Crass Posted August 27 Share Posted August 27 My 750L Slingy has done 40k-odd miles and I have no reason to believe the carbs are in any other condition than as fitted in the factory. It runs a bit rich at very small throttle, especially when hot trying to filter through traffic or picking up out of a corner, tends to stutter before clearing. Fiddling with pilot screw hasn't helped. It's been dynoed which confirms. My suspicion is that the carbs are well overdue some TLC, possibly emulsion tubes going oval etc. Whilst I could theoretically do a rebuild myself I'd prefer someone who knows what they're doing to do it so that anything that needs doing can be done rather than me winging it. I would be looking to have genuine Mikuni parts used where possible, I'm not looking for 'a cheap job'. Can members recommend anyone? Quote Link to comment
Upshotknothole Posted August 27 Share Posted August 27 If you've got the BST38 carbs, your emulsion tubes have probably been worn for quite some time. Easy way to check if they're stock or not, drain one of the bowls and open the quick access plug to get to the main jet, pull one of your mains and check the size compared to stock. I've got a 750M and just rebuilt my carbs and rejetted them. Emulsion tubes are hard to find, they've been discontinued but still pop up on Eblag. I managed to find a set of NOS for pretty cheap last year. Only other option is a Dynojet stage 1 kit as they use their own emulsion tubes. Most of the gaskets and stuff can be had still from Suzuki, but you should go ahead and check first. Is the bike stock or have you swapped out the exhaust or air box? Sorry I can't help with a local shop to do the work as I'm in the states, but they're not terribly difficult carbs to rebuild yourself. 2 Quote Link to comment
clivegto Posted August 28 Share Posted August 28 Brian McCall of Centurion Motorcycle Projects cleans carburettors and sells replacement parts for them. 4 Quote Link to comment
DAZ Posted August 28 Share Posted August 28 I also believe @imagodoes this kind of work through his business and is an OSS trader too maybe drop him a pm ? 2 Quote Link to comment
imago Posted August 28 Share Posted August 28 Brian does top quality work, I guess it depends on how much of a rush you're in and who's got what on. Also, Brian can refinish the carbs to make them pretty as well. Full carb rebuilds is a bloody expensive game now, as @Upshotknotholesays OE emulsion tubes are all but impossible to get now which adds to the time and cost. 3 Quote Link to comment
clivegto Posted August 28 Share Posted August 28 2 hours ago, DAZ said: I also believe @imagodoes this kind of work through his business and is an OSS trader too maybe drop him a pm ? Brian is an OSS member as well but he's easy to find on ACS on FB page. 2 Quote Link to comment
Crass Posted August 28 Author Share Posted August 28 (edited) Thanks everyone for the recommendations. I'm not in a huge rush, was going to do this over the winter so plenty of time if parts take time to source and people have a queue of work. Yes, they're BST38s and AFAIAA are stock. I still have an airbox although there's a K&N in there and the exhaust system has been replaced. I won't know for sure until I have a looksee if they've been fiddled with in the past but I'll do that once I have them off. I'll contact people in a couple of months or so when it's time to get started. They could definitely do with a proper clean up externally as part of the work too. Appreciated, cheers. Edited August 28 by Crass Quote Link to comment
imago Posted August 28 Share Posted August 28 8 minutes ago, Crass said: Thanks everyone for the recommendations. I'm not in a huge rush, was going to do this over the winter so plenty of time if parts take time to source and people have a queue of work. Yes, they're BST38s and AFAIAA are stock. I still have an airbox although there's a K&N in there and the exhaust system has been replaced. I won't know for sure until I have a looksee if they've been fiddled with in the past but I'll do that once I have them off. I'll contact people in a couple of months or so when it's time to get started. They could definitely do with a proper clean up externally as part of the work too. Appreciated, cheers. In that case I'd suggest you spend time between now and then searching out some OE bits. They are difficult to come by, but they do turn up and the more time you have to look the higher the success rate. As already said, you will definitely need emulsion tubes as it doesn't sound like they've been replaced. If you can find a new set of those you'll have done the hard work. 1 Quote Link to comment
