TR4ffic Posted April 16 Report Share Posted April 16 Hi All, I'm after a bit of advice if I may... I'm having to replace the seals on the bottom of the carbs, where the float chamber attaches. I have the arrangement on the right in the image - Stud (123) and the nut (120). New seals received from Moss... Questions is: How tight should the nut be done up? After a long time standing idle (The TR, not me!), on trying to start it over the weekend, discovered fuel leaks from both carbs and the nuts weren't tight ...tightening them didn't stop the leaks and could almost have made them worse! Many thanks in advance Nick Quote Link to post Share on other sites
TR4ffic Posted April 21 Author Report Share Posted April 21 Afternoon All So... I've made good progress and resolved the problem posted above. In dismantling everything and removing the stud (123) I discovered that a PO had put the studs in without the fibre washers (124) and with something that could have been PTFE tape on the thread! Giving everything a good clean, fitting new fibre washers and seals (118) has resolved the leak. I couldn't find any info on how tight to do up the nut (120) - I didn't want to over tighten and deform the rubber washers - but in the end I did everything up pretty tight! Sorted..! I now have a different problem in starting and keeping the engine running... In the past, it has been a pretty good starter on the 2nd/3rd go. I've primed the float chambers manually via the fuel pump, checked I have fuel in the chambers. Choke set. The engine turns over with no sign of life at all - no attempt to catch, and various throttle settings. Nothing... Then, close the choke and throttle it will spring instantly into life - open the throttle to catch it and the engine will run smoothly and sweetly with good revs ...for about 5-10 seconds.!! Try to start again straight away - Nothing... Try with choke and throttle - Nothing... Close choke and throttle - starts straight away and dies after 5-10 seconds... This has been repeated 3 or 4 times... I'm assuming that the 'trying to start' gets plenty of fuel into the carbs. It starts but then it's a problem of ongoing fuel delivery the is the problem ...it's getting starved of fuel? But I don't know what/how to check? The engine last ran last year with no issues. Last week when I came to start it, I had the same symptoms as above once but didn't progress due to the fuel leak now rectified. Any ideas please? Quote Link to post Share on other sites
RobH Posted April 21 Report Share Posted April 21 (edited) It sound as though you may be emptying the float chambers more quickly than they can replenish, though 5-10 seconds is pretty short for that so perhaps just emptying the jet tube . Are you sure there is good flow from the float chamber to the jet, through the bits you have replaced? Have some particles of that old ptfe tape caused a blockage? Edited April 21 by RobH Quote Link to post Share on other sites
TR4ffic Posted April 21 Author Report Share Posted April 21 Hi Rob Whilst I had the tops off the float chambers I did check the setting of the levers (129) as per the manual - I had to raise (bend) both levers (one more than the other) but this will have increased the amount of fuel in the chambers before the valve is closed by the rising float. I have got the Grose Jets as opposed to the standard Needles & Seats - I changed these last year (Has it run properly since - I can't remember!?). I haven't checked the float chambers after the short run so that is worth looking at - I'll do this tomorrow... There is definitely fuel getting to the jets as the jet assemblies at the bottom of the carbs are wet with fuel (I thinking this isn't another leak but due to the amount of unused fuel getting into the carbs?) Nick Quote Link to post Share on other sites
stuart Posted April 21 Report Share Posted April 21 Grose jet dont have a good rep Im afraid, I would be changing them for standard Delrin tipped needles. Stuart. Quote Link to post Share on other sites
RobH Posted April 21 Report Share Posted April 21 (edited) Have you removed the carb piston chamber and looked at the fuel level in the jet Nick? That's the important thing. It should be a short way down from the top (not critical - 1/8 to 1/4 inch is fine). The wetness you describe sounds like it could be overflow from too high a level. The starting problem you describe could be a grossly (!) over-rich mixture due to that. Edited April 21 by RobH Quote Link to post Share on other sites
Ralph Whitaker Posted April 22 Report Share Posted April 22 Bin the Grosse jets. Caused me no end of flooding problems which were all sorted when I went back to standard . Ralph Quote Link to post Share on other sites
james christie Posted April 22 Report Share Posted April 22 I've been using Grose jets on my HS6 float chambers for well over 40 years. They solved a permanent smell of leaking fuel at the time. Curiously, given the above remarks, I have only praise for them!! Maybe the quality of manufacture has changed for the worse. james Quote Link to post Share on other sites
stuart Posted April 22 Report Share Posted April 22 1 hour ago, james christie said: I've been using Grose jets on my HS6 float chambers for well over 40 years. They solved a permanent smell of leaking fuel at the time. Curiously, given the above remarks, I have only praise for them!! Maybe the quality of manufacture has changed for the worse. james Sadly that s the case, when they first appeared they were well made and did the job well, unfortunately not now. Stuart. Quote Link to post Share on other sites
Kiwifrog Posted April 22 Report Share Posted April 22 I had one stick open on first run round the block this spring, I now know that there is an overflow/air hole in the top of HS6 carbs and petrol comes out at quite a rate when the needle is stuck open. Replaced with Delrin tipped needles on both carbs. Cheers Alan Quote Link to post Share on other sites
