Posted July 20, 2012 Hi, Does anyone know what causes this effect on the plugs. I have something similar on a recently re-built engine which runs fine, I am just interested to know what causes it. Cheers, Richard. Hi Richard, For my part I think that I am slowly getting there, just held up awaiting new needles from Burlens before finessing the carbs (allegedly due in the end of this month but I have heard that before). With regard to the uneven plug colouring, I have been mulling it over for a while now and have concluded that it must be due to different temperatures on either side of the plug, which initially I thought was unlikely. However, it does seem that I had set Ludo's engine up too lean and this could have lead to overheating of the exhaust valve. My thinking is that a temperature gradient formed across the plug with the hot side adjacent to the exhaust valve and the cooler side the inlet valve (cool fuel/air charge). Once I get hold of my card service kits I'll check this out but at the moment my plugs are more even so I'm not proposing raising the jets to test my theory! HTH, Tony Quote Link to post Share on other sites
sandandlime Posted August 24, 2012 Author Report Share Posted August 24, 2012 Evening folks, Just to wrap-up this thread, I thought that I'd report back regarding the current status. Well, I eventually received the carb service kits from Burlens and had the opportunity to strip the carbs down last Friday. All went fine and I managed to get everything cleaned, sorted and back in place the following day. The only thing remaining was to set the jet heights and balance the carbs before adjusting the idle speed. However, this is where things started to go wrong. It was a pretty warm day, on the top side of 35°C, and eventually I noticed that the Kenlowe had stopped working and the engine was getting a bit hot. To cut a long story short, I stopped setting-up the carbs and began fault-finding the wiring to the Kenlowe. It was difficult to be certain exactly what the problem was but it was related to connections/cables breaking down under load. To resolve the issue properly I opted to rewire the Kenlowe with its own relay, manual override and nice bright green led indicator light. Whilst doing this little task I also decided to fix a few other wiring issues that were niggling me. One thing lead to another and six days later I was back to setting-up the carbs again. Today was pretty much job done. During road testing it was quite clear what TR4Tony meant by saying that Ludo was 'mildly modified'. She went like a pocket rocket and her performance from 50 to 80 something was pretty impressive. Not only that, she ran spot-on temperature wise, was quiet, pinking free, cycling free and no signs of anything untoward. In fact she was like a different car: the one she always should have been! Like the wiring, it's difficult to be sure about what exactly was fixed but I think that it was an amalgam of things that added up to a lot of irritating issues that are, at least for the time being, now history. Only one small thing remains to be completely resolved and that's the tickover. Ludo is now smooth and steady but with a tickover of around 950 to 1000 rpm. I'd like to drop it a bit but I think that I've now got to the stage where the slow running screws are just about clear of the throttle stops. I'm not going to worry about too much, there aren't any traffic queues around here so idling isn't that important. In conclusion, congratulations to TR4Tony for doing such a sound job 15 years ago. Now it's my job to keep her up to scratch. Thanks for everyone's input and support. All the best, Tony PS: the jets are around 75 thou below the bridge. She responds pretty much text book like to raising the pistons but, if anything, the plugs suggest she is still a tad on the lean side but not enough to sweat about. Quote Link to post Share on other sites
Richard V Posted September 19, 2012 Report Share Posted September 19, 2012 (edited) PS: the jets are around 75 thou below the bridge. She responds pretty much text book like to raising the pistons but, if anything, the plugs suggest she is still a tad on the lean side but not enough to sweat about. Due to this thread, I measured my jets for the first time today. On RH needles in HS6 carbs. The plug colour is perfect and she pulls like a grand national winner. jets measured at 92 thou. (thats 17 flats down) The books say to start at 2.5 turns down, thats 15 flats, and as most know the TR's need to run slightly rich, so 17 flats does not seem excessive. I dont know how some cars are running smoothly at speed on 38 to 40 thou? Try another flat or 2 Sandandlime. (Too rich doesnt hurt, too lean does!) Richard. Edited September 19, 2012 by Richard V Quote Link to post Share on other sites
Ashley James Posted September 20, 2012 Report Share Posted September 20, 2012 They were originally set up 38-40 though down, but if the butterfly spindles are worn or the floats low......... Quote Link to post Share on other sites
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