Upshotknothole Posted August 28 Share Posted August 28 1 hour ago, Crass said: Thanks everyone for the recommendations. I'm not in a huge rush, was going to do this over the winter so plenty of time if parts take time to source and people have a queue of work. Yes, they're BST38s and AFAIAA are stock. I still have an airbox although there's a K&N in there and the exhaust system has been replaced. I won't know for sure until I have a looksee if they've been fiddled with in the past but I'll do that once I have them off. I'll contact people in a couple of months or so when it's time to get started. They could definitely do with a proper clean up externally as part of the work too. Appreciated, cheers. If you're already running an aftermarket exhaust and a K&N in the air box, a Dynojet stage 1 kit will probably save you a lot of time searching for emulsion tubes. Quote Link to comment
Crass Posted August 28 Author Share Posted August 28 4 hours ago, imago said: In that case I'd suggest you spend time between now and then searching out some OE bits. They are difficult to come by, but they do turn up and the more time you have to look the higher the success rate. As already said, you will definitely need emulsion tubes as it doesn't sound like they've been replaced. If you can find a new set of those you'll have done the hard work. Thanks, I'll do that. Quote Link to comment
Crass Posted August 28 Author Share Posted August 28 3 hours ago, Upshotknothole said: If you're already running an aftermarket exhaust and a K&N in the air box, a Dynojet stage 1 kit will probably save you a lot of time searching for emulsion tubes. What's the quality like with the Dynojet stuff? I don't want to try and save myself trouble but end up with only a temporary fix but if it's good quality it may well be the way to go. Would a stage 1 kit need setting up on the dyno or does it just work out of the box? Quote Link to comment
Upshotknothole Posted August 28 Share Posted August 28 (edited) 1 hour ago, Crass said: What's the quality like with the Dynojet stuff? I don't want to try and save myself trouble but end up with only a temporary fix but if it's good quality it may well be the way to go. Would a stage 1 kit need setting up on the dyno or does it just work out of the box? They're decent quality, and you can get replacement parts individually from them. You should be able to get it as good as it currently is with the stock jetting, K&N, and an exhaust. What I mean is you're probably not gonna get it perfect without a dyno session, but you should be able to get it as good as it is now if not better. And the only reason I really suggest it is they include emulsion tubes and sell replacements if you need them again in the future. If you can find a set of stock ones, go with those. If you're having a shop rebuild them, ask them what they prefer doing. You can also go to the dynojet website and read the instructions for installing the jet kit if you're curious. Edited August 28 by Upshotknothole more info Quote Link to comment
Crass Posted August 28 Author Share Posted August 28 Thanks. There's a place near Doncaster where I live run by ex racer Ashley Law who does carb work and set-up on a dyno, including Dynojet work. I'm beginning to think that it might make more sense rather than having them rebuilt, then probably having to take the bike to a dyno to get it fully set up, to actually speak to him about doing the whole job. If I'm going to tackle this I might as well get it sorted properly in one go. This by no means suggests I'm ungrateful for the suggestions on here, in fact everyone's advice has enabled me to understand the best way to go with this and the scale of work which might be involved. 1 Quote Link to comment
clivegto Posted August 29 Share Posted August 29 Dyno jet kits are pretty much plug and play out of the box. Quote Link to comment
Crass Posted August 29 Author Share Posted August 29 1 hour ago, clivegto said: Dyno jet kits are pretty much plug and play out of the box. If this is the case the best way to do this may be for me to take the carbs off and fit the dynojet kit myself. If it's going to run pretty well out of the box it would be rideable to the dyno place to have any final setup done there, so I'm only paying for the session. My initial concern was not knowing what needed replacing and what was ok but if I'm sticking a kit in that's irrelevant as it's all being swapped out. Quote Link to comment
Nick Posted August 29 Share Posted August 29 2 hours ago, clivegto said: Dyno jet kits are pretty much plug and play out of the box. This is not my experience - certainly with 1100M carbs. Also, be advised that modern dynojet kits dont come with new emulsion tubes - the jets use the OE Suzuki ones now. So, if your emulsion tubes are ovalled, it will be terminally rich in any case... Just a thought. I gave up with the stage 1 dynojet kit on my 1100M - it was killing plugs and unrideable, despite using their settings - and the tech support wasn't great. So bad I would've needed a van to get to a dyno, in fact. I've gone back to OE needles and jets and have tweaked that slightly (1100M, akra system, airbox with k&n)... Quote Link to comment
Gixer1460 Posted August 29 Share Posted August 29 1100M 40mm carbs are renowned to be an absolute bitch to set-up in anything other than absolute bone stock installs! I've done a few 1100 kits with 36mm carbs - different filters (generally K&N pods though) and pipes or full systems and they are 'plug & play' in my experience - follow the instructions and at most they've needed a two point MJ change - never ever changed an idle jet. Worst thing is the Titanium needles wearing out but lifetime guarantee so . . . . . 1 Quote Link to comment
Crass Posted August 29 Author Share Posted August 29 (edited) 30 minutes ago, Nick said: This is not my experience - certainly with 1100M carbs. Also, be advised that modern dynojet kits dont come with new emulsion tubes - the jets use the OE Suzuki ones now. So, if your emulsion tubes are ovalled, it will be terminally rich in any case... Just a thought. I gave up with the stage 1 dynojet kit on my 1100M - it was killing plugs and unrideable, despite using their settings - and the tech support wasn't great. So bad I would've needed a van to get to a dyno, in fact. I've gone back to OE needles and jets and have tweaked that slightly (1100M, akra system, airbox with k&n)... Oh right, thanks for that, that doesn't sound much good to me then as the emulsion tubes are likely the issue. Edited August 29 by Crass Quote Link to comment
Crass Posted August 29 Author Share Posted August 29 Is a Factory Pro kit (including emulsion tubes) available for BST38s running on a 750 motor? I can see an 1100 version. Quote Link to comment
Upshotknothole Posted August 29 Share Posted August 29 8 minutes ago, Crass said: Is a Factory Pro kit (including emulsion tubes) available for BST38s running on a 750 motor? I can see an 1100 version. I’m running the factory pro kit, prefer them over dynojet, they use the OEM emulsion tubes, and they do not include them or carry them. You’ll need to source them yourself. Factory Pro is also super helpful if you have any questions. Quote Link to comment
Upshotknothole Posted August 29 Share Posted August 29 7 hours ago, Nick said: This is not my experience - certainly with 1100M carbs. Also, be advised that modern dynojet kits dont come with new emulsion tubes - the jets use the OE Suzuki ones now. So, if your emulsion tubes are ovalled, it will be terminally rich in any case... Just a thought. I gave up with the stage 1 dynojet kit on my 1100M - it was killing plugs and unrideable, despite using their settings - and the tech support wasn't great. So bad I would've needed a van to get to a dyno, in fact. I've gone back to OE needles and jets and have tweaked that slightly (1100M, akra system, airbox with k&n)... Their 750 kits do come with emulsion tubes, their needles won’t work with stock emulsion tubes. I just ordered replacement emulsion tubes from them in the past year. 1 Quote Link to comment
Jeb Posted August 29 Share Posted August 29 Hi, ...I got keyster repair kit complete with emulsion tubes...had absolutely no probs, the bike started on the button after the swap ...cost about £140 but well worth it as I was fannying on with acetone. Bikes a gsx1100f 1 Quote Link to comment
Crass Posted August 29 Author Share Posted August 29 2 hours ago, Jeb said: Hi, ...I got keyster repair kit complete with emulsion tubes...had absolutely no probs, the bike started on the button after the swap ...cost about £140 but well worth it as I was fannying on with acetone. Bikes a gsx1100f Interesting, thanks. A quick search shows they do a kit for the 750 Slingy and the photos of the kit appear complete with emulsion tubes, needles etc. Anyone else had any experience with this brand, they appear to be quality Japanese engineered aftermarket kit? Quote Link to comment
Simbec1863 Posted August 30 Share Posted August 30 Used them on my race bikes and never had any issues with Keyster, NRP carbs are a dealer in the UK or you can also buy direct from Japan Quote Link to comment
Crass Posted August 30 Author Share Posted August 30 4 hours ago, Simbec1863 said: Used them on my race bikes and never had any issues with Keyster, NRP carbs are a dealer in the UK or you can also buy direct from Japan Thanks. I'd trust anything NRP sell as they're a reputable carb specialist. This sounds like the way to go then. Quote Link to comment
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