re500 Posted June 15, 2005 Report Share Posted June 15, 2005 Hi Anyone taken apart a hot start system on their 4 stroke Enduro/MX? How big is the jet(?) that allows air into the intake manifold? Can you see any pipework externally, if so what size is it? Does the engine run (fast) with the hot start in use or do you close it as soon as the engine fires? Any info would be usefull.. cheers Quote Link to comment Share on other sites More sharing options...
woody Posted June 15, 2005 Report Share Posted June 15, 2005 I fitted a remote hot start kit to my YZ426 a few years ago. All this involved was unscrewing the standard one from the carb, replacing that with an adaptor to which was fixed a piece of clear pipe (same size as carb overflow pipe roughly). The pipe went to a device on the handlebar which was just an on/off valve - when open it let air in to help with hot starting. It wasn't any more effective than the standard device in terms of starting efficiency but it just meant I didn't have to grovel with the carb mounted lever when I'd crashed and burned a stinking hot engine so it was a time saver. The inlet into the carb (inlet side of the body) was I'd guess about the same diameter as the internal diameter of the pipe but all this is approximate you understand. I don't know how you would modify your carb to take something like this though. In operation, as soon as the engine fires you knock the hot start off as it only serves to aid starting, the engine won't perform with it open. I have a WR426 now with the standard hot start as I fitted a YZ450 cam which has auto decomp fitted and starting is much easier. If I can get the hot start button out I'll try and measure the intake hole for you but it may be a couple of days before I can do it. Quote Link to comment Share on other sites More sharing options...
re500 Posted June 15, 2005 Author Report Share Posted June 15, 2005 Woody Many thanks for the explanation and info. Wouldn't be differcult to fit to the carb' especially ~1/8" tube, like the overfolw pipes. Any measurments you can find would be much apprieciated. Cheers RE500 Quote Link to comment Share on other sites More sharing options...
woody Posted June 17, 2005 Report Share Posted June 17, 2005 Took the hotstart button out and had a look. It is just a simple pull/push plunger that sits in an inlet tube which is 8mm in diameter and about 1 and a half centimetres deep - although this depth is irrelavent really as it depends on the design of the carb. At the end of this tube is another which looks to be 5 - 6mm diameter but I have no idea where that goes - presumably into the carb inlet itself. The plunger I guess uncovers a jet somewhere in the side of the 8mm tube to allow cold air in - couldn't see into it properly but I can't see any other way it works. This jet must be open to the atmosphere somehow, presumably through one of the many pipes that come off the 426 carb. I guess the remote handlebar fitted hotstart wouldn't need the additional internal jetting/plumbing, just the inlet, as the valve which opens the inlet to the atmosphere is on the handledar mechanism and connected to the inlet via the pipe. The kit can be bought from any motocross/enduro retailer but they aren't cheap - about Quote Link to comment Share on other sites More sharing options...
re500 Posted June 17, 2005 Author Report Share Posted June 17, 2005 Woody Many thanks for taking the time to have a look for me. Extremely usefull info'. Following your first post i have simply modified the carb on the 4T so that the choke is now a air by pass. Not fresh air, but additional air from the air box. Very easily done invloving no irreversible changes. Now when you operate the choke lever the engine revs increase, max around 5mm lift until too lean to run. In my next trial i will try 'very hot' starts at 5mm and full lift and see what difference there is! Hope the weather doesn't turn cold...as theres no choke start now! Again, many thanks for the help. Cheers RE500 Quote Link to comment Share on other sites More sharing options...
woody Posted June 17, 2005 Report Share Posted June 17, 2005 No problem, just glad if I can be of any help and hope you solve your problem. Although I own and like my Mont 4RT I like the Sherco too and hope they relosve the little niggles they seem to have. Nothing like a bit of variety out there in the sections. Sounds like a novel solution you may have found to your hot starting problem. You ought to post that on Thumpertalk as mulling that one over would keep them busy for days Quote Link to comment Share on other sites More sharing options...
re500 Posted June 27, 2005 Author Report Share Posted June 27, 2005 Update 3 trials now using 'hot start' on my Sherco4T..... SORTED..bike starts first kick every time, even in the hottest of trials (last week 33C), no problems whatsoever. 2 trials this weekend..again faultless starting. Such an easy solution, shame the factory didn't fit it, transformed my bike! RE500 Quote Link to comment Share on other sites More sharing options...
atomant Posted June 27, 2005 Report Share Posted June 27, 2005 RE500 Can you please expand a little further what you have done ? Do you have any photos or anything? Thanks Quote Link to comment Share on other sites More sharing options...
outlaw dave Posted June 28, 2005 Report Share Posted June 28, 2005 RE 500 - I am also curious to know exactly what you did ( As are probably all the other 4T owners) - Pleas give with more info. with pics if possible Outlaw Dave Canada Quote Link to comment Share on other sites More sharing options...
re500 Posted June 28, 2005 Author Report Share Posted June 28, 2005 No need for pictures as its a very simple mod. Remove the carb' float bowl and remove the choke jet. The thread on the end of the choke jet is M5x0.8mm which is standard metric coarse. Replace the choke jet with a M5 cap head screw of the right length, same as the jet. You must put a seal/o ring under the head of the screw to seal it. Note that the bolt head fits into a recess in the float bowl, you must use a cap head screw. Alternatively, if you have a spare jet that fits you can simply solder the jet hole to blank it off and use this. Reassemble carb'. Thats it. Now when you start the bike from warm/hot, simply put the 'choke' on, absolutley no throttle. One firm kick on compression and the engine will start. It will run very fast for a few seconds, enough time to close the 'choke' and will then run as normal. Now the downside ...you may need to find a different way to start the engine from cold ( there is no choke!). However, this is normally just once, compared to ~40 times or more when warm/hot. I just flood it by kicking a couple of times with the throttle open. The kick with closed throttle. Give it a try, i hope like mine it will transform the starting of your 4T bike. RE500. Quote Link to comment Share on other sites More sharing options...
atomant Posted June 28, 2005 Report Share Posted June 28, 2005 Do you have problems starting it when hot when the bike has been turned off normally? say, you just come to a section.. turned it off for a few minutes.. then go to restart it again and have problems then? Coz if you do, mine hasnt got that problem. It nearly always restarts first compression kick. What it doesnt do though is restart easy if i stall it in a section of lay it down on a bank in a section and the engine stops.. can take 5 mins to get it going again Will this help with curing that problem? Quote Link to comment Share on other sites More sharing options...
re500 Posted June 28, 2005 Author Report Share Posted June 28, 2005 Webmonkey I don't know if the mod will sort out your particular problem as i haven't come across that particular starting issue with mine...yet. If you think yor problem is likely caused by flooding/richness the mod may well help. My issue was that the starting was seemingly random....often, first/second kick, then for no apparent reason would take several kicks. Not acceptable to me, so tried the mod outlined above. RE500 Quote Link to comment Share on other sites More sharing options...
dixie Posted June 30, 2005 Report Share Posted June 30, 2005 RE 500 did your hot start mod by nessesity last nite . read flooding in sherco section BLOODY GOOD SHOW. so simple yet so good thanks one thing you dont need when you and the bike are hot is bad starting thanks again Quote Link to comment Share on other sites More sharing options...
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