TR4ffic Posted April 23 Author Report Share Posted April 23 On 4/21/2024 at 5:20 PM, RobH said: Have you removed the carb piston chamber and looked at the fuel level in the jet Nick? That's the important thing. It should be a short way down from the top (not critical - 1/8 to 1/4 inch is fine). Hi Rob/All Update: Started the engine this afternoon with the now familiar 5-10 seconds of runtime before it faded away and stopped! I immediately checked the fuel level in the Float Chambers and both still had fuel in them - to approx the same level as before starting ...so I'm assuming the fuel pump is OK, and the Grose Jets. I removed the Chamber and Piston of both carbs; the fuel level in the jet you describe above - Is that in the small hole the Needle sits in? I couldn't see into the hole to gauge the fuel level - far too small or my aging eyesight! It certainly wasn't full.!! Regards the Grose Jets: It's a pity these 'superior replacements' (Moss's description!) don't appear to live up to expectations... Unfortunately I don't have the original Needles & Seats to swap back to - I dropped and lost a needle last year and couldn't find it which prompted the swap! New Needles & Seats are on back order with Moss at the moment but could look elsewhere. Is there anything else I can do/check prior to swapping back to the original Needles & Seats to eliminate the Grose Jets (just in case they are causing the issue)? Nick Quote Link to post Share on other sites
RobH Posted April 23 Report Share Posted April 23 If you couldn't see any fuel in the jet it might be a clue as to why the engine stops Nick. Perhaps it has used up all that was there? You can usually see the glint of the liquid if you shine a torch down the hole. The float chamber might be full but if fuel isn't getting through to the jet properly, it can't run. After all, that is the thing you have been working on and sudden onset of a new fault afterwards might be a pointer to all not being well.........?. Quote Link to post Share on other sites
Lebro Posted April 23 Report Share Posted April 23 It's much easier to see the fuel level in the carb body if you pull the choke right out to max, there is then a much larger hole to peer down. Bob Quote Link to post Share on other sites
TR4ffic Posted April 23 Author Report Share Posted April 23 26 minutes ago, Lebro said: It's much easier to see the fuel level in the carb body if you pull the choke right out to max, there is then a much larger hole to peer down. Bob ...that sounds like a plan! Quote Link to post Share on other sites
TR4ffic Posted Tuesday at 06:07 PM Author Report Share Posted Tuesday at 06:07 PM (edited) 2 hours ago, RobH said: The float chamber might be full but if fuel isn't getting through to the jet properly, it can't run. After all, that is the thing you have been working on and sudden onset of a new fault afterwards might be a pointer to all not being well.........? As mentioned previously, the bottom of the jet/choke mechanism under both carbs is getting wet with fuel. Signs that my recent work on the Float Chambers hasn't hindered fuel flow..? Also, I can see signs of fuel in the carb body and on the Throttle Disc, and I also noticed fuel dripping from the vacuum advance pipe connection under the front carb today - after much cranking over attempting to start. Is this all signs of too much fuel.!? Edited Tuesday at 06:08 PM by TR4ffic Quote Link to post Share on other sites
RobH Posted Tuesday at 06:22 PM Report Share Posted Tuesday at 06:22 PM The choke mechanism certainly shouldn't be wet with fuel - and neither should the vacuum advance pipe. These are possibly signs of the jet overflowing due to too high a fuel level in the float chamber. If the mixture is way too rich the engine won't fire. Quote Link to post Share on other sites
Kiwifrog Posted Tuesday at 07:28 PM Report Share Posted Tuesday at 07:28 PM 3 hours ago, TR4ffic said: Hi Rob/All Update: Started the engine this afternoon with the now familiar 5-10 seconds of runtime before it faded away and stopped! I immediately checked the fuel level in the Float Chambers and both still had fuel in them - to approx the same level as before starting ...so I'm assuming the fuel pump is OK, and the Grose Jets. I removed the Chamber and Piston of both carbs; the fuel level in the jet you describe above - Is that in the small hole the Needle sits in? I couldn't see into the hole to gauge the fuel level - far too small or my aging eyesight! It certainly wasn't full.!! Regards the Grose Jets: It's a pity these 'superior replacements' (Moss's description!) don't appear to live up to expectations... Unfortunately I don't have the original Needles & Seats to swap back to - I dropped and lost a needle last year and couldn't find it which prompted the swap! New Needles & Seats are on back order with Moss at the moment but could look elsewhere. Is there anything else I can do/check prior to swapping back to the original Needles & Seats to eliminate the Grose Jets (just in case they are causing the issue)? Nick You need to try Burlen fuel systems, they are the modern day incarnation of SU https://burlen.co.uk/ Quote Link to post Share on other sites
Ralph Whitaker Posted Wednesday at 05:53 AM Report Share Posted Wednesday at 05:53 AM (edited) On 4/21/2024 at 1:17 PM, RobH said: It sound as though you may be emptying the float chambers more quickly than they can replenish, though 5-10 seconds is pretty short for that so perhaps just emptying the jet tube . Are you sure there is good flow from the float chamber to the jet, through the bits you have replaced? Have some particles of that old ptfe tape caused a blockage? +1 I would take the jet tubes out and check they are clear. Problem starting sounds like classic weak mixture, will start but as soon as it does the pistons lift and lets more air in and the mixture goes weak. Ralph Edited Wednesday at 05:56 AM by Ralph Whitaker Